Suspension and Traction Systems

Abstract

A suspension and traction system is described for a vehicle equipped with a frame and propulsion elements (92) that rotate on the ground. An electric actuator (M3) is used to determine the steering angle (β) of the propulsion elements. [Selected Figure] Figure 1

Description

[Technical field]

[0001] The present invention relates generally to suspension and traction systems, and more particularly to electric vehicles. [Background technology]

[0002] In the latest generation of electric vehicles, the traction force is transferred directly into the wheels. WO 2015 / 155670, for example, describes two electric motors controlled independently of each other, which are able to vary the distance between the vehicle frame and the wheels. However, no indication is given of how to steer the wheels, specifically addressing the difficult problem resulting from the complexity of the structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2015 / 155670 Summary of the Invention [Problem to be solved by the invention]

[0004] The main object of the present invention is to improve on the invention of WO 2015 / 155670, in particular by solving the problems related to steering the system as mentioned above.

[0005] This object is achieved by a system and / or method according to the appended claims, the dependent claims defining advantageous variants. [Means for solving the problem]

[0006] A suspension and traction system is presented for a vehicle equipped with a frame and propulsion elements by rolling on a ground adapted to move the vehicle relative to the ground, Two rotary electric motors, mounted to impart angular torques in equal directions to the propulsion elements to propel the vehicle over a surface; are controllable independently of each other; Each of the rotors includes a stator and a rotor. The two rotors are a transmission shaft coupled to the propulsion element and transmitting a rotational motion to the propulsion element; having a common axis of rotation fixed relative to the vehicle frame; The stator is are controllable to rotate about their respective rotors independently of one another; two rotary electric motors substantially rigidly connected to the same point on the exterior of the motors so as to exert at said point a thrust generated by coordinated angular displacement of the motors about their respective rotors in opposite angular directions; a transmission for transmitting a thrust generated at the point to the propulsion element, whereby the thrust determines a relative position of the propulsion element with respect to the frame; and and an electric actuator (e.g., a rotary motor or a linear actuator) mounted to provide a steering angle for the propulsion element.

[0007] By determining the steering angle, it is meant determining the instantaneous direction of advance of the propulsion elements. In a rotating wheel, this direction can be indicated geometrically by a vector perpendicular to the instantaneous axis of rotation, or by the direction of a plane perpendicular to the axis of rotation and passing through the wheel.

[0008] Rotor is commonly used in the art to denote the rotating part in contrast to the stator, which is instead the stationary part of the electric motor. However, according to the present invention, both the rotor and the stator can move, but the rotor is the part that rotates the most in order to provide the rotational motion to the propulsion elements. The rotor rotates at the revolutions per minute (RPM) required to transfer kinetic energy to the propulsion elements, and the stator moves angularly if and when necessary to transfer the thrust at that point. Then, by rotor or stator, it is meant here generally that the two parts of the electric motor can move in proportion to the rotational motion after the appropriate power supply. However, the commonly used definitions are useful to identify parts in known electric motors that correspond to the rotor or stator defined above, which can be utilized interchangeably.

[0009] By moving the stator about the common axis of rotation of the rotors, a force is produced at that point and can be utilized to modify the suspension, for example to vary the distance between that point and the propulsion element.

[0010] The general principle is that depicted in Figure 2 of WO2015155670, which is included herein by reference and for the purposes of informing the reader. Two electric motors are controlled to both transmit torque to the propulsion element and to adjust the height or distance of the frame (e.g. relative to the ground or the propulsion element). - moving only one stator around a common axis of rotation of the rotors, and / or - Note that it is possible to move the two stators in the same angular direction around a common axis of rotation of the rotor.

[0011] In these cases, the point will rotate also or only about axis X.

[0012] With regard to the configuration defined above, it is not only possible to equip the idler wheels of vehicles to be motorised, but also to equip the idler wheels with an integrated suspension.

[0013] The stators are angularly movable relative to each rotor, and can adjust their angular position about the rotor (and relative to the rotor's axis of rotation), for example by control of the torque exerted by the stator on that rotor. Adjustment of the position of each stator translates into an adjustment of the position or height of that point, and thus of the frame, relative to the propulsion elements. In effect, when a thrust generated at that point is transmitted to the propulsion elements, the frame moves away from the propulsion elements in response.

[0014] Other important advantages of the system include the ability to equip vehicles with active suspensions that are able to adapt the vehicle balance to road and driving conditions, and the fact that it can be easily integrated into the most common suspension standards, allowing the installation of the suspension on new or existing vehicles.

