FR2914260A1 - Four wheeled motor vehicle e.g. industrial vehicle, for e.g. building site, has electronic control unit including auxiliary units decelerating torques to be applied on wheels found at interior or exterior of turning via units, respectively - Google Patents

Abstract

The vehicle (1) has an electronic control unit (20) coupled to a drive wheel orientation unit and to an electrical control braking unit and activated during turning of the vehicle. The unit has a deceleration unit that decelerates dissymmetrical braking and engine torques to be applied on left and right drive wheels (9, 10) of the vehicle during turning. The unit has auxiliary deceleration units that decelerate braking and engine torques to be applied on the wheels that are found at the interior or exterior of turning via braking and orientation units, respectively. An independent claim is also included for a method for controlling a drive wheel of a four wheeled motor vehicle.

Description

Project 5566 / DF B06 / 4383EN ù LB / cec

  Simplified joint-stock company: RENAULT s.a.s. Motorized vehicle comprising a control unit of the vehicle in a turning situation and corresponding method.

  Invention of: Fabien MOREAU Christophe BOUE

  Motorized vehicle comprising a control unit of the vehicle in a turning situation and corresponding method.

  The present invention relates to a motor vehicle equipped with a steering and electrically controlled brakes, decoupled from the brake pedal, that is to say can be controlled independently of any action on the brake pedal. More particularly, the invention aims at the control of such a vehicle when it is found in a cornering situation.

  The presence of many electrically or electronically controlled components within the vehicle leads to the appearance of new electrical / electronic failures. These faults can for example affect the steering actuator of the vehicle. A degraded mode must then be provided to replace the faulty steering actuator. Another solution is to provide a redundant device, able to operate in case of failure. More particularly, one of the failures of a power steering actuator is for the driver, the inability to steer the vehicle wheels left or right, especially in a cornering situation. This failure may be due for example to the malfunction of one or more wheel steering actuators or to a failure of the onboard network. Another problem related in particular to the use of an electric steering actuator is the monitoring of the radius of curvature of the turn, which is generally not optimal (non-optimal cornering registration time, lack of precision ...) Document EP 0 493 206 discloses a motorized military type vehicle with a relatively accurate trajectory tracking, whatever the type of terrain, particularly when the vehicle is turning. In this case, the vehicle uses a skid direction (skidsteering in English) to perform a pivoting.

  More specifically, the vehicle of EP 0 493 206 is mixed direction, and can change direction through a direction of rotation of the wheel located inside the opposite turn to that of the wheel located outside of the turn.

  However, this embodiment is not recommended with the use of so-called electrical direction technology, commonly called By Wire technology in the art. Document EP 0 627 335 discloses an independent wheeled vehicle having a steering wheel and skid steering. However, this vehicle is limited to the use of hydrostatic transmission with a hydraulic propulsion system. Documents EP 0 443 830, EP 1 559 837, EP 0 932 729 and EP 0 443 829 relate to industrial or agricultural vehicles, in particular load-carrying vehicles in a small environment such as a factory or a construction site. The vehicles described in these documents comprise two inverted transmission systems (one for the right wheels and one for the left wheels) to control the wheels, and this only in nominal mode. The document FR 2 070 620 relates to an agricultural vehicle whose wheels can be driven only with the aid of different couples. The vehicle does not have a degraded mode. The object of the invention is to improve the control of skidding of a vehicle in a cornering situation, in particular used in the event of failure of the electronically controlled steering column, or to assist the steering column, so as to optimize the performance of the vehicle, especially when cornering. The invention proposes to define a motorized vehicle comprising a skid control unit of the vehicle, in particular able to operate to overcome any failure of electronically controlled actuators, and this regardless of the operating phase of the vehicle. For this purpose, the subject of the invention is a four-wheeled motorized vehicle comprising at least two driving wheels, an orientation means capable of orienting the driving wheels, at least one electrically-controlled braking means decoupled from the driving pedal. brake and able to apply an asymmetrical braking torque on the right and left wheels of the vehicle, at least on each drive wheel. According to a general characteristic of the invention, the vehicle further comprises an electronic control unit coupled to the steering means and to the braking means, which can be activated in a cornering situation, said electronic unit comprising means for producing the torques to be applied. on the drive wheels of the motor vehicle. This means of production comprises: a first auxiliary means of elaboration capable of developing a braking torque to be applied to the driving wheel located inside the turn via the braking means, and a second means of elaboration. auxiliary adapted to develop a driving torque to be applied to the drive wheel located outside the bend, via the orientation means. In other words, it is possible to control the orientation of the vehicle when cornering, by applying a driving torque on the driving wheels of the motor vehicle, and a braking torque, unlike the solutions of the prior art who proposed to drive the differential. The vehicle has the advantage of being able to be controlled even in the event of failure of the steering actuator, by activating the control unit. The control unit therefore offers the possibility of having - a degraded mode for steering the vehicle in the event of failure of the electric control of the steering actuator, or - assistance of the steering actuator in a cornering situation , to optimize the performance of the vehicle. The invention thus generates a great improvement: - the driver's safety, - his driving pleasure. According to one embodiment, the orientation means may comprise a heat engine and a differential arranged on a driving axle connecting the drive wheels located face-to-face, via a gearbox, said control unit further comprising a means control device adapted to develop a command set to apply to the differential in said turning situation.

