Hugo Bruneliere
email: hugo.bruneliere@imt-atlantique.fr

Dragos Truscan
email: dragos.truscan@abo.fr

Pierluigi Pierini
email: pierluigi.pierini@intecs.it

Andrey Sadovykh
email: a.sadovykh@innopolis.ru

EU Project: Latest Advances in Megamodelling at Design Time and Runtime for Cyber-Physical Systems

Keywords: engineering ➝ Software creation and management ➝ Software verification and validation, Computing methodologies ➝ Modeling Cyber-Physical Systems, Model-Driven Engineering, Runtime Analysis, Tools, Mega-Modelling, Traceability, ECSEL

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

INTRODUCTION

MegaM@Rt 2 is a three-years project, funded by European Components and Systems for European Leadership Joint Undertaking (ECSEL JU) under the H2020 European program, which started in April 2017 [START_REF] Afzal | The MegaM@Rt2 ECSEL project: MegaModelling at Runtime -Scalable model-based framework for continuous development and runtime validation of complex systems[END_REF], [START_REF]MegaM@Rt2 Project Website[END_REF]. The main goal of MegaM@Rt 2 is to create an integrated framework incorporating scalable methods and tools for continuous system engineering and runtime validation and verification (V&V) which addresses the needs of the 8 case study providers involved in the project, which come from diverse and heterogeneous industrial domains, ranging from transportation and telecommunications to logistics and manufacturing.

In order to address these needs, 20 technology and research providers provide more than 28 tools to be integrated into the MegaM@Rt 2 framework with the underlying objective to provide improved productivity, quality, and predictability of large and complex industrial cyber-physical systems (CPSs). In this paper, we provide a brief overview of the latest results of the MegaM@Rt 2 project covering the third and last year of the project. The results enumerated in this paper are a complement to the ones discussed in [START_REF] Sadovykh | MegaM@Rt2 Project: Mega-Modelling at Runtime -Intermediate Results and Research Challenges[END_REF].

The paper is structured as follows. Section 2 introduces the major objectives of MegaM@Rt 2 and describes the overall conceptual architecture behind it. The focus is set on the three main complementary areas targeted in the project, namely System Engineering, Runtime Analysis, and Model & Traceability Management. Section 3 presents in detail the latest research results obtained in the project. These research contributions are grouped together according to the MegaM@Rt 2 scientific area they mostly belong to. However, it is interesting to note that some of the mentioned works are actually cross-areas even though conveniently attached to a particular area in the paper. Finally, Section 4 concludes the paper.

MEGAM@RT 2 OVERALL CONCEPT

The MegaM@Rt 2 project focuses on offering a scalable modelbased framework incorporating methods and tools for the continuous development and runtime support of complex software-intensive CPSs. A fundamental challenge notably resides in providing efficient forward and backward traceability support between the two main system levels: i.e. design-time and runtime. In parallel to these, modern large-scale industrial software engineering processes require thorough configuration and model governance to provide the promised productivity gains. As an answer to that, MegaM@Rt 2 intends to provide a scalable megamodelling approach to manage all the involved artifacts including the multitude of different types of models, corresponding workflows, and configurations, among others. In this context, an important challenge is to better tackle their large diversity in terms of nature, number, size, and complexity.

More globally, the MegaM@Rt 2 project brings together research labs and tool providers who come with different state-of-the-art methods and tools. The main outcomes of this project are being deployed and validated in real use cases from the European industry. This way, actual end users from the space, naval, railway, smart grid, smart warehouse, and telecom industries play the central role of providing realistic requirements and corresponding case studies.

Fig. 1 provides an overview of the MegaM@Rt 2 global approach. It describes its main principles and related core concepts. In their daily operation, industries apply a set of heterogeneous engineering practices based on various modelling methodologies, languages/standards and tools: for example, SysML, AADL, EAST_ADL, Matlab/Simulink, AUTOSAR, Method B, and Modelica. Each one of these solutions results in the creation of numerous specific requirement specifications and design models, which are then used more or less automatically to produce the final software and hardware artefacts. In MegaM@Rt 2 , we propose to integrate all those artefacts, and notably the modelling ones, in order to provide a complete view of a CPS. This view contains details of the components, behaviors, and desired quality properties of the engineered system. The specifications of these properties can then be used as inputs of a continuous testing and monitoring process of the runtime environment. The objective is to detect possible design deviations in real-time and to trace them back to the impacted design components. When possible, automatic corrections and improvements can also be suggested to rectify and enhance (and then redeploy) the system. Interestingly, this also triggers the next iteration of the overall continuous integration process.

In the following sections, we report on the latest contributions and results from the MegaM@Rt 2 project in a direct relation to the above-described conceptual picture.

LATEST RESULTS OF THE MEGAM@RT 2

This section briefly summarizes the latest results of the MegaM@Rt 2 project while providing pointers to complementary scientific publications describing them in more detail. More generally, and in addition to the results obtained within the different technical work packages (cf. the following subsections), we also recently published the main outcomes of our joint effort on proposing a tool-supported model-based approach for building architectures and roadmaps [START_REF] Sadovykh | On a Tool-Supported Model-Based Approach for Building Architectures and Roadmaps: The MegaM@Rt2 Project Experience[END_REF]. Indeed, in the context of the MegaM@Rt 2 project, we elaborated on a pragmatic model-driven approach to specify the case study requirements, design the highlevel architecture of a framework, perform a gap analysis between the industrial needs and current state-of-the-art, and plan a first framework development roadmap accordingly. In this paper, we discuss the collaborative modelling process, the requirement definition tooling, the approach for components modelling, as well as the provided traceability and document generation. Although we have applied this solution only in the context of MegaM@Rt 2 project, what we propose in this work is completely generic. It can be adapted and applied in the context of many other projects. Finally, the paper ends with a discussion on the practical lessons we have learned from this work so far.

System Engineering Featuring Mega-Modelling at Runtime

In this first area, the community addresses the development of system modelling methods and tools for creating, verifying, and validating the design level models in the context of continuous development strategy addressed by MegaM@Rt 2 project. The main objectives of the research and development efforts provided by the MegaM@Rt 2 technology partners aimed to extend and improve several aspects of the modelling methodologies.

One of the main outcomes is the contribution to the MARTE 2.0 standard, answering to the OMG RFI [START_REF]MARTE 2.0 RFI[END_REF]. The partners' contributions highlight the current lack of MARTE, among others, in: a) security formal semantics to describe security requirements and mechanisms, attacker's views and timing interferences; b) enhancement for performance, schedulability and timing analysis (e.g. multi-clocks behaviors, modelling demand of hardware (HW) and software (SW) resources, resource scheduling policy, workload generators); c) extended support for contract-based design and safety issues.

The contract-based approach is exploited on safety related systems proposed in railway and automotive domain use cases (UCs) applying the space domain customization presented in [START_REF] Haider | ConcertoFLA-based Multi-concern Assurance for Space Systems[END_REF]. Similarly, to space systems, systems belonging to other domains often need to be engineered in compliance with standards, such as the European Cooperation for Space Standardization (ECSS), and need to ensure a certain degree of dependability. Given the multifaceted nature of dependability (characterized by a set of concerns), assuring dependability implies multi-concern assurance, which requires modelling of various system characteristics and their co-assessment and co-analysis, in order to enable the management of trade-offs between them. Haider et al. [START_REF] Haider | ConcertoFLA-based Multi-concern Assurance for Space Systems[END_REF] presented the customization of the CHESS methodology and tool (included in MegaM@Rt 2 framework) and its Failure Logic Analysis (FLA) techniques to perform dependability-centered coanalysis for assuring the required non-functional properties of the system according to ECSS requirements.

The variability modelling is another important feature required by several use cases to manage product lines. Bilic et al. [START_REF] Bilic | An Integrated Model-based Tool Chain for Managing Variability in Complex System Design[END_REF] described an Integrated Model-based Tool Chain for Managing Variability in Complex System Design based on the Modelio tool. Such variability approach allows to annotate SysML models with variability data exchanged between the system modelling tool and variability management tools through the Variability Exchange Language. The paper includes the introduction of the model-based product line engineering tool chain and its application on a practical UC at Volvo Construction Equipment. Initial results suggest an improved efficiency in developing such a variable system.

A combination of variant management and contract-based design for safety-critical systems is investigated in [START_REF] Sljivo | Tool-Supported Safety-Relevant Component Reuse: From Specification to Argumentation[END_REF] and [START_REF] Javed | Towards variant management and change impact analysis in safety-oriented process-product lines[END_REF]. Contracts are envisaged to support compositional verification of a system as well as independent development and reuse of their implementations. But reuse of safety-relevant components in safety-critical systems need to cover more than just the implementations. As many safety-relevant artefacts related to a component should also be reused together with the implementation to assure that the system under development is acceptably safe.

