METHOD FOR FORMULATING A TORQUE COMMAND SUBMITTED BY AN ENGINE OF A VEHICLE WITH ELECTRIC AUXILIARY DRIVE

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a method for developing a control system for the torque supplied by a motor of an electrically assisted vehicle, such as an electric bicycle. It also relates to a computer program implementing this control development method, and to the electrically assisted vehicle thus controlled. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] Electrically assisted vehicles are designed to be powered by the effort of their users. These vehicles are equipped with a battery and an electric motor to assist these users.

[0003] Conventionally, the motor is controlled to provide a constant torque, meaning it applies a constant driving force to the vehicle. Alternatively, it can be equipped with a sensor that measures the effort exerted by the user—for example, a sensor on the bicycle's crankset measuring the pedaling torque. In this case, the motor includes an "open-loop" control device that applies a fixed gain to the torque supplied by the user. The control system is designed to provide a complementary torque that is proportional to the torque supplied by the user. The applied gain is sometimes selectable by the user, for example, using a selector on the handlebars, to provide more or less assistance.

[0004] In both cases mentioned above, the assistance provided by the electric motor does not take into account the user's comfort, allowing them to manage the effort exerted over the entire length of their journey and making the most of the energy available in the battery.

[0005] Document FR2938233 discloses an electric bicycle equipped with sensors that adjust the motor's drive or braking force to the user's effort, thus ensuring the user exerts a target effort. When the bicycle's control system determines that the battery charge level is insufficient to complete the planned route, the user is offered the option to modify the route, limit the electric assistance, or even stop it altogether. It therefore appears that the battery energy management implemented in the solution proposed by this document is very rudimentary, with the available energy being drawn without any modulation until it is depleted.

[0006] Document FR2976693 proposes determining the amount of energy required to complete a journey and distributing this energy, over successive sections of the journey, between a portion supplied by the electric motor and a supplementary portion supplied by the cyclist. The solution proposed by this document therefore consists of preparatory work to plan the effort required from the cyclist, which the cyclist must strive to maintain throughout the journey. The document optionally provides for controlling the electric motor so that it consumes precisely the allocated energy on each section of the journey. However, this control (the principle of which is the only explanation provided in this document) remains focused on the battery's electrical consumption and does not take into account the actual effort exerted by the cyclist, and therefore their comfort during the journey.

[0007] Document EP1324913Al discloses a method for developing torque control provided by a motor of an electrically assisted vehicle, the motor being powered by a battery, the control being developed by a control unit, connected to a vehicle speed sensor and a user-applied force sensor, the method comprising the following steps: a step of determining a value of vehicle speed and user-applied force from measurements provided by the speed sensor and the force sensor, and a step of determining the torque control including the application of a gain to the force, the gain having a value that varies with the speed measurement.

[0008] Other relevant documents are US2018 / 319457Al, WO2014 / 033388A1, EP2548795 A1, JP2001199378 A, EP3408168Al, US 2004 / 206563Al and EP2644492A1. SUBJECT OF THE INVENTION

[0009] One aim of the invention is to remedy, at least in part, the aforementioned drawbacks. More specifically, it aims to provide an electrically assisted vehicle that takes into account user comfort, allowing the user to manage the effort exerted throughout their journey while taking advantage of the available battery energy at all times. BRIEF DESCRIPTION OF THE INVENTION

[0010] To achieve this goal, the object of the invention proposes a method for developing a torque control supplied by a motor of an electrically assisted vehicle, the motor being powered by a battery, the control being developed by a control unit to compensate for an excess of effort supplied by a user beyond a target effort.

[0011] The process includes the following steps: a step of determining a vehicle speed value and the additional effort provided by the user corresponding to the portion of the effort that exceeds the target effort; a step of determining the torque control including the application of a gain to the additional effort, the gain having a variable value with the measurement of the speed.