[0015] Another advantage is that the electric motor is separated from the propulsion element by the shaft, so that the stresses captured by the propulsion element are not released on the propulsion element. This effect is further improved if the transmission shaft comprises at least two segments interconnected by a joint (e.g. a universal joint), so that the axis of rotation of the propulsion element is offset with respect to the axis of rotation of the rotor. This makes it possible to install the electric motor at a point where it is better protected by the on-board electronics and / or where it is easily connectable to it.

[0016] The electric motor may also be separated from the propulsion element by different and / or more complex kinematics involving a shaft.

[0017] Another advantage is that during the starting or acceleration phase of the vehicle, the system can obtain surprising dynamic effects. At the same time, by controlling the electric motor so that the rotor applies a rotational torque to the propulsion elements and the stator moves to generate a force on the propulsion elements towards the ground, the initial adhesion of the propulsion elements on the ground is significantly improved. Thus, the vehicle can accelerate without the propulsion elements becoming oily or skidding.

[0018] The aforementioned greasy or skidding can occur during braking phases when the electric motor can be controlled so that the stator moves to generate a force on the propulsion element towards the ground, thus increasing the adhesion of the vehicle during braking.

[0019] In short, the above mentioned control makes it possible to generate a force pushing the propulsion element not only in the tangential direction but also perpendicular to the ground when the vehicle is stationary or in motion or accelerating or braking. The same phenomenon occurs naturally in fairly fast moving predatory felines such as accelerating cheetahs by pushing their hind legs not only backwards but also towards the ground.

[0020] Another advantage of the present system is that it is possible to accommodate safety brakes or parking disc brakes on the propulsion element, as the actuating elements are external to the propulsion element.

[0021] The system also operates with a stationary propulsion element by means of a reaction force exerted by the stator on the (further) rotor.

[0022] Preferably, the rotor is coupled to the frame by means of rotational bearings (eg ball bearings or cylindrical bearings) mounted thereon to keep its axis of rotation fixed relative to the frame.

[0023] The transmission that transfers the thrust generated at that point to the propulsion element can have many embodiments.

[0024] The transmission may preferably be structured such that the thrust also generates a displacement of the point, which can be exploited to move the propulsion element by means of a rope or chain with suitable return means. In another embodiment, the transmission contains a fluid, the compression of which is achieved by the generated thrust. The pressure increase serves to move the propulsion element, for example by means of a hydraulic piston.

[0025] The transmission transmitting the thrust is preferably so structured as to reverse the direction of the thrust generated at that point in order to direct the thrust towards the propulsion element. For that purpose, and in addition for the sake of constructional simplicity, the transmission preferably comprises: Equipped with a lever that pivots on the frame, The lever includes a point of application of the generated force and a force transmission point towards the propulsion element, whereby when the generated force moves the application point, the lever moves the force transmission point.

[0026] In particular, the lever includes an oscillating axis fixed relative to the frame, such that the lever (e.g., a rocking arm, etc.) oscillates relative to the frame. Preferably, the oscillating axis of the lever is midway between the application point of the generated force and the force transmission point towards the propulsion element. In this way, the lever is able to reverse the displacement direction of the application point towards the propulsion element, facilitating force transmission.

[0027] Specifically, the levers are connected to the stator by two rigid arms each, with each rigid arm having a point or end connected to the stator and a point or end connected to the lever.

[0028] In particular, the oscillation axis of the lever is substantially perpendicular to a vertical plane passing through the transmission shaft and / or through the axis of rotation of the rotor.

[0029] Specifically, the propulsion element is connected to a lever by a rigid arm.

[0030] Preferably, the system comprises an electronic control unit for controlling the motor, which uses digital algorithms to allow precise, and in particular reliable, control.

[0031] Preferably, the electronic control unit is configured to control the third actuator to provide a steering angle of the propulsion element in accordance with a reference value set by a driver of the vehicle.

[0032] The reference value may be set, for example, by a steering wheel or lever, or by other means of an analog interface. The electronic control unit is connected to a sensor that detects the driver's actions on the steering wheel or lever, or on an analog interface. From the signal detected by the sensor, the electronic control unit then determines or calculates the directional reference to be given to the wheels by the third actuator.

[0033] Preferably, the electronic control unit is configured to calculate said steering angle in response to 1) said direction reference value and 2) said value indicative of said relative position.

