T Nguyen

J.- C Popieul

Abstract-This paper presents a new shared control method with a dynamic driver-automation conflict management for cooperative lane keeping systems (LKS) of automated vehicles. Based on a human-centered control approach, the proposed shared control design takes into account the driver's activity and availability, as well as the surrounding risk to dynamically adapt the driving assistance level via an adaptive cost function. To this end, we propose a method to characterize in real-time the driver's activity, which allows for an appropriate assistance level according to the driving conditions. Linear parameter-varying (LPV) control technique is leveraged to deal with the time-varying nature of the vehicle speed and the level of assistance. The uncertainties of the lateral tires forces are taken into account in the control design via a norm-bounded representation. Using Lyapunov stability theory, the control design conditions are derived in terms of linear matrix inequality (LMI) constraints, which can be effectively solved by semidefinite programming techniques. User-test experiments are performed with the SHERPA dynamic car simulator to demonstrate the effectiveness of the proposed shared control method from both objective and subjective viewpoints.

Index Terms-Lane-keeping systems, cooperative control, human-in-the-loop control, human-machine interaction, shared control, automated driving. Steer gear ratio, steering system damping I. INTRODUCTION In the field of automated vehicles, the notion of cooperation between the human driver and the automation system in advanced driver assistance systems (ADAS) has been received increasing attention from both academic and industrial researchers [START_REF] Kato | An open approach to autonomous vehicles[END_REF]- [START_REF] Zhou | Driver-centric lane-keeping assistance system design: A noncertainty-equivalent neuroadaptive control approach[END_REF]. An ADAS system actively helps the driver to execute the driving task, such as lane keeping systems (LKS), or lane change systems (LCS). However, the interaction between the driver and the ADAS raises a number of questions about the transfer of authority and responsibility between them [START_REF] Sentouh | Driverautomation cooperation oriented approach for shared control of lane keeping assist systems[END_REF], [START_REF] Xing | Toward human-vehicle collaboration: Review and perspectives on human-centered collaborative automated driving[END_REF]. The current challenge of ADAS developments is to incorporate the driver as an active operator in the vehicle control loop. In recent works, ADAS based on driver-in-theloop designs have been used to solve a variety of humanmachine interaction issues, including the sharing and transfer of authority [START_REF] Saito | Control authority transfer method for automated-to-manual driving via a shared authority mode[END_REF]- [START_REF] Pano | Obstacle avoidance in highly automated cars: can progressive haptic shared control make it safer and smoother?[END_REF], the conflict minimization [START_REF] Sentouh | Driverautomation cooperation oriented approach for shared control of lane keeping assist systems[END_REF], [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF]- [START_REF] Li | A two-layer potential-field-driven model predictive shared control towards driver-automation cooperation[END_REF], and the reduction of the driver workload [START_REF] Wada | Simultaneous achievement of supporting human drivers and improving driving skills by shared and cooperative control[END_REF]- [START_REF] Luo | A workload adaptive haptic shared control scheme for semi-autonomous driving[END_REF]. Despite technological advances, the development of control strategies that allow ADAS systems to share the driving responsibility and authority with the human driver still remains an open research question [START_REF] Xing | Toward human-vehicle collaboration: Review and perspectives on human-centered collaborative automated driving[END_REF], [START_REF] Marcano | A review of shared control for automated vehicles: Theory and applications[END_REF].

NOMENCLATURE

A. Related Works

Shared control strategies taking into account the driver behaviors have been largely studied to improve the humanmachine cooperation [START_REF] Xing | Toward human-vehicle collaboration: Review and perspectives on human-centered collaborative automated driving[END_REF], [START_REF] Ansari | Human-machine shared driving: Challenges and future directions[END_REF]. Based on the driver's actions, a cooperative path planning algorithm was proposed in [START_REF] Benloucif | Cooperative trajectory planning for haptic shared control between driver and automation in highway driving[END_REF] to deal with the driver-automation conflict issue. A cooperative framework based on data-driven adaptive dynamic programming and a learning iteration model was developed in [START_REF] Huang | Data-driven shared steering control of semi-autonomous vehicles[END_REF] to achieve desired steering performance. A driver-automation cooperation oriented approach was proposed in [START_REF] Sentouh | Driverautomation cooperation oriented approach for shared control of lane keeping assist systems[END_REF] for shared control between the human driver and the LKS system. Based on a weighting approach, Nguyen et al. [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF] developed a shared steering controller, which is able to effectively manage the trade-off between the lane keeping performance and the negative system interference. An H 2 /H ∞ haptic shared control method was proposed in [START_REF] Pano | Obstacle avoidance in highly automated cars: can progressive haptic shared control make it safer and smoother?[END_REF] to facilitate the transitions between manual and autonomous driving modes. However, these shared control methods require the information about the driver parameters, which cannot be obtained precisely for a large class of human drivers with various driving styles [START_REF] Oudainia | Online driver model parameter identification using the Lyapunov approach based shared control[END_REF]. It is important to note that these existing works do not consider the driver inattention or hypovigilance in the shared control design. Ansari et al. [START_REF] Ansari | Human-machine shared driving: Challenges and future directions[END_REF] investigated the impact of different driving conditions as well as driver behaviors and errors on the vehicle control performance. To enhance the dependability and the safety of shared steering control systems, an extended system with an adaptive authority allocation model was proposed in [START_REF] Li | Adaptive authority allocation approach for shared steering control system[END_REF]. Using a model reference adaptive control algorithm, Wu et al. [START_REF] Wu | A novel adaptive steering torque control approach for human-machine cooperation autonomous vehicles[END_REF] proposed a method to adjust the steering torque based on the driver's behavior and the vehicle dynamics. Considering the vehicle handling dynamics and the driver's driving intention, a shared control method was developed in [START_REF] Deng | Shared control for intelligent vehicle based on handling inverse dynamics and driving intention[END_REF] based on an inverse vehicle dynamics model. An adaptive shared control approach was proposed in [START_REF] Huang | Human-machine adaptive shared control safe driving under automation degradation[END_REF] to mitigate the risks associated with partial automation failures by enabling smooth and safe transitions between autonomous and manual driving modes. Based on a model predictive control (MPC) technique, a new shared steering controller was designed in [START_REF] Liu | Human-oriented online driving authority optimization for driver-automation shared steering control[END_REF] to dynamically optimize the driving authority allocation between the human driver and the autonomous system. An indirect shared control method for steer-by-wire vehicles was developed in [START_REF] Li | Indirect shared control for cooperative driving between driver and automation in steer-by-wire vehicles[END_REF], where the authors employed a weighted summation approach to balance the control inputs of the driver and the automation. Another indirect shared control method, designed under the framework of non-zero sum differential game, was proposed in [START_REF] Li | Indirect shared control through non-zero sum differential game for cooperative automated driving[END_REF]. A safe cooperative driving approach on curvy roads through coordinated longitudinal and lateral control strategies was introduced in [START_REF] Zhao | Indirect shared control strategy for human-machine cooperative driving on hazardous curvy roads[END_REF]. A multiconstraints MPC shared controller was proposed in [START_REF] Lu | A shared control design for steering assistance system considering driver behaviors[END_REF] to assist drivers in path tracking and collision avoidance, where driver-data-based performance indices are used to define the control authority for the steering assistance system. In [START_REF] Han | Adaptive steering torque coupling framework considering conflict resolution for human-machine shared driving[END_REF], an adaptive steering torque coupling framework was proposed, where the shared steering system is modeled based on a noncooperative dynamic game.

Despite great advances, the existing shared control approaches still face major challenges related to vehicle stability guarantee and allocation of driving responsibility [START_REF] Marcano | A review of shared control for automated vehicles: Theory and applications[END_REF]. Indeed, the well-known weighted summation method, used to distribute the control authority between the driver and the automation, has limitations in ensuring the overall stability of the human-machine vehicle system. Moreover, allocating the responsibility with human drivers under various driving scenarios remains a complex issue [START_REF] Xing | Toward human-vehicle collaboration: Review and perspectives on human-centered collaborative automated driving[END_REF]. To overcome these challenges, we propose a new human-machine interaction strategy to allow for a gradual and continuous sharing of the vehicle control between the driver and the LKS system.

B. Proposed Methodology and Contributions

This paper investigates the human-centered concept for shared steering control design of a cooperative LKS system. Using the steering torque input as a control signal, we focus on minimizing the conflict when both the human driver and the LKS automation jointly perform driving tasks. The proposed adaptive human-machine shared control architecture is illustrated in Fig. 1. To effectively handle the driver-LKS conflict, we dynamically adjust the objective cost function used for shared control design. This adaptive cost function is defined using the real-time driving assistance level to appropriately assist the driver to perform the driving task. The assistance level is determined based on the online information related to the surrounding driving risks, as well as the driving availability and activity of the human driver. To deal with the time-varying nature of the vehicle speed and especially the driving assistance parameter, linear parameter-varying (LPV) control framework is leveraged together with Lyapunov stability theory to design a robust shared steering controller. A preliminary version of this work was presented in [START_REF] Oudainia | Dynamic conflict mitigation for cooperative driving control of intelligent vehicles[END_REF]. The new contributions can be summarized as follows.

• We propose a method to characterize the online driver's driving activity, depending his/her physical and mental workloads. Such a characterization is crucial to construct a multi-objective cost function for shared control design.

