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: 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: In an electric power assisted steering system, the output signal from a motor position sensor (9) comprising a number of Hall effect devices (A,B,C) or the like is combined with an index signal from a sensor (108) connected to the steering column shaft (1) or the rack (6) or a yaw sensor or other angular position dependent device to produce an accurate measure of steering angle relative to the straight ahead position. In a preferred arrangement, transitions in the Hall effect sensor output are used to drive a counter (106) which is reset whenever the index signal is produced to ensure it does not drift out over a period of time. Most conveniently, the index signal corresponds to the steering gear straight ahead position.

Abstract: A combined torque and angular position detector includes two disks rotatable about a common axis. Relative angular displacement of the disks results from torque applied thereto. Each disk has a number of regions of differing optical transmissivity and these control the transmission of optical radiation from a source to an array on which an image of the regions of the disks is formed. A data processor processes image intensity data and determines the angular positions of the disks and their relative displacement. Alternative arrangements are descried in which positional information is derived by providing one disk regions of intermediate transmissivity of width varying around one disk, by having the regions of lesser transmissivity of width varying around one disk or by arranging combinations of regions of several different widths around one disk.

Abstract: A gearbox monitoring apparatus is disclosed for use in combination with a gearbox (4) which provides a connection between an input shaft (3) driven by a motor (1) and an output shaft (2), said gearbox monitoring apparatus comprising a first position sensing means (11) and a second position sensing means (12), said first and second position sensing means generating a respective first and second output signal, said first output signal being representative of the angular position of the input shaft and said second output signal being representative of the angular position of the output shaft, a torque signal generating means (6) which generates a third output signal representative of the torque carried by the gearbox (4), and signal processing means (15) adapted to receive said output signals and to process said output signals to produce one or more modified output signals representative of the wear in the gearbox.

Abstract: A housing assembly for an electrical device (such as an electronic circuit) is disclosed in which a support member is provided in a compartment to physically divide a componentry sensitive to such radiation. In a preferred embodiment, an electric power-assisted steering system is disclosed of the kind in which an electric motor (12) is connected through a gearbox to an output shaft operatively connected to a steering column of the vehicle and in which a one-piece housing (1) is provided which defines two discrete compartments (2, 3). A first compartment (3) is adapted to house the motor and the gearbox, and a second compartment (2) is adapted to house a motor control circuit and a motor drive circuit, a support member (21) being adapted to provide a physical banner between the two circuits. The one-piece housing (1) is advantageous in that it reduces the number of potential openings through which electromagnetic radiation may pass compared with providing multiple housings.