[0034] This variant can be used to solve problems with bump steering, which refers to the tendency of the wheel to steer while it moves along the suspension stroke, regardless of the driver's control. The problem is felt more when the wheel hits a bump or hits a pothole, because bump steering rotates the vehicle by itself. It goes without saying that it is useful to be able to control the vehicle even on bumpy roads. The steering angle calculated as defined above can then include two contributions, one to a value indicative of the relative position, which can be used to solve problems with bump steering or to compensate for steering inaccuracies due to bump steering.

[0035] Another aspect of the present invention relates to a method for compensating for bump steering. It should be understood that each step of the method described herein is preferably performed by an electronic control unit, which is for example programmable (such as a microprocessor or DSP) and executes the method by software program instructions.

[0036] The method provides, for example, for detecting in real time the actual steering angle and the actual value of said relative position. Using the two values, for example by means of a table function or a mathematical function, a control signal is generated for the third actuator to always return the steering to a value equal to the value set by the driver and which would not result in road imperfections.

[0037] Alternatively, the method provides for detecting, in real time, an actual steering angle and comparing it with a nominal value (i.e., a value set by the driver and equal to a value that would not result in road imperfections). The difference or inequality between the two values ​​is due to bump steering. The comparison between the value set by the driver and the detected actual value can be performed, for example, by subtraction to calculate the difference between the two values, although other explanations are possible. It is sufficient to establish a hierarchical relationship between the actual steering angle and the nominal steering angle, for example, determining which of the two is larger, or calculating a binary value indicating equality or inequality.

[0038] Preferably, by processing the difference or the ranking relationship or the result of the comparison, a control signal is generated for the third actuator, for example by a table function or a mathematical function, so as to always return the steering to a value equal to the value set by the driver and which would not result in road imperfections.

[0039] Preferably, the difference or the rank relationship or the result of the comparison can be a correction signal (e.g., an input to a feedback system) that modifies and corrects the value of the steering angle in real time. Even more preferably, the correction signal is sent to a third actuator to effect a corrective shift, if necessary, to return the steering angle to a nominal value.

[0040] To simplify the system, it preferably comprises a sensor for detecting said relative position, the sensor being connected to an electronic control unit and transmitting to said electronic control unit a signal indicative of the relative position.

[0041] More preferably, the value or signal indicative of the relative position is obtained by processing feedback signals coming from the first motor and the second motor. In other words, electronic controls already present in the motors or sensors pre-placed on the motors are utilized as sensors. In particular, the value or signal indicative of the relative position is obtained by processing positions related to the angular positions of the stators of the first motor and the second motor. This solution has the characteristics of the active suspension structure defined above and offers the advantage of utilizing components and / or signals already present in the system to add bump steering compensation. Effect of the Invention

[0042] Thus, the method generally provides for calculating a steering angle depending on a reference value and a value indicating a relative position so as to correct a deviation from the reference value caused by vertical vibration of the propulsion element relative to the plane of rotation of the propulsion element (e.g. due to a hole or a bump).

[0043] The advantages of the present invention will become more apparent from the following description of preferred embodiments of the suspension and traction system, taken in conjunction with the accompanying drawings.

[0044] In the figures, arrows between components indicate signal lines and point to the component receiving the signal. [Brief description of the drawings]

[0045] [Figure 1] A block diagram of the principle is shown. [Diagram 2] FIG. 2 shows a block diagram for calculating a correction value for a steering angle. [Diagram 3] 1 shows a simplified mechanical scheme with components shown as they are in use. [Figure 4] 1 shows a cross section of an electric actuator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0046] The system MC shown is used to control the steering movement of a propulsion element, for example in the form of a wheel 92, which moves an associated vehicle (not shown) by rolling on a ground surface T (FIG. 3). The system MC is, for example, duplicated on all wheels of the vehicle.

[0047] System MC is two identical electric rotary motors M1, M2 capable of rotating a wheel 92 by means of a shaft 90; and a third actuator or motor M3.

[0048] The power supply of the motors M1, M2, M3 can be achieved, for example, by inverter stages or power electronics stages of known topology.

[0049] An electronic control unit U, for example using a microprocessor, is programmed or configured to control the motors M1, M2. For example by controlling an inverter or motor stage, the control unit U is able to control the rotation speed of the wheels 92 and the heights of the points P and Q (see below). For this purpose, the electronic control unit U controls the motors M1, M2 by signal lines M1L, M2L and the motors M2 by signal lines SM3, SM4, SM5, SM6, SM7, SM8, SM9, SM10, SM11, SM12, SM13, SM14, SM15, SM16, SM17, SM18, SM19, SM20, SM21, SM22, SM23, SM24, SM25, SM26, SM27, SM28, SM29, SM30, SM31, SM32, SM33 * and a third actuator or motor M3.