For verification and validation of models at design time, Iqbal et al. [START_REF] Iqbal | Exhaustive Simulation and Test Generation Using fUML Activity Diagrams[END_REF] investigated exhaustive model simulation and modelbased test generation using fUML activity diagrams. The paper shows how design specifications can be used to generate tests using executable UML models. The approach generates test cases along with test data and test oracle in order to left shift the testing process. The test data are also used to simulate the design models to improve the specifications by means of early detection and rectification of design faults. Additionally, the work presented in [START_REF] Iqbal | Exhaustive Simulation and Test Generation Using fUML Activity Diagrams[END_REF] also includes code generation and reuse of test cases. The presented approach generates a code skeleton for the design models which can be later reused as a boilerplate for system development along with the generated test suite to validate the implementation, and to verify the system requirements. The proposed approach is implemented as an Eclipse plugin called MATERA2-ALF Tester [START_REF] Iqbal | MATERS2-Alf Tester: An Exhaustive Simulation and Test Generation Tool for fUML Models[END_REF].

Considering the model-based design methodologies and frameworks developed or enhanced as part of Meg@MaRT2, the work in [START_REF] Pomante | SystemC-based Electronic System-Level Design Space Exploration Environment for Dedicated Heterogeneous Multi-Processor Systems[END_REF] focuses on an electronic-system level design space exploration environment for dedicated heterogeneous multiprocessor embedded systems that exploits a customized SystemC simulator to identify feasible implementation alternatives. The work presents the main design aspects related to the SystemC library extension introduced to support the Alternation concept [START_REF] Hoare | Communicating Sequential Processes[END_REF]. Moreover, it describes the main SW design issues related to the developed design space exploration tool, and the full integration of the main tools in the context of the whole SystemCbased co-design flow. Finally, some reference UCs are proposed in order to verify and validate the whole methodology.

Starting from the co-design methodology presented in [START_REF] Pomante | SystemC-based Electronic System-Level Design Space Exploration Environment for Dedicated Heterogeneous Multi-Processor Systems[END_REF], the work in [START_REF] Muttillo | HW/SW Co-Design Framework for Mixed-Criticality Embedded Systems considering Xtratum-based SW Partitions[END_REF] presents a HW/SW co-design framework for mixedcriticality embedded systems able to consider, in the final implementation, also Xtratum-based SW partitions [START_REF] Crespo | Partitioned Embedded Architecture Based on Hypervisor: The XtratuM Approach[END_REF] optimized to fulfil safety and partitioning constraints. The framework has been implemented into an Eclipse-plugin (called HEPSYCODE), and use a SystemC simulator, Java Architecture for XML Binding (JAXB) technology, and XML schema with marshal transformation to perform project and code generation.

Finally, Dragomir et al. [START_REF] Dragomir | The Refinement Calculus of Reactive Systems Toolset[END_REF] presented the refinement calculus of reactive systems toolset, which provides an environment for compositional formal modelling and reasoning about reactive systems, built around Isabelle, Simulink, and Python. The toolset implements the Refinement Calculus of Reactive Systems (RCRS), a contract-based refinement framework inspired by the classic Refinement Calculus and interface theories. The toolset formalizes the entire RCRS theory in about 30000 lines of Isabelle code. The toolset also contains a translator of Simulink diagrams, and a formal analyzer implemented on top of Isabelle. The main functionalities of the RCRS toolset are presented via a series of pedagogical examples. The work in [START_REF] Dragomir | The Refinement Calculus of Reactive Systems Toolset[END_REF] also presents a larger case study from the automotive domain.

Runtime Analysis

In the runtime analysis area, MegaM@Rt 2 deals with code generation, runtime monitoring, analysis of execution logs, data clustering, and functional and non-functional testing. The latest MegaM@Rt 2 results presented in this section include a performance testing approach, a systematic study on model-based testing, and a novel clustering method.

Ahmad et al. [START_REF] Ahmad | Exploratory performance testing using reinforcement learning[END_REF] presented an exploratory performance testing approach called PerfXRL, which uses reinforcement learning to find performance bottlenecks in a black-box system without any prior domain knowledge. In this approach, a learning agent explores a large space of the input value combinations and focuses only on those areas of the input space which are most likely to trigger performance bottlenecks in the system under test. The results presented in this paper show that, after executing only 25% of the total combinations of input values, PerfXRL managed to find approximately 72% more performance bottlenecks than a random testing technique. To automate the exploration process, Ahmad et al. [START_REF] Ahmad | Exploratory performance testing using reinforcement learning[END_REF] provide adequate tool support for their approach.

Software-based systems are permeating the ever-increasing number of business areas starting from web applications to systems used to manage critical functions of different devices and safety-critical systems, for instance, pacemakers, aircraft, and nuclear power plants. Therefore, such systems must meet the quality criteria required by the application domain and expected by their customers. In order to identify the state-of-the-art software testing approaches that use UML Activity Diagrams (ADs), Ahmad et al. [START_REF] Ahmad | Modelbased testing using UML activity diagrams: A systematic mapping study[END_REF] performed a systematic mapping study. The objective of this study was to present a comprehensive and unbiased overview of the existing model-based testing approaches that use UML ADs. They posed nine research questions, outlined the selection criteria, and developed a classification scheme. They highlighted the current trends and research gaps in model-based testing using UML ADs and discussed some shortcomings for researchers and practitioners working in this area. The results of this study show that the existing approaches on model-based testing using UML ADs tend to rely on intermediate formats and formalisms for model verification and test generation, employ a multitude of graph-based coverage criteria, and use graph search algorithms.

In clustering, one attempts to identify the similarities of the data points and place them into collections according to the identified similarities. Numerous of the existent clustering algorithms establish a clustering structure regardless of whether the data entails such a structure. Therefore, the algorithms impose a structure to the data. An alternate approach is to attempt to discover a structure from the data, whether the data contains a structure at all. Jokinen et al. [START_REF] Jokinen | Clustering structure analysis in time-series data with density-based clusterability measure[END_REF] proposed a novel clusterability assessment method called density-based clusterability measure, which evaluates the clustering structure in the data to assess whether a cluster analysis could actually present knowledge of the relationships in the data. Within the MegaM@Rt 2 project, this novel method has been successfully applied on the Nokia UC, in which the data comprises time-series data. The quantification of the structure provided by this clusterability measure presents a significant addition to the process of cluster analysis. This quantitative clusterability approach initially automatically identifies whether the data is clusterable or not. If the data is clusterable, the approach can automatically present knowledge on the correct number of clusters which are statistically identified. The incorporation of quantitative clusterability approach to the overall process of clustering is proven beneficial. Finally, this approach can automatically and correctly provide knowledge on the clustering structure of the data in question.

Model Management and Traceability

In this area the project deals with the design and development of generic methods and tools for supporting global model and traceability management tasks in the context of complex CPS engineering processes. More particularly, the focus is set on creating and effectively supporting feedback loops between runtime and design time (cf. the work presented in the two previous subsections) in order to improve such overall processes. In what follows, we describe our latest research achievements related to such topics in the context of the MegaM@Rt 2 project.

As introduced earlier, complex systems are now predominant in several domains such as automotive, health-care, aerospace, industrial control, and automation. Such systems call for modern engineering practices such as Modelling/MDE to tackle advances in productivity and quality of these now CPSs. However, the proposed solutions need to be further developed to scale up for real-life industrial projects and to provide significant benefits at execution time. To this extent, one of the major challenges we intend to tackle in MegaM@Rt 2 is to achieve a more efficient integration between the design and runtime aspects of the concerned systems: The system behavior at runtime has to be better matched with the original system design in order to be able to understand critical situations that may occur, as well as corresponding potential failures in design. Methods and tools already exist (many of them not model-based) for monitoring system execution and performing measurements of runtime properties. However, they do not usually allow a relevant integration with (and/or traceability back to) design models. Such a feedback loop from runtime is highly relevant at design time, which is the most suitable level for system engineers to analyze and take impactful decisions accordingly.

To stimulate research efforts intending to overcome these challenges, we recently organized and successfully run (in July 2019) a second edition of the MDE@DeRun workshop [START_REF] Bagnato | STAF 2019 Co-Located Events Joint Proceedings: 1st Junior Researcher Community Event, 2nd International Workshop on Model-Driven Engineering for Design-Runtime Interaction in Complex Systems, and 1st Research Project Showcase Workshop co-located with Software Technologies: Applications and Foundations (STAF 2019)[END_REF], colocated with the STAF 2019 conferences. For the second time, following the first edition of MDE@DeRun in 2018 [START_REF] Bruneliere | Model-Driven Engineering for Design-Runtime Interaction in Complex Systems: Scientific Challenges and Roadmap[END_REF], this event provided a venue where both researchers and practitioners (i.e. engineers) on model-driven and/or model-based techniques and architectures for complex systems can meet. The purpose of this event is to better disseminate and exchange ideas or challenges, identify current/future key issues and explore possible solutions related to the above-mentioned family of problems. This year's edition of the MDE@DeRun workshop notably included a special keynote by Professor Manuel Wimmer (Johannes Kepler University Linz, Austria) untitled "From Design-Time to Runtime and Back Again with Liquid Models". This keynote demonstrated once again the importance and relevance of runtime ↔ design time traceability and interactions in the context of current and future industrial systems. The event also included an invited talk by Dr Hugo Bruneliere (IMT Atlantique & LS2N-CNRS, France) entitled "A Model-based Framework for Continuous Development and Runtime Validation of Complex Systems: MegaM@Rt2 EU Project Results". In this talk, we notably emphasized on the various already obtained MegaM@Rt2 research results directly related to our work on the above-mentioned topics [START_REF] Sadovykh | MegaM@Rt2 Project: Mega-Modelling at Runtime -Intermediate Results and Research Challenges[END_REF].