[0012] According to other advantageous and non-limiting features of the invention, taken alone or in any technically feasible combination: The gain exhibits a decreasing value with speed; the method includes a step of adjusting the target effort; the gain value is constant over a speed range extending from zero speed to a threshold speed, and strictly decreasing over a range extending from the threshold speed to a cutoff speed strictly greater than the threshold speed; the gain value is linearly decreasing over the range extending from the threshold speed to a cutoff speed; the method includes a step of adjusting the threshold speed; the method includes a step of determining an available battery energy level, and the threshold speed adjustment step includes determining the threshold speed according to the battery charge level; the threshold speed adjustment step includes the user selecting a threshold speed from a list of predetermined threshold speeds;The method comprises: a preliminary input step of a starting point and a destination point for a route; a step of determining an available battery energy level; and wherein the threshold speed adjustment step comprises determining an optimal threshold speed corresponding to the maximum threshold speed enabling the user to complete the route without depleting the battery; the preliminary step comprises determining the route as a sequence of contiguous segments, each segment being associated with a segment length and a segment gradient; the threshold speed adjustment step comprises repeating the following substeps: allocating to each segment an amount of battery energy necessary for its travel at a given threshold speed; determining an amount of energy required to complete the route at the given threshold speed;Compare the amount of energy required to complete the journey to the available battery energy level; modify the given threshold speed according to the result of the comparison; the amount of energy allocated to each segment is determined by using a vehicle parameterization function that links the battery energy required to travel a given distance, for a given gradient, and for a given threshold speed. The parameterization function is established or adjusted based on data collected from the user.

[0013] The invention also relates to a computer program comprising instructions adapted to the implementation of each of the steps of the process of developing a torque control as described above, when the program is executed at least partially by the control unit.

[0014] Finally, the invention relates to an electrically assisted vehicle comprising a battery-powered motor, a vehicle speed sensor, a user-provided force sensor, and a control unit executing a program configured to compensate for an excess of effort provided by a user, the program determining a torque control of the motor by applying a gain to the excess of effort, the excess of effort being the effort measured by the force sensor beyond a target effort, the gain having a variable value, possibly decreasing, with the speed measurement provided by the speed sensor. BRIEF DESCRIPTION OF THE FIGURES

[0015] Other features and advantages of the invention will become apparent from the detailed description of the invention which follows with reference to the accompanying figures in which: [ Fig. 1a ] ] Fig. 1b ] THE figures 1a and 1bschematically represent a bicycle conforming to the invention; [ Fig. 2 ] There figure 2 represents the architecture of a control unit; [ Fig. 3 ] There figure 3 represents a schematic diagram of a process according to the invention; [ Fig. 4 ] There figure 4 represents an example of a law of evolution of a gain of a regulation program conforming to the invention; [ Fig. 5 ] There figure 5 represents an example of a parameterization function. DETAILED DESCRIPTION OF THE INVENTION

[0016] In reference to the figures 1a and 1b , we first present an electrically assisted vehicle, here a bicycle 1, which can implement a process according to the invention.

[0017] The mechanical structure of this bicycle is well known and will therefore not be detailed here. Bicycle 1 is equipped with a motor unit 2, comprising an electric motor positioned in the example shown on the bottom bracket, but which could equally well have been placed on a front or rear wheel. The motor unit 2 includes a controller 2a for generating torque control for the electric motor based on a control signal provided by a control unit 3 to which the controller 2a is electrically connected. This controller can be digitally configured by the control unit 3 to implement any type of control law, for example, a PID controller. Generally, it can apply a gain to the control signal provided by the control unit 3 so that the motor M develops the commanded torque.By "applying a gain", it may mean performing the product of the gain with the value of the control signal (and implementing proportional control in this case) or applying any other more complex form of operation, such as the aforementioned PID control law, linear or non-linear.

[0018] The motor unit 2 may also include a force sensor K, and the controller 2a may also provide signals representing the effort exerted by the user. These signals may include the power and / or torque applied by the user to the pedals, measured by sensors that can be integrated into the motor unit 2. These power and / or torque signals are provided to the control unit 3 for processing. Alternatively, or in addition, an acceleration sensor may be used, and more generally, any device that allows for the evaluation of the driving effort level of the vehicle 1.