Taking into account the real-time information on the availability and activity of the driver, and the traffic conditions, this adaptive cost function allows for an effective driver-LKS conflict management. • A polytopic LPV control framework is used to take into account the dynamic variation of not only the vehicle speed but especially the driving assistance parameter, involved in the adaptive cost function. The design conditions are expressed in terms of LMI constraints, where the cost function can be minimized via a convex optimization. • User-test experiments are performed with the SHERPA car simulator and human drivers to show the effectiveness of the proposed shared control method in terms of lane keeping performance, control robustness with respect to uncertainties/disturbances, human-machine conflict mitigation, and especially driver acceptability. Notations. R m×n denotes the set of m × n matrices with real elements. I is an identity matrix of appropriate dimensions. For a matrix X, X is the transpose of X, X -1 is its inverse, and He(X) = X + X . The expression X Y means that X -Y is a positive definite matrix. For matrices Y 1 and Y 2 , diag(Y 1 , Y 2 ) stands for block diagonal matrix. The symbol * stands for matrix blocks that can be deduced by symmetry. Let L 2 [0, +∞] be the set of bounded functions f : R + → R m with respect to the norm

f 2 = ∞ 0 f (t)f (t)dt < ∞.

II. VEHICLE MODELING

For shared driving control design, we consider a two degrees-of-freedom vehicle model depicted in Fig. 2. Under standard driving conditions with small angles assumption and no longitudinal slip, the vehicle dynamics is described as [START_REF] Sentouh | Driverautomation cooperation oriented approach for shared control of lane keeping assist systems[END_REF]

β = - 2 (C f + C r ) M v v x β + 2 (C r l r -C f l f ) M v v 2 x -1 r + 2C f M v v x δ + 1 M v v x f w ṙ = 2 (C r l r -C f l f ) I z β - 2 C r l 2 r + C f l 2 f v x I z r + 2C f l f I z δ + l w I z f w ( 1
)
where δ is the steering wheel angle. The dynamics of the lateral position error y L , and the heading errors ψ L at a lookahead distance l p can be represented by [START_REF] Sentouh | Driverautomation cooperation oriented approach for shared control of lane keeping assist systems[END_REF]

ψL = r -ρ c v x ẏL = βv x + l p r + ψ L v x (2)
where ρ c is the road curvature. The dynamics of the steering column system is given by

J s δd = -B s δd + T c -T s ( 3
)
where T c = T a + T d is the combined steering torque. The self-alignment torque T s in (3) can be expressed as

T s = -2C f g t R s β + -2l f C f g t R s v x r + 2C f g t R 2 s δ
where g t is the width of the tire contact. To take into account the properties of the road surfaces, e.g., dry, wet or snowy roads, the following uncertain tires model is used to represent the tire-friction interaction [START_REF] Nguyen | Robust set-invariance based fuzzy output tracking control for vehicle autonomous driving under uncertain lateral forces and steering constraints[END_REF]:

C f = C f0 + ∆ f ζ(t), C r = C r0 + ∆ r ζ(t) (4)
where |ζ(t)| ≤ 1, for ∀t ≥ 0, is an unknown parameter, and

C f0 = 1 2 C f + C f , C r0 = 1 2 C r + C r ∆ f = 1 2 C f -C f , ∆ r = 1 2 C r -C r
The upper bounds and lower bounds of the front and rear cornering stiffness coefficients, i.e.,

C f ∈ C f , C f and C r ∈
C r , C r , can be determined by exploiting the relationship between slip angle and lateral tire forces for a class of road surfaces. Then, the road-vehicle system can be defined from ( 1), ( 2), ( 3) and ( 4), as

ẋ = (A(v x ) + ∆A(v x ))x + Bu + E(v x )d (5)
where x = β r ψ L y L δ d δd is the vehicle state, u = T c is the vehicle control input, and d = f w ρ c is the disturbance vector. The state-space matrices of system (5) are defined by

A(v x ) =         a 11 a 12 0 0 a 15 0 a 21 a 22 0 0 a 25 0 0 1 0 0 0 0 v x l s v x 0 0 0 0 0 0 0 0 1 a 61 a 62 0 0 a 65 a 66         , B =         0 0 0 0 0 b 6         E(v x ) = e 1 e 2 0 0 0 0 0 0 0 -v x 0 0 with a 11 = - 2(C f0 + C r0 ) M v v x , a 12 = 2(C r0 l r -C f0 l f ) M v v 2 x - 1
a 15 = 2C f0 R s M v v x , a 21 = 2(C r0 l r -C f0 l f ) I z a 22 = - 2(C r0 l 2 r + C f0 l 2 f ) v x I z , a 25 = 2l f C f0 R s I z a 61 = 2C f0 g t R s J s , a 62 = 2C f0 l f g t v x R s J s , b 6 = 1 J s a 65 = -2C f0 g t R 2 s J s , a 66 = -B s J s , e 1 = 1 M v v x , e 2 = l d I z .
Note that the nominal parts C f0 and C r0 of the cornering stiffness coefficients are included in A(v x ), whereas the uncertain parts ∆ f ζ(t) and ∆ r ζ(t) are used to define ∆A(v x ) as

∆A(v x ) = H(v x )∆(t) (6)
where

∆(t) = ζ(t)I ∈ R 6×6 .
The explicit expression of H(v x ) can be easily obtained following the same line as [START_REF] Nguyen | Robust set-invariance based fuzzy output tracking control for vehicle autonomous driving under uncertain lateral forces and steering constraints[END_REF], [START_REF] Hu | Robust H∞ outputfeedback control for path following of autonomous ground vehicles[END_REF], which is omitted here for brevity.

III. DRIVER ACTIVITY CHARACTERIZATION AND DYNAMIC DRIVING ASSISTANCE

This section presents the characterization of the driver activity and the dynamic driving assistance, which are crucial for shared control design.

A. Driver Activity Characterization

The driver's driving capacities strongly depend on his/her both physiological and psychological states. It has been shown that the human driver cognitive (physical and mental) workload strongly impacts on the capacity to perform certain driving tasks [START_REF] Zhao | The Relationship between Driver Fatigue and Monotonous Road Environment[END_REF]. In addition, the authors show that there is a close relationship between the driver fatigue and a monotonous road environment. Moreover, the level of driving assistance, required by a driver, should be appropriate to his/her cognitive driving workload [START_REF] Sentouh | Driverautomation cooperation oriented approach for shared control of lane keeping assist systems[END_REF]. The relationship between the cognitive workload and the driver task performance can be represented as the U -shape function [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF], where the driving workload can be categorized into three types: under-load, normal-load, and over-load, as shown in Fig. 3. Most of existing shared driving control results have focused on the right-half part of the U -shape function [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF], which is related to the active fatigue due to an overload workload. The left-half part of the U -shape is concerned with the passive fatigue of the driver, mainly due to his/her cognitive underload, which can also significantly decrease the driver's driving performance [START_REF] Mcwilliams | Underload on the road: Measuring vigilance decrements during partially automated driving[END_REF]. Indeed, an undemanding task still reduces attentional resources, which can lead to changes in driver's performance characterized by a decrease of vigilance. Many experimental researches have been performed to study various indicators to identify the passive and active fatigue of the human driver. These indicators can be classified into direct and indirect methods [START_REF] Boverie | Driver vigilance diagnostic based on eyelid movement observation[END_REF], depending on whether they come from measurements carried out on the driver for the mental workload, e.g., eye blinks, head movements, etc., or on the vehicle for the physical workload, e.g., steering wheel angle, steering torque, lateral position on the road, etc. A consensus has gradually emerged that a reliable diagnosis of the driver's state should be based on a combination of these two methods through a driver and driving data fusion process [START_REF] Liu | Driver distraction detection using semi-supervised machine learning[END_REF]- [START_REF] Wang | Driver distraction detection based on vehicle dynamics using naturalistic driving data[END_REF]. Hereafter, we characterize the driver's activity (DA) in function of his/her cognitive workload, i.e.,

• Under-load DA variable is used to represent the mental part of the driver. • Normal-load DA variable is used to represent both the mental and physical parts of the driver. • Over-load DA variable is used to represent the mental and physical driver state, and the risk assessment related to the driving situation. Likewise, the inattention level indicates whether the driver focuses on the road or not. Fig. 4: Continental driver monitoring system.

To better represent the driver's activity in terms of mental workload, the driver monitoring information has been combined with the detection of the presence of the hands on the steering wheel. Then, the variable representing the DA in the under-load region is defined as

DA U = 1 -exp -(σ1×DS×HD) σ 2 (7)
where DS is the driver state. This information can be directly obtained from the driver monitoring system. We have 0 ≤ DS ≤ 1, and an increased value of DS denotes a vigilant and attentive driver. The variable HD ∈ {0, 1} represents the detection of the driver's hands on the steering wheel from a hand detection sensor, i.e., HD = 0 means "hands-off", and HD = 1 means "hands-on". The expression ( 7) is designed to identify situations in which the driver might be considered underloaded or in a scenario where s/he does not require assistance. This is crucial because not every instance of low torque input signifies a need for assistance. For instance, when driving straight on a clear road, minor torque fluctuations are typical and do not necessarily indicate a lack of driver awareness. Such a diving situation is not yet well represented with the DA characterization in [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF].

2) Normal-Load DA Region: The physical workload is quantified by the measured torque of the driver at the steering wheel. Then, the nonlinear variable representing the DA in the normal-load region is defined as

DA N = 1 -exp -(σ1×T dN ×DS×HD) σ 2 (8)
where the driver's physical workload is normalized by the driver's torque as

T dN = T d T d max .
Note that T d max is the driver's maximum torque required for the steering task, averaged over different drivers. The expression (8) represents a typical driving scenario in which driver activity falls within an expected range. It serves as a baseline for evaluating normal driving behavior without the necessity of additional assistance.