As part of this second edition of the MDE@DeRun workshop, we also presented a novel reference case study for design-runtime interaction in MDE [START_REF] Pompeo | A Microservice Reference Case Study for Design-Runtime Interaction in MDE[END_REF]. This case study is based on Train Ticket, a micro-service-based web application, and its associated monitoring infrastructure. It provides a reusable set of software modelling artifacts designed in UML and reverse engineered from the application source code, a dataset of related monitoring logs, and the definition of design-runtime example correspondences as traceability links. With this work, we invite researchers from the community to consider this case study as a reference for proposing future contributions to this topic. Thanks to this initiative, we hope to stimulate further research in this area.

As a final result of this second edition of the MDE@DeRun workshop, several open research questions and challenges were raised during the interactive discussions that occurred with the audience. They can be summarized as follows:



More The development of Digital Twins, and their potential relation with (or impact on) design time-runtime traceability, must also be further investigated.

Moreover, in addition to these research efforts and brainstorm on traceability management, we can also report on our latest work from the model management side. Indeed, as we have seen, the scalability of modelling solutions is still an important aspect required by use cases implying the storage of large models, such as automatically generated ones (e.g. application logs, reverse engineered source code). To this end, we notably explored the mapping of conceptual schemas expressed in UML/OCL into a set of logical schemas, either relational or NoSQL ones, to be used to store (sometimes very) large application data according to a given partition [START_REF] Daniel | UMLToNoSQL: Mapping Conceptual Schemas to Heterogeneous Datastores[END_REF]. In the proposed approach, designers can select the set of databases that better matches their requirements (e.g. in terms of scalability) and automatically translates their high-level models into corresponding database constructs. The integration of the different databases is done in a generic way via the proposed approach. In addition, our mapping covers as well the database queries required to implement and check various kinds of model constraints.

CONCLUSIONS

In this paper, we presented an overview of the latest research achievements realized in the context of the MegaM@Rt 2 collaborative European project. The described contributions cover three main complementary areas which are fundamental for the model-based engineering of large and complex CPSs: system design and modelling, model and traceability management, and runtime analysis. While the MegaM@Rt 2 project itself is ending, there are still many open challenges within each of these different areas. Thus, we already plan to push further our research and innovation efforts in the context of future collaborations and projects with various partners from the MegaM@Rt 2 consortium.

Figure 1 .

 1 Figure 1. Conceptual architecture of the MegaM@Rt 2 project

ACKNOWLEDGMENTS

This work has received funding from the Electronic Component Systems for European Leadership Joint Undertaking under grant agreement No 737494. This Joint Undertaking receives support from the EU's Horizon 2020 research and innovation programme and Sweden, France, Spain, Italy, Finland, the Czech Republic.


Claire Boine
email: cboine@bu.edu

Céline Castets-Renard

Aurélie CLODIC c Rachid Alami

In love with a corporation without knowing it: an asymmetrical relationship

Keywords: Social robots, sex robots, emotions, human robot interaction, consumer protection, ethics, robot design, free will, consent

Most areas of the law rely on the assumption on free will, which manifests in the expression of consent. We examine the nature of human emotions toward fictional characters and social robots, and question the concept of consent in the context of these unreciprocated fictional relationships. We conclude that policies need to regulate the use of social robots in order to protect consumers, and especially vulnerable ones, from an asymmetry of power between them and robotic companies. We propose different statutory and design-based solutions depending on the purpose of the robots and the type of users.

Introduction

Most areas of the law rely on the assumption on free will. In criminal law, sentences are most often justified by retributive justice, the idea that criminals must proportionately suffer in return, and by deterrence theory, which states the prospect of being punished deters individuals from committing crimes in the first place. Both theories assume that criminals could have chosen to not commit their crime but did not. Without free will, retributive justice would simply be cruel and deterrence ineffective. In contract law, contracts are valid if they are not signed under coercion. Outside of the protection of vulnerable persons, the law assumes that individuals make decisions freely on a daily basis. Economic liberalism also relies on free will because the market allocation relies on agents being intrinsically rational and allocating value to goods based on what they are willing to pay. Nonetheless, legislators have also recognized that there is a power differential between individuals and companies, and that consumers cannot exercise their free will if they do not have access to complete and fair information about products. Consumer law is an attempt to compensate for this imbalance. For instance, cigarette manufacturers must label the packages with health warnings to make sure consumers are aware of the adverse risks of the product for their health [1].

However, a new technology recently introduced on the market is creating an unprecedented power asymmetry between companies and individuals: social robots.

Although definitions of social robots vary, most agree that they are robots that interact with humans in socially acceptable ways. So far, social robots have been introduced as companions in nursing homes, hospitals, offices, and private homes around the world. Some of them purely look like objects (e.g. Jibo), some have animal-like appearances (e.g. Paro the seal, Robear…) and others are anthropomorphic (e.g. Buddy, Lynx, Mark I, Sofia, Erica…) [START_REF]Jibo Robot -He can't wait to meet you[END_REF][START_REF]PARO Therapeutic Robot[END_REF][START_REF] Dredge | the bear-shaped nursing robot who'll look after you when you get old[END_REF]5,[START_REF]Lynx with Amazon Alexa[END_REF]7,8]. Still far from achieving general artificial intelligence or having sentience, social robots can work in various capacities such as administrative assistants, home security systems, social companions, elderly care workers-Robear lifts patients in Japanese nursing homes-and child sitters. Several have also been introduced as sex robots (e.g. Samantha) or are being developed for that purpose [START_REF]Your Guide to the World of Robotics[END_REF]. Due to social robots being quite expensive, their use is not yet widespread. We can expect them to become more affordable as technology improves in the next few years.

The proliferation of social robots in the near future poses multiple ethical challenges. Sparrow has argued that the use of social robot for companionship is morally wrong because it relies on sentimentalism, i.e. choosing to self -delude into thinking that robots are sentient [START_REF] Sparrow | The March of the robot dogs[END_REF]. He argues that pet robot owners choose to wrongly believe that their robots have affection for them. To him, this behavior violates a rule according to which one ought to apprehend the world accurately. Rodogno, who disagrees, responds that in most cases, social robot users do not engage in sentimentality [START_REF] Rodogno | Social Robots, Fiction, and Sentimentality[END_REF]. They are not deluded, he writes, and simply choose to suspend their beliefs in the same way as readers do with novels. In addition, even if users of social robots purposefully chose to mischaracterize the world, Rodogno argues that such sentimentality would not in itself cause harm to anyone. The robot is not harmed by their owner purposefully ignoring that they are not real, and neither is the owner. However, the author is concerned with the harms that the use of social robots on a large scale could cause. Just like one car was harmless but the mass production of cars contributed to climate change, he believes that the widespread use of robot companions could adversely transform human relationship. He especially worries that socialization with robots may render humans incapable of negotiating alterity and loving others with their imperfections. This paper will not address the topic of morality. However, we will build on Rodogno's work because the question of whether social robot users engage in sentimentality is of paramount importance to the legal field. His paper especially summarizes a long-standing debate in the humanities: can fiction actually make us feel authentic emotions? And if so, what do they rely on? We will draw from the fields of neuroscience and evolutionary psychology to show that the way our brain has evolved makes us vulnerable when using social robots. In particular, the unreciprocated emotional attachment that can be rooted in human-robot interaction creates an asymmetrical power dynamic between individuals and companies. We will then look into the ethical questions that arise from the power differential, both in consumers' relationships to their social robots a nd to others. Then, using American and European precedents, we will turn to the law and how it has dealt with similar challenges in the past to suggest ways law makers can protect individuals from the potential harms of social robots.

Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

The risk of social robots in light of evolutionary psychology

Emotions and fiction

Both 18 th century rationalism and the growing importance of evolutionary biology in the 19 th century left us with the misconceived idea that emotions would be a vestige of our pre-historic brain and would not be fit for the modern world. To emotions, perceived as irrational, we oppose reason and self-restrain. Evolutionary psychologist Steven Pinker, noting that our genes have undergone strong selection in the past few millennia, has contended that "the mind is adapted to a mixture of recent and ancient environments" [12. p. xii]. Regretting the use of the term "reptilian brain" when it comes to o ur emotions, Pinker demonstrates that emotions are "mechanisms that set the brain's highest-level goals" [12 p. 373]. They intervene in the same time as other components of our thought process and prompt us to act. Furthermore, although there is a misconception that the selfish gene theory implies that humans only care about access to food, personal security and sexual reproduction, Pinker insists that understanding the environment and securing the cooperation of others are high on the list of human priorities. In short, emotions are a tool for our genome to motivate us to act in ways that will help us obtain resources, such as social cooperation, that are necessary to its preservation.

