Method for controlling yaw and transversal dynamics in a road vehicle

• US 20040015284A1
• Filed: 02/10/2003
• Published: 01/22/2004
• Est. Priority Date: 08/16/2000
• Status: Active Grant

• Current Assignee: Mind Fusion, LLC (Ascend Innovation Management, LLC)
• Original Assignee: Daimler Chrysler Company LLC (Stellantis NV)
• Inventors: Suissa, Avshalom
• Granted Patent: US 6,909,957 B2
• Time in Patent Office: Days
• US Class Current: 701/82
• CPC Class Codes: B62D 6/00 Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits means for initiating a change in direction B62D1/00; steering valves B62D5/06; combined with means for inclining the vehicle body or wheels on bends B62D9/00
• CPC Class Codes: B62D 7/159 characterised by computing methods or stabilisation processes or systems, e.g. responding to yaw rate, lateral wind, load, road condition

Abstract

For the purpose of controlling the yaw dynamics and lateral dynamics in a road vehicle with electrically controlled four-wheel steering, in the case of which the setting of the front axle steer angle δ_v and of the rear axle steer angle δ_h is performed by means of mutually decoupled control loops, a desired value S_vsoll for the lateral force S_v to be built up at the front axle is determined in the control loop assigned to the front axle and, for this desired value S_vsoll, the value of the slip angle, linked to the desired value S_vsoll, is determined as desired value α_vsoll from an S_v(α_v) characteristic representing the dependence of the lateral force S_v, to be built up at the front axle, on the slip angle α_v. In the control loop assigned to the rear axle, a desired value S_hsoll for the lateral force S_h to be built up at the rear axle is determined in a control process in accordance with a controller law of the form $S_{\mathrm{hsoll}}=\frac{l_v·m·v_x}{L}·\left[\stackrel{.}{\Psi }-{\stackrel{.}{\beta }}_{\mathrm{hsoll}}+k_1·\left({\beta }_h-{\beta }_{\mathrm{hsoll}}\right)\right]$

and, for this desired value S_hsoll, the value of the slip angle, linked to the desired value S_hsoll, is determined as desired value α_hsoll from an S_h(C_h) characteristic. These desired values α_vsoll and α_hsoll are used to determine the desired values δ_vsoll and δ_hsoll of the steer angle, taking account of an estimated value of the sideslip angle β at the centre of gravity of the vehicle, the position of the centre of gravity and measured or estimated values of the yaw velocity {dot over (Ψ)} and of the longitudinal speed v_x of the vehicle.

Claims

1. Method for controlling the yaw dynamics and lateral dynamics in a road vehicle having one steering device each for the front axle and for the rear axle, and having electrically drivable 8v and δ

_h steer angle actuators (17 and 18), which are assigned to said axles individually, can be driven via a controller each and which generate from desired/actual value comparisons of variables which are characteristic of the yaw-dynamic and the lateral-dynamic behaviour of the vehicle, for example of the yaw velocity {dot over (Ψ

)} and of a sideslip angle β

, drive signals, required for correcting the controlled variables, for the steer angle actuators, the control loops provided for setting the steer angles δ

_v and δ

_h being decoupled from one another, and the desired value prescription signals, required for the two control loops, for the control parameters being generated by means of a reference model (28), implemented by an electronic computer, from a processing of at least one output signal, representing the driver'"'"'s wish, from a steering element position sensor (31), and of a sensor output signal characteristic of the operating state of the vehicle, for example a speed sensor, characterized by the following features;

(a) a desired value S_vsoll for the lateral force S_v to be built up at the front axle is determined in a control process in the control loop assigned to the front axle;

(b) for this desired value S_vsoll, the value of the slip angle, linked to the desired value S_vsoll, is determined as desired value α

_vsoll from an S_v(α

_v) characteristic representing the dependence of the lateral force S_v, to be built up at the front axle, on the slip angle α

_v at the front axle, and the absolute value δ

_vsoll of the front axle steer angle, which is set by means of the front axle steer angle actuator, is determined in accordance with the relationship

${\mathrm{\delta <br><br>}}_{\mathrm{vsoll}}=-\mathrm{\beta <br><br>}+\frac{l_v·<br><br>\stackrel{.}{\mathrm{\Psi <br><br>}}}{v_x}+{\mathrm{\alpha <br><br>}}_{\mathrm{vsoll};<br><br>}$