3) Over-Load DA Region: As mentioned above, the risk assessment is also considered in the over-load DA region. We evaluate the risk of the overtaking maneuver and take it into account the arbitration process of the driving supervisor. In this context, the risk of a maneuver can be expressed as the risk of head-on and rear-end collisions with leading and trailing vehicles, respectively. To evaluate the risk, we consider the time-inter-vehicle (TIV) metric from the ego vehicle to the adjacent vehicle as [START_REF] Oudainia | Personalized decision making and lateral path planning for intelligent vehicles in lane change scenarios[END_REF]

Risk = T IV max -T IV T IV max T IV = D v ego , T IV max = D max v ego ( 9
)
where D is the gap between two vehicles, and D max is the maximum possible distance detected by the vehicle's perception system. The variable characterizing the DA in the over-load region can be defined as

DA O = 1 -exp -(σ1×DS×HD×Risk) σ 2 (10)
The expression [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF] is specifically applicable to situations in which the driver may be overloaded or confronted with demanding driving conditions. This expression helps identify when the driver may require assistance due to the increased workload, such as during emergency maneuvers.

The driver activity function plays a key role for the proposed driver-automation shared driving controller. This function determines the level of the driver's involvement in the vehicle control process with respect to the automation. The use of an exponential function to model the driver activity in ( 7), ( 8) and ( 10) avoids abrupt and sudden changes between two discrete states (0 and 1) that could lead to unstable or inappropriate system behavior. The tuning parameter σ 1 is used to represent the driver's involvement in driving tasks, while σ 2 represents the degree of influence of different indicators on the DA variable. The model parameters σ 1 and σ 2 are used as in [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF]. From [START_REF] Saito | Control authority transfer method for automated-to-manual driving via a shared authority mode[END_REF], ( 8) and [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF], the DA variable representing the driver activity in the three working regions can be expressed as

DA = 1 3 (DA U + DA N + DA O ) (11)
The continuity of the variable DA in [START_REF] Flad | Cooperative shared control driver assistance systems based on motion primitives and differential games[END_REF] • For 0s < t < 10s, the driver is not available DS = 0, then DA = 0. • For 10s < t < 20s, the driver is available DS = 1 with the hands on the steering wheel HD = 1. However, he/she does not apply any steering torque, i.e., T dN = 0. Then, DA varies within the under-load region. • For 21s < t < 35s, we have DS = 1 and HD = 1.

Moreover, the driving situation is not risky (Risk = 0) and there is a physical activity, i.e., T dN = 0. Then, DA varies within the normal-load region. • For 35s < t < 50s, we have DS = 1 and HD = 1.

Although the driver's physical activity is non-null, but the driving situation is risky. Then, the variable DA varies within the over-load region.

B. Dynamic Driving Assistance

From the DA characterization within three workload regions, the level of assistance or the need of assistance, as illustrated in Fig. 3, can be evaluated via the time-varying parameter ρ ∈ [0, 1], defined as

ρ = (λ 1 × DA U × (DA -λ 2 ) 2 + λ 3 ) + (1 -DA U ) (12)
where λ 1 , λ 2 and λ 3 are respectively given by 3.6, 0.5 and 0.1. Note from [START_REF] Li | A two-layer potential-field-driven model predictive shared control towards driver-automation cooperation[END_REF] that the level of assistance is conditioned by DA U to give the control authority to the LKS if the driver is out of the driving loop. In the case where the driver is in the driving loop, the authority is shared between the LKS and the driver according to the variable DA to minimize the human-machine conflict, thus the driver's physical steering workload. When the driver's steering action leads to a risky driving situation, the variable DA is shifted to the over-load region, then the control authority is given to the LKS.

IV. LPV SHARED DRIVING CONTROL DESIGN This section presents the design of an adaptive shared controller. The driver-automation control authority is arbitrated via a dynamic cost function, which is defined taking into account the level of assistance provided by the driving supervisor. To deal with the time-varying parameters, a polytopic LPV control technique is used for the shared control design.

A. Polytopic LPV Vehicle Modeling

Note that the system matrices A(v x ), ∆A(v x ) and E(v x ) in ( 5) explicitly depend on the following speed-related terms:

v x , 1 v x , 1 v 2 x , v min ≤ v x ≤ v max . (13)
To reduce the complexity of the polytopic representation of the LPV vehicle model ( 5) and the induced design conservatism, we perform the following variable change and first-order Taylor approximations [START_REF] Li | Polytopic LPV approaches for intelligent automotive systems: State of the art and future challenges[END_REF], [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF]:

1 v x = 1 v 0 + 1 v 1 α, v x v 0 1 - v 0 v 1 α 1 v 2 x 1 v 2 0 1 + 2 v 0 v 1 α (14)
with v 0 = 2vminvmax vmin+vmax and v 1 = 2vminvmax vmin-vmax . Note that the new time-varying parameter α ∈ [-1, 1] can be used to describe the variation of v x , i.e., v x = v min for α = α min = -1, and v x = v max for α = α max = 1. Replacing ( 14) into (5), we obtain a vehicle model, whose state-space matrices linearly and solely depend on α. Then, using the sector nonlinearity approach [41, Chapter 2], we can derive the following polytopic LPV representation of model ( 5):

Σ α : ẋ = 2 i=1 h i (α)((A i + ∆A i )x + E i d) Bu ( 15
)
where the state-space matrices of the two linear submodels are given by Σ α1 : A(α min ), B, E(α min ) Σ α2 : A(α max ), B, E(α max ).

It follows from ( 6) that ∆A i can be represented as

∆A i = H i ∆(t), i = 1, 2 (16)
with ∆(t) ∆(t) ≤ I. Furthermore, the membership functions of the polytopic LPV model ( 15) are defined as

h 1 (α) = 1 -α 2 , h 2 (α) = 1 -h 1 (α). (17)

B. LPV Shared Control Design

To take into account the lane-keeping performance, we define the performance output of system [START_REF] Luo | A workload adaptive haptic shared control scheme for semi-autonomous driving[END_REF] as

z = Cx = β r ψ L y L δd . ( 18
)
For shared control purposes, the following cost function is defined to take into account the dynamic driving assistance, represented by the time-varying parameter ρ in [START_REF] Li | A two-layer potential-field-driven model predictive shared control towards driver-automation cooperation[END_REF]:

J (ρ) = ∞ 0 z (τ )ρQz(τ ) + u (τ )Ru(τ ) dτ ( 19
)
where Q = W W 0 and R 0 are the weighting matrices. Since ρ ∈ [0, 1], we can perform the decomposition

ρQ =   2 j=1 g j (ρ)W j     2 j=1 g j (ρ)W j   (20) with g 1 (ρ) = √ ρ, g 2 (ρ) = 1 -g 1 (ρ), W 1 = W and W 2 = 0.
Remark 1. Inspired by the well-known principle of an linear quadratic regulator (LQR), we can see in [START_REF] Huang | Data-driven shared steering control of semi-autonomous vehicles[END_REF] that when the control authority is entirely entrusted to the LKS, i.e., ρ = 1, the control action T c is designed to achieve the best lane keeping performance by mainly penalizing the lane-keeping related term z (τ )ρQz(τ ). Conversely, when the control authority is entirely allocated to the human driver, i.e., ρ = 0, a minimized control action T c is designed to minimize J (ρ) by penalizing the control effort term u (τ )Ru(τ ). Hence, integrating the time-varying parameter ρ into the cost function J (ρ) allows to adaptively balance the control authority between the human driver and the LKS in function of the driving situation and the specific need of assistance from the driver without a direct weighting of the control input as in most of existing related works on driver-automation shared control [START_REF] Marcano | A review of shared control for automated vehicles: Theory and applications[END_REF]. This can contribute to improving driving safety and comfort while avoiding human-machine conflicts.

We consider the following LPV control law for system [START_REF] Luo | A workload adaptive haptic shared control scheme for semi-autonomous driving[END_REF]:

u = 2 i=1 2 j=1 h i (α)g j (ρ)K ij x (21)
where the control gains with of appropriate dimensions K ij , for i, j ∈ {1, 2}, are to be determined. Then, the closed-loop system can be defined from ( 15) and ( 21) as

Σ αρ : ẋ = 2 i=1 2 j=1 h i (α)g j (ρ)(( Âi + BK ij )x + E i d) (22)
with Âi = A i + ∆A i . For control synthesis, we consider the Lyapunov function candidate as

V(x) = x P x (23)
with P 0. The following theorem provides sufficient LMIbased conditions to design the LPV controller [START_REF] Li | Adaptive authority allocation approach for shared steering control system[END_REF].

