Abstract: A torque sensor, or relative angular movement sensor, capable of measuring the angular displacement of a component in a power-assisted steering system, comprises an input member coupled to one end of a torsion bar, an output member coupled to another end of the torsion bar, LED light sources, a pair of photodetector units adapted to receive light from the LED light sources, and signal processing means adapted to receive output signals from the photodetector units, the output signals of the photodetector units being dependent upon the light signals which they receive, and wherein the signal processing means is adapted to produce a modified output signal which closely matches and is representative of the angular position of a chosen portion of the torsion bar.

Abstract: Shunt results from drive line resonance of a vehicle's transmission superimposing cyclic oscillations onto the speed of the vehicle's engine. A feedback loop comprising at least one of a band pass filter having a high frequency cut-off characteristic greater than first order, a feedback loop in which the loop gain is a function of transmission ratio, and a non-linear transfer element arranged to have a gain whose magnitude increases with the magnitude of the input to the non-linear transfer element. Additionally shunt may also be controlled by a feed-forward controller based on an engine demand signal.