WO2007071853A1

WO2007071853A1 - Anti-roll device for vehicles

Info

Publication number: WO2007071853A1
Application number: PCT/FR2006/051060
Authority: WO
Inventors: Yves Le Vourch; Richard Pothin
Original assignee: Renault S.A.S.
Priority date: 2005-12-21
Filing date: 2006-10-19
Publication date: 2007-06-28
Also published as: FR2894878B1; FR2894878A1

Abstract

Method and system for controlling an anti-roll system for a vehicle (1) having at least three wheels, in which, depending on the lateral acceleration of the vehicle, the vehicle movement data, and the engaged gear ratio, a roll correction instruction is formulated and said roll correction instruction is sent to an actuator (14, 15) capable of applying an anti-roll torque.

Description

ANTI-ROLL DEVICE FOR VEHICLES

The present invention relates to the field of land vehicle control systems, particularly wheeled motor vehicles.

Traditionally, motor vehicles are provided with a chassis, a passenger compartment, wheels connected to the chassis by a suspension mechanism with front wheels controlled by a steering wheel available to the driver in the passenger compartment of the vehicle, and steering or non-steering rear wheels.

US 2004/0117085 discloses a yaw stability control system of a vehicle equipped with a lateral acceleration sensor, a roll sensor, a steering angle sensor and a steering angle sensor. at least one 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 discloses 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 road conditions. Some situations may result in a loss of vehicle control, such as 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 still unpredictable.

The aim of the invention is a progressively adjustable anti - roll control system which provides safety, a feeling of safety, comfort and a high driving pleasure.

The anti - roll vehicle control method for a vehicle with at least three wheels includes developing a free wheel set - point according to the vehicle lateral acceleration, vehicle displacement data and speed ratio. engaged, and sending said free wheel correction instruction to an actuator capable of applying an anti - roll torque. The quasi static roll of the vehicle is reduced by applying the anti-roll torque for a speed range from reverse to forward. The anti-rollover torque can be reset gradually as the vehicle comes to a stop or when approaching a low steering angle. The progressivity of the anti-rollover torque can be adjusted to avoid any uncomfortable driving sensation. The 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 may be between a straight line and an increasing parabola between the first and second lateral acceleration thresholds.

The roll acceleration target may be zero below a threshold speed or gear ratio engaged. The anti-roll vehicle system with at least three wheels includes means for developing a roll correction setpoint based on vehicle lateral acceleration, vehicle travel 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 developing a setpoint comprises a module for normalizing lateral acceleration. The normalization module may include a vehicle lateral acceleration angle input, a static gain input between the roll and the lateral acceleration, and a static gain input between the roll and the anti - roll torque. The means for developing 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 an acceleration sign parameter. lateral. The vehicle is provided with a frame and at least three wheels elastically connected to the chassis. The vehicle comprises an anti-roll system provided with means for developing a roll correction setpoint based on the lateral acceleration of the vehicle, the vehicle traveling data, and the gear ratio engaged, and an actuator capable of apply an anti-roll torque according to the roll correction instruction. The system is open loop.

The actuator may be part of a controllable anti-roll bar or active suspension. In one embodiment, the vehicle displacement data may include a measurement of the steering angle of the rear wheels, in the case of a steered rear wheel vehicle. The development of the system is facilitated by the small number of parameters implemented and allows a progressivity of quasi-static adjustments.

The present invention will be better understood on reading the detailed description of some embodiments taken as non-limiting examples and illustrated by the appended drawings, in which:

FIG 1 is a schematic view of a vehicle equipped with 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 the 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 disposed between the front wheels 3 and 4, a rack actuator 9 adapted to orient the front wheels 3 and 4 via the rack 8 as a function of orders received, mechanically or electrically, from a steering wheel, not shown, available to a driver of the vehicle. In the variant with rear guide wheels, 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 Y _T 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 the vehicle. steering angle of the front wheels 3 and 4, for example mounted on the actuator 9. The sensor 12 may be disposed at the center of gravity of the vehicle 1. The speed sensor may be optical or magnetic type, for example to 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 pilotable antiroll bars 15 capable of modifying the parameters of the suspension disposed 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 S _v 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 can be implemented in the form of a microprocessor equipped with a random access memory, a read only 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 coming from the sensors 12 and 13, more particularly the vehicle speed V and the transverse acceleration γ-r. 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 1 1 to provide 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 Sy, a dead zone parameter Z _m , a static gain parameter

G and a slope parameter p. The speed sign is 1 if a positive gear is engaged and -1 if reverse gear is engaged or the gear lever is in neutral. The stop parameter B is equal to the maximum torque applicable and can be used 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 Z _m is homogeneous with a lateral acceleration and determines the lateral acceleration threshold γ _τ 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 Y _T between the dead zone and the stop.

