Abstract: An electric power assisted steering assembly comprises a steering mechanism which operatively connects a steering wheel to the roadwheels of a vehicle, a sensor adapted to produce a first output signal indicative of the torque carried by a portion of the steering mechanism and to produce a second output signal indicative, an electric motor, a signal processing unit having a lead-lag filter to produce an overall torque demand signal, and a motor drive stage adapted to provide a drive current to the motor responsive to the torque demand signal.

Abstract: A method of controlling a motor of an electric power assisted steering system, the motor having a plurality of phases, the method comprising taking as an input an input signal indicative of a desired assistance torque and determining from the desired assistance torque a voltage to be applied to each of the phases of the motor, in which the step of determining the voltage to be applied to each of the phases comprises limiting the voltage determined to be applied to each of the phases of the motor dependent upon the voltage provided by a power supply to the motor.

Abstract: A method of controlling a motor of an electric power assisted steering system, the motor having a plurality of phases, the method comprising taking as an input an input signal indicative of a desired assistance torque and determining from the desired assistance torque a voltage to be applied to each of the phases of the motor, in which the step of determining the voltage to be applied to each of the phases comprises limiting the voltage determined to be applied to each of the phases of the motor dependent upon the voltage provided by a power supply to the motor.

Abstract: An electric power assisted steering assembly comprises a steering mechanism which operatively connects a steering wheel to the roadwheels of a vehicle, a torque sensing means adapted to produce a first output signal indicative of the torque carried by a portion of the steering mechanism, a means for producing a second output signal indicative from a signal indicative of the angular velocity of the portion of the steering mechanism, an electric motor operatively connected to the steering mechanism, a signal processing unit adapted to receive the two output signals and to produce therefrom an overall torque demand signal representative of a torque to be applied to the steering mechanism by the motor, and a motor drive stage adapted to provide a drive current to the motor responsive to the torque demand signal. The overall torque demand signal includes a damping component that is dependent upon the second output signal.

Abstract: A controller for an electric power assisted steering system includes a steering mechanism and an electric motor that can apply an assistance torque to the steering mechanism. The controller has an input for an input torque signal indicative of the torque applied by a user to the steering mechanism and an output for an assistance torque demand indicative of the assistance torque to be applied to the steering mechanism by the electric motor. The controller includes: a first subcontroller having an input for the input torque signal, an output for a first assistance torque and a process arranged to determine the first assistance torque; a second subcontroller having an input for the input torque signal, an output for a second assistance torque and a processor arranged to determine the second assistance torque; and a blending unit, which provides as an output the assistance torque demand.

Abstract: An electric power assisted steering system comprises a torque sensor, a motor connected to a part of the steering system to provide motor torque to the steering system and a motor controller which is adapted to receive an output signal from the torque sensor and to generate a motor torque demand signal indicative of the torque to be applied by the motor to the steering system. The motor torque demand signal comprises a driver demand component dependent upon the torque applied by the driver; and a diagnostic component independent of the torque applied by the driver and which varies in value over time in a predetermined manner. The system further comprises a monitor that correlates the diagnostic component with the output signal and generates a signal indicating that the output signal is faulty if the correlation falls outside of a predefined range.

Abstract: An electric power assisted steering system comprises a torque sensor, a motor connected to a part of the steering assembly to provide an assistance torque to the steering assembly and a motor controller which is adapted to receive an output signal from the torque sensor and to generate a motor torque demand signal indicative of the torque to be applied by said motor to said steering system. The motor torque demand signal comprises a driver demand component with a value dependent upon the value of said handwheel torque applied by the driver; and a diagnostic component with a value independent of said handwheel torque applied by said driver and which varies in value over time in a predetermined manner. The system further comprises a monitor that correlates the diagnostic component with the output signal and generates a signal indicating that the output signal is faulty if the correlation between the two correlated signals falls outside of a predefined range.

Abstract: An electric power assisted steering assembly comprises a steering mechanism which operatively connects a steering wheel to the road wheels of a vehicle, a torque sensing means which is adapted to produce an output signal indicative of the torque applied to a portion of the steering mechanism by the driver, a signal processing means which is adapted to control the motor so as to cause the motor to apply a torque to the steering mechanism to assist the driver, and a compensation torque generating means which is adapted to combine a torque value representative of the motor applied torque with the output of the torque sensor to produce a compensation torque signal that is to be applied by the motor to the steering mechanism that at least partially compensates for any pull on the steering due to suspension misalignment.