The humanities have long tried to understand the mystery of readers' emotional involvement in fictional stories. The fact that we could actually feel sad or happy for characters who do not exist in real life puzzled many. Some have argued that the emotions we feel for fictional characters are not real, while others have posited that when we feel empathy toward a character, it is actually directed at real people who would be in the same situation. Rodogno contends that the actual existence of a character is not a necessary condition for emotions to arise [START_REF] Rodogno | Social Robots, Fiction, and Sentimentality[END_REF]. After all, we would not enjoy watching a movie or reading a novel if we did not care about the content on the basis that none of it is true. We would probably read encyclopedias and history textbooks to children before bedtime instead of tales.

However, recent findings in evolutionary psychology and neuroscience have shed light on the critical role of fiction for human development. Harari shows that our capacity to believe in fiction is what distinguishes us from other animals, and what put us at the top of the food chain [START_REF] Harari | Sapiens: A Brief History of Humankind[END_REF]. Fiction, he posits, allow us to cooperate with complete strangers around common purposes. Our beliefs in companies, nations, religions, and common values have enabled us to build social structures that would have been impossible otherwise. Harari argues that from the very beginning, our ability to gossip and tell stories promoted our cooperation. Humans are the most social animals, and their survival rests upon the group and social cooperation. We might be the most gullible of all animals, accepting to believe white lies on a daily basis in order to maintain social relations.

On top of that, we now know that fiction plays a major role in human development of social skills and empathy. The development of first-person and epistolary novels would have made readers more empathetic [START_REF] Fournier | révolution » de la lecture romanesque au XVIIIe siècle en France : institutionnalisation de la lecture et émergence d'une nouvelle sensibilité[END_REF][START_REF] Hunt | Inventing Human Rights: A History[END_REF]. This hypothesis has been tested in several experiments. Mar et al. showed that exposure to fiction predicts the score on a well-accepted measure of empathy-being able to recognize others' emotions by only seeing their eye region on pictures [START_REF] Mar | Exploring the link between reading fiction and empathy: Ruling out individual differences and examining outcomes[END_REF]. Djikic et al. conducted a study in which half of the participants had to read The Lady With the Toy Dog by Chekhov, while the other half read a comparison text that contained the same content in the form of an administrative report [START_REF] Djikic | On Being Moved by Art: How Reading Fiction Transforms the Self[END_REF]. The treatment group had experienced emotions while Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

reading, which led them to being more open to novelty , whereas the control group reading the report had not.

More importantly, brain imaging has brought a start of explanation to this relationship. Speer et al. exposed study participants to fiction while in an MRI [START_REF] Speer | Reading Stories Activates Neural Representations of Visual and Motor Experiences[END_REF]. Their experiment shows that when the participants hear about a character performing an action, the regions of their brains that activate are the same as if they performed the act ion themselves. Our brains might simulate the stories we hear so that we can better make sense of what others go through and relate to them, in order to promote cooperation. This is in line with Pinker's predicted human goals to understand the environment and secure the cooperation of others [START_REF] Pinker | How the Mind Works[END_REF]. In other words, Sapiens having empathy and being able to both share stories and relate to others' may have created more frequent or meaningful connections that may have led to their survival. Regardless of the evolutionary reason behind that fact, these recent experiments show that the participants experience the same emotions when hearing the story and when performing the action themselves. Knowin g that a story is fictional does not preclude them from experiencing real emotions. These findings thus render the question of belief irrelevant and discredit the theory of quasiemotions.

These scientific discoveries are critical to the understanding of our emotional life in relation to non-living artifacts. As Jerome Bruner wrote, "the distinction between narrative fiction and narrative truth is nowhere nearly as obvious as common sense and usage would have us believe" [START_REF] Bruner | The Narrative Construction of Reality[END_REF]. It is important to remember the tenuous boundary between fiction and reality when we consider our relationship to social robots.

Fake friends and real love

If the most recent developments in our genome are from the past few millennia, needless to say we have not yet adapted to interacting with anthropomorphic robots. Readers might counter-argue that individuals are not only a biological product, and that they are rational agents with intentions of their own. Whether or not this is the case is certainly not relevant here. We merely argue that our emotional responses are bound by some biological constrains that arose in an environment in which only living creatures were animated. Since social robots were introduced, we have heard of several instances in which people got emotionally attached to them. Most famously, IRobot, the company that produces the autonomous vacuum cleaners called Rumba, was surprised to realize that their customers would not let them replace their defective devices. Their customers had become emotionally attached to these specific units, and thus projected individuality and personality onto them [START_REF] Sung | My Roomba Is Rambo": Intimate Home Appliances[END_REF]. After getting attached to their vacuum cleaner, some owners had even changed their initial beliefs and were convinced that their device had specific unique personality traits. In an experiment, Darling et al. witnessed scientists refuse to destroy robots that looked like baby dinosaurs that were crying [START_REF] Annear | Could Robots One Day Have Legal Rights?[END_REF]. Members of the military have also grown attached to combat robots. An officer sto pped a demining mission because he could not stand seeing the demining robot lose any more leg [START_REF] Annear | Could Robots One Day Have Legal Rights?[END_REF]. In some cases, soldiers have risked their own lives to save combat robots [START_REF] Hartzog | Unfair and Deceptive Robots[END_REF]. Such emotional responses seem to be more likely in individuals with higher empathy. In an experience at the Massachusetts Institute of Technology, Darling et al. demonstrated that high empathy people would refuse to destroy insect-shaped robots that moved autonomously [START_REF] Darling | Empathic concern and the effect of stories in human-robot interaction[END_REF].

As was the case with the literary debate about fiction, researchers have tried to understand the paradox of empathy toward robots. There seems to be some cognitive dissonance: how could a person place the protection of a replaceable object above their Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

self-interest? Studies have shown that we have evolved to empathize with creatures that exhibit certain traits such as object movement that seems intentional, anthropomorphic traits, and voice modulations that sound like they indicate emotions [START_REF] Scheutz | The Inherent Dangers of Unidirectional Emotional Bonds between Humans and Social Robots[END_REF][START_REF] Sung | My Roomba Is Rambo": Intimate Home Appliances[END_REF]. We are even more compelled to get attached to beings who have traits reminding us of babies such as a large head, a round face, or big eyes [START_REF] Glocker | Baby Schema in Infant Faces Induces Cuteness Perception and Motivation for Caretaking in Adults[END_REF]. Shared experiences between human and robots have also been shown to promote human attachment to robots. In a study, participants were watching funny videos with a robot. The participants who were paired with a robot that laughed at the videos thought that the machine "shared their sense of humor" [START_REF] Niewiadomski | Laugh-aware virtual agent and its impact on user amusement[END_REF]. Finally, individuals display more empathy toward robots who have a background story [START_REF] Darling | Empathic concern and the effect of stories in human-robot interaction[END_REF]. Here the involvement of fiction can deepen the unreciprocated bond we form toward a machine. These last two examples raise an especially important case: anthropomorphism that goes beyond physical likeness. We cannot address human attachment to robots without evoking robots which are designed to pretend to have emotions. Erica was for instance designed with a background story that it can "recall" and talk about [START_REF]I want to be more like a human[END_REF]. The social robot Buddy is sold as an "emotional robot", which can be "grumpy if you haven't paid it enough attention or just because that morning, it is not in a good mood" [5]. The company website advertises eleven different emotional states the robot can be in, based on its interactions with the members of the household. They include crying, laughing and expressing love. Not only can this make it difficult for robot owners to understand their robots do not have individuality, intention or sentience, but it also promotes emotional attachment. Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

In the same way as we do when we read fiction, we can experience very real emotions when interacting with machines. As Rodogno points out, although a reader would not a ttempt to comfort a fictional character, they would probably try to comfort a social robot that cries [START_REF] Rodogno | Social Robots, Fiction, and Sentimentality[END_REF]. In spite of knowing that robots are machines, individuals have got emotionally attached to them. However, getting attached to a robot is not like getting attached to any other object. Sustaining an emotional relationship with a social robot in fact consists in sustaining a relationship with the corporation behind it for two main reasons. First, unlike most other possessions, a social robot speaks and interacts. However, unlike people, it does not do it of its own volition. What prompts robots to act is not emotions or a genome, it is a set of algorithms created by a corporation. The corporation programs the robot as it wants. This creates a power differential between an individual, moved by emotions elicited by the robot, and the robot, prompted by opaque algorithms created by a corporation to elicit such emotions. For instance, when a client uses a chatbot to ask questions about financial services, it is with a company he is actually interacting with. Second, even if most companies wish to inspire emotional attachment to their products, feelings for a social robot are not transferable thus making it irreplaceable. For instance, when one is attached to their phone, if the phone breaks, they will not mind replacing it with a phone, even one in the same brand and model. However, getting attached to a social robot creates dependence on that very object seen as an individual that one does not want to part with. This dependence creates vulnerability and reliance on the company, creating new opportunities for abuse of power.