(c) a desired value S_hsoll for the lateral force S_h to be built up at the rear axle is determined in a control process in accordance with a controller law of the form

$S_{\mathrm{hsoll}}=\frac{l_v·<br><br>m·<br><br>v_x}{L}·<br><br>\left[\stackrel{.}{\mathrm{\Psi <br><br>}}-{\stackrel{.}{\mathrm{\beta <br><br>}}}_{\mathrm{hsoll}}+k_1·<br><br>\left({\mathrm{\beta <br><br>}}_h-{\mathrm{\beta <br><br>}}_{\mathrm{hsoll}}\right)\right]$

 

in the control loop assigned to the rear axle; and

(d) for this desired value S_hsoll of the rear axle lateral force, the value of the slip angle, linked to the desired value S_hsoll, is determined as desired value α

_hsoll from an S_h(α

_h) characteristic, and the absolute value δ

_hsoll of the rear axle steer angle which is set by means of the rear axle steer angle actuator is determined in accordance with the relationship

${\mathrm{\delta <br><br>}}_{\mathrm{hsoll}}=-\mathrm{\beta <br><br>}-\frac{l_h·<br><br>\stackrel{.}{\mathrm{\Psi <br><br>}}}{v_x}+{\mathrm{\alpha <br><br>}}_{\mathrm{hsoll}}.$

2. Method according to claim 1, characterized in that the desired value S_vsoll of the lateral force to be built up at the front axle is determined in a control process in accordance with a controller law of the form

3. Method according to claim 1, characterized in that the desired value S_vsoll of the lateral force to be built up at the front axle is determined in a control process in accordance with a controller law of the form

4. Method according to one of claims 1 to 3, characterized in that the desired value α

_vsoll of the slip angle α

_v at the front axle and/or the desired value α

_hsoll of the slip angle ah at the real axle is obtained from a linear relationship of the form

5. Device for carrying out the method according to one of claims 1 to 4 on a road vehicle (11) having one steering device each for the front axle (24) and for the rear axle (26), and having electrically drivable steer angle actuators (17 and 18), assigned to said axles individually, for two mutually decoupled control loops by means of which the front axle steer angle δ

_v and the rear axle steer angle δ

_h can be set, characterized in that there is provided in each case at least one lateral acceleration sensor (47) by means of which a lateral acceleration a_y occurring on the vehicle (11) can be detected at a defined point of the vehicle, preferably at its centre of gravity.

6. Device according to claim 5, characterized in that two lateral acceleration sensors (48 and 49) are provided which, seen in the direction of the vehicle longitudinal axis, are arranged at a spacing from one another, it being preferred for one lateral acceleration sensor (48) to be arranged in the region of the front axle (24) and for the other lateral acceleration sensor (49) to be arranged in the region of the rear axle (26) of the vehicle (11).

7. Device, in particular according to claim 5 or claim 6, characterized by its ability to switch over between the control mode in which the desired value S_vsoll of the lateral force at the front axle is determined in accordance with the controller law

8. Device, in particular according to one of claims 5 to 7, characterized in that a reference model (28) provided for generating the prescribed desired values for the front axle and rear axle steer angles δ

_v and δ

_h to be set can be set to various defined algorithms for generating these desired values.

9. Device according to claim 7 or 8, characterized in that an automatic switchover is performed from the control mode in which the desired value S_vsoll of the lateral force at the front axle is determined as a function of the system deviation (β

_v−

β

_vsoll) of the sideslip angle in the region of the front axle, into the control mode in which the desired value S_vsoll of the lateral force at the front axle is determined as a function of the system deviation ({dot over (Ψ

)}−

Ψ

_soll) of the yaw velocity when the ability of the tyre to transmit lateral force is exhausted, or virtually exhausted, in the extreme range, and/or the rear axle steer angle actuator (18) has failed.

10. Device, in particular according to one of claims 5 to 9, characterized in that a disturbance estimator (66 and/or 67) is provided for at least one of the control loops provided for setting the front axle and the rear axle steer angles δ

_v and δ

_h.

11. Device according to claim 10, characterized in that the controller and the disturbance estimator which are assigned to the same controlled variable are designed using the same design model.