  This command setpoint may be a blocking setpoint or a control setpoint according to the architecture used for the differential. According to another embodiment, the vehicle can comprise for each of its driving wheels, an electric propulsion and braking motor, said electric propulsion and braking motor forming both the orientation means and the braking means. The invention is therefore compatible with different types of engines. The control unit may comprise in a preferred embodiment, a wheel anti-lock system which includes a comparison means capable of comparing the value of the braking torque and a threshold, said anti-lock system of the wheels being able to reduce the braking torque if its value exceeds said threshold. Furthermore, the second auxiliary processing means can develop the engine torque to be applied to the driving wheels depending on the values of longitudinal speed and yaw rate measured and the instructions of longitudinal speed and yaw rate requested by the driver. Preferably, the vehicle may comprise a detection module that can: - detect a failure of the electrical control of the steering actuator, and - activate the control unit when a fault is detected. According to another aspect of the invention, there is provided a method of controlling the driving wheels of a four-wheeled motor vehicle comprising at least two driving wheels and an electrically controlled steering actuator. The drive wheels are oriented, braking with an asymmetric braking torque on the right and left wheels of the vehicle and applied at least on each drive wheel, regardless of an action of the brake pedal.

  According to a general characteristic of this other aspect of the invention, the method comprises a phase of control of the driving wheels of the motor vehicle in a cornering situation comprising a step of developing the torques to be applied to the driving wheels of the motor vehicle in a driving situation. turn, said development step comprising: - a first sub-step of developing a braking torque to be applied to the driving wheel located inside the bend, and - a second sub-step of developing a a driving torque to be applied to the driving wheel located outside the bend. According to one embodiment, it is also possible during the turning situation to apply a steering angle to the drive wheels of the motor vehicle.

  In this case, the method can be applied during the nominal operating mode of the vehicle, so as to have an optimal trajectory tracking. Furthermore, in the case where the vehicle comprises a differential disposed on a motor shaft connecting the two drive wheels located face-to-face, via a gearbox, said control phase comprises, prior to the production step, a control step where is developed a control instruction to be applied to the differential in said turning situation.