[0019] To enable the operation of the electric motor M, the bicycle 1 is also equipped with an energy storage device, here in the form of a battery 4. The storage device can be a lithium-ion, lithium-polymer, supercapacitor, or any other type of battery and will be referred to as "battery" in the remainder of this application for simplicity. The battery 4 is electrically connected to the motor unit 2 and the control unit 3 to supply them with operating energy. The battery 4 may be equipped with its own controller 4a, as is very conventional, so that it can provide the control unit 3 with its charge level. Alternatively, or in addition, this charge level can be estimated by the control unit 3 from the voltage and current measurements delivered by the battery 4.

[0020] Bicycle 1 is equipped with at least one speed sensor V, electrically connected to the control unit 3. Any type of sensor is suitable; for example, it could be a reed switch located near one of the bicycle's wheels. The switch is activated by the passage of a magnet carried by the wheel. The frequency of the switch actuation signal can be decoded by the control unit 3 to determine the wheel's rotational speed and thus the drive speed of bicycle 1. In the example shown, bicycle 1 has two speed sensors V, one on the front wheel and the other on the rear wheel.

[0021] Of course, any other form of speed sensor may be suitable, and the speed of the bicycle can generally be determined from any information provided by any form of sensor other than the one just listed.

[0022] Bicycle 1 may optionally include at least one selector switch, operable by the user, for example, to allow them to choose the level of assistance provided by the electric motor. The selector switch may be mounted on the handlebars and electrically connected to one of the input / output (I / O) ports of the control unit 3 so that the user's selection can be processed there.

[0023] Finally, bicycle 1 carries an electronic housing containing the control unit 3. This unit, schematically represented on the figure 2The device may take the form of a single electronic board or a plurality of electronic boards comprising, in a known manner, at least one processor or microcontroller P enabling the execution of computer programs stored in a memory module. This memory module may also be used to store all the data provided by the sensors and all the parameters necessary for implementing the method according to the invention.

[0024] The control unit 3 is electrically connected to the various electronic or electrical components on the bicycle 1 via its input / output ports (I / O), which allow it to acquire the electrical signals provided by these components. The control unit 3 can also generate signals, under the control of the various computer programs it runs, for example, to configure the controller 2a of the motor unit 2.

[0025] The control unit 3 includes (or is connected to) a GPS geolocation device, for example of the GPS or more generally INSS type, and an inertial measurement unit (IMU). The control unit 3 can thus determine the position and attitude of the bicycle, which allows it, in particular, to determine the gradient of the section on which the bicycle is traveling, and even its speed, either in addition to or as a replacement for the speed sensors already described.

[0026] The control unit 3 can be connected to remote computing and / or storage devices or other types of electronic devices via a COM communication interface. This interface can implement any suitable protocol. This could involve connecting the control unit 3 wirelessly via 4G, 5G, Wi-Fi, NFC, Bluetooth, etc. It could also involve connecting the control unit 3 via a wired connection, for example, via USB. For instance, a Bluetooth connection can be used to connect the control unit 3 to a user-worn heart rate sensor, allowing the data to be transmitted to the unit for processing. Such a sensor can form a K-sensor, as will be detailed later in this description.

[0027] The control unit 3 is therefore capable of collecting a large amount of data on a regular basis for storage in the internal memory (MEM) and / or uploading it to a remote computing and storage device (C) using its COM communication interface. It can thus be anticipated that all measurements will be stored in the internal memory (MEM) as they are acquired and that a program running on the processor will initiate the transfer of this data on a regular basis (e.g., daily) or opportunistically (e.g., upon detection and connection to a known Wi-Fi network) to the remote computing and storage device (C) to make it available to the user.

[0028] Similarly, the COM communication interface can allow the user to configure or set up their bicycle, for example using their smartphone directly by communicating with the control unit 3 or via a program running on the remote device C.

[0029] In order to enable the implementation of the method which is the subject of the invention in an elaborate form (and without this forming either a necessary or a limiting list), the control unit 3 is configured to proceed iteratively (for example every 100 ms or every second depending on the nature of the quantity measured) to the measurement or determination of the following data: Battery charge level 4; Bicycle drive speed 1; Bicycle incline used to determine the slope of the course; Bicycle position (latitude, longitude, elevation) 1; User effort (power and / or torque applied to the pedals, bicycle acceleration, or user heart rate).

