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AssigneeTRW Lucas Varity Electric Steering Ltd.
InventorsSimon David Stevens, Anthony Walter Burton, Andrew James Stephen Williams, John Nicholas Cheel, Russell Wilson Jones
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An electric power assisted steering system is disclosed in which a torque demand signal (8) is generated and applied to an electric motor (1) operatively connected to a steering mechanism (5) in order to assist a driver of the vehicle when steering the vehicle. The torque demand signal (8) 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 ω of the steering mechanism. The torque produced by the motor (1) is not obtrusive during “hands-on” manoeuvers but provides enhanced damping in other manoeuvers such as a steering flick.
An electric power assisted steering assembly comprising a steering mechanism which operatively connects a steering wheel to roadwheels of a vehicle, a torque sensor adapted to produce a first output signal indicative of a torque T carried by a portion of said steering mechanism, an angular velocity sensing sensor for producing a second output signal indicative of an angular velocity of said portion of said steering mechanism, an angular position sensor adapted to produce a third output signal dependent on an angular position of said portion of said steering mechanism, an electric motor operatively connected to said steering mechanism, a signal processing unit adapted to receive said first output signal and said second output signal and to produce a torque demand signal representative of an assistance torque to be applied to said steering mechanism by said motor, and a motor drive stage adapted to provide a drive current to said motor responsive to said torque demand signal, and in which said torque demand signal includes a damping component that is dependent upon said first output signal, said second output signal and said third output signal.
Dependencies are inferred from the claim text.