Theorem 1. If there exist a positive definite matrix X, matrices N ij , for i, j ∈ {1, 2}, of appropriate dimensions, positive scalars γ and ε such that

  Γ ij εΞ i Λ * -εI 0 * * -εI   ≺ 0, i, j ∈ {1, 2} (24)
with

Γ ij =     He(A i X + BN ij ) E i XC W j N ij * -γI 0 0 * * -I 0 * * * -R -1     Ξ i = H i 0 0 0 , Λ = X 0 0 0 .
Then, the LPV controller ( 21) stabilizes the vehicle system [START_REF] Luo | A workload adaptive haptic shared control scheme for semi-autonomous driving[END_REF], and guarantees an upper-bound for the cost function [START_REF] Huang | Data-driven shared steering control of semi-autonomous vehicles[END_REF] under zero-initial condition as

J (ρ) < γ d 2 2 . ( 25
)
Furthermore, the feedback control gains can be computed as

K ij = N ij X -1 , i, j ∈ {1, 2}. (26)
Proof. Multiplying [START_REF] Huang | Human-machine adaptive shared control safe driving under automation degradation[END_REF] with h i (α)g j (ρ) ≥ 0, and summing up for i, j = 1, 2, we can obtain

  Γ αρ εΞ α Λ * -εI 0 * * -εI   ≺ 0 (27)
with

Γ αρ = 2 i=1 2 j=1 h i (α)g j (ρ)Γ ij and Ξ α = 2 i=1 h i (α)Ξ i . Ap-
plying successively two times the Schur complement lemma [START_REF] Boyd | Linear matrix inequalities in system and control theory[END_REF], we can show that inequality ( 27) is equivalent to

Γ αρ + εΞ α Ξ α + ε -1 Λ Λ ≺ 0. (28)
Using the following matrix property [START_REF] Boyd | Linear matrix inequalities in system and control theory[END_REF]

Ξ α ∆(t)Λ + Λ ∆(t)Ξ α ≺ εΞ α Ξ α + ε -1 Λ Λ condition (28) implies that Γ αρ + Ξ α ∆(t)Λ + Λ ∆(t)Ξ α ≺ 0. (29)
Using expression [START_REF] Marcano | A review of shared control for automated vehicles: Theory and applications[END_REF], inequality ( 29) can be rewritten as

    Σ αρ E i XC W j N ij * -γI 0 0 * * -I 0 * * * -R -1     ≺ 0 (30)
with

Σ αρ = 2 i=1 2 j=1
h i (α)g j (ρ)He( Âi X + BN αρ ). Applying again the Schur complement lemma, it follows that inequality (30) is equivalent to

Σ αρ + N αρ RN αρ + XC ρQCX E i * -γI ≺ 0. (31)
Let us denote P = X -1 and N αρ = K αρ X. Pre-and postmultiplying (31) with diag(P, I), it follows that

Π αρ + K αρ RK αρ + C ρQC P E α * -γI ≺ 0 (32)
where Π αρ = He(P ( Âα + BK αρ )). Pre-and post-multiplying (32) with x d and its transpose, we can obtain the following condition after some algebraic manipulations:

V(x) + z ρQz + u Ru < γd d (33)
where V(x) is the time-derivative of the Lyapunov function [START_REF] Deng | Shared control for intelligent vehicle based on handling inverse dynamics and driving intention[END_REF] along the trajectory of the closed-loop system [START_REF] Luo | A workload adaptive haptic shared control scheme for semi-autonomous driving[END_REF]. From (33), we distinguish the two following cases.

• Case 1. If d(t) = 0, for ∀t ≥ 0. Then, it follows from (33) that V(x) < 0, for ∀x = 0. Hence, the closed-loop-system ( 15) is globally exponentially stable.

• Case 2. If d(t) = 0, for ∀t ≥ 0. Then, integrating both sides of (33) from 0 to ∞, it leads to

V(∞) -V(0) + J (ρ) < γ ∞ 0 d (t)d(t). (34)
Since V(∞) > 0, under zero initial condition, i.e., V(0) = 0, it is clear that (34) implies inequality [START_REF] Liu | Human-oriented online driving authority optimization for driver-automation shared steering control[END_REF]. Note also from (25) that the adaptive cost function J (ρ) can be minimized by minimizing γ. Then, the proof can be concluded.

Remark 2. The control design conditions in Theorem 1 are expressed in terms of LMIs, which can be effectively solved with YALMIP toolbox and SeDuMi solver [START_REF] Löfberg | YALMIP: A toolbox for modeling and optimization in Matlab[END_REF].

V. EXPERIMENTAL VALIDATIONS

This section provides illustrative results to demonstrate the performance of the proposed shared controller in terms of conflict reduction and lane-keeping. All the experiments are performed with the SHERPA dynamic car driving simulator, depicted in Fig. 6, under highway driving conditions. The values of the control parameters and the vehicle parameters used in this paper are shown in Table II. Solving the LMI design conditions in Theorem 1, the following control feedback gains can be obtained for real-time experiments:

K 11 = -105.

A. Robustness Control Performance

We perform three tests to evaluate the robustness performance of the proposed shared controller in self-driving mode with respect to the time-varying vehicle speed, external disturbances, and tires stiffness uncertainties.

First, the lane keeping performance results obtained with a time-varying vehicle speed profile are presented in Fig. 7. With the lane width of 3.5m, we can see that the LKS ensures a good lane keeping performance, where the maximum lateral and heading errors are |y L | max = 0.6m and |ψ L | max = 0.37deg, respectively. Second, to show the control robustness against external disturbances, an automatic driving test is performed with a constant speed of v x = 22m/s and a strong lateral wind force with a magnitude of 1000N . Observe in Fig. 8 that the wind disturbance effect can be effectively attenuated since the maximum lateral and heading errors still remain small during the test, i.e., |y L | max = 0.98m and |ψ L | max = 0.41deg, respectively. Third, to verify the control robustness with respect to the tires stiffness uncertainties, we use random parametric variations in the vehicle parameters to consider uncertain values of C f and C r . For comparison purposes, we evaluate the lane keeping performance obtained with two controllers: Controller C1 proposed in [START_REF] Oudainia | Dynamic conflict mitigation for cooperative driving control of intelligent vehicles[END_REF] without considering the stiffness uncertainties, and Controller C2 proposed in this paper. The comparison results are summarized in Table III. We can see that the amplitudes of the maximum lateral deviation and heading errors are more notable for Controller C1 than Controller C2. Indeed, for 20% of parameter variation, we can note |y L | max = 0.537m, |ψ L | max = 0.388deg for Controller C2, and |y L | max = 0.647m, |ψ L | max = 0.422deg for Controller C1. In addition, it can be seen that the steering effort provided by Controller C1 is smaller than that of Controller C2, which confirms the effectiveness of the proposed controller in handling parametric uncertainties.

B. Adaptive Shared Control with Risk Assessment

This test presents an example on how the proposed shared controller can ensure a safe driving in a risky situation. To this end, we consider an overtaking scenario at a constant vehicle speed, where the human driver jointly controls the vehicle with the LKS automation, and is instructed to overtake two other vehicles on the highway. The first overtaking is safe, while the second one is risky due to the presence of another car on the left lane, as depicted in Fig. 9. The results of this test scenario are presented in Fig. 10.

• During the first overtaking (at t = 28s), we can see that the human driver can easily executes the driving task. The level of assistance decreases when the DA is in the normal-load region, i.e., the driving authority is given to the driver. • During the second overtaking (at t = 60s), the driver is guided by the shared controller to stay within the current lane (y L < 1m) because the driving situation is risky. Also, the DA shifts to the over-load region, which means that the driver needs to be assisted to avoid a crash with the adjacent vehicle. Therefore, the assistance level increases to 1 to give the authority to the LKS automation. • When the adjacent vehicle moves forward and the situation becomes safe, the driver performs the third overtaking (at t = 65s). We can see that he can easily pass the second vehicle, and the level of assistance decreases to allow the driver to control the vehicle since the DA decreases to the normal-load region.

C. User-Test Experiments

Hereafter, the vehicle control results obtained with usertest experiments are presented. Both objective and subjective evaluations are made for an obstacle avoidance scenario to compare the proposed shared controller with the one in [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF], where there is no adaptive cost function. Six participants took part in these experiments (4 males and 2 females). The average age is 34 ± 9 years, and an average annual mileage of 8500km. A short obstacle avoidance scenario was considered. The experiment took place on a straight two-lane road that extends for 4km. With the instruction to stay in the lane, the drivers were required to avoid several stopped obstacles. The participants were asked to change the lanes to avoid possible collisions, while driving at a fixed speed of 70km/h. This speed allows to easily compare the driving behaviors between different participants by avoiding inter-individual differences in the choice of vehicle speed, and by assuming also that obstacles are not perceived by the system. With the same scenario, the participants drove with three control strategies:

• M anual: manual control strategy • LKS W OA : lane keeping control strategy with the shared controller in [START_REF] Nguyen | Driver-automation cooperative approach for shared steering control under multiple system constraints: Design and experiments[END_REF] • LKS W A : proposed adaptive shared control strategy. Questionnaires were provided after each test phase to collect subjective assessment of the driving experience. The data analysis is divided into two parts.

1) Objective Evaluation: This evaluation is carried out by using indicators to evaluate the human-machine interaction and the shared control quality. The four following metrics are analyzed for this study as in [START_REF] Oudainia | Online driver model parameter identification using the Lyapunov approach based shared control[END_REF].

