Trw Limited

Lucas Industries Limited

Andrew Dennis Barton

James Owen Patrick Farrelly

Simon David Stevens

Adam John Heenan

Anthony Walter Burton

Timothy Sworn

Mark Richard Tucker

Andrew James Pick

Edward John Milbourn

Michael John Bayes

Nicholas Alford

An electric assisted steering control strategy for a steering system for a vehicle is arranged to assist the driver in controlling the vehicle during a split mu braking operation. The steering is provided with assistance being based on at least one operational variable representing a corrective steer angle for the vehicle which is added to a main assistance torque via a driver feedback controller, and the strategy is adapted to employ an estimate of yaw moment of the vehicle as the operational variable, the yaw moment being determined by processing the speed of wheels on opposite sides of the vehicle.

Steering control during split mu braking

A road vehicle steering system which is adapted to use measurements and estimates characterising the motion of and forces acting on the vehicle and the steering system such as to derive an estimate of steering system disturbance force and to then use the latter estimate to establish a torque demand for the vehicle electronic power steering (EPS) which substantially compensates for this disturbance force.

Rack force disturbance rejection

An electric assisted steering system for a motor driven road vehicle, having assist torque signal generating means which generates an assist torque signal for the steering system in response to the driver's applied torque and sensed vehicle speed to reduce the driver's steering effort. A yaw rate haptic torque is generated which is based upon vehicle rate error and is arranged to be added to the torque assist signal such that, when the yaw rate error builds up corresponding to increasing steering instability (e.g. understeer or oversteer) of the vehicle, the haptic torque added to the torque assist signal reduces the effective road reaction feedback sensed by the driver in advance of any actual vehicle stability loss whereby to allow the driver to correct appropriately in good time before terminal steering instability is reached. Alternatively, the haptic torque can be based upon vehicle lateral acceleration which is arranged to be subtracted from the torque assist signal such that when vehicle lateral acceleration builds up, corresponding to tighter cornering of the vehicle, the haptic torque subtracted from the torque assist signal increases the effective road reaction feedback sensed by the driver corresponding to the increase in cornering forces generated by the tires of the vehicle.

Haptic controller for road vehicles

An electric assisted steering system for a motor driven road vehicle, having assist torque signal generating means which generates an assist torque signal for the steering system in response to the driver's applied torque and sensed vehicle speed to reduce the driver's steering effort. A yaw rate haptic torque is generated which is based upon vehicle rate error and is arranged to be added to the torque assist signal such that, when the yaw rate error builds up corresponding to increasing steering instability (e.g. understeer or oversteer) of the vehicle, the haptic torque added to the torque assist signal reduces the effective road reaction feedback sensed by the driver in advance of any actual vehicle stability loss whereby to allow the driver to correct appropriately in good time before terminal steering instability is reached. Alternatively, the haptic torque can be based upon vehicle lateral acceleration which is arranged to be subtracted from the torque assist signal such that when vehicle lateral acceleration builds up, corresponding to tighter cornering of the vehicle, the haptic torque subtracted from the torque assist signal increases the effective road reaction feedback sensed by the driver corresponding to the increase in cornering forces generated by the tyres of the vehicle.

A vehicle stability compensation system, which is arranged to adjust dynamically the self-centering position and the steering feel of the vehicle steering system during split mu braking operation. The adjustment being based on at least one operational variable representing a corrective steer angle for the vehicle and hence representing a target self-centering position. A target self-centering error is derived from the difference between the target self-centering position and an actual vehicle steering angle. A torque demand that is proportional to the target self-centering error is then added to an assistance torque generated by the electrically assisted steering system to shift the self-centering position so as to encourage the vehicle driver to move the steering wheel such as to reduce the target self-centering error to zero for maintaining the vehicle stable and controllable.

Steering control during split-mu ABS braking

A steering assistance controller for the generation of a compensating torque which assists the driver in overcoming the tendency of a vehicle to oversteer by encouraging the driver to steer the vehicle back to a non-steering condition through the application of said compensating torque which is based substantially upon an estimate of magnitude of oversteer.

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Coventry, United Kingdom

Andrew Dennis Barton