Trw Lucasvarity Electric Steering Limited

Trw Limited

Other

Lucas Industries Limited

Simon David Stevens

Russell Wilson Jones

Anthony Walter Burton

Andrew James Stephen Williams

James Owen Patrick Farrelly

Andrew Dennis Barton

John Nicholas Cheel

Alan Leslie Harris

Russell Wilson-Jones

Kevin M McLaughlin

Steven John Horton

Mark Leighton Howell

Marie Saunier

Tom Michael Richard Ernest Roberts

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.

An electric power assisted steering system is disclosed in which a torque demand signal ( ) is generated and applied to an electric motor ( ) operatively connected to a steering mechanism ( ) in order to assist a driver of the vehicle when steering the vehicle. The torque demand signal ( ) includes a damping component that is dependent upon a measurement of torque T carried by the steering mechanism and a measurement of the angular velocity &ohgr; of the steering mechanism. The torque produced by the motor ( ) is not obtrusive during &ldquo;hands-on&rdquo; maneuvers but provides enhanced damping in other maneuvers such as a steering flick.

Electrical power assisted steering systems

An electric power assisted steering system is disclosed in which a torque demand signal ( ) is generated and applied to an electric motor ( ) operatively connected to a steering mechanism ( ) in order to assist a driver of the vehicle when steering the vehicle. The torque demand signal ( ) includes a damping component that is dependent upon a measurement of torque T carried by the steering mechanism and a measurement of the angular velocity &ohgr; of the steering mechanism. The torque produced by the motor ( ) is not obtrusive during &ldquo;hands-on&rdquo; manoeuvers but provides enhanced damping in other manoeuvers such as a steering flick.

Relating to electrical power assisted steering systems

An apparatus and method for controlling an electric steering assist system, which system provides assist in response to a steering control signal, the apparatus comprising: torque sensing means ( ) operatively connected to a vehicle hand wheel ( ) for providing a torque signal (Ts) indicative of applied steering torque, blending filter means connected to the torque sensing means ( ) for providing a blended filtered torque signal having a first functional characteristic at torque frequencies less than a blending frequency and a second functional characteristic at torque frequencies greater than the blending frequency, the blending filter means including a low pass filter ( ) which passes all frequencies below the blending frequency and a high pass filter ( ) which passes all frequencies above the blending frequency, steering assist means for providing steering assist in response to a control signal, control means operatively connected to the blending filter means for providing said control signal to the steering assist means in response to the blended filtered torque signal, and means ( ) whereby high frequency gain of the steering assist system is arranged to be low for on-center operation of the hand wheel and relatively higher for off-center operation.

Method and apparatus for controlling an electric powered assisted steering system using an adaptive blending torque filter

An electric power assisted steering system of the kind in which an electric motor is operatively connected to a steering assembly through a gearbox to apply an assistance torque to the steering assembly and in which the steering assembly includes a steering column coupled at one end to a driver's handwheel and at the other end to steerable wheels, a means being provided for generating a signal representative of the velocity of rotation of the steering column. The system includes a high pass filter which is adapted to generate, for frequencies below a prescribed threshold, a signal at least approximately proportional to steering column acceleration and representative of the inertia of the rotor of the electric motor, the latter signal being arranged to be used to compensate for the motor rotor inertia in an overall assistance torque demand as developed by the system.

Compensation for motor inertia in electric power assisted steering systems

An electric power assisted steering system is disclosed which comprises a steering shaft connected at one end to the handwheel and at its other end to at least one roadwheel, while an electric motor is connected to the steering a gearbox having a non-integer reduction gear ratio. Two sensors are also provided with one sensing the angular position of the motor rotor and the other sensing the angular position of the steering shaft. The presence of the non-integer gear ratio produces a beat frequency between the output of the two sensors from which an unambiguous measurement of the angular position of the steering shaft over a range of greater than one complete revolution can be made. The sensors may comprise either absolute position sensors or index-type sensors.

Electric power assisted steering systems

An electronic braking system for a vehicle wherein control of the vehicle brakes is achieved by the use of electric control signals generated at a brake pedal in response to a driver's braking demand and an electronic controller which is adapted to control the supply of fluid under pressure from a power source to the brakes in accordance with said electronic signals corresponding to the driver's demand, the system being adapted to raise the brake pressure to a first predetermined level(jump-in) at a prescribed level of initial brake pedal travel and to release the brake pressure (reverse jump-in) as a second predetermined level, which is lower than at jump-in. The jump-in brake pressure level can be arranged to be variable with vehicle speed. In some cases, the brakes are arranged to be prefilled to a low pressure at a low pressure at an early stage in the pedal travel and then maintained at that low level until jump-in is triggered, whereupon the braking pressure is raised to the jump-in level. In other cases where jump-in is not necessarily used, the prefill pressure is maintained at that level until actual brake demand exceeds the prefill pressure whereupon the brake pressure is then controlled in accordance with actual brake demand.

Growing community of inventors

Birmingham, United Kingdom

Simon David Stevens