• Driver steering effort during the experimental period

T ex StD = Tex 0 T 2 d (τ )dτ (35)
• Controller steering effort during the experimental period

StC = Tex 0 T 2 a (τ )dτ (36)
• Driver-automation conflict during the experimental period

Conf lict = Tex 0 |T a (τ ) -T d (τ )| dτ (37)
• Steering workload SW generated when the driver interacts with the automation to jointly perform the driving

SW = Tex 0 T a (τ ) • T d (τ ) • δd (τ ) dτ (38)
As shown in Fig. 11, using the LKS W OA strategy, the effort required to steer the vehicle and avoid obstacles is very high when the system is not cooperating when compared to the manual control strategy. However, the LKS W A strategy leads to a driver's driving effort of the same order as under the manual control condition. It is also clear from Fig. 11 that using the LKS W A strategy the LKS system significantly reduces its effort and resistance to the driver compared to the LKS W OA control condition. The quantitative results strongly demonstrate that the proposed shared control method is highly effective in mitigating the driver's effort and the driverautomation conflict. 2) Subjective Evaluation: The questionnaires provided to the participants allow for an analysis of subjective data. This consists of five metrics, including driving comfort, feeling of control and safety, ease of avoiding obstacles, and global evaluation of the overall driving performance for each test phase. The first four subjective metrics are reported on a scale of 0 to 100 (worst to best). The fifth metric is a simple choice of one of the three possibilities: Good, Medium or Bad. As reported in Fig. 12, compared to the other two control strategies, the LKS W OA strategy allows achieving the lowest level for the four subjective metrics: Control, Comfort, Easiness and Safety. We can see clearly via these four metrics that the feeling of control, the comfort, the ease of obstacle avoidance and the feeling of security and trust in the LKS system are rated worse with the LKS W OA strategy, whereas the LKS W A strategy results in an equivalent or slightly lower feeling than the Manual strategy. Finally, the subjective evaluation of the overall driving performance during the test scenario with the different conditions is shown in Fig. 13. As expected, the perceived driving performance during the obstacle avoidance is the worst with the LKS W OA strategy.

VI. CONCLUSIONS AND FUTURE WORKS

An LPV method has been proposed for shared driving control while managing the authority between the human driver and the LKS system. Based on an adaptive cost function for the control design, the level of assistance is dynamically adjusted according to the driving conditions as well as the availability and the driving activity of the driver in real-time. The LPV control design takes into account the time-varying nature of the vehicle speed and the driving assistance level, as well as the uncertainties in the lateral tires forces. Based on Lyapunov stability theory, the control design conditions are expressed in terms of LMI constraints, where the adaptive cost function can be minimized under the disturbance effects. Usertest experiments are performed with the SHERPA dynamic car simulator. The experimental results show the effectiveness of the proposed shared control method over related existing works in terms of control robustness, and especially driver acceptability with a minimized level of driver-automation conflict driver effort. For future works, a dynamic impedance driver model can be integrated into the shared control scheme to further personalize the cooperative LKS functionalities.

Fig. 1 :

 1 Fig. 1: Adaptive cost function-based shared control scheme.

Fig. 2 :

 2 Fig. 2: Schematic of a two degrees-of-freedom vehicle model.

Fig. 3 :

 3 Fig. 3: Illustration of driver activity and performance, and the respective driving assistance level.

  is ensured by the mental load indicators DS and HD, which are common in the three regions. The driver activity is divided into three categories: under-load DA U , normal-load DA N , and overload DA O . The mental load indicators DS and HD are used to characterize DA U and DA N . Moreover, the physical indicator T dN is used to characterize DA N . For the over-load region, the driver activity is characterized by the mental load indicators DS and HD, and the risk indicator Risk. The overall driver activity DA is calculated in (11) as an average of the three variables DA U , DA N , and DA O . Averaging these DA values creates a composite metric that accounts for various driving scenarios and mitigates potential fluctuations or outliers in individual expression outputs. Table I summarizes the availability of various DA indicators in the three workload regions.

Fig. 5

 5 Fig.5shows the DA evolution in the three workload regions for different situations according to different indicators: DS, HD, T dN and Risk.

Fig. 5 :

 5 Fig. 5: Driver activity variation according to mental, physical workload indicators and risk assessment.

  44 8.19 131.62 3.38 8.67 0.03 K 12 = 9.29 0.79 12.53 0.32 0.83 0.01 K 21 = -110.43 8.35 137.59 3.54 9.06 0.03 K 22 = 9.98 0.81 13.65 0.34 0.90 0.01 .

Fig. 6 :

 6 Fig. 6: SHERPA dynamic driving simulator.

Fig. 7 :

 7 Fig. 7: Lane keeping performance with a time-varying vehicle speed profile.

Fig. 8 :

 8 Fig. 8: Lane keeping performance under a strong crosswind disturbance scenario.

Fig. 9 :Fig. 10 :

 910 Fig. 9: Risky and non-risky lane change scenarios.

Fig. 11 :

 11 Fig. 11: Objective evaluation of different shared control strategies under an obstacle avoidance scenario.

Fig. 12 :

 12 Fig. 12: Subjective evaluation of different shared control strategies under an obstacle avoidance scenario.

Fig. 13 :

 13 Fig. 13: Global driving performance of different shared control strategies under an obstacle avoidance scenario.

  Adaptive Cost Function-Based Shared Driving Control for Cooperative Lane-Keeping Systems with User-Test Experiments Mohamed Radjeb Oudainia, Chouki Sentouh, Anh-Tu Nguyen * , Senior Member, IEEE, Jean-Christophe Popieul

  Distance from COG to front and rear axles [m] T s , T d , T a Self-align, driver and automation torque [N.m] R s , B s

	M v	Mass of vehicle [kg]
	I z , J s	Yaw and steer inertia [kg.m 2 ]
	v x	Longitudinal velocity [m/s]
	β, δ d	Sideslip angle, steering wheel angle [rad]
	f w	Crosswinds force [N ]
	ψ L	Heading error [rad]
	y L	Lateral position error [m]
	α f , α r	Front and rear slip angles [rad]
	C f , C f	Front and rear cornering stiffness [N/rad]
	r	Yaw rate [rad/s]
	l f , l r

TABLE I :

 I DA indicators present in the three workload regions.

	Driver Activity / Indicators DS	HD	T dN	Risk
	DA U		-	-
	DA N			-
	DA O		-
	DA

TABLE II :

 II Control design and vehicle parameters.

	Parameter	Value	Unit	Parameter	Value	Unit
	l f	1.3	m	Js	0.05	kg.m 2
	lr lw	1.6 0.4	m m	C f 0 Cr 0	57000 59000	N/rad N/rad
	lp	5	m	Rs	16	-
	Bs	5.73	-	vx	[8,30]	m/s
	Rs	0.9	-	gt	0.13	m
	Iz	2800	kg.m 2	Mv	2024	kg
	W	diag(9,9,5,8,5)	-	ρ	[0,1]	-

TABLE III :

 III Lane keeping control performance with respect to parametric uncertainties.

	Uncertainty	Controller	|y L |max	|ψ L |max	|Ta|max
		C1	0.628	0.391	1.245
	5%	C2	0.509	0.377	1.074
		C1	0.641	0.404	1.392
	10%	C2	0.516	0.382	1.152
		C1	0.674	0.422	1.446
	20%	C2	0.537	0.388	1.211

This research has been done within the framework of the CoCoVeIA project (ANR-19-CE22-0009-01), funded by the Agence Nationale de la Recherche, the Ministry of Higher Education and Research and the French National Center for Scientific Research.


Didier Cariou

LA MACHINE FREINET : LES DIFFICULTÉS D'UNE INSTITUTION DIDACTIQUE Une lecture de l'ouvrage À côté de Freinet de Henri Louis go et Xavier Riondet

Mots-clés : Freinet, histoire de l'éducation, Henri Louis Go, Xavier Riondet, école naturiste, école prolétarienne

Un projet : Une généalogie de la « pédagogie Freinet » Précisons d'emblée que cet ouvrage peut être pris comme un modèle de méthodologie historique. Il ne cherche pas à raconter la formation, l'apogée et le destin de l'oeuvre du grand pédagogue selon une perspective linéaire et téléologique menant de la grave blessure de guerre reçue au Chemin-des-Dames, à l'incapacité du jeune instituteur à « tenir » sa classe et à l'invention d'une pédagogie sans leçons désormais mondialement connue. L'ouvrage propose une généalogie qui vise à « défataliser l'histoire » (Chapoutot, 2021, p. 43) pour aborder des logiques qui nous échappent aujourd'hui (par exemple la préoccupation hygiéniste d'Élise Freinet motivée par les ravages de la tuberculose dans les milieux populaires de l'Entre-deux-guerres), pour envisager des tâtonnements, des expériences et des connexions oubliées et pour penser les choix et les bifurcations qui ont été opérés par les Freinet face à divers possibles. À cet égard, la description de l'intérêt de Freinet pour Lyssenko qui, à la fin des années 1940, postulait l'hérédité des caractères acquis à l'encontre de la génétique de Mendel, est exemplaire de la démarche suivie. Les auteurs ne condamnent pas après coup une attirance coupable pour ce qui s'est révélé être une imposture scientifique, mais ils cherchent à comprendre comment il était possible que Freinet adhère au lyssenkisme stalinien dans le contexte historique du début de la Guerre froide. Il apparaît ainsi que cette auto-proclamée science prolétarienne évolutionniste était en phase avec la conception de Freinet selon laquelle le milieu, celui de l'école et de la « pédagogie Freinet », rendait possible le développement harmonieux des enfants des milieux populaires. Plus largement, cette généalogie de l'École Freinet relève d'un parti-pris assumé par les auteurs : épouser le point de vue des personnes qui étaient les plus proches de l'oeuvre de Freinet, en opérant un gros travail dans les archives du Mouvement Freinet et en recueillant de nombreux témoignages. Il s'agit de retrouver Freinet et de savoir de quoi l'on parle à son propos afin de déconstruire ou de neutraliser le discours dominant aujourd'hui sur la « pédagogie Freinet ». En effet, selon les auteurs, depuis plusieurs décennies, l'enjeu théorique et politique de l'expérience des Freinet a été dénaturalisé et banalisé afin de le rendre compatible avec l'institution de l'Éducation nationale qui en a récupéré certains mots (autonomie, coopération, individualisation, expression…) pour mieux rejeter ce qui pourrait remettre en cause son fonctionnement propre. Comme c'est fréquemment le cas, on a gardé « les mots sans les choses » [START_REF] Chauvier | Les mots sans les choses[END_REF]. Ce compte-rendu, suivant le plan chronologique des deux volumes de l'ouvrage, va donc souligner certains points pour tenter de rendre compte de la manière dont les auteurs décrivent la construction de la « pédagogie Freinet » dans l'Entre-deux-guerres puis les problématiques liées à sa diffusion depuis 1945.