  According to an embodiment, said checking step may also comprise a comparison of the value of the braking torque with a threshold and a reduction of the braking torque if its value exceeds said threshold. For example, the method may comprise, prior to the control step, a step of detecting a failure of the power steering actuator so as to apply said control step when a failure is detected. The present invention will be better understood on reading the detailed description of an embodiment and an embodiment taken as non-limiting examples and illustrated by the appended drawings, in which: FIG. 1 schematically represents a part of a motor vehicle, and more particularly the steering system; FIG. 2 illustrates a flowchart comprising the various steps of an embodiment of the method according to the invention; - Figures 3 and 4 show two examples of application of a braking torque and a driving torque on the drive wheels of the motor vehicle in different configurations; - Figure 5 shows an embodiment of an electronic control unit of the motor vehicle according to the invention. In Figure 1, there is shown a motor vehicle 1, in particular provided with a By Wire type steering system. The motor vehicle 1 is provided with a motor, for example a heat engine 2. This is connected to a gearbox 3 via a clutch 4. The gearbox 3 is actuated with a selector 5 ( shifter) via a connection 6. A differential 7 is mounted at the rear of the gearbox 3 on the axis of symmetry of a driving axle 8, connecting the two front wheels 9 and 10 In this example, the two front wheels 9 and 10 are driving. Furthermore, the differential 7 is connected via a transmission shaft 11 to a rear axle 12 via a secondary differential 13. The rear axle 12 connects the two rear wheels of the vehicle referenced 14 and 15. These can to be two-wheel drive or not. The vehicle 1 comprises a braking means able to exert asymmetrical braking on the right and left wheels of the vehicle. In other words, the value of the braking torque applied to the left wheels may be different from the value of the braking torque applied to the right wheels. This type of asymmetric braking is characteristic of By Wire type steering systems. The braking means comprises in this example four brakes 25 respectively disposed on the inner face of the vehicle wheels. These brakes are respectively referenced 16, 17, 18 and 19. The brakes 16 and 17 of the motor vehicle are electrically controlled and decoupled, that is to say that they can be controlled independently of an action on the pedals of brake of the vehicle.

  The brakes may be of electromechanical or electrohydraulic type. In addition, the vehicle 1 comprises a control unit 20. This control unit 20 controls the brakes 16 and 17 associated with the driving wheels 9 and 10, respectively via connections 21 and 22. The control unit 20 also controls the wheels 9 and 10 via the motor 2, to which it is connected by a connection 23. Finally, the control unit 20 can control the differential 7 10 to which it is connected by a connection 24. The differential 7 can be a differential with automatic or manual locking. It may also possibly be a viscous-coupling differential. Any differential technology that allows the existence of different pairs on the two wheels of the same axle in a sufficient proportion can be used. Furthermore, it is possible to use electric propulsion motors associated with a braking system on each wheel (commonly called independent wheel system by the skilled person). This system replaces the aforementioned brake and makes it possible to overcome the use of a differential. In case of failure of the electrical control of the steering function, a degraded mode is set up, so that the driver can still steer his vehicle. In this case, the control unit 20 controls the differential 7, the brakes 16 and 17 and the drive wheels (the two wheels 9 and 10 in this example) so as to ensure the function which was normally performed by the column of direction, before the failure occurs. The driving axle 8 coupled to the driving wheels 9 and 10, as well as the engine 2 then form the means of orientation of the vehicle 1.

  The various control steps performed by the control unit 20 are shown in FIG. 2. The flowchart describes the case where a failure of the electrical control of the steering column is detected, and a degraded mode is triggered. However, the control unit can also operate in nominal mode to optimize the performance of the motor vehicle. First, the detection of the failure of the electrical control of the steering actuator (step 100) takes place. When this fault detection occurs, the control step is implemented (step 101) so as to ensure the implementation of the degraded mode of operation. More precisely, this control step comprises the control of the differential (in the case of an architecture of the transmission system with differential), step 1001. This command may consist in blocking or controlling the differential, depending on the differential technology used. Then during two other sub-steps, a braking torque (having a value less than zero) is developed to be applied to the drive wheel located inside the turn (step 1002), and a driving torque (having a value greater than zero) to be applied to the drive wheel 20 outside the bend, step 1003. Then, during a step 1004, a driving instruction is developed which groups together the torques to be applied for each of the wheels. drive (front left and right front in the case of two-wheel drive in front of the vehicle). Finally, at the end of the control step, the corresponding torque is applied to each drive wheel (step 102). If the vehicle has a wheel anti-lock system, the method may include, just after the detection of a failure, a step of regulating the braking torque, if after a comparison of the sliding of the vehicle with a threshold of maximum slip, its value exceeds this maximum slip threshold. Referring now to Figure 3 which illustrates the application of the braking torque or motor on the drive wheels of the vehicle 1.

