Motion sensor useful for power assisted steering systems

Abstract

A motion sensor which includes, in a basic embodiment, two sensing elements of any type disposed so as to detect the relative passing thereby of perturbations. The sensing elements are disposed so that they are offset with respect to the perturbations, such that the sensing elements cannot both be activated simultaneously. When one sensing element is activated, thus indicating motion, timing means starts counting and, if the other sensing element is activated within a predetermined length of time, the sensor infers that purposeful motion has been detected and may, for example, activate a power steering assist unit. The spacing of the perturbations determines the minimum degree of motion required for the motion sensor to provide an output and the timing mechanism determines how rapidly that degree of motion must occur for the motion sensor to provide the output. Thus, the spacing and time parameters may be set so that purposeful motion may be discriminated from random motion such as vibration. The sensing elements may be photodetectors, microswitches, pressure sensors, reed switches, or conductive, inductive, or capacitive proximity sensors, or of any other type. The corresponding perturbations may be arrayed on either a rotating or a linearly moving member.