La genèse de la Machine Freinet

Cet ouvrage se compose donc de deux forts volumes correspondant aux deux périodes de l'histoire de Freinet. Le premier volume décrit la construction, durant l'Entre-deux-guerres, de ce que les auteurs nomment la Machine Freinet, une machine pédagogique complexe, construite par le couple Freinet en fonction de ses tâtonnements et de ses préoccupations, au fil de ses lectures et de ses rencontres au sein d'un large réseau militant et malgré les nombreux obstacles opposés par une administration anti-communiste. Le but était de mettre en place une école active, non coupée de la vie réelle, favorisant la libre expression et l'instruction par le travail, afin de rendre l'élève actif (et pas « en activité ») selon un projet d'émancipation sociale et politique. La Machine Freinet résulte aussi de l'étude et de l'adaptation de l'oeuvre de grands pédagogues tels que Claparède, Decroly, Cousinet, Dewey ainsi que les penseurs soviétiques de l'éducation. Elle a produit une nouvelle forme scolaire [START_REF] Vincent | L'éducation prisonnière de la forme scolaire ? Scolarisation et socialisation dans les sociétés industrielles[END_REF] et une nouvelle organisation du temps scolaire visant à prendre soin de l'enfant pour le faire grandir sans l'arracher à l'enfance, en dépassant le dualisme opposant l'enfant à l'élève. Cette reconstruction de la forme scolaire supposait des innovations matérielles et pédagogiques : la coopérative scolaire, la bibliothèque de travail, la conférence d'enfants, le plan de travail, les petits ateliers, le journal scolaire polycopié, l'atelier des expérimentations scientifiques, l'usage de la machine à écrire et de la linotypie. Les bases de la Machine Freinet furent multiples. Il s'agissait tout d'abord du naturisme matérialiste dont Élise Freinet prit connaissance au contact des militants révolutionnaires allemands durant les années 1920. Ce naturisme, que l'on pourrait qualifier aujourd'hui d'écologisme, était une pratique de soi, un art de vivre lié au végétarisme, visant la modération en toutes choses. Il cherchait à s'émanciper de la relation de domination instaurée par les institutions scientifiques dans le cadre du système capitaliste, qui pousse à dépenser toujours plus d'argent, à consommer toujours davantage de produits toxiques. À cet égard, les auteurs de l'ouvrage montrent l'importance de la sagesse orientale et de la médecine chinoise dans ce cheminement un peu « new-age » qui puisait donc à des sources variées. Une autre base de la Machine Freinet en découle : elle consistait à entrer dans le conflit contre l'aliénation produite par le système capitaliste. Dans un texte de 1934, Freinet refusait par exemple le « fascisme scolaire » qu'impose le régime capitaliste au système scolaire : des locaux vétustes, une mauvaise alimentation, un trop grand nombre d'élèves par classe, un asservissement généralisé qui cantonne l'instituteur à la délivrance d'un savoir scolaire et qui ne permet pas de contester l'oppression sociale. D'une certaine manière, Freinet conduit à considérer la forme scolaire actuelle comme un instrument d'oppression. C'est pourquoi il est nécessaire de repenser la forme scolaire, par ce que Freinet nommait une « éducation prolétarienne », qui supposait la libre expression des enfants, et qui devait se recentrer au quotidien sur le travail perçu comme une libération et non comme une aliénation : le travail scolaire, le travail manuel, le travail d'entretien de l'école, le travail des champs. Cette centration sur le travail permettait d'envisager un nouveau temps scolaire qui n'était plus scandé par la succession des objets étudiés tout au long de la journée, mais qui était organisé par les enquêtes des élèves. Enfin, l'engagement communiste des époux Freinet, dès le début des années 1920, imprégnait évidemment leur projet pédagogique. Cet engagement n'était pas aveugle, il consistait moins à soutenir l'URSS de Staline -même si Freinet semble avoir toujours refusé d'évoquer la répression stalinienne -que le pays de la Révolution d'Octobre qui avait beaucoup dépensé pour l'instruction des masses et pour les innovations pédagogiques.

À ce point de mon compte-rendu, je souhaite poser une première question aux auteurs. Il convient certes de considérer que ces références et ces engagements sont ceux de deux instituteurs communistes des années 1920 et 1930, il y a près d'un siècle. Les auteurs nous invitent, à juste titre, à considérer la distance temporelle qui nous sépare de ce monde enseveli où les bâtiments scolaires étaient insalubres, au point d'avoir conduit Élise à contracter la tuberculose, où les enfants des milieux défavorisés ne mangeaient pas toujours à leur faim et où le contexte climatique, politique et international était fort différent du nôtre. Cependant, risquons-nous vraiment de commettre un anachronisme en considérant que, nonobstant ces réserves, les questions de la santé dans la société comme à l'école, de la nécessaire modération de notre consommation, des conditions de travail dans les écoles, de la réhabilitation du travail dans la formation des enfants-élèves, de l'orientation vers une forme scolaire réellement ne restent-elles pas toujours à l'ordre du jour ? Finalement, les préoccupations des époux Freinet dans l'Entre-deux-guerres nous sont-elles vraiment exotiques ? La Machine Freinet s'incarne dans un lieu, que les auteurs nomment à la suite de Foucault une hétérotopie scolaire, celui de l'École Freinet de Vence, installée sur un terrain acheté par les époux Freinet au début des années 1930. Élise Freinet a théorisé cette hétérotopie sous le terme de la « réserve d'enfants » en faisant allusion aux réserves naturelles, aux espaces protégés destinés à sauvegarder les espèces végétales et animales menacées. En effet, cette école devait offrir un milieu à l'éducation qui concilie l'école et l'enfance, selon une continuité entre la vie et l'école, refusant la logique de l'école républicaine qui sépare l'élève de l'enfant en l'assujettissant aux normes de l'institution scolaire. Cette école repensait les conditions de l'accueil matériel des enfants mais aussi les conditions et la temporalité des apprentissages. C'est pourquoi cette école à Vence articulait (et articule encore aujourd'hui) différents milieux de vie : le milieu écologique de l'école dans la nature (les arbres, le jardin, les coins de nature), le milieu géographique de l'école dans une commune des Alpes-Maritimes, le milieu sociologique accueillant des enfants de milieu populaire et un milieu didactique (la salle de classe, le matériel pédagogique et technique).