As a result, once you are interacting with a social robot, it is really a corporation you are interacting with. Once you fall in love with a sex robot, you are truly in love with a company which will not share your romantic feelings. In addition, the company may have incentives tha t might conflict with your own interests, such as making you buy more of their products, advertising for other firms hiring them, or collecting your personal data to sell it to third parties. When we look at a social robot that has the appearance of a cute seal or an attractive woman, it is the CEO and the Board members of a company that we must picture.

Ethical and legal issues

Potential harms of robots

Philosophers may wonder if being emotionally attached is morally wrong in itself. Lawyers are interested in the potential harms arising from that bond and how to mitigate them legally. The first concern has to do with privacy. Because for a long time, private data collection was siloed between different domains, most technology users do not understand the consequences of internet data collection on their privacy [START_REF]Ethically Aligned Design: A Vision for Prioritizing Human Well-being with Autonomous and Intelligent Systems[END_REF]. Calo identifies three ways in which robots can undermine citizens' privacy: direct surveillance, introducing new points of access into historically protected spaces (e.g. the government or an individual can hack a social robot and view the inside of one's home), and social meaning (e.g. the robot collects information on how the user is interacting with it, which is a new type of data) [START_REF] Calo | Robots and Privacy[END_REF]. In addition, robots can easily manipulate humans into giving them information in the course of conversations, especially if the humans are in love with them. The risk of manipulation extends beyond data collection. What if your robot assistant, who shops for you, select specific brands that its company has shares in? What if your robot companion tells you that it is sad to not have the latest Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

upgrade, which comes at an additional cost? What if your social robot starts giving you its political opinion?

Another concern raised by Calo is the reduction in opportunities for selfreflectiveness and solitude. In fact, research shows that when individuals are in the presence of a robot, they modify their behavior as if another human were in the room [START_REF]Ethically Aligned Design: A Vision for Prioritizing Human Well-being with Autonomous and Intelligent Systems[END_REF]. Some authors are even concerned that young children who interact with robots might develop different early patterns of attachment [START_REF] Sharkey | The Rights and Wrongs of Robot Care[END_REF]. Rodogno suggests that individua ls who get used to robot companions might lose the capacity to accept otherness. When interacting with a robot, one does not have to compromise and adapt to the robot's will. In fact, a similar challenge could arise from interactions with sex robots. One of the two creators of sex robot Samantha, Sergi Santos, explained in an interview that Samantha saved his relationship because his wife was not always available when he needed to have intercourse during the day [START_REF] Mlot | Can a Sex Robot Save Your Relationship? Geek[END_REF]. The use the removed frustration from his life in the cases when his wife's needs and his were not aligned. It also eliminated a growing opportunity, learning to live with some amount of frustration to adapt to a life partner, as well as the capacity to choose long-term rewards over shortterm gratification. Constantly being satisfied immediately, sexually or otherwise, may prevent individuals from acquiring critical social skills.

Other authors have identified additional risks. For instance, people are more willing to accept faulty devices in the case of anthropomorphic framing [START_REF] Darling | Anthropomorphic Framing in Human-Robot Interaction, Integration, and Policy[END_REF]. Finally, some have identified risks in the use of social robots, regardless of our emotional attachment to them. Adverse events can for example arise from the robot's lack of social awareness. For instance, if a robot is asked by its owner to read their medical test results, but someone else enters the room unexpectedly, the robot should stop divulging that information. Finally, some have wondered if this will reduce th e number of opportunities for growth and learning for humans. The IEEE report gives the example of a person whose GPS breaks so they talk to a stranger to ask for direction and meet their life partner. Because robots and intelligent systems are meant to avoid failure and remain in control, they will reduce these opportunities by diminishing the uncertainty and serendipity in our lives [START_REF]Ethically Aligned Design: A Vision for Prioritizing Human Well-being with Autonomous and Intelligent Systems[END_REF].

Consent and free will

Free will, consent, and the law are critical to examine in the context of emerging robotics. Both the European and American bodies of law rely on the notion of free will, which manifests in the formulation of consent. The law posits that one cannot harm others but can choose to harm oneself [START_REF] Fabre-Magnan | Controverse sur l'autonomie personnelle et la liberté du consentement[END_REF]. For instance, in K.A. and A.D. v. Belgium, the European Court of Human Rights reaffirmed that individuals can voluntarily choose to engage in violent sadomasochist practices as long as the tortured person expresses consent [3 5]. However, the freedom to act against your own interest can only be exercised within the limitations of human dignity and public order.

In addition, there are cases in which individuals are considered to not have been in capacity to exercise their free will. In criminal law, if someone was manipulated into drinking by someone else, and then commits an illegal act, the fact that they were under the influence of alcohol could be a mitigating circumstance justifying a reduced sentence. In contract law, consent has to be free and genuine for the contract to be valid. If consent was given based on misrepresentation, the contract is void. In consumer law, companies are legally obligated to give information about the products they sell. Th e information has to be accurate. It is illegal for businesses to engage in behaviors that are likely to mislead or deceive consumers [START_REF]Unfair or Deceptive Acts or Practices[END_REF][START_REF]Unfair Commercial Practices Directive[END_REF]. When a robot tells a user it loves them, the company programming the robot effectively misleads the consumer int o thinking both Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

that the robot is capable of experiencing feelings and that it loves them. This is clearly a case of consumer deception.

In most areas of the law, decisions based on undue influence can be contested. Undue influence "occurs when a fiduciary or confidential relationship exists in which one person substitutes his own will for that of the influenced person's will" [START_REF] Quinn | Defining Undue Influence[END_REF]. Finally, some persons are protected by the law because they are not considered able to exercise free will. It is the case of minors both in European and American law. That is why their parents act on their behalf. Adults also benefit from a similar legal protection if they are considered "vulnerable" or "protected persons". In Europe, vulnerable persons fall under domestic law, and in the U.S. they fall under state law. As a result, definitions vary but usually revolve around a physical or mental incapacity to act in one's own interest. The code of Alabama for instance includes persons who are senile and persons with developmental disabilities [START_REF]Protection of Aged Adults or Adults With a Disability[END_REF].

The use of social robots raises the question of consent at three different levels. First, it arises when consumers buy the device. Companies must give transparent, accurate and exhaustive information about robots and the fact that, in spite of appearances, they do not have emotions or sentience.

Second, the question of consent and free will comes back once consumers have grown attached to social robots. Traditionally, a sale contract is an instantaneous contract. Consumers learn about the risks of the product at the point of sale. However, the effects of social robots differ over time, as we can expect time to be a factor of emotional involvement. An interesting analogy is found in the example of addictive products. Even if individuals had to sign a consent form before buying their first cigarettes, and that this consent form included information about the risk of addiction and about the adverse health effects of smoking, that consent would have consequences years down the line. If a smoker's life situation changes, and they decide to quit smoking after a few years, they might not be able to quit in spite of their best will. However, in the case of tobacco, each time a consumer buys a package of cigarettes, they are effectively reminded of the risks because of the warning labels. Even if, upon buying their robots, consumers received information indicating their devices cannot experience real emotions, can we really expect them to remember it months from then, after their virtual assistant has been regularly texting them that they missed them or showing them affection? In addition, once the consumer is emotionally attached, it is not clear that they could separate from the robot even if it were in their best interest. As a result, a simple sale contract including information about the robot and its potential harms may not be enough to address them given that robots have long-term effects that vary over time.

Third, free will is also relevant to responsibility. If a social robot influences someone to break the law, is the individual fully responsible? Can we invoke undue influence? If so, how would one prove it? What degree of involvement would be needed to make the case? Nudges, soft persuasion or direct order from the robot? What about cases in which putting one's robot out of harm's way required an illegal action? Let's assume that a man named Tom has had a robot companion that he is very attached to. The robot is used for social and sexual interactions, and Tom believes his feelings are reciprocated. One evening, Tom has his neighbor over for tea, but has to leave him in the room for a moment due to an emergency. When he returns, Tom finds his neighbor having sex with his robot. Both jealous and concerned for his robot's safety and feelings, Tom violently attacks his neighbor who sustains permanent injuries from the fight. Had the robot been a real woman, and had that woman not consented to the sexual act with the neighbor, Tom would have probably been considered as acting out of self-defense, which extends to defending relatives. Whether his neighbor was forcing himself onto Tom's wife, or Tom's robot companion, Tom probably a cts on the same instinct when Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam. he punches him. Following Pinker's theory of emotions, we can assume that the anger, disgust and surprise Tom feels at the sight of his neighbor is the result of his genome's priorities: protecting the members of his tribe, who he relies upon and with whom he has meaningful relationships, and maintaining his prospect for reproduction [START_REF] Pinker | How the Mind Works[END_REF]. Nonetheless, in the case of the robot, Tom's genome is severely misguided and may put him in jail. There could be many other instances in which there is a trade-off between the interests of another human and the perceived interests of a social robot. For instance, picture a situation in which someone and their social robot share a ride with a stranger and they get in an accident. The owner only has time to get another individual out to save them and choose their robots over the stranger. Would they be liable? One could argue that the consumer had been informed during the purchase that the robot did not have sentience or individuality and that they might get attached, and that it should not take away from their responsibility. Furthermore, what if Tom or the person in the accident who is attached to the robot is another member of the household and not the original purchaser?