  In the case where the vehicle is two-wheel drive, the torques are applied to the wheels 9 and 10 (arrows in solid lines 30 and 31). In the case where the vehicle 1 is four-wheel drive, it also applies a torque on each rear drive wheel 14 and 15. These pairs are represented by arrows in dashed lines 32 and 33.

  Regarding the braking torque, it can be applied to a wheel even if it is non-driving. In Figure 3, we consider the case where a failure of the electrical control of the direction has been detected. It is assumed in this figure 3 that the steering wheels are straight.

  In this case, to make a left turn, the torque applied to the wheel inside the turn, the left front wheel 9 in this example is a braking torque (or braking torque). Conversely, the torque applied to the drive wheel outside the turn, in this example the front right wheel 10 is a driving torque.

  The resulting yaw moment is symbolized by arrow 34. FIG. 4 considers the case where it is desired to optimize the nominal mode of operation of the vehicle, in the case of cornering. The drive wheels 9 and 10 of the vehicle 1 therefore have a given steering angle.

  In this case, the application of a braking torque on the wheel 9 and a driving torque on the wheel 10 makes it possible to improve the monitoring of the curve of the turn taken by the vehicle 1. Moreover, the application braking torque and engine torque is done while controlling the oscillations of the motor vehicle (transmission system, wheels ...) in order to avoid oscillations of trajectory. Referring now to Figure 5 which shows an embodiment of the control unit 20 in the case of a two-wheel drive vehicle.

  The control unit 20 comprises a generating means 41 receiving at the input the measured longitudinal velocity of the vehicle VLOM in km / h via a connection 40a, the longitudinal speed reference of the vehicle km / h CVLO via a connection 40b, the speed measured yaw of the vehicle VLAM in rad / s via a connection 40c, the reference speed of yaw CVLA in rad / s via a connection 40d, as well as the trajectory tracking gain GP via a connection 40e. This GP gain makes it possible to adjust the tracking dynamics of the turn radius taken by the motor vehicle. The higher the GP gain, the faster the vehicle will reach the bend radius of the turn.

  The means of production 41 comprises a first auxiliary forming means 42 able to develop a braking torque to be applied to the drive wheel located inside the turn. It also comprises a second auxiliary means 43 for developing an engine torque to be applied to the drive wheel located outside the bend. The means of production 41 elaborates a control set CP in N.m. This control setpoint is delivered by a connection 45 to an adder 46.

  The control unit 20 also includes an anti-lock system 47 (ABS anti-blocking system, in English). As a variant, the control unit 20 can just as easily operate with a conventional anti-lock wheel system disposed near the wheels of the motor vehicle.

  The wheel anti-lock system 47 receives the measured wheel angular velocity VARM via a connection 48a, this speed being expressed in rad / s. This angular velocity VARM is divided into two signals, respectively a signal for the left front wheel RAVG delivered to the system 47 via a connection 48b and a signal for the right front wheel RAVD delivered to the system 47 via a connection 48c. The system 47 also receives the maximum GMAX slip allowed on the front wheels of the motor vehicle in percentage. This maximum slip value GMAX is delivered via a connection 48d to the system 47. Finally, the anti-lock system of the wheels 47 receives the speed V of the motor vehicle in m / s, via a connection 48e and the measured yaw rate VMAL via a 48f connection.

  The wheel anti-lock system 47 delivers its anti-lock torque set point CPABS wheels to the adder 46, using a connection 49. This setpoint prevents the wheels from getting off. completely block (especially below a certain speed value), thus preventing the application of a braking torque. For this, using the input parameters, the anti-lock system of the wheels 47 compares through a comparison means 47a, the sliding of the vehicle with the maximum slip GLMAX. From the torque set point CP and the anti-lock torque set point of the CPABS wheels, the adder 46 finally generates two setpoints of torque to be applied respectively to the left front wheel CPAVG and to the right front wheel CPAVD via connections 50 and 51.