[0030] In a very general way, the invention seeks to assist the user of the bicycle 1 so that the latter deploys a moderate effort, referred to as the "target" in the rest of this description, for the entire duration of his journey, or for the longest possible duration.

[0031] The term "user effort" refers to the physical effort exerted, which can be measured by any appropriate mechanical or physiological quantity. This can include, as previously noted, pedaling power or torque, as measured by the V and K sensors on bicycle 1. It can also include energy expended in calories or the user's heart rate, either of which can be measured by a sensor worn by the user and displayed on the control unit 3. The target effort is a process parameter that can be stored in the control unit's MEM memory. As will be detailed later in this discussion, this target effort does not necessarily have a fixed value.

[0032] To achieve this objective, the control unit 3 and the motor controller 2a implement a method for generating a motor torque control designed to compensate for excess force applied by the user. This excess force simply corresponds to the portion of the force that exceeds the target force. The excess force is, of course, zero if the user's effort is less than the target force.

[0033] The method according to the invention comprises the following steps: the determination of a value of the speed of the bicycle 1, and of the effort provided by the user from the measurements provided by the different sensors V, K carried by the bicycle 1 or by the user; the determination of the excess effort by calculating the difference between the target effort and the effort provided by the user in order to retain only the negative part.

[0034] These steps can be implemented by a control program of the control unit 3 and the excess effort forms the control signal supplied to the motor controller 2a. the determination of the torque control by applying a gain to the additional transmitted forces.

[0035] This step can be implemented by a control program of controller 2a which thus applies the torque control to the electric motor M. The latter deploys the corresponding torque to provide the driving force to the system formed by the bicycle 1 of its user U, 1+U.

[0036] As can be clearly seen on the figure 4 This creates a closed-loop regulation of the 1+U system, constantly seeking to reduce or eliminate any excess effort exerted by the user, thus ensuring their comfort. However, if this effort is less than the target effort, they receive no assistance.

[0037] According to the invention, the gain G has a variable value, and the method includes a step (which can be implemented by the control unit 3) for determining the value of this gain G according to the determined value of the bicycle's speed 1. "Variable value" refers to a continuous evolution of the gain G with speed, without any singular points. It is therefore not a prior art regulator configured to abruptly cut off all electrical control when the speed exceeds a maximum, often regulated, value of 25 km / h.

[0038] In a preferred embodiment, the variable value of the gain decreases with speed. Put another way, the invention aims to reduce the assistance provided to the user as the bicycle's speed increases. Since energy varies significantly with speed, this method preserves the battery's energy level, allowing the user to be assisted over an extended distance, advantageously the entire length of their journey.

[0039] In practice, the value of the gain G can be determined by the control program running on the control unit 3, based on the determined speed value and using a behavior law that forms a parameter stored in the MEM memory. The law can be stored in this memory in any suitable form, for example, as a table of values ​​or as coefficients of a generic function. The value of the gain G, once calculated by the control program, is communicated to the controller 2a so that it can configure itself to apply the appropriate torque command.

[0040] This succession of steps forming the core of a process according to the invention is reproduced iteratively, for example every 100 ms, in order to ensure the regulation of the motor M.

[0041] The law governing the evolution of the gain G with velocity can take any suitable form. However, and according to an advantageous approach represented on the figure 4 The gain G forms a proportional term in the control signal, and the gain G evolution law exhibits a constant value G0 over a speed range extending from zero to a threshold speed Vs, then a strictly decreasing value from the threshold speed Vs to a cutoff speed Vc (beyond which the gain is zero, and the assistance is effectively cut off). Within the constant range, and up to the threshold speed Vs, the user therefore receives full assistance designed to very dynamically offset the additional effort they exert. Beyond the threshold speed Vs, the assistance is reduced and cuts off completely from the cutoff speed Vc onward. This law is represented on the... figure 4 .

[0042] The decay of the gain G between the threshold speed Vs and the cutoff speed Vc can follow any evolution. For ease of implementation, a linear decay can be chosen.