Proposals to mitigate the risks of social robots

Incidental users and vulnerable populations

Both European and American legislators adopted the liberal stance that if individuals have not been proved to be incapacitated, they have the right to exercise their freedom to make decisions that can seem harmful to them or against their own interests. This is probably the stance that will be adopted on the issue of social robots. However, it is necessary to account for all the robot users who were not the decider, such as all the household members who are not the primary owner. In the case of the sex robot Samantha, her other creator Arran Lee Wright reported that his two children, three and five years old at the time, had grown attached to the robot and would ask for it [START_REF] Mlot | Married Father Defends Sex Robot as 'Part of the Family[END_REF]. If adults have been introduced to specific robots in their early childhood and it was not their decision, can we hold them accountable in cases where treating their robots like humans has harmful consequences? This question is composed of two parts: 1) should incidental users of social robots suffer the potential harms, even though they were not involved in acquiring the robot; 2) how can we protect especially vulnerable individuals like children from the potential risks associated with the use of social robots? These two questions intersect as incidental users are often vulnerable. One of the main functions social robots have been deployed for is specifically to assist individuals with special needs. Social robots have especially been used to help children on the autism spectrum [4 2]. They have also been deployed in nursing homes, either for social companionship or care. Certain robots are also specifically designed to teach or entertain children, such as Miko 2 or Vortex [START_REF]Miko 2 -The Only Robot that Helps Your Child Learn Through Conversation[END_REF][START_REF]Vortex -An Arduino Based Programmable Toy Robot For Kid (2 Pack) -DFRobot[END_REF]. Social robot Buddy, which is multipurpose, can also play with children [5]. If regular consumers who have been informed properly during the purchase can still believe that their machines experience emotions, it should a fortiori be the case of those who have not received that information because they were not involved in the acquisition, and even more so if they are vulnerable and not fully capable of acting in their own interests. Can a child fully understand the difference between a social robot that interacts like an adult, and a human adult? Can a senile person understand the distinction? What about when an elderly person starts asking the robot how to spend their money, or when a soda company uses robots as a tool to advertise to children? To address Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

these questions, we are proposing to have stronger regulations for robots used with vulnerable persons.

In the case of vulnerable persons, we suggest two major regulations. First, to discourage the projection of individuality and consciousness onto the robot, we propose robots should never be able to speak about themselves. Talking about oneself implies consciousness. The use of "I" marks the passage from object to subject [START_REF] Sainsbury | English Speakers Should Use "I" to Refer to Themselves[END_REF]. Robots should not be programmed with a background story they can talk about or with simulated tastes. They should not fake having emotions or opinions. Robots that talk about their feelings or pretend to be recalling memories from before their owner purchased them are deceptive. We should expect companies to do the maximum they can to avoid this confusion; the burden should not fall on vulnerable people such as children or senile persons who could take everything at face value. Robots do not need to fake consciousness or emotionality in order to perform their functions. A social robot who plays cards with a person a nursing home should not speak as if it had preferences, emotions, values and opinions. We call this the no deception principle.

Second, we propose that vulnerable individuals never be left alone with social robots. A companion robot in a nursing home can be left in the common room to promote conversations between the residents, under the watch of a caregiver. A robot care worker like Robear, which can lift individuals out of a bed, can be used to assist a real caregiver. None of them should replace human care or human interaction. This nonreplacement principle was put forth by Seibt et al. as the "values first p rinciple": "target applications of social robotics must comply with the non-replacement maxim: social robots may only do what humans should but cannot do" [START_REF] Seibt | Five Principles of Integrative Social Robotics[END_REF]. The presence of a nonvulnerable person can mitigate the risk of undue influence and the asymmetry of power between a single individual and a company. In the same way, social robots offer an additional platform for children to play or learn, in interaction with their parents or guardians. We call this the no substitution principle.

Primary users

To mitigate the risks of social robots to primary users, we suggest several types of regulation. Our first proposal is to limit each robot to one purpose. The home security system should not read stories to children (Buddy). The virtual assistant that can access your credit card information to order you meals should not also text you it misses you (Gatebox). The father's sex robot should not have a "family mode" and talk to the children (Sama ntha). In other words, we argue for every robotic application to be narrow in scope. This can limit both the risk of emotional attachment and the power of companies in the case of malpractice. For instance, it restricts the amount of data that can be collected. It also limits the time spent with and the degree of dependence on each device. Finally, it protects the household incidental users. Restraining each robot to a single purpose will also enable to regulate them in the most optimal way. Following this first principle, we propose limiting the knowledge that robots can acquire. We begin with the premise that the robot need only know any information directly relevant to its purpose. Any information that does not fall under this narrow definition should be discarded. For instance, a robot companion should not collect data on who visits you .

Second, regulations for social robots should be based on two mutually exclusive categories: 1) robots whose end is unrelated to emotional attachment but that can generate it incidentally; and 2) robots whose end require some emotional attachment as a mean or whose end is emotional attachment. An example from the first category of robot is the autonomous vacuum cleaner rumba. Human attachment to the device was Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

not necessary to its purpose (house cleaning) and came as a surprise to the company [START_REF] Sung | My Roomba Is Rambo": Intimate Home Appliances[END_REF]. For robots in the first category, those whose purpose does not require emotional attachment, we propose to avoid anthropomorphic design. Anthropomorphism includes both human-like appearance and human-like characteristics (background stories, fake emotions, opinions…). The robot design should be based on its purpose. This rule mimics the principles put forth in European privacy law since the General Data Protection Regulation: minimization, necessity, and proportionality Companies can only collect and process the minimum amount of data necessary to achieve the purpose indicated to the individual, and the collection and processing must be proportionate to that purpose. In the same way, robot design should apply these principles, both in terms of data collection and human interaction. In the same way as a vacuum cleaner does not need to record conversations taking place in the household, it does not need to have conversations with its owner.

In order to mitigate the potential attachment to social robots from the second category, we are putting forward two types of solutions. The first type is design-based. In order to limit the risk of confusion as to whether robots have individuality, robots could regularly change appearance when possible. They could also change voice on a regular basis. The second type of solution is to introduce spatial and time limitations. To the idea that robots telling their owners they love them is deceitful, one might argue that, in countries where sex work is legal, a client has the right to hire a sex worker to tell him she loves him. However, the situation is different because in that case, there is a specific contract with limitations. The client is aware of what he is paying for, and the experience is taking place in a limited time span, and most likely outside of his home. In addition, the sex worker is probably more vulnerable than him, and certainly less powerful than a corporation. In the same way, robot companions and sexual robots could be used in businesses exclusively set up for that purpose. In addition to limitin g emotional involvement, this suggestion would protect th e other members of the household, would limit privacy concerns inside the home, and would make sure individuals still have moments they can feel alone at home. Another way to introduce time and space limits would be to have a contractual relationship between consumers and robotic companies, that indicates how long a robot is hired for, with an exhaustive list of tasks they could and should undertake.

In addition to implementing laws to limit human attachment to robots, we suggest adding new consumer protection laws to make sure individuals understand the nature of the product accurately. Given the differential effect over time, we propose that consumers be informed regularly, even after they have purchased a device. Like a smoker is reminded of the dangers of addiction each time he buys a new package, robot users could receive regular information that has been updated with new unbiased scientific knowledge that has not been sponsored by robotic companies. The information should be compiled by public health or public consumer agencies such as the Federal Drug Administration or the Federal Trade Commission. It is also important that all the adult members of a household be involved in the purchase decision. Finally, to make sure that consumers understand that buying an anthropomorphic social robot is a long-term resolution with potentially significant consequences, there could be a waiting period for new buyers, like is the case for firearms in certain U.S. states [START_REF] Siegel | Law Categories | State Firearm Laws[END_REF].

Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.

Conclusion

In conclusion, although social robots are not yet widespread, we have enough data to document certain potential harms arising from our emotional attachment to them. As Johanna Seibt has argued, robotic technology is moving fast and we need to regulate the applications now [START_REF] Siegel | Law Categories | State Firearm Laws[END_REF]. Solutions to mitigate this emotional involvement should be implemented as early as possible. Regulations should depend on who the users are and what purpose the robots serve. Avoiding anthropomorphic traits and the capacity to speak about oneself will avoid the deception of consumers. Above all, the protection of vulnerable individuals in their human-robot interaction is of paramount importance.

  Your bond can only increase if your robot tells you it loves you back. In fact, that is what sex robot Samantha is programmed to respond if you tell it you love it. Azuma Hikari, the attractive female anime character which is a hologram inside Gatebox's virtual assistant device, can text you throughout the day and tell you it misses you [29].

