Abstract: A method of controlling an electric motor in an electric power assisted steering system, the motor being arranged so as to apply a force to part of a steering mechanism of a vehicle, in which the method comprises calculating a force demand indicative of an assistance force dependent upon the torque applied by a user (TD) to the steering mechanism that it is to be applied to the steering mechanism to reduce the exertion required by the user to steer the vehicle; combining the force demand with an overlay force demand (TER) indicative of a force which it is desired to overlay over the assistance force, to generate a combined assistance force (TA); and controlling the motor according to the combined assistance force, such that together with the force applied by the user, a total force is applied to the steering mechanism, in which, in order to generate the combined assistance force the torque applied by the user is subjected to a non-linear boost function and in which the overlay force demand is combined with th

Abstract: 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.

Abstract: 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.

Abstract: A method of controlling an electric motor in an electric power assisted steering system, the motor being arranged so as to apply a force to part of a steering mechanism of a vehicle, in which the method comprises calculating a force demand indicative of an assistance force dependent upon the torque applied by a user (TD) to the steering mechanism that it is to be applied to the steering mechanism to reduce the exertion required by the user to steer the vehicle; combining the force demand with an overlay force demand (TER) indicative of a force which it is desired to overlay over the assistance force, to generate a combined assistance force (TA); and controlling the motor according to the combined assistance force, such that together with the force applied by the user, a total force is applied to the steering mechanism, in which, in order to generate the combined assistance force the torque applied by the user is subjected to a non-linear boost function and in which the overlay force demand is combined with th

Abstract: A method for controlling an electric assist motor for providing steering assist in response to a sensed torque signal includes the step of filtering the sensed torque signal to provide a low frequency torque signal and a high frequency torque signal. A low frequency assist torque signal is determined as a function of the low frequency torque signal. A high frequency assist gain signal is determined as a function of the sensed torque signal and a sensed vehicle speed. The high frequency assist gain signal is applied to the high frequency torque signal to determine a high frequency assist torque signal. A torque command signal is determined as a function of the low frequency assist torque signal and the high frequency assist torque signal. The electric assist motor is commanded to provide steering assist in accordance with the torque command signal.

Abstract: 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 &ohgr; of the steering mechanism. The torque produced by the motor (1) is not obtrusive during “hands-on” maneuvers but provides enhanced damping in other maneuvers such as a steering flick.

Abstract: 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 &ohgr; 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.

Abstract: 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 (20) operatively connected to a vehicle hand wheel (12) for providing a torque signal (Ts) indicative of applied steering torque, blending filter means connected to the torque sensing means (20) 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 (70) which passes all frequencies below the blending frequency and a high pass filter (71) 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 s

Abstract: 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.

Abstract: A method of calculating the position of the rotor of a motor (1) in for example an electrical power assisted steering assembly is disclosed. The method comprises the steps of measuring the output shaft (2) (i.e. steering column) position, and scaling the measured value to produce an estimated motor rotor position value. This estimated value will be relative to an arbitrary datum point, and so the method further includes steps of adding an offset value derived from low resolution measurements of rotor position obtained using Hall effect sensors provided on the motor. Offsets for compensating for backlash and (in a second embodiment) compliance can also be included. Thus, the method allows high resolution information from an output shaft sensor (e.g. a torque sensor with a position dependent output) to be combined with the low resolution output from the Hall effect sensors to produce a high resolution rotor position signal.

Abstract: 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 o) of the steering mechanism. The torque produced by the motor (1) is not obtrusive during “hands-on” manoeuvres but provides enhanced damping in other manoeuvres such as a steering flick.

Abstract: 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 (20) operatively connected to a vehicle hand wheel (12) for providing a torque signal (TS) indicative of applied steering torque, blending filter means connected to the torque sensing means (20) 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 (70) which passes all frequencies below the blending frequency and a high pass filter (71) 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 s

Abstract: 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.

Abstract: A motor control strategy for use in combination with an electric motor (1) having a number of phase windings (201, 202, 203) is disclosed, the motor (1) being adapted to produce an output torque in response to current in the windings comprising the steps of during normal operation generating a motor torque demand signal indicative of the output torque required from the motor (1), applying a first set of currents to the windings of the motor in response to the motor torque demand signal to produce a first output torque from the motor and during a test operation to enable diagnostics to be performed generating a motor current demand signal indicative of the total current required in the motor windings (201, 202, 203) and adjusting the currents applied to one or more of the windings in response to both the torque demand signal and the motor current demand signal, whereby the adjusted currents produced in the windings are substantially equal to the total current demanded by the motor current demand signal regardl

Abstract: A method of monitoring the operation of a brushless motor is disclosed. The method comprises the steps of monitoring the current flowing into or out of the windings of the motor using a current measurement circuit to produce an output signal indicative of the current; measuring the output of the current measurement circuit when the instantaneous current flow through the current measurement circuit is known to be substantially zero; and producing a modified output signal which is compensated for any differences between the actual measured output signal value and an ideal output signal value. The method enables any drift in the output signal to be compensated “on-line” whilst the is running.

Abstract: 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 &ohgr; of the steering mechanism. The torque produced by the motor (1) is not obtrusive during “hands-on” maneuvers but provides enhanced damping in other maneuvers such as a steering flick.