[0050] The two electric motors M1, M2 are formed by respective stators M1s, M2s and respective rotors M1r, M2r.

[0051] The rotors M1r, M2r are coaxial and have a common axis of rotation indicated by X. The axis X is fixed relative to the vehicle frame, for example by mounting the rotors M1r, M2r and / or the shaft 90 on ball bearings (not shown) with a ring integral with the frame.

[0052] Each of the stators M1s, M2s is connected to a respective rigid arm 22, 24, which in turn is connected to a common point P external to the electric motors M1, M2.

[0053] Point P is attached to or connected to the end of lever 40 which oscillates approximately at the center of the lever 40 itself, about axis Y which is fixed relative to the vehicle frame. The other end of lever 40 (point Q) is connected by rigid arm 26 to hub 94 of wheel 92.

[0054] Preferably, the wheel 92 is also connected to a suspension arm B (eg, a spring-actuated vibration reduction arm).

[0055] Rotation of the rotors M1r, M2r about the axis X causes the wheel 92 to rotate about its axis of rotation W.

[0056] By controlling the power supply of the electric motors M1, M2 (i.e. by providing more or less power than required by the wheels 92), it is possible to move the stators M1s, M2s about the axis X simultaneously in opposite angular directions (i.e. one clockwise and the other counterclockwise).

[0057] For example, arms 22, 24 can rise, pushing point P upwards (in this case, point P moves away from axis X). Lever 40 then rotates about axis Y (changing the angle α formed by lever 40 and the horizontal plane), moving point Q downwards. It follows that arm 26 therefore pushes hub 94 downwards and towards the ground, thereby achieving, inter alia, a change in distance between axes W and X, which in the example are parallel. In the example, axis Y is perpendicular to an imaginary vertical plane passing through X (and / or W).

[0058] Upward movement of hub 94 can be accomplished by reversing all of the movements described for the previous case (point P proximate axis X).

[0059] It should be noted that the rotational torque applied to the wheels 92 by the rotors M1r, M2r and the force exerted on the wheels 92 towards the ground by the stators M1s, M2s are independently controllable variables. Thus, for example, it is possible to push the wheels 92 further towards the ground during acceleration to increase their grip.

[0060] A third motor or actuator M3 is mounted on the vehicle to exert a force on the wheel 92 by means of a drive element 91 (e.g. a rigid arm). The force generated by the third motor or actuator M3 is controlled to vary the steering angle β (see Figures 1 and 3), i.e. to rotate the wheel 92 about a vertical axis K passing through the support point of the wheel 92 on the ground.

[0061] The electronic control unit U also controls a third motor or actuator M3. Furthermore, the electronic control unit U is connected to the following components: For example, a reference signal ST for steering is input to the electronic control unit U. * A steering control element 80, such as a steering wheel or cloche, transmits the signal ST *contains information or data regarding the direction desired by the driver of the vehicle. - the electronic control unit U receives a reference signal ACC relating to the speed or acceleration * The signal ACC is connected to a vehicle speed control element 82, such as an access pedal or lever, which transmits * contains information or data regarding the speed or acceleration desired by the driver of the vehicle. to the electronic control unit U, a signal V relating to the actual angular velocity or acceleration of the wheel 92 * A vehicle speed sensor 84, such as an optical encoder or tachometer, transmits a signal V * contains information or data regarding the actual angular velocity or acceleration of the wheels 92 and, therefore, the angular velocity or acceleration of the vehicle.

[0062] The electronic control unit U is signal ST * and actuating motor M3 to achieve the desired steering (i.e., the desired angle β); signal ACC * and speed sensor 84 and is then programmed to drive motors M1, M2 to maintain vehicle speed at a set reference, for example by known feedback control schemes.

[0063] To solve the problems with bump steering, the system MC works as follows, see FIG. 2 which shows a block diagram illustrating the calculation steps in the control unit U.

[0064] signal ST * is the reference steering angle β * is processed in the electronic control unit U by the calculation block W1 to generate the reference β * is processed by the calculation block W2 and the electrical standard SM3 * Generates electrical standards SM3 * is used to drive the motor M3 to obtain the desired steering angle. For example, the electrical reference SM3 *is the input reference for the feedback control acting on the motor M3.

