FR2894878A1 - CONTROL METHOD, ANTI-ROLL SYSTEM OF A VEHICLE AND CORRESPONDING - Google Patents

Abstract

A method and system for controlling an anti-roll system for a vehicle 1 to at least three wheels, wherein according to the lateral acceleration of the vehicle, the vehicle traveling data, and the gear ratio engaged, a set-point is developed roll correction device and said roll correction instruction is sent to an actuator 14, 15 capable of applying an anti-roll torque.

Description

Method and anti-roll system of a vehicle and corresponding vehicle The

  This invention pertains to the field of land vehicle control systems, particularly wheeled motor vehicles. Conventionally, motor vehicles are provided with a frame, a passenger compartment, wheels connected to the chassis by a suspension mechanism with front wheels steering commandoes by a steering wheel at the disposal of the driver in the vehicle, and rear wheels steering or non-steering. Document US 2004/0117085 describes a system for controlling the yaw stability of a vehicle equipped with a lateral acceleration sensor, a roll sensor, a steering angle sensor and a steering angle sensor. minus a speed sensor providing information to a yaw stability control unit, a roll stability control unit and a priority and integration function unit for controlling an active suspension system and a control system. active anti-roll bar system. The system operates in a closed loop. US 2004/0117071 describes a method for reducing roll oscillations of a vehicle by a closed loop system taking into account roll angle, roll speed and roll acceleration.

  US 4,939,654 discloses a control system of the driving characteristics of a vehicle according to the steering of the wheels of the vehicle by means of a steering angle sensor and at least one speed sensor to act on controllable dampers. However, these systems require many sensors and provide the vehicle behavior insufficiently stable during certain requests from the driver or on certain states of shoes. Certain situations can lead to a loss of control of the vehicle, for example a single or double obstacle avoidance. The loss of control in this case is often due to an inadequate response of the vehicle because too bright, not enough amortized or not very predictable. The invention relates to a progressive control anti-roll control system ensuring safety, a sense of security, comfort and a high driving pleasure. The method for controlling an anti-roll system for vehicle A. at least three wheels comprises the development of a setpoint for correcting freewheels according to the lateral acceleration of the vehicle, the vehicle displacement data and the gear ratio. speed engages, and sending said free wheel correction instruction to an actuator capable of applying anti-roll torque. The quasi-static roll of the vehicle is reduced by application of the anti-roll torque for a speed range from the reverse to the forward. The anti-rollover torque may be reset to zero progressively as the approach to the vehicle stall or approaching a low steering angle approaches. You can adjust the progressiveness of the anti-rollover torque to avoid any uncomfortable driving sensation.

  Said vehicle movement data may include the longitudinal vehicle speed and / or a measurement of the steering angle of the front wheels. In one embodiment, below a first lateral acceleration threshold, the roll correction instruction is zero.

  In one embodiment, above a second lateral acceleration threshold, the roll correction instruction is constant. In one embodiment, the roll correction instruction is monotonically increasing between first and second lateral acceleration thresholds. The roll correction instruction can be between a straight line and an increasing parabola between the first and second lateral acceleration thresholds. The roll acceleration instruction can be null under a speed threshold or engaged gear ratio.

  The vehicle anti-roll system having at least three wheels comprises means for developing a roll correction setpoint in accordance with vehicle acceleration, vehicle movement data, and engaged gear ratio, and an actuator capable of applying an anti-roll torque according to the roll correction instruction. In one embodiment, the means for constructing a setpoint includes a side acceleration normalization module. The normalization module may include a vehicle lateral acceleration angle input, a static gain gain between the roll and the lateral acceleration, and a static gain input between the roll and the anti-friction torque. roll. The means for elaborating a setpoint may comprise a calculation module and a speed table. The calculation module may include a minimum positive speed parameter and a maximum anti-roll torque parameter. The speed table may include, for each speed value, a minimum lateral acceleration parameter, a maximum lateral acceleration parameter, a steering wheel angle parameter, a slope parameter, and a parameter of sign of lateral acceleration.

  The vehicle is provided with a chassis and at least three wheels connected elastically to the chassis. The vehicle comprises an anti-roll system provided with means for developing a roll correction setpoint as a function of vehicle acceleration, vehicle movement data, and engaged gear ratio, and an actuator capable of applying an anti-roll torque according to the roll correction setpoint. The system is open loop. The actuator may be part of a controllable anti-roll bar or active suspension.

  In one embodiment, the vehicle movement data may include a measurement of the rear wheel steering angle, in the case of a vehicle with rear-wheel steering.

