Vehicle Steering Control Without Mechanical Connection Between Steering Wheel and Steered Wheels

• US 20080114514A1
• Filed: 03/24/2006
• Published: 05/15/2008
• Est. Priority Date: 04/01/2005
• Status: Active Grant

• Current Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Original Assignee: Michelin Recherche et Technique SA (Compagnie Generale DES Etablissements Michelin SCA)
• Inventors: Auguet, Thierry, Sebe, Marc
• Granted Patent: US 8,046,132 B2
• Time in Patent Office: Days
• US Class Current: 701/42
• CPC Class Codes: B62D 6/003 in order to control vehicle yaw movement, i.e. around a vertical axis B62D6/007 takes precedence
• 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

Steering control system for a land vehicle where all the wheels are steered (1), the said steering system comprising at least one actuator (3_Av) for acting on the steering angle of the at least one front steered wheel and at least one actuator (3_Ar) for acting on the steering angle of the at least one rear steered wheel, the said steering system comprising a controller (4) using as input variables at least the speed of the vehicle (V) and the said requested steering signal (θ) in order to determine for each of the actuators a control angle (α) according to which the actuator is controlled for the steering, the system comprising a module for controlling the steering behaviour (5) of the vehicle, making it possible to determine the longitudinal coordinate (x_R) of the instantaneous centre of rotation of the vehicle from the speed of the vehicle (V) and a rule characteristic of the dynamic equilibrium of the vehicle and the choice of a maximum transverse acceleration value (γ_{y max}) of the vehicle, and a block (433) for determining the control angle (α) of each of the steered wheels from the longitudinal and transverse coordinates (x_R, y_R) of the instantaneous centre of rotation.

Claims

1-12. -12. (canceled)

13. A steering control system for a land vehicle that includes at least one front wheel and one rear wheel, the vehicle including a control member available to a driver for steering the vehicle, the control member delivering a requested steering signal quantified in terms of amplitude and direction, the steering control system comprising:

a first actuator configured to act on a steering angle of a front steered wheel;

a second actuator configured to act on a steering angle of a rear steered wheel; and

a controller that uses as input variables at least a speed of the vehicle and the requested steering signal in order to determine, for each of the first and second actuators, a control angle according to which the actuator is controlled for steering the vehicle, wherein the controller includes;

a unit configured to determine an equivalent steering angle of a steered wheel of an equivalent bicycle model according to the requested steering signal and to determine a transverse coordinate of an instantaneous center of rotation of the vehicle,

a module configured to control a steering behaviour of the vehicle to enable a longitudinal coordinate of the instantaneous center of rotation of the vehicle to be determined from the speed of the vehicle and a rule characteristic of a dynamic equilibrium of the vehicle, and

a block configured to determine the respective control angles of the steered wheels from the longitudinal and transverse coordinates of the instantaneous center of rotation of the vehicle.

14. A system according to claim 13,

wherein the rule characteristic of the dynamic equilibrium of the vehicle includes a calculation of a connection curve between an initial center of rotation at zero speed and a transition instantaneous center of rotation at a transition speed, the connection curve being tangent to a straight line parallel to an axle of the vehicle, and

wherein the longitudinal coordinate of the instantaneous center of rotation of the vehicle is determined by reading a transverse coordinate at a site that includes the connection curve and the straight line parallel to an axle of the vehicle for a speed of the vehicle below the transition speed, and the longitudinal coordinate of the instantaneous center of rotation of the vehicle is equal to a longitudinal coordinate that is a function of a speed of the vehicle above the transition speed.

15. A system according to claim 14, wherein the connection curve is an ellipse.

16. A system according to claim 13, wherein the rule characteristic of the dynamic equilibrium of the vehicle includes a choice of a maximum transverse acceleration parameter of the vehicle.

17. A system according to claim 14, wherein the transverse coordinate of the instantaneous center of rotation of the vehicle at the transition speed is determined using, in the rule characteristic of the dynamic equilibrium of the vehicle, a choice of a maximum transverse acceleration parameter of the vehicle and the transition speed.

18. A system according to claim 15, wherein the transverse coordinate of the instantaneous center of rotation of the vehicle at the transition speed is determined using, in the rule characteristic of the dynamic equilibrium of the vehicle, a choice of a maximum transverse acceleration parameter of the vehicle and the transition speed.

19. A system according to claim 16, wherein the maximum transverse acceleration parameter is an adjustment parameter of the system and keeps a fixed value of a functioning of the system.

20. A system according to claim 17, wherein the maximum transverse acceleration parameter is an adjustment parameter of the system and keeps a fixed value of a functioning of the system.

21. A system according to claim 17, wherein the maximum transverse acceleration parameter is an adjustment parameter of the system and keeps a fixed value of a functioning of the system.

22. A system according to claim 15, wherein the maximum transverse acceleration parameter is calculated in real time according to conditions of use of the vehicle.

23. A system according to claim 16, wherein the maximum transverse acceleration parameter is calculated in real time according to conditions of use of the vehicle.

24. A system according to claim 17, wherein the maximum transverse acceleration parameter is calculated in real time according to conditions of use of the vehicle.

25. A system according to claim 13,

wherein the control member is maneuverable within a maximum range between a leftward stop and a rightward stop, and

wherein the controller includes:

a first unit configured to determine, at least according to the speed of the vehicle, a maximum steering angle on the steered wheel of the equivalent bicycle model of the vehicle,

a second unit configured to determine a gearing-down ratio according to the maximum range of the control member and the maximum steering angle, and

a third unit configured to determine a steering angle according to the gearing-down ratio.

26. A system according to claim 13,

wherein the vehicle includes four steered wheels that are mechanically connected in terms of steering via a plurality of axles,

wherein the system further comprises an actuator per axle, and

wherein the block is configured to determine, from the transverse and longitudinal coordinates of the instantaneous center of rotation of the vehicle, respective control angles of the actuators of the plurality of axles.

27. A system according to claim 13,

where the vehicle includes four steered wheels,

wherein the system further comprises an actuator per steered wheel,

wherein the block is configured to determine, from the transverse and longitudinal coordinates of the instantaneous center of rotation of the vehicle, respective control angles of the steered wheels.

28. A system according to claim 13, wherein the requested steering signal delivered by the control member is an electrical signal, and wherein each actuator is electrical.

29. A path controller for controlling a path of a vehicle, comprising a steering control system according to claim 13 for determining control angles, wherein the path controller superimposes corrections determined by a control function and determines a corrected steering angle for each of the wheels, each corrected steering angle including a component resulting from the requested steering signal and a correction component.