[0065] To compensate for the steering bump, the calculation block W2 calculates the electrical reference SM3 in response to the second signal S. * and S indicates the deviation of the level of the wheel 92 compared to its nominal value (one that does not affect bumps or holes, or that relates to the straight-line trajectory of the vehicle).

[0066] In other words, SM3 * =F(S;β * ), F() are two variable mathematical functions or algorithms executed inside block W2.

[0067] The signal or data S may be, for example, can be calculated from the feedback signals M1f, M2f coming from the motors M1, M2, respectively, and then processed by a calculation block W3; and / or - signal α coming from sensor 88 detecting angle α in real time current For example, the electronic control unit U calculates in block W4 (which is for example a subtractor) the difference: Δα * = α * -α current It is calculated as Electrical signal SM3 * As a further argument to the function or algorithm for calculating Δα * Use the angle reference α * is calculated by the calculation block W5, for example, as the signal ST * It is obtained by processing

[0068] When the wheel 92 does not have a constant height, on a flat or uniform ground (e.g., Δα * ≠0), block W2 generates electrical signal SM3 to compensate for steering variations due to changes in suspension of wheel 92' (i.e., bump steering). *That is, the block W2 changes the electrical signal SM3 * Then, the signal LV or Δα * and the contribution derived from LV and / or Δα * This contribution, function, translates into a corrective movement of the motor M3 on the wheel 92. This corrective movement is represented by the signal ST * and is set by the signal ST * In the example shown, the corrective movement involves the displacement of element 91.

[0069] For example, block W2 may have two or three input indices (e.g., Δα * , LV and β * ) and output data (i.e., SM3 * ) The lookup table may be a lookup table having β * and LV and / or Δα * The electrical signal SM3 for each of the various values * Alternatively, for example, if the signals in FIG. 2 are digital (i.e., obtained by sampling) or analog, the calculations of block W2 may be performed in real time in the digital domain.

[0070] The illustration in FIG. 2 is merely illustrative of the general logic, and some calculation blocks may be implemented or arranged in different ways, or may even not exist. * It is not necessary to provide a calculation of , and one or another of the two equivalent signals is not sufficient.

[0071] Or signal SM3 * can be derived by utilizing other signals. For example, some or all of the calculation blocks shown may be integrated with each other or made into a single algorithm calculated inside a microprocessor.

[0072] 4 shows a diagram of the actuator M3. The actuator M3 is a rotary electric motor equipped with a screw 70 and a recirculating ball nut screw 72. The screw 70 is integral with an element 91 (e.g. a piston) and the nut screw 72 is integral with a rotor 74 of the motor 50. An optional but advantageous protective cap 76 (e.g. made from rubber) is present to prevent dust from entering the screw.

[0073] Control of motor 50 allows element 91 to move back and forth, controlling angle β.

[0074] System MC accommodates many variations and variables.

[0075] The electric motors M1 and M2 are not necessarily equal.

[0076] It is preferable to mount at least one joint (eg, a Cardan joint) on shaft 90 that allows or facilitates offsetting of axis W and axis X and / or different orientation of axis W.

[0077] Each of the stators M1s, M2s may also be connected to point P by means different from the arms 22, 24, and point P does not necessarily represent a geometric point, and point P may be an extension element to which the stators M1s, M2s are connected at points slightly apart due to mechanical necessity.

[0078] The lever 40 may oscillate at a point other than its centre, the axis Y being fixed relative to the frame, for example being obtained by simple pivoting.

[0079] Also, the location of points Q and P on lever 40 may vary, as may the location of the means for transmitting the force generated by moving stators M1s, M2s from point Q to wheel 92.

[0080] To compensate for the weight of the frame, it is preferable to mount a mechanical spring (eg, a helical spring) or a gas spring in parallel with the arm 26 between the wheel 92 and the frame.

[0081] The signals in FIG. 1 and / or FIG. 2 may be digital (eg obtained by sampling an electrical quantity) or analog.

[0082] Also, the motor M3 may be of the pneumatic type.

[0083] A kinematic chain of the wheel suspension is not necessary; it is sufficient to be able to vary the distance between the wheel and the frame using an electric motor.