[0043] As an illustration, a cut-off speed Vc of 25 km / h may be used, particularly when regulations require the electric assistance to be cut off beyond this speed, and the threshold speed Vs may, for example, be set at 20 km / h.

[0044] The target force does not necessarily have a constant value stored in the MEM memory of the control unit 3. In an advantageous implementation of the method, this target value can be selected by the user. This selection can be made using a selector, for example, located on the handlebars of the bicycle, or via the remote calculation and storage device. In a variant of this implementation, the target force has a variable value with respect to the speed of the bicycle 1. As an example, and in the specific case where the effort exerted by the user is measured by the torque applied by the user to the crankset, the target force can be chosen to vary, for example, linearly, between 15 Nm at zero speed and 10 Nm at 25 km / h.The processes aimed at adjusting the target effort value (by user selection or by calculation) can be implemented during an adjustment step of the control program which runs on control unit 3.

[0045] According to a highly advantageous feature of the invention, the threshold speed Vs is also an adjustable parameter of the process. Depending on whether this threshold speed is adjusted upwards or downwards, it is very easy to implement assistance regulation that favors either speed or battery conservation. But whatever the chosen level of the threshold speed Vs, this regulation constantly aims to limit the excess effort exerted by the user beyond the target effort.

[0046] Several ways of implementing this feature are possible, which in all cases can be implemented by the control program executed on the control unit 3, during a step of adjusting the threshold speed Vs. First method of implementation

[0047] This first implementation mode is particularly useful when the user wishes to perform a free-roaming route, that is, without having previously communicated a destination point to the control unit 3 or the remote computing and storage device C. In this free-roaming mode, it is therefore not possible to take into account the distance or the topology of the route to precisely manage the available energy from battery 4.

[0048] However, in this case, a selector switch on bicycle 1 can be used to allow the user to choose between an "eco" mode and a "sport" mode, each corresponding to a different, predetermined threshold speed Vs. The "eco" mode is associated with a lower threshold speed Vs than the "sport" mode. More generally, a list of predetermined threshold speeds can be stored in the MEM memory of the control unit 3. The method of the invention can then include a step for selecting the threshold speed Vs from among the predetermined speeds in the list. In this example, this selection is made by the user using a dedicated selector switch on the bicycle.In practice, and when the cut-off speed Vc is 25 km / h, the "sport" operating mode can correspond to a speed of 20 km / h and the "eco" mode to a threshold speed of 10 km / h.

[0049] In a variant of this implementation (which can be combined with the manual selection of the threshold speed just described), the threshold speed Vs is determined according to the charge level of battery 4. The method of the invention provides in this case a step of determining the level of energy available in battery 4. The adjustment step can include the selection of a first predetermined threshold speed if the available energy level of the battery is less than a predetermined threshold, and the selection of a second predetermined threshold speed, higher than the first, if the available energy level of the battery is greater than the predetermined energy level threshold of battery 4.

[0050] Rather than selecting the threshold speed from a list of predetermined values, we can more generally determine this threshold speed Vs so that it is made continuously variable or piecewise constant with the available energy level of the battery 4. Second method of implementation

[0051] The second implementation mode is possible when the user's route is known or, at the very least, when their destination is established. This destination may, for example, have been entered by the user, estimated based on their route history, or provided by an additional device, such as their smartphone. In all cases, in this embodiment, the command generation process includes a preliminary input step of a starting point for the route (which can be automatically determined from measurements provided by the location unit) and a destination point. This preliminary step is preferably implemented by the control unit 3, which has all the necessary resources to perform it, and therefore does not require a connection to the remote computing and storage device C.

[0052] Using this information, a planning program executed by the remote device C can calculate or develop a route in the form of a sequence of segments. This calculation can utilize a topographic information map accessible to the remote device C. More precisely, the calculated route can be represented numerically as a graph with multiple interconnected nodes, each node corresponding to an endpoint of a route segment. Each segment can be associated with the distance between the two nodes and the average slope or elevation difference between them. This information can be extracted from the topographic information map. The route calculation can be performed using any known method, often employing a combinatorial optimization technique to limit the route length, its cumulative elevation difference, or an estimated travel time.