Après la guerre : l'institutionnalisation de l'école Freinet

Les années d'après-guerre sont marquées par un processus d'essaimage dans l'institution scolaire, en France et au-delà. L'élargissement de l'audience des Freinet suppose des adaptations et des réajustements (par exemple, en 1945, le titre de la revue du mouvement L'Éducateur prolétarien devient simplement L'Éducateur ; plus tard, l'École prolétarienne devint l'École du peuple puis l'École moderne) car le monde qui a vu naître la Machine Freinet a disparu avec la Seconde Guerre mondiale. L'objectif de Freinet était désormais de se rapprocher de l'Éducation nationale pour y essaimer et participer à la réforme en gestation de l'école. Pour décrire les combats menés par les époux Freinet, les auteurs mobilisent le concept de collectif de pensée de Fleck (1935), un ensemble constitué d'agents qui échangent des idées, qui partagent des savoirs considérés comme stables et qui s'accordent sur la nature des problèmes qu'il convient d'investiguer. Le concept d'institution, au sens où il est entendu par Durkheim (1894, p. 89-90), peut également convenir. Une institution est une forme d'organisation sociale qui institue des modes de pensée et de conduite partagés et considérés comme légitimes par les membres de cette institution. Il nous semble que le second volume de l'ouvrage décrit la Machine Freinet comme une institution didactique [START_REF] Sensevy | Le sens du savoir. Éléments pour une théorie de l'action conjointe en didactique[END_REF] elle-même traversée par des conflits et qui se trouva progressivement confrontée à d'autres institutions avec lesquelles elle s'entendit ou entra en conflit. Un premier conflit opposa Freinet au Parti communiste tout au long des années 1950. Ce conflit permet aux auteurs de l'ouvrage de préciser encore davantage les ressorts de la pensée de Freinet. L'oeuvre de Freinet fut critiquée par Henri Wallon et quelques « intellectuels » du Parti. Pour ces derniers, l'étude psychologique de l'enfant devait fonder l'épistémologie de la pédagogie. La théorie de la psychopédagogie inspirée du marxisme devait irriguer les pratiques enseignantes et, selon eux, la démarche de Freinet relevait en conséquence d'un pur empirisme. En outre, la multiplicité de ses références -Nietzsche, Bergson, Krishnamurti, Marx, Condorcet, Teilhard de Chardin, les médecins naturistes, etc. -relevait à leurs yeux d'un éclectisme coupable. Freinet pensait au contraire que la pratique permettait de questionner les problèmes travaillés en convoquant la théorie, la connaissance pratique précédant la science. Il était donc nécessaire de lancer un important travail de description et de théorisation des pratiques construites dans l'Entredeux-guerres afin de se protéger des attaques du Parti communiste et d'éviter leur dissolution dans les pratiques habituelles de l'Éducation nationale. Mais sa position était fragilisée par les militants pédagogiques qui, se revendiquant de la légitimité de la pratique pédagogique contre la position surplombante des universitaires, justifiaient finalement le dualisme, combattu par Freinet, opposant les universitaires aux instituteurs primaires, la pensée scientifique à l'empirisme. Deux collectifs de pensée, deux institutions, s'affrontèrent ainsi. Mais l'affrontement était aggravé par la fragilité interne de l'institution École Freinet. En effet, à partir de la fin des années 1950, le Mouvement Freinet, en élargissant son audience, développa également en son sein de nombreux conflits et de multiples fractures. Le mouvement de la Pédagogie institutionnelle derrière Fernand Oury se détacha tout d'abord du Mouvement Freinet, en se présentant comme un dépassement et une adaptation au monde moderne de la « pédagogie Freinet ». De nombreuses incompréhensions générèrent également des tensions. Selon Freinet, les pratiques pédagogiques éprouvées, les Techniques Freinet (du nom de la revue Techniques de vie, publiée à partir de 1959), résultaient d'une histoire et d'une logique qu'il fallait décrire minutieusement pour les partager et les faire proliférer. Les auteurs montrent que ce projet fit long feu et que les époux Freinet ne parvinrent pas, malgré tous leurs efforts, à faire partager l'histoire de ces techniques et la culture dont elles relevaient. Ils ne parvinrent pas à constituer un collectif de pensée ou une institution dans laquelle chacun aurait pu se reconnaître et qui aurait été susceptible de faire penser tout le monde dans une même direction. Certains militants souhaitaient s'emparer de méthodes à dupliquer dans leurs classes sans forcément prendre le temps d'en comprendre les ressorts. On sait que cette tentation reste très forte dans une profession soumise à de nombreuses contraintes. D'autres militants ne partageaient pas non plus toutes les références à l'origine de la « pédagogie Freinet » et n'en identifiaient pas tous les ressorts. Or, les époux Freinet partageaient une conception très radicale de la profession d'enseignant qui relevait selon eux tout à la fois d'un engagement intellectuel, personnel, par le rapport à soi, à son mode de vie et à son engagement, et éthique, par le rapport aux autres, l'intérêt pour le débat et la coopération. Ces difficultés internes à l'institution Freinet furent exacerbées par la confrontation à l'institution Éducation nationale. Pour intégrer cette dernière, le Mouvement Freinet dut procéder à certains compromis pour rendre la « pédagogie Freinet » compatible avec le cadre institutionnel général, au risque d'un grand flou conceptuel. Selon les auteurs, cet assujettissement du Mouvement Freinet à l'Éducation nationale produisit une vision minimaliste de la « pédagogie Freinet » réduite à ce qui la rendait acceptable, telles la coopération et la mise en activité de l'élève. Cette confrontation entre deux institutions, au poids respectif très inégal, produisit des débats au sein du Mouvement Freinet qui témoignèrent de la difficile conciliation de deux cultures institutionnelles. Ainsi, les militants de la région parisienne estimaient nécessaire de remettre en cause l'expérience spécifique de l'école de Vence plongée dans le milieu naturel et rural des Alpes-Maritimes, au nom de leur pratique d'une école dans un milieu très urbanisé et sociologiquement très défavorisé. De même, certaines écoles Freinet rétablirent l'usage de la récréation, au grand dam des Freinet pour lesquels la récréation n'était pas nécessaire si les élèves étaient passionnés par leur travail et investis dans leurs enquêtes. Selon eux, la récréation n'était utile que dans les écoles où les élèves, peu intéressés par des pratiques scolaires peu enrichissantes, avaient besoin de se défouler régulièrement. Selon les auteurs, l'expérience de l'école de Vence et les époux Freinet eux-mêmes furent marginalisés au sein de l'Institut Coopératif de l'École Moderne (ICEM). La transmission de la pensée de Freinet s'effectuait difficilement auprès des nouveaux acteurs qui affluèrent en grand nombre à partir des années 1960. Deux points de vue s'opposèrent désormais : l'ICEM s'enrichit de la diversité des points de vue de ses membres qui permettent une évolution des pratiques pédagogiques versus l'ignorance de l'histoire du Mouvement Freinet conduit à une désagrégation de la pédagogie de Freinet. Ce n'est pas la « pédagogie Freinet » qui doit bouger, c'est elle qui doit faire bouger ceux qui la pratiquent, en retrouvant la dimension profondément politique et


Nicola Peter Todorov

HAL is

Review by Nicola P. Todorov, Université de Guyane.

More than thirty years ago, Stuart Woolf published his book Napoleon's Integration of Europe, commonly considered to have been ground-breaking for what has been coined the "New Napoleonic history." [START_REF] Woolf | Napoleon's integration of Europe[END_REF] In contrast to the abundant historical literature devoted to the life of Napoleon and that of his family and to the numerous narratives of battles and military campaigns, Woolf focused on the actors of Napoleonic empire-building. According to Woolf, many French officials sent out to administer incorporated territories were convinced that they were the driving force behind modernization. The French administrators struggled ruthlessly to make the administration in the occupied territories uniform and to shape their societies on the model of the post-revolutionary French one.

Martijn van der Burg applies the concept of integration to what he calls the "northern periphery" of the French Empire, the Netherlands and the so-called Hanseatic departments, which, as far as Napoleonic empire building is concerned, have remained understudied. Incorporated nearly at same time, in the year 1810, they belonged to the French Empire for approximately three years. In line with these historiographical trends Van der Burg aims at exploring "the ways in which Napoleon and his imperial agents tried to integrate the present-day Netherlands and Northwest Germany into the French Empire by replacing local institutions and traditional governing practices with French ones" (p. 3). In agreement with Woolf, Van der Burg, acknowledges that Napoleonic officials often had to compromise, and hence to accept limits to obtain "collaboration."

To explore this dynamic interplay between Napoleonic empire-builders and local societies, the author has carefully studied the secondary literature, published sources, and a limited selection of archival material, such as correspondence between officials (regional and local), formal reports, memoranda, newspapers, and memoirs. Given the fragmentation of German source material, the analysis of the German departments is relatively more dependent on secondary literature and published source material than that of the Dutch departments (p 16). By proposing a comparative and transregional approach to Napoleonic governance in the Netherlands and Northwest Germany, this study certainly fills a gap in the Dutch-German body of scholarly literature. It also allows a wider international audience not fluent in Dutch and German access to research published in these languages.

The author carefully delineates the area under study by providing maps of the administrative divisions. After defining the key concepts of his study-conquest, incorporation, and integration-he provides a historiographical overview that underlines the difficulties of such a transregional and even transnational comparative approach. He divides his book into five chapters, addressing the North before conquest, conquest and incorporation, the work of the intermediary bodies of governance (the gouvernements généraux), the prefects appointed during the time these territories belonged to the French Empire, the subprefects, and a conclusion.

The author underlines the fundamentally different political experiences of the Dutch Republic and the northwestern German territories before they came under the influence of French Revolutionary policy and later their incorporation into the Napoleonic Empire. The Dutch Republic had been a powerful federal state since the beginning of the seventeenth century, undergone an endogenous revolutionary process during the 1780s, and seen its domestic policy influenced by the French since the outbreak of the Revolution before becoming a Napoleonic client state governed by Napoleon's brother Louis in 1806. The situation was quite different in the German territories. Much less politicized than the Netherlands, Northwest Germany remained politically fragmented before Napoleon decided to incorporate it into his Empire in 1810. Political thinking and activity flourished mainly in the Hanseatic towns of Hamburg, Bremen, and Lübeck. Moreover, even if Hamburg's merchants felt close to France's Girondins and the city's craftsmen more to the Montagnards, nobody in Northern Germany attempted to put the principles of the French Revolution into practice (p. 30). Van der Burg writes that most of Northwest Germany had experienced a degree of enlightened absolutism, but the relatively small Prussian territories later incorporated into Napoleon's Empire were largely administered by collegiate bodies whose organization differed from the French monocratic system.

In his chapter "Conquest and Incorporation," the author describes how the territories of the present-day Netherlands and Northwest Germany were seized by French troops and subsequently incorporated by imperial decree. While the French government orchestrated coups d'état in the Batavian Republic like that in 1801, Napoleon initially left some autonomy to the Dutch. As for Germany, Van der Burg recalls how Germany's political map was redrawn under France's influence by the Reichsdeputationshauptschluss (1803). The renewal of war with Britain in 1803 led the French immediately to occupy the electorate of Hanover, whose Prince-elector was the King of Britain.

The chapter devoted to the intermediary bodies of governance begins with an interesting overview of previous experiences with provisional administrative entities during the Napoleonic era which were thought to facilitate the integration of newly incorporated territories into the French Empire. Normally, these regional entities encompassing several departments were thought to be temporary, but in the case of the Gouvernement de Hollande supervised by the former Third Consul Lebrun, arch-treasurer of the Empire, and the Hanseatic Departments supervised by marshal Davout, they did not disappear until Napoleon's defeat. Reluctant to accept the task the emperor wanted to entrust to him, Lebrun was not the incarnation of the ruthless Napoleonic empire-builder. As for Davout, according to a French official, the marshal lived "like a prince," though, of course, Davout was a prince, Duke of Auerstaedt from 1808, promoted Prince of Eckmühl after the Wagram campaign against Austria (1809). Both governors were assisted by professional civil administrators, though Lebrun favored a milder approach than his counterpart in Germany.