Claims

1. A suspension system and vehicle propulsion system for a vehicle equipped with a frame and a propulsion element (92), comprising: The propulsion element (92) itself is adapted to propel by rotating on a ground surface and move the vehicle relative to the ground surface; Those systems are Two rotating electric motors (M1, M2), mounted to impart torque to the propulsion elements in equal rotational directions to propel the vehicle over the ground; are controllable independently of each other; Each of the rotors M1s and M2s has a stator M1r and a rotor M2r. The two rotors (M1r, M2r) are a transmission shaft (90) coupled to said propulsion element (92) and transmitting a rotational motion to said propulsion element (92); having a common axis of rotation (X) fixed relative to the frame, The stators (M1s, M2s) are each connected to a rigid arm (22, 24) connected to a point (P) external to the rotary electric motor; The points (P) are controllable to rotate about their respective rotors independently of each other to obtain up and down displacements; two rotary electric motors (M1, M2) whose stators (M1s, M2s) exert, via said rigid arms (22, 24), tangential forces on a point (P) generated by coordinated angular displacements of said stators about their respective rotors in opposite directions about an axis X; a means (26) configured to mechanically transmit the tangential force acting on the point (P) to the propulsion element, whereby the tangential force determines the relative position of the propulsion element with respect to the frame; an electric actuator (M3) mounted to determine the steering angle (β) of the propulsion element; A sensor (88) for detecting said relative position; an electronic control unit (U) for controlling said rotary electric motor, The electronic control unit includes: The reference value (ST ＊ and configured to control the actuator to provide a steering angle of the propulsion element according to The electronic control unit determines the reference value (ST ＊ ) and a value indicating the relative position (α ｃｕｒｒｅｎｔ ) calculating the steering angle according to calculating said value indicative of said relative position by processing feedback signals (M1f, M2f) coming from a first motor and a second motor; calculating said value indicative of said relative position by processing processed signals (M1f, M2f) for the angular positions of the first stator and the second stator; In order to correct the deviation from the reference value caused by the vertical vibration of the propulsion element caused by the unevenness of the ground T, which is the rotation plane of the propulsion element, the reference value (ST ＊ ) and a value indicating the relative position (α ｃｕｒｒｅｎｔ ) calculating the steering angle (β) in response to

2. 2. A system according to claim 1, wherein said point (P) is connected to the end of a lever (40) which oscillates independently about an axis (Y) fixed relative to said frame.

3. The reference value (ST ＊ a steering wheel (80) or lever for setting a steering angle (A) or a steering position (B), a sensor for detecting a driver's operation with respect to the steering wheel (80) or the lever, and an electronic control unit (U) connected to the sensor, Detecting a driver's action on a steering wheel (80) or lever; 2. A system according to claim 1, characterized in that it determines or calculates, from the signals detected by the sensors, a directional reference applied to the steering wheel (80) through an actuator (M3).

4. to correct deviations relative to a reference value caused by vertical vibrations of the propulsion element relative to the plane of rotation of the propulsion element, The reference value (ST ＊ ) and a value indicating the relative position between the propulsion element and the frame (α ｃｕｒｒｅｎｔ 2. The bump steering correction method implemented in a system as recited in claim 1, further comprising the step of calculating said steering angle (β) as a function of:

5. 5. The method of claim 4, wherein the actuator control signals are generated from the calculated steering angle (.beta.).

6. The method according to claim 5 , wherein the control signal is generated by a tabular function or a mathematical function.

7. The actual steering angle and the actual value of the relative position (LV, α ｃｕｒｒｅｎｔ ) in real time; Using these two values, a control signal (SM3) is generated for the actuator (M3) so as to always return the steering to a value equal to the value set by the driver and which would not result in road imperfections. ＊ 2. A method of bump steering correction implemented in a system as recited in claim 1, comprising:

8. 8. The method according to claim 7, wherein the value (LV) or signal indicative of the relative position is obtained by processing feedback signals coming from the first motor and from the second motor (M1, M2).

9. 8. The method according to claim 7, wherein the value or signal indicative of the relative position is obtained by processing a position related to the angular position of the stators of the first and second motors (M1, M2).

10. The current steering angle is detected in real time; The current steering angle is set by the driver and is equal to the current steering angle when the road is smooth. ＊ ) compared to The comparison result (Δα) is a corrected control signal (SM3) for the third actuator (M3) acting on the propulsion element (92). ＊ ) is generated, Thereby, the displacement of the actuator induced by the correction signal changes the steering angle (β) to the reference value (ST ＊ 2. The bump steering correction method implemented in the system of claim 1, wherein the bump steering correction method is implemented in the system of claim 1.

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