[0053] Regardless of how the calculated route is digitally represented, the threshold speed adjustment step (Vs) involves determining an optimal threshold speed. This corresponds to the maximum speed that allows the user to complete the route without depleting the battery. In other words, the optimal threshold speed is determined, at which point the electric assistance is reduced. This optimal regulated threshold speed remains fixed for the entire route, ensuring that the electric motor's assistance is maintained until the destination.

[0054] To establish this optimal threshold speed, the planning program uses a bicycle parameterization function that links the battery energy needed to travel a given distance, a given slope, and a given threshold speed.

[0055] Such a parameterization function can be stored in the remote device C. It can be in any useful numerical form: for example, as a table of values ​​or a numerical function. This has been graphically represented on the figure 5A specific example, by way of illustration, of such a function generally links battery energy to the gradient in the form of a sigmoid function indexed by the threshold speed. The parameters of the sigmoid can be established from data collected on battery energy consumed, gradient, and threshold speed from a large number of users in order to determine an average function. Advantageously, this function can be established or adjusted from data collected from the user themselves so that it accurately reflects their usage or physical performance. This personalization can be achieved by an optimization program implemented by the remote device, using data collected by the control unit 3, which is regularly uploaded to it.This personalized setting function can only be available after the user has used their bicycle sufficiently and, in the meantime, a generic setting function can be used by the remote computing and storage device C as well as by the control unit 3.

[0056] Alternatively, the generic parameter function can be representative of a group of users, for example users located in a specific region: in the mountains, on the plains or in a specific city.

[0057] In all cases, there is a parameter setting function linking the battery's energy requirement to travel a determined distance along a determined slope, with the electric assistance being regulated using a control law according to the invention and presenting a determined threshold speed.

[0058] Determining the optimal threshold speed of a pre-established path uses the parameterization function and forms a simple combinatorial optimization problem to solve.

[0059] Thus, the threshold speed adjustment step may include repeating the following sub-steps: assign to each segment a quantity of battery energy required to complete its journey at a given threshold speed (by applying the parameterization function to the data of each segment of the graph); determine the quantity of battery energy required to complete the journey at the given threshold speed (by adding the energies assigned to each segment); compare the quantity of battery energy required to complete the journey to the available battery energy level; modify the given threshold speed according to the result of the comparison.

[0060] If the amount of battery energy required to complete the journey exceeds the available battery energy, the given threshold speed is lowered before the sequence of steps is repeated. Conversely, if the threshold speed is higher, it is increased.

[0061] This repetition can be carried out a predetermined number of times or to satisfy an end criterion. For example, the substeps can be repeated until the threshold speed given in the last iteration leads to the consumption of between 80% and 90% of the remaining battery energy level.

[0062] If this sequence does not converge, i.e. if it is impossible to find a threshold speed allowing the entire journey to be completed while preserving at least part of the battery energy level, then a pre-established minimum threshold speed (for example 10 km / h) can be chosen and the user warned that it is likely that they will not be able to get assistance throughout their journey.

[0063] Otherwise, an optimal speed value is determined using a binary search. When the substeps are implemented by the remote computing and storage unit C, the optimal threshold speed value is communicated to the control unit 3 so that it can configure the control program with the determined threshold speed Vs. Once configured in this way, the control unit 3 and the motor controller 2a implement the regulation that naturally limits the excess effort exerted by the user while preserving maximum battery energy. This ensures maximum user comfort for the bicycle 1.

[0064] Any optimization method implementing the repetition of previous substeps may be suitable, such as a gradient method, a stochastic optimization method of the simulated annealing type, or any other numerical optimization method.

[0065] Of course the invention is not limited to the implementation methods described and alternative embodiments can be made without departing from the scope of the invention as defined by the claims.

[0066] It can therefore be applied to all types of vehicles benefiting from electric assistance designed to supplement the user's efforts. For example, this could be an electric scooter.

