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: A circuit is provided for testing a drive stage of an actuator, such as a motor of an EPAS system. A power supply circuit comprises a contact for supplying normal drive stage current and a resistor for supplying reduced drive stage current before the normal current is supplied. A measuring circuit measures a drive stage electrical parameter such as supply voltage and a comparator compares this with an acceptable value. If the measured parameter corresponds to a current through the drive stage which is different from an expected value, a fault is signaled and the contact is prevented from closing.

Abstract: An electrical power assisted steering system is disclosed having a boost curve which has inverse symmetry about a zero input torque value, each half of the boost curve comprising a first portion defined by a first polynomial equation between a zero value and a first value, and a second portion defined by a second polynomial between a second value and a third value, in which the gradient of the first portion of the curve at the first value is equal to the gradient of the second portion of the curve at the second value. By storing values for the first, second and third values and the gradient of each polynomial at those values a smooth boost curve can be defined by storing only a small amount of parameters.

Abstract: A controller for an electric power assisted steering system comprises a drive circuit (2) for controlling current to a motor (1) and a data processor (8) for controlling the motor current and hence assistance torque. A circuit (9) generates a current limit which is a monotonically decreasing function of vehicle speed. A comparator (6) compares motor current with the current limit and switches off the drive circuit (2) if the current limit is exceeded.

Abstract: This invention relates to a method of recovering a polymer from an organic mixture comprising polymer and an organic solvent, the method comprising: a) admixing an aqueous solution and the organic mixture by the application of a combined mechanical and hydraulic shear force, the combined mechanical and shear force being sufficient to form a liquid-liquid dispersion; b) removing the organic solvent from the liquid-liquid dispersion thereby forming a remaining solution; and c) separating the polymer from the remaining solution. In one embodiment the polymer is a polycarbonate prepared by the interfacial method, and the organic solvent is methylene chloride.

Abstract: An electrical power-assisted steering system is disclosed comprising a brushless electric motor (1) which has a plurality of phase windings connected at a start point and in which a switching means (13) such as a relay is provided in at least one phase of the motor, the switching means being movable between a closed position in which current is able to flow in the phase winding and an open position which prevents current flowing in the respective phase in the event of a fault. Also disclosed is a substantially rigid connector assembly (19) onto which is mounted the switching means (13), conductors (20) for connecting the motor phase windings and a motor position sensor (21) to an associated motor control means (6), the connector acting as a support for the motor stator, which simplifies the steps involved in assembly.

Abstract: An electrical power-assisted steering system comprising a brushless electric motor which has a plurality of phase windings connected at a star point and in which a switching device such as a relay is provided in at least one phase of the motor, the switching device being movable between a closed position in which current is able to flow in the phase winding and an open position which prevents current flowing in the respective phase in the event of a fault.

Abstract: A control strategy for a multiple phase brushless motor (1) is disclosed in which the top (2, 3, 4) and the bottom (5, 6, 7) switching devices in two arms of the motor bridge are driven using complementary pulse width modulated waveforms, so that the top device (2, 3, 4) in one of the arms is in the ON state while the bottom device (5, 6, 7) is in the OFF state and vice versa. In an alternative arrangement, the control strategy described hereinbefore is used at high motor speeds while at low motor speeds a conventional modulation scheme is used in which a top switching device (2, 3, 4) in one arm of the bridge is in the ON state and a bottom device (5, 6, 7) in a different arm of the bridge is pulse width modulated. In another aspect, a method of calculating the position of the motor rotor is disclosed.

Abstract: A control strategy for a multiple phase brushless motor (1) is disclosed in which the top (2, 3, 4) and the bottom (5, 6, 7) switching devices in two arms of the motor bridge are driven using complementary pulse width modulated waveforms, so that the top device (2, 3, 4) in one of the arms is in the ON state whilst the bottom device (5, 6, 7) is in the OFF state and vice versa. In an alternative arrangement, the control strategy described hereinbefore is used at high motor speeds whilst at low motor speeds a conventional modulation scheme is used in which a top switching device (2, 3, 4) in one arm of the bridge is in the ON state and a bottom device (5, 6, 7) in a different arm of the bridge is pulse width modulated. In another aspect, a method of calculating the position of the motor rotor is disclosed.

Abstract: A video camera or equivalent sensor is mounted on a vehicle and used to detect the lane markings on the road (usually the white painted lines). An associated signal processor (11) estimates the vehicle's lateral position in relation to the lane markings. An electric motor (4) coupled to the steering mechanism (1) is used to provide a torque input to the steering which may either assist or oppose the steering torque from the driver. The processor (11) is designed to assist the driver to maintain the vehicle's lane position by holding the vehicle at a set-point using a biasing torque. This simulates the effect of the lane being cambered upwards towards the lane edges. However the driver is able to override or cancel the effect if the driver applied steering torque exceeds a prescribed torque threshold.

Abstract: The invention relates to a novel process for depolymerizing polyesters by subjecting the polyesters to catalysts and organic solvents which are substantially free of oxygen and water in order to produce macrocyclic polyester oligomers substantially free of hydroxybutyl terminated linear impurities.