The calculation block 23 comprises a normalization block 29 receiving the lateral acceleration value Y _T and performing the normalization calculation of the lateral acceleration to obtain:

with Gγ the static gain between the roll and the lateral acceleration of the vehicle and G the static gain between the roll and the anti - roll couple.

The calculation block 23 comprises a quasi-static control generation module 30 associated with a table 31 of anti-roll speed and torque, which, as a function of the speed, the steering wheel angle, the lateral acceleration normalized γτ _n and parameters B, S _v , Z _m , G and p, generates an anti-roll torque instruction. The parameters determine the anti-roll torque curve as a function of the lateral acceleration γ _Tn , an example of which is illustrated in FIG. 3 and for a large number of speed values V ₁ stored in a table. In other words, the parameters B, S _v , Z _m , G and p depend on the speed.

The determination of the anti-roll torque setting can be carried out as follows. For a speed of absolute value less than V _min or a steering wheel angle of absolute value less than α _min , the anti-rollover torque is zero. For a value of lateral acceleration of absolute value lower than a threshold or dead zone Z _m , then the anti-rollover torque is zero. The anti-roll torque setting is capped at a stop or maximum value B. In other words, if the lateral acceleration is greater than a second threshold γ _max , the anti-roll torque setpoint is equal to the stop B.

We calculate the signed speed Vs equal to the product of the speed V by the sign S _v and we search in the table 31 a speed value less than and / or as close as possible to the value Vs. For absolute values of normalized lateral acceleration γ _Tn between the first threshold Z _m and the second threshold γ _max , the anti-roll torque is determined by a parabolic function. of the lateral acceleration γ _Tn - We calculate then:

a = (1-slope) db = d (slope (γ _max + Z _m ) - 2 Z _m ) c = a

The set anti-roll torque C = a γτ _n + b \ ^ _Tn \ + c

The determination of the sign of the anti-roll torque instruction can be carried out as follows. If the absolute value of the lateral acceleration

is different from zero, then the sign of the lateral acceleration is equal to the quotient of the lateral acceleration γ-m by the absolute value of the lateral acceleration

. Otherwise, the sign of the lateral acceleration is zero. 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 oppose in phase or in phase the anti-roll torque with respect to the lateral acceleration.

The final value of the torque of the setpoint and of the anti-rollover torque can then be calculated by linear interpolation on the speed, taking a speed V ₁ immediately below the speed V and a speed V _{1 + 1} immediately greater than the speed V hence two values of the anti - roll couple C ₁ and C _{1 + 1} .

Thanks to the invention, a roll correction is obtained that is relatively simple to implement and allows 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 accelerations and ensuring a progressivity between the absence of correction and the maximum correction.

Claims

An anti-roll system control method for a vehicle with at least three wheels, wherein depending on the lateral acceleration of the vehicle, the vehicle traveling 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 longitudinal velocity V of the vehicle and / or a measurement of the steering angle of the front wheel.

3-process 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-A 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-Process 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 setpoint as a function of lateral acceleration of the vehicle, vehicle movement data, and gear ratio engaged, and an actuator (14, 15) capable of applying an antiroll torque as a function of the roll correction instruction.

The system of claim 6, wherein said means for developing a setpoint comprises a lateral acceleration normalization module (29).

The system of claim 7, wherein said normalization module (29) comprises a lateral acceleration angle input of the vehicle, a static gain input between the roll and lateral acceleration, and a static gain input. between the roll and the anti-roll couple.

The system of 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 computation module comprises a minimum positive speed parameter and a maximum anti-roll torque parameter.

The 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 parameter of slope, and a sign parameter of lateral acceleration.

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 developing a roll correction instruction in of the lateral acceleration of the vehicle, of the vehicle displacement data, and of the gear ratio engaged, and an actuator (14, 15) capable of applying an antiroll torque as a function of the roll correction setpoint.