[0067] Although the example described illustrates the implementation of the control generation process by a control unit assisted by a motor controller 2a, and possibly a remote computing and storage device C, other computer architectures are possible. For instance, all calculations could be performed by the control unit 3, which then directly applies the torque command to the motor M.

[0068] Also, although preferentially the gain has a decreasing variable value with the measurement of speed, a different control law can be considered, with a gain that can evolve at least in some cases to have an increasing value with speed, for example in the form of steps, so as to actively solicit the user.

Claims

1. A method of generating a torque command provided by a motor (M) of an electrically assisted vehicle (1), the motor (M) being powered by a battery (4), the command being generated by a control unit (3), connected to a speed sensor of the vehicle (V) and to a sensor for a force (K) provided by a user, in order to compensate for a surplus force provided by a user beyond a target force, the method comprising the following steps: - a step for determining a vehicle speed value and a value of the surplus force provided by the user from measurements provided by the speed sensor (V) and the force sensor (K), the surplus force corresponding to the portion of the force that exceeds the target force; - a step for determining the torque command comprising applying a gain (G) to the surplus force, the gain having a value that varies with the speed measurement.

2. The generating method according to the preceding claim, wherein the value of the gain (G) decreases with speed.

3. The generating method according to any one of the preceding claims, comprising a step of adjusting the target force.

4. The generating method according to any one of the preceding claims, wherein the value of the gain (G) has a constant value over a speed range extending from zero speed to a threshold speed (Vs), and a strictly decreasing value over a range extending from the threshold speed (Vs) to a cut-off speed (Vc), strictly greater than the threshold speed (Vs).

5. The generating method according to the preceding claim, wherein the value of the gain (G) has a linearly decreasing value over the range extending from the threshold speed (Vs) to a cut-off speed (Vc).

6. The generating method according to one of the two preceding claims, comprising a step of adjusting the threshold speed (Vs).

7. The generating method according to the preceding claim, comprising a step of determining an available energy level of the battery (4), and the step of adjusting the threshold speed (Vs) comprises determining the threshold speed (Vs) according to the charge level of the battery (4).

8. The generating method according to one of the two preceding claims, wherein the step of adjusting the threshold speed (Vs) comprises the user selecting a threshold speed (Vs) from a list of predetermined threshold speeds.

9. The generating method according to claim 5, comprising: - a preliminary step of entering a starting point and a destination point of a route; - a step for determining an available energy level of the battery (4); and wherein the step of adjusting the threshold speed (Vs) comprises determining an optimum threshold speed corresponding to the maximum threshold speed enabling the user to complete the route without draining the battery (4).

10. The generating method according to the preceding claim, wherein the preliminary step comprises determining the route as a sequence of contiguous segments, each segment being associated with a segment length and a segment slope.

11. The generating method according to the preceding claim, wherein the step of adjusting the threshold speed (Vs) comprises repeating the following sub-steps: - allocating each segment the amount of battery energy required to complete its route at a given threshold speed; - determining the amount of energy required to complete the route at the given threshold speed; - comparing the amount of energy required to complete the route with the level of energy available from the battery (4); - modifying the given threshold speed according to the result of the comparison.

12. The generating method according to the preceding claim, wherein the amount of energy allocated to each segment is determined by calling up a vehicle parameterization function relating the battery energy required to cover a given distance, for a given gradient and for a given threshold speed.

13. The generating method according to the preceding claim, wherein the parameterization function is established or adjusted based on data collected from the user.

14. A computer program comprising instructions adapted to the implementation of each of the steps of the method for generating a torque command according to one of the preceding claims, when the program is executed at least partially by the control unit (2).

15. An electrically assisted vehicle (1) comprising a motor (M) powered by a battery (4), a vehicle speed sensor (V), a force sensor (K) for a force provided by the user, and a control unit (3) executing a program configured to compensate for an excess force provided by a user, the program determining a torque command of the motor (M) by applying a gain to the excess force, the excess force being the force measured by the force sensor above a target force, the gain having a value which varies with the speed measurement provided by the speed sensor.

16. The electrically assisted vehicle (1) according to the preceding claim, wherein the value of the gain (G) decreases with speed.