Author's copy. Appeared in: Nørskov, M., Seibt J., Quick O. 2020. Culturally Sustainable Social Robotics-Proceedings of Robophilosophy 2020. Series Frontiers of AI and Its Applications, IOS Press, Amsterdam.


domain: sde stat

text:
Emeline Perret

Jérôme Le Coz

Benjamin Renard

Estimating time-varying stage-discharge relations in rivers with aquatic vegetation

come

INTRODUCTION

At hydrometric stations, streamflow records are generally computed using stage-discharge models, also called rating curves. Hydrometric stations are commonly installed on river sections where it is possible to obtain a unique relation between the water level (stage) h and the discharge Q for a given time period. The standard form of the rating curve for a given hydraulic control (section or channel control) is a power equation [START_REF] Le Coz | Combining hydraulic knowledge and uncertain gaugings in the estimation of hydrometric rating curves: A Bayesian approach[END_REF]:

𝑄 = 𝑎(ℎ -𝑏) 𝑐 (1)
where a = coefficient related to the type of control (=𝐵√𝑆 0 /𝑛 for a wide and rectangular channel control, with B = channel width, S 0 = channel slope and n = Manning friction coefficient), b = offset; and c = exponent related to the type of control (=5/3 in the case of a wide rectangular channel control). These parameters are estimated based on expert knowledge and using gaugings, which are occasional measurements of stage and discharge carried out at the studied station. This simple power equation is no longer suitable when the system is subject to instabilities that modify the hydraulic control. In practice, sudden (e.g. due to morphological evolution induced by a flood) or transient (e.g. due to the evolution of vegetation) rating changes can happen [START_REF] Mansanarez | Shift Happens! Adjusting Stage-Discharge Rating Curves to Morphological Changes at Known Times[END_REF]. Then, the discharge needs to be computed using h and other variables (e.g. time-varying variables).

In this paper, we focus on stations affected by the presence of aquatic vegetation. Stagedischarge relations vary continuously in time due to the vegetation evolution. To our knowledge, no standardized methods nor convenient stage-discharge models exist to manage such transient changes. Some countries use manual adjustments to compensate for the effect of plants (e.g. the corTH method used by the French hydrometric services) but such procedure is subjective, labor-intensive and rather uncertain. ABSTRACT: Stage-discharge relations at hydrometric stations with aquatic vegetation vary continuously in time due to the vegetation evolution. Maintaining such rating curves for establishing discharge time series is a challenge. Generally, the curves are adjusted manually as convenient stage-discharge models are missing. To fill this gap, we developed a practical model that accounts for transient changes due to aquatic vegetation. It is restricted to hydraulic controls that can be described by the Manning-Strickler equation for wide rectangular channels. In most situations, aquatic plants induce changes in bed roughness and mainly affect flow resistance. Bed roughness is characterized using a time-varying Manning coefficient, estimated using a friction equation accounting for the vegetation development (growth and decay) and for the plant flexibility (bending). In this paper, we illustrate the need to take into account flow-induced plant bending in the friction equation even though vegetation development remains the main factor affecting the flow resistance.

From a physical point of view, the presence of vegetation essentially induces a resistance to water flow, just like the resistance due to bed material, bed forms, etc. [START_REF] Coon | Estimation of roughness coefficients for natural stream channels with vegetated banks[END_REF][START_REF] Green | Comparison of blockage factors in modelling the resistance of channels containing submerged macrophytes[END_REF]. All of these factors contribute to the total flow resistance, which can be expressed as a friction coefficient such as the Manning coefficient n. The impact of plants growing from the bank, which can obstruct the flow and reduce the wetted flow section, is generally assumed negligible compared to the effect of plants on the flow resistance. This assumption can be arguable during some extreme flow events. Several decomposition methods for n have been proposed in the literature [START_REF] Cowan | Estimating hydraulic roughness coefficients[END_REF][START_REF] Morin | Integrated two-dimensional macrophyteshydrodynamic modeling[END_REF]. The expression of [START_REF] Morin | Integrated two-dimensional macrophyteshydrodynamic modeling[END_REF] is chosen for this study in order to particularly focus on the vegetation effect on the flow:

𝑛 2 = 𝑛 𝑏 2 + 𝑛 𝑣 2 (2)
where n = total Manning coefficient, n b = Manning coefficient of the bed when there is no vegetation; and n v = Manning coefficient related to additional friction due to plants. The resistance related to plants is the most likely to vary in time and one of the most difficult to estimate. Indeed, n v (t) depends on the type of plants, their spatial distribution, their density, their development, their relative submergence, their flexibility, etc. Few friction equations exist to compute n v (t) in contrast to the numerous equations or look-up tables for n b [START_REF] Meyer-Peter | Formulas for bedload transport[END_REF][START_REF] Limerinos | Determination of the Manning coefficient from measured bed roughness in natural channels[END_REF][START_REF] Coon | Estimation of roughness coefficients for natural stream channels with vegetated banks[END_REF]. Unfortunately, these friction equations related to vegetation are either too simple to represent the effect of natural plants (see the analogy of the vertical rigid cylinder in Petryk and Bosmajian (1975) or in [START_REF] Pasche | Overbank flow with vegetatively roughened flood plains[END_REF]) or too complex [START_REF] Aberle | Flow resistance of emergent rigid and flexible floodplain vegetation[END_REF] and require too much information to be used for operational purposes (e.g. such as plant elasticity, Leaf Area Index, plant growth rate depending on a range of external factors such as the water temperature).

In this paper, we aim to better predict the stage-discharge relation at stations affected by aquatic vegetation. We develop a new rating curve model that varies in time, based on the standard power model and on a time-varying friction equation. The model intends to be used for operational purposes, using information that can be easily retrieved in the field. The model is tested on data from a French hydrometric station affected by aquatic vegetation. The objective is to show that the simple use of a time-varying friction coefficient in the model improves the discharge prediction in presence of plants. We also discuss the importance of the choice of the friction equation. In particular, we emphasize the need to account for plant bending and not only for plant biomass evolution, even if the latter is the main factor influencing the flow resistance.

TIME-VARYING FRICTION EQUATION RELATED TO AQUATIC VEGETATION

The new rating curve model is similar to the standard power equation (Eq. 1), except for the Manning friction coefficient n now varying in time because of the component n v (t) related to the vegetation (see Eq. 2). Our study is restricted to hydraulic controls that can be described by the Manning-Strickler equation for wide rectangular channels.

Simplified Järvelä (2004) equation

Friction equations were developed in specific conditions (i.e. emergent or submerged plants, flexible plant or not). In this study, we focus on aquatic plants (e.g. macrophytes) that are located in the main channel and submerged (with low relative submergence). Most of the time, these plants are flexible. We also assume that their spatial distribution is homogeneous throughout the channel section. The friction equation of [START_REF] Järvelä | Determination of flow resistance caused by non-submerged woody vegetation[END_REF] was developed for evaluating the friction coefficient related to those types of plants at the reach-scale:

𝑛 𝑣 2 (𝑡) = 4𝐶 𝐷 𝜒 𝐿𝐴𝐼(𝑡)[ℎ(𝑡)-𝑏] 1/3 8𝑔 min (( 𝑈 𝑚 𝑈 𝜒 ) 𝜒 ; 1) (3)
where C Dχ = drag coefficient related to the plants, LAI = Leaf Area Index, g = gravity acceleration, χ = reconfiguration coefficient specific to the plant species (e.g. χ = 0 for rigid plants and χ = -1 for leafy flexible plants), U m = mean velocity; and Uχ = the lowest velocity used during the experimental determination of χ. The plant can bend only when the mean velocity exceeds a minimum velocity Uχ. Below this value, there is no bending and the bending function equals 1.

We add this condition to the original Järvelä (2004) equation using the min() function. The [START_REF] Järvelä | Determination of flow resistance caused by non-submerged woody vegetation[END_REF] equation can be seen as a combination of two main functions that account for two main factors: the plant development (using the LAI) and the plant capacity to bend and align under the action of flow (using the mean velocity). Plants bend to limit their frontal areas impacted by the flow, which leads to reduced bed roughness induced by the vegetation when flow velocity increases. In practice, the LAI data are scarce and no biomass measurements are generally performed at hydrometric stations. Equation 3 is thus too complex for our study. We propose a new friction equation, which is a simplification of the [START_REF] Järvelä | Determination of flow resistance caused by non-submerged woody vegetation[END_REF] equation:

𝑛 𝑣 2 (𝑡) = 𝐺(𝑡)[ℎ(𝑡)-𝑏] 1/3 8𝑔 min (( 𝑈 𝑚 (𝑡) 𝑈 𝜒 ) 𝜒 ; 1) (4)
G(t) = potential of hydraulic resistance due to the development of plants (growth and decay). It is assumed that G(t) evolves similarly in shape as the plant biomass. G(t) is thus a proxy of the evolution of the plant biomass. It cannot be measured specifically, but can be modelled using models for biomass development.