In his chapter "Prefects--tools of integration" he states that some landrosts, the Kingdom of Holland's equivalent of the French prefects, were maintained in their positions, but sometimes employed in a different department. Above all, in the strategically important northerly coastal departments, administrators born in the South Netherlands were often appointed as prefects. In Northwest Germany prefects were more often born in France and Belgium and had served throughout the Empire. This difference appears even more pronounced in his study of the subprefects. His chapter "Subprefects regional tools of integration?" includes a very valuable prosopographical study of the sixty-six individuals employed as subprefects in the Dutch and the Hanseatic departments with information on their origin, age, and career. The recruitment of the subprefects appointed in the Dutch departments was more local, and only in 1812 and 1813 were some of these subprefects replaced by administrators born in the territories of what the author calls "old" France and present-day Belgium, the latter of which had undergone the integration process since 1795. Indeed, before their incorporation into the Empire, the Dutch territories had formed a client state ruled by Napoleon's brother Louis for more than four years. Even if it was not meant to be a model for other polities like Napoleon's kingdom of Westphalia (created in 1807), the Dutch kingdom under Louis did experience a reform policy. Louis initiated the codification of civil law and established a uniform subnational administration, aligning Dutch traditions with Frenchlike institutions and governance practices. He struggled, not always successfully, to replace the more collegiate Dutch administration by the more monocratic Napoleonic system.

In the more urbanized west of the Netherlands, subprefects without aristocratic origins dominated, while in the more rural east the regional nobility administered in the manner of the pre-revolutionary landed gentry, sometimes from their country houses instead of their offices in the district capitals. This recruitment practice shows both the achievements and the limitations of Napoleonic governance in a client state. Van der Burg sees the subprefect as an official who had to balance local interests and the requirements of the central government.

Thirty percent of the subprefects appointed in the Dutch territory were born in "old" France and present-day Belgium. The appointment of "Belgians" demonstrates their successful integration into the imperial system. King Louis' former kwartierdrosts were appointed subprefects in the Dutch departments of the Empire and not sent outside to administer newly incorporated northwestern German territories. The maps showing their circulation reveal two distinct clusters for the prefects appointed in the Netherlands and Northwest Germany. The appointment of more subprefects from outside the kingdom of Holland towards the end of the Empire, as well as the geographical patterns of their careers, demonstrates that the impetus to enforce French legislation intensified over time.

Apart from the very short-lived incorporation of the remaining electorate of Hanover into the kingdom of Westphalia in 1810, only small parts of the Hanseatic departments had experienced Napoleonic governance by a client state: the Northern part of the grand duchy of Berg and a part of the Westphalian Weserdepartment around Osnabrück. Few administrators with Napoleonic governance practice were available there, and many more officials born in France and earlier annexed territories were appointed.

Van der Burg concludes that integration remained incomplete. Traditionally, he says, the relative success or failure of integration was explained by the cultural or geographical distance from the imperial core, the duration of Napoleonic rule, and reform policy. The German territories on the left bank of the Rhine thus experienced nearly twenty years of French rule and almost fifteen years of revolutionary and Napoleonic legislation, while most of the German north experienced less than three. Van der Burg suggests that an additional factor in the difficulty of integrating the North resulted from the lack of both coordination between the different actors and a clear integration plan, as well as the internal rivalries between French administrations and intermediate bodies. This is perhaps debatable. Napoleon often encouraged rivalry among different administrations, a practice witnessed by contemporary administrators, and it would perhaps not have been in the interest of the central government to encourage the formation of large regional blocks in this Dutch-Northwest German periphery. It should be recalled that the creation of relatively small administrative units such as the departments in 1790, compared to the average size of the former Ancien Regime provinces, was an important tool of French centralization.

Given the short time these territories belonged to the French Empire, an unachieved process of integration was hardly surprising, and the brevity of their inclusion would perhaps be explanation enough.

Van der Burg's approach and his conclusions, however, raise methodological questions. Even if Napoleonic administrators had an empirical understanding of the degree of integration, and disagreed about the degree of integration achieved, it must be asked whether the degree of integration may be assessed alone by studying the "tools" of integration. Can the success or failure in the implementation of Napoleonic governance be evaluated simply by the actions of professional administrators from the governor-general to the subprefects and their diverging impressions of the degree of otherness and their opinions of the ways to achieve integration, without assessing the involvement of the population?

As the author acknowledges, the empire's ability to raise huge armies is presented as a measure of its success or failure. Thus, the rebellions against the French Gendarmerie, especially because of military conscription, were relatively numerous both in the incorporated Dutch and northwestern German territories, whereas in territories incorporated earlier, resistance to conscription tended to lessen over time. [START_REF] Aurélien Lignereux | Policiers et gendarmes dans les départements annexés[END_REF] Nevertheless, even prefects like Petit de Beauverger, pessimistic about the population's willingness to cooperate, recognized that "taxation and conscription encountered few problems" (p. 115). Moreover, the "blood tax" required by Napoleon, above all for the French Navy, was certainly higher than in other territories.

The degree of integration into the Napoleonic system has led Michael Broers to distinguish between an inner Empire (the imperial core), intermediate zones, and an outer empire, the periphery. The delimitations of these types of territories might be refined in the light of new research and new evidence such as that provided in the book under review. In his second edition of Europe under Napoleon, Broers published a map including the Netherlands in the inner Empire and justified this choice by the early and relatively easy introduction there of French Laws, whereas the neighboring German Northwest, where the new regime was radically introduced as a block, was placed in the outer Empire. [START_REF] Broers | Europe under Napoleon[END_REF] Hence, one might wonder whether beyond the judgment of incomplete integration and internal diversity from district to district, there were regional differences in the degree of integration between both areas. Were the Netherlands, initially more politicized and then administered by mainly "smooth" Dutch subprefects, more or better integrated into the Napoleonic system than the German North, where young and zealous French subprefects worked to implement harshly French laws and institutions? Van der Burg sees the maintenance or rejection of the Napoleonic heritage in governance by the successor states as an indicator of the acceptance or not of integration. The revolutionary and Napoleonic period played an important role in Dutch nation building, and the French legacy was better maintained there than it was in Northwest Germany. In Hamburg, pre-Napoleonic conservatism once again dominated, but there was a minority who wanted to "preserve the best of Napoleonic governance" (p. 156). But what was this "best"? Having extensively written about Louis' and Napoleon's reform policy in the Netherlands, Van der Burg does not tell us much in this book about the social issues that were at stake in implementing Napoleonic governance. For instance, what precisely was already adapted to Dutch customs in Louis' hybrid Code civil? If the subprefect had to balance between local interests and the requirements of the central government, as Van der Burg argues, it would have been interesting to know how the Dutch local subprefects from the gentry behaved when faced with enforcing the legislation on seignorial duties, fiscal equity, or even conscription that withdrew manpower from agriculture.

The study of the actors of integration rarely goes below the district level, that of the subprefects. But there were administrators closer to the ground: the mayors of the communes. Analyzing administration at the communal level would, I think, offer additional insight into the nature of local "collaboration" and the limits that Napoleonic empire-builders had to accept. The lack of such analysis might of course be due to the rarity of research on communal administration, but Antoinette Joulia's work provides some evidence, and an article by John Dunne shows that in the annexed territories, the central government adapted the size of the basic units without suppressing administration on the village level. In his study of the mayors of the Bouches-du-Weser, Dunne notes a stabilization of the communal mayors at the end of the Empire [START_REF] Antoinette | Les institutions administratives des départements hanséatiques[END_REF].

More generally, a more systematic reflection on the choice of the area under scrutiny would be helpful. There have been previous projects of comparative research like Monarchy in Turmoil. Rulers, Courts and Politics in The Netherlands and Germany, C.1780 -C.1820.[5] While the Dutch and Hanseatic departments shared a common duration of incorporation into the French Empire and a certain geographic and linguistic proximity, the author could have said more about the geopolitical aims of quasi-simultaneous incorporation. We learn that the kingdom of Holland was incorporated because "Napoleon was growing frustrated with the military weakness of Louis' army and continuing illegal trade with England" (p. 54). As for Northwest Germany, its annexation "marked a new phase in Napoleon's enforcement of the Continental blockade" (p. 57) and his foreign minister "Champagny pointed at possible economic benefits of canalization, also to avoid the British fleet in the North Sea" (p. 61). The year 1810 was indeed a year of a thorough change in Napoleon's policy. The northern parts of the electorate of Hanover had been a pays reserve until that time, and their incorporation into the kingdom of Westphalia had been subject to a future peace with England as stipulated by the secret articles of the treaty of Tilsit with Russia (1807). But on 14 January 1810, Napoleon concluded a treaty with Westphalia ceding those parts of Hanover. Then, in August 1810, Napoleon summoned his brother Jerome to withdraw his troops from the North Sea coast and canceled the treaty in October. The control of this Northern "periphery" was of high strategic importance in Napoleon's eyes, and strategic aims can help explain the lack of a clear integration plan as well as the military exploitation by conscription that hampered the acceptance of the Napoleonic system.

All in all, Van der Burg provides a clearly structured analysis of Napoleonic governance in the Netherlands but also shows the paths for future research in this area.

H

  -France Review Vol. 22 (July 2022), No. 111 Martijn van der Burg, Napoleonic Governance in the Netherlands and Northwest Germany: Conquest, Incorporation, and Integration. Basingstoke: Palgrave Macmillan, 2021. $59.99 U.S. (hb). ISBN 9783030666576; Open Access (eb). ISSN 9783030666583.