  Finally, the control unit 20 can be activated by a detection module 52, able: - to detect a failure of the electrical control of the steering column, and - to activate the control unit 20 when a failure is detected, by delivering a signal DF via a connection 53. The control unit 20 comprises a blocking means 54 able to receive the signal DF via a connection 55. The blocking means 54 then generates a blocking instruction CB delivered via a connection 56 to the differential 7 of the vehicle. This setpoint makes it possible to block the differential as soon as a fault is detected so as to be able to apply the CPAVG and CPAVD pairs of the degraded mode for example. In a variant, the detection module 52 can activate the control unit 20 in the nominal mode when the driver desires assistance in a turning situation for example.

Claims (11)

  1-motorized four-wheeled vehicle comprising at least two driving wheels (9,10), an electrically-controlled steering, an orientation means (2,8) capable of orienting the driving wheels, at least one control braking means electrical, decoupled from the brake pedal and adapted to apply an asymmetrical braking torque on the right and left wheels of the vehicle, at least on each driving wheel, characterized in that it further comprises an electronic control unit (20). ) coupled to the steering means and the braking means, which can be activated in a cornering situation, said electronic unit comprising a means (41) for producing the torques to be applied to the drive wheels of the motor vehicle in a turning situation, comprising - a first auxiliary generating means (42) adapted to develop a braking torque to be applied to the drive wheel located inside the turn via the braking means, and - a second means of developing auxiliary ion (43) adapted to develop a driving torque to be applied to the drive wheel located outside the bend, via the orientation means.   2-vehicle according to claim 1, wherein the orientation means comprises a heat engine (2) and a differential (7) arranged on a driving axle (8) connecting the two drive wheels (9,10) located face-to- -face, via a gearbox (3), said control unit further comprising a control means adapted to develop a command set to apply to the differential in said turning situation.   3-motor vehicle according to claim 1, comprising for each of its driving wheels, an electric motor for propulsion and braking, said electric propulsion and braking motor forming both the orientation means and the braking means.   4. Vehicle according to one of the preceding claims, wherein the control unit further comprises a wheel anti-lock system (47) which includes a comparison means (47a) able to compare the value of the torque of braking and threshold (GLMAX), the anti-lock system of the wheels (47) being able to reduce the braking torque if its value exceeds said threshold.   5. Vehicle according to one of the preceding claims, wherein the second auxiliary processing means is adapted to develop the engine torque to be applied to the drive wheels according to the values of longitudinal velocity (VLOM) and yaw rate (VLAM). ) and the longitudinal speed guidelines (CVLA) and yaw rate (CVLO) requested by the driver.   6-vehicle according to one of the preceding claims, further comprising a detection module (52) able: - to detect a failure of the electrical control of the steering actuator, and - to activate the control unit (20). ) when a failure is detected.   7-Process for controlling the driving wheels of a four-wheeled motor vehicle comprising at least two driving wheels and an electrically-controlled steering actuator, in which the driving wheels are oriented, braking with the aid of a pair of asymmetric braking on the right and left wheels of the vehicle and applied at least on each driving wheel, independently of an action of the brake pedal, characterized in that the method comprises a control phase (101) of the driving wheels of the vehicle automobile in a turning situation comprising a step of elaboration of the torques to be applied to the driving wheels of the motor vehicle in a turning situation, said development step comprising - a first substep (1002) of generating a torque braking force to be applied to the drive wheel located inside the turn, and - a second sub-step of producing (1003) a driving torque to be applied to the drive wheel this is outside the bend.   8. The method of claim 7, wherein during the turning situation, a steering angle is additionally applied to the drive wheels of the motor vehicle.   9- Method according to the preceding claim, wherein the vehicle comprises a differential (7) disposed on a motor shaft (8) connecting the two drive wheels located face-to-face, via a gearbox (3), said phase of control comprising prior to the development step, a control step (1001) where is developed a command set to apply to the differential in said turning situation.   10- Method according to one of claims 7 to 9, wherein said controlling step further comprises a comparison of the value of the braking torque to a threshold, and a decrease in the braking torque if its value exceeds said threshold.   The method according to one of claims 7 to 10, further comprising, prior to the control step, a step of detecting a failure (100) of the power steering actuator, so as to apply said checking step when a failure is detected.