  The miss at the point of the system is facilitated by the small number of parameters implemented and allows a progressivity of quasi-static settings. The present invention will be better understood on reading the detailed description of some embodiments taken as non-limiting examples and illustrated by the accompanying drawings, in which: FIG 1 is a schematic view of a vehicle equips a control system; FIG. 2 is a logic diagram of the system of FIG. 1; and FIG. 3 is an anti-roll torque diagram as a function of lateral acceleration. As can be seen in FIG. 1, the vehicle 1 comprises a chassis 2, two front steering wheels 3 and 4 and two rear wheels 5 and 6 which may or may not be steering. The vehicle 1 is completed by a steering system 7 comprising a rack 8 arranged between the front wheels 3 and 4, a rack actuator 9 adapted to guide the front wheels 3 and 4 through the rack 8 according to orders received, mechanically or electrically, from an unrepresented steering wheel at the disposal of a driver of the vehicle. In the variant rear-wheel steering steering actuators 19 and 20 of said rear wheels are provided. The anti-roll system 10 comprises a control unit 11, a sensor 12 of the lateral acceleration YT of the vehicle, a sensor 13 of the speed of rotation of the front wheels making it possible to determine the speed V of the vehicle and a sensor 18 of steering angle of the front wheels 3 and 4, for example mounted on the actuator 9. The sensor 12 can be disposed at the center of gravity of the vehicle 1. The speed sensor can be optical or magnetic type, for example effect Hall, cooperating with an encoder secured to a moving part, while the sensor is non-rotating. The acceleration sensor may be accelerometer type (flyweight and spring).

  In addition, the anti-roll system 10 comprises front and rear controlable anti-roll bars 15 capable of modifying the parameters of the suspension provided between the chassis 2 and the wheels 3 to 6. The anti-roll bars 14 and 15 may comprise hydraulic or electric cylinders. The anti-roll system 10 comprises a sensor 16 of the position of the shift lever 17 controlling a gearbox, not shown, of the vehicle 1. The sensor 16 supplies a signal Sv of value 1 when a forward gear is engaged and of value -1 when a reverse gear is engaged or in neutral. The control unit 11 may be in the form of a microprocessor equipped with a memory, a memory, a central unit and input-output interfaces for receiving information from the sensors. and to send the instructions to the anti-roll bars 14 and 15. More precisely, the control unit 11 comprises an input block 22 receiving the signals from the sensors 12 and 13, more particularly the speed of the vehicle V and Transverse acceleration 7T. The speed of the vehicle can be obtained by averaging the speed of the front wheels or the rear wheels, as measured by sensors of an anti-lock wheel system. In this case, there is provided a sensor 13 per wheel, the anti-lock system comprising an output connected to an input of the control unit 11 for providing the vehicle speed information.

  Alternatively, each sensor 13 is connected to an input of the control unit 11, the control unit 11 then performing the average of the wheel speed. The control unit 11 also comprises a calculation block 23 provided with a stop parameter B, a speed sign input Sv, a dead zone parameter Zm, a static gain parameter G and a slope parameter p. The speed sign is equal to 1 if a positive gear ratio is engaged and a -1 if the reverse gear is engaged or if the gear lever is in neutral. The stop parameter B is equal to the maximum torque applicable and makes it possible to avoid the application of excessive torque that is unpleasant for the driver and / or harmful to actuators of the controllable anti-roll bars. The deadband parameter Zm is homogeneous at a lateral acceleration and determines the lateral acceleration threshold yT below which the setpoint takes a zero value. The slope parameter p determines the slope of the torque setpoint as a function of the lateral acceleration T between the dead zone and the stop. The calculation block 23 comprises a normalization block 29 receiving the lateral acceleration value yT and performing the normalization calculation of the lateral acceleration to obtain: yTn = yT Gy / G with Gy the static gain between the roll and 1 ' lateral acceleration of the vehicle and G the static gain between the roll and the anti-roll torque. The calculation block 23 comprises a quasi-static control generation module 30 associated with a table 31 of anti-roll speed and torque, which, depending on the speed, the steering wheel angle, the lateral acceleration normalized yTn and parameters B, S ,,, Z ,,,, G and p, generates an anti-roll torque setpoint. The parameters determine the anti-roll torque curve as a function of the lateral acceleration YTn, an example of which is illustrated in FIG. 3 and for a large number of speed values V; stored in a table. In other words, the parameters B, S ,,, Z ,,,, G and p depend on the speed. The determination of the anti-roll torque setting can be made as follows. For a speed of absolute value less than Vm; n or a steering angle of absolute value below am; n, the anti-rollover torque is zero. For a value of lateral acceleration of absolute value lower than a threshold or dead zone Zm, then the anti-rollover torque is zero. The anti-roll torque instruction is capped at a stop or maximum value B. In other words, if the lateral acceleration is greater than a second threshold y max, the anti-roll torque setpoint is equal to the stop B We calculate the speed sign Vs equal to the product of the speed V by the sign Sv and we search in the table 31 for a value of speed lower and / or equal as close as possible to the value Vs. For absolute values of acceleration With the normalized longitude yTn between the first threshold Zm and the second threshold ymax, the anti-roll torque is determined by a parabolic function of the lateral acceleration YTn.