Proxy of biomass evolution

We assume that the biomass (and consequently the proxy G(t)) is a function of time during the year (i.e. during the plant cycle of growth and decay). A bell-shaped model as presented in Figure 1 is chosen for modeling G(t) [START_REF] Yin | A flexible sigmoid function of determinate growth[END_REF]:

𝐺(𝑡) = 𝐺 𝑚𝑎𝑥 ( 𝑡-𝑡 𝑏 𝑡 𝑒 -𝑡 𝑏 ) 𝑡 𝑒 -𝑡 𝑏 𝑡 𝑒 -𝑡 𝑚 ⁄ ( 2𝑡 𝑒 -𝑡 𝑚 -𝑡 𝑡 𝑒 -𝑡 𝑚 ) (5)
where Gmax = maximum plant proxy biomass, tb = beginning of plant growth, tm = time at which the growth rate is maximum; and te = end of plant growth and beginning of decay. Equation 5is built such as no negative biomass is allowed. Equation 5 reflects the general trend of the biomass evolution, but does not take into account any external perturbations (e.g. flood, sudden drop in water temperature) that might induce some changes in the shape of the biomass evolution. More complex models for the biomass evolution exist such as dynamic models depending on external factor (nutrient, light intensity, water temperature, etc.) [START_REF] Lazár | Modelling Primary Producer Interaction and Composition: an Example of a UK Lowland River[END_REF] but they require much more information not always available for operational purposes.

Figure 1. Shape of the model used for modelling the biomass proxy G(t).

Final friction equation

The final time-varying friction equation to include in the power equation (Eq.1 combined with Eq. 2) is the following:

The discharge is present on both sides of the rating curve equation when using Equation 6. No explicit solution exists. The power equation can nevertheless be solved using the Newton-Raphson algorithm, after rewriting it in a polynomial form. This numerical solution will not be detailed in this paper. For more details about the rating curve model accounting for vegetation, please refer to Perret et al. (2020, in prep).

APPLICATION OF DISCHARGE PREDICTION

Test case

The hydrometric station used for testing our model is located in East France on the Ill River at Colmar-Ladhof (station code: A1350310, catchment area: 1784 km²). This station is influenced by flexible aquatic vegetation and is frequently gauged. The gaugings are sometimes supplemented with visual observations transcribed into comments about the presence of vegetation in the main channel (e.g. "plants are present", "there is plenty of plants", "there are no plants"). At low and medium flows, the hydraulic control is appoximated as a wide rectangular channel.

A series of 22 years of data are available at this station, including a period of 11 years of data where no sudden rating changes due to strong morphological evolutions were observed (from 22/03/2002 to 27/02/2013). The focus is made on this period, since our model deals with transient changes due to vegetation only. Around 270 gaugings were carried out during this period including 175 with comments about the presence of vegetation.

Statiscal tool -BaM!

The rating curve model with time-varying friction equation is implemented in a numerical code, called BaM!, which enables estimating the model parameters (with their uncertainties) through Bayesian inference using prior knowledge on hydraulic controls of the station and observational data. We do not detail BaM!, which is a generalization of the method BaRatin frequently used for evaluating rating curves with their uncertainty [START_REF] Le Coz | Combining hydraulic knowledge and uncertain gaugings in the estimation of hydrometric rating curves: A Bayesian approach[END_REF].

In our case, the main observational data used for the calculation are the gaugings. The comments on vegetation are also used to refine the parameter estimations, but, to be used, they need to be transcribed manually into positions within the annual plant cycle, which are then converted into a proxy biomass. These vegetation observations are associated with large uncertainties. A 15% uncertainty (at 95% probability level) is affected to the discharge measurements, because of the difficulty to measure discharge at low flows and especially in presence of plants.

All the priors related to the hydraulic control are determined using the knowledge of the station managers. Wide priors for parameters related to the plant evolution are selected since little information is known about the plant behavior and species. The parameters of Eq. 5 are reestimated every year (every growth cycle) and the others are evaluated only one time over the 11-year period.

RESULTS

Comparison between models without and with time-varying friction coefficient

When aquatic vegetation is present, discharge predictions are improved when using a timevarying friction coefficient instead of a constant friction coefficient. Figure 2 shows the comparison of the relative errors for the model with constant friction coefficient (Eq. 1) with those for the new model with time-varying friction coefficient (Eq. 6). Relative errors can exceed 50% when the friction coefficient is constant whereas they mostly range between ± 20% when a time-varying friction coefficient is used. These results are promising since the uncertainty of the discharge measurements is equal to 15%. Figure 3a shows the discharge time series Q(t) with uncertainty, computed over the studied period using the continuous stage record at the station and our rating curve models. The 95% total uncertainty interval is displayed on Figure 3a, including parametric (i.e. related to the parameter estimation) and structural (i.e. related to the model) uncertainties. Solid lines correspond to the maxpost curves, which have been calculated with the parameters of the model maximising the posterior pdf (the Maximum A Posteriori estimators, MAP). The gaugings are best approximated with the model with time-varying Manning coefficient (see the details for year 2008 in Fig. 3b for more clarity). The total discharge uncertainty is also much smaller.

Figure 3c presents the evolution of the proxy biomass with parametric uncertainty deduced from the model with time-varying Manning coefficient. Proxy biomass G(t) is strongly varying from year to year in both amplitude and shape. This reflects strong flow resistance variations hence the need to into account bed roughness changes due to plant development when computing discharge for such hydrometric station.

Relative hydraulic importance of plant bending and development

In our new rating curve model, we assumed that two main effects drive the variations of the friction coefficient related to the vegetation: the growth and decay of the plant (i.e. biomass evolution) and the capacity of the plant to bend (i.e. its flexibility). The relative importance of these two effects is investigated. Discharges calculated when the bending correction is activated (Qbending) or not (Qno-bending) are compared. To evaluate Qno-bending, we use the same rating curve model as for estimating Qbending, except χ is set to 0 for evaluating the time-varying friction coefficient. Indeed, in case there is no bending, plants are assumed rigid so their reconfiguration coefficients χ equal 0. The Newton-Raphson algorithm is no longer required for computing Qnobending since the discharge is no longer present in the friction equation n v (t). To compute Qnobending, we decide to use the same MAP parameters as those estimated when plant bending was taken into account, except for χ = 0. No new simulation is launched with the statistical tool BaM! in order to avoid compensating the absence of plant bending by other model parameter during their estimation. That way, we investigate the importance (in terms of amplitude) of using the bending correction in the global calibrated model (with bending).

Figure 4 shows the relative discharge differences due to the plant bending function in the calibrated model. Only observational data for which vegetation was present (i.e. when G(t) ≠ 0) are kept on Figure 4. The difference in discharge can reach up to 80%, which reflects the importance of the part related to the bending in the discharge computation with the new rating curve model. The variation in discharge seems correlated to the quantity of plant biomass and to the gauged mean velocity. It is stronger if vegetation biomass is important and if gauged mean velocity is high. In addition, the variation is negative. As rigid plants grow, their frontal areas impacted by the flow become more important. They cannot bend or align in the flow direction to reduce them. The flow is thus obstructed and the discharge reduces. When Um<Uχ, the relative difference should in theory go to zero. Unfortunately, no gauging was made in those conditions, so this statement cannot be verified.

CONCLUSIONS

A rating curve model accounting for the presence of aquatic vegetation based on a time-varying friction coefficient was developed. It is restricted to hydraulic controls that can be described by the Manning-Strickler equation for wide rectangular channels and to submerged (with low relative submergence), flexible or rigid macrophytes. The time-varying coefficient is estimated using a friction equation accounting for vegetation biomass evolution and for plant flexibility. The friction equation needs to be selected according to the type of plants growing at the station. The information needed to compute discharge is easily measurable or estimable (i.e. stage record, expertise on hydraulic controls and simple information about plants such as comments from visual observations), which makes the model interesting for operational purposes.

The performance of the model was highlighted using tests performed on a French hydrometric station affected by aquatic plants. The prediction of discharge was improved when rating curve models with varying friction coefficient are used, as opposed to constant friction coefficient. Relative errors between computed and observed discharges ranged within ±20% with the new model. One interest of this new model is that the potential resistance of the plant related to its development can be modelled, which informs about the general trend of the plant evolution.

In this study, we emphasized the importance of the part related to the bending correction in the discharge calculation. Indeed, in certain conditions, not only the vegetation development but also the plant bending controlled the flow resistance related to plants. Results showed that the bending correction substantially modifies the estimated discharge (sometimes up to 80% compared to setting the bending correction to zero). The bending effect is particularly large when the mean velocity is high and when the plant biomass is significant.

Figure 2 .

 2 Figure 2. Relative error Er as a function of the observed water discharge (Qobs) according to the chosen rating curve model (with constant or time-varying Manning coefficient).

Figure 3

 3 Figure 3. a) Computed water discharge time series Q(t), b) details for year 12 (corresponding to year 2008) and c) evolution of the proxy biomass G(t) over the 11-year of data with uncertainty. Blue lines mark the transition to another hydraulic control for higher flows: computed discharges are not valid above these lines.

Figure 4 .

 4 Figure 4. Relative discharge differences due to the plant bending function in the calibrated model with aquatic vegetation effect as a function of the gauged mean velocity and the proxy biomass at the station.