  Then calculate: d = ymax / (ymax - Zm) 2 a = (1-slope) db = d (slope (y, nax + Zm) ù 2 Zm) c = aZm2ûbZ ,,, The anti-roll torque setpoint C = a YTn2 + blyräI + c The determination of the sign of the anti-roll torque setpoint can be carried out in the following way. If the absolute value of the lateral acceleration is different from zero, then the sign of lateral acceleration is equal to the quotient of the lateral acceleration YTn by the absolute value of the lateral acceleration lyTn1. Otherwise, the sign of lateral acceleration is nil. The value of the anti-roll torque C can then be provided by the product of the absolute value of the anti-roll torque by the sign of the lateral acceleration and by a phase opposition parameter equal to 1 or -1 and making it possible to put in opposition in phase or in phase the anti-roll torque with respect to lateral acceleration. The final value of the torque of the setpoint and the anti-roll torque can then be calculated by linear interpolation on the speed, taking a speed V; immediately below the velocity V and a velocity V; +1 immediately above the velocity V of or two values of the anti-roll torque C, and C; + i. Thanks to the invention, a roll correction is obtained which is relatively simple to implement and which enables a roll correction improving the safety of the vehicle and the driving comfort experienced by the driver by maintaining a zero correction for low speeds and low speeds. Lateral accelerations, limiting the anti-roll torque to a maximum for high lateral acceleration and ensuring a progression between the absence of correction and the maximum correction.

Claims (12)

  A method of controlling an anti-roll system for a vehicle having at least three wheels, in which, depending on the lateral acceleration of the vehicle, the vehicle movement data, and the gear ratio engaged, an instruction of roll correction and said roll correction instruction is sent to an actuator capable of applying anti-roll torque.   The method of claim 1, wherein said vehicle movement data comprises the vehicle longitudinal velocity V and / or a measurement of the front wheel steering angle.   3-Method according to any one of the preceding claims, wherein below a first lateral acceleration threshold, the roll correction setpoint is zero and / or above a second lateral acceleration threshold, the Roll correction setpoint is constant.   4-Method according to any one of the preceding claims, wherein between a first and a second lateral acceleration threshold, the roll correction instruction is monotonous increasing.   5-Method according to claim 4, wherein between a first and a second lateral acceleration threshold, the roll correction instruction is between a straight line and an increasing parabola.   An anti-roll system for a vehicle (1) having at least three wheels, comprising means (11) for developing a roll correction instruction as a function of lateral acceleration of the vehicle, vehicle movement data, and a gear ratio, and an actuator (14, 15) capable of applying an anti-roll torque in accordance with the roll correction setpoint.   The system of claim 6, wherein said means for forming a setpoint comprises a side acceleration normalization module (29).   The system of claim 7, wherein said normalization module (29) comprises a lateral acceleration angle entry of the vehicle, a static gain gain between the roll and the lateral acceleration, and a static gain input. between the roll and the anti-roll torque.   9-System according to claim 7 or 8, wherein said means for developing a setpoint comprises a calculation module (30) and a gear table (31).   The system of claim 9, wherein said compute module comprises a minimum positive speed parameter and a maximum anti-roll torque parameter.   11-System according to claim 9 or 10, wherein the speed table comprises, for each speed value, a minimum lateral acceleration parameter, a maximum lateral acceleration parameter, a steering wheel angle parameter, a slope parameter, and a side acceleration sign parameter.   Vehicle (1) provided with a chassis (2) and at least three wheels elastically connected to the chassis (2), comprising an anti-roll system comprising means (11) for producing a roll correction setpoint depending on the lateral acceleration of the vehicle, the vehicle displacement data, and the gear ratio engaged, and an actuator (14, 15) capable of applying an anti-roll torque as a function of the roll correction setpoint.