Patent ID: 6450044
Filing Date: 2002-09-17
Classification: G01L

Abstract:
A torque transducer comprising a rotating shaft at least partially surrounded by a fixed housing, an axis of rotation of the shaft fixed with respect to the housing, the shaft comprising first and second torque input members, which are connected by a torsionally compliant coupling, the coupling enabling angular deflection of the first torque input member relative to the second torque input member as a function of a magnitude of the torque in the shaft, a first grating element attached to or integral with the first torque input member and a second grating element attached to or integral with the second torque input member, the first grating element comprising a first surface and the second grating element comprising a second surface, the transducer also comprising at least one electromagnetic radiation (EMR) source and at least one array of EMR sensitive detectors, wherein said source irradiates one or both of the surfaces and said array receives incident EMR reflected from one or both of the surfaces, the at least one source irradiating each surface and the at least one array receiving incident EMR reflected from this surface are all positioned on the same side of this surface and fixed with respect to the housing, both surfaces comprise alternating regions of high and low reflectivity, a pattern produced by incident EMR of the at least one array at any instant of time resulting from the alternating regions of low and high reflectivity on the one or both surfaces providing reflected EMR to this array, regardless of the angular position of the shaft and irrespective of the relative angular deflection of the first and second torque input members, the output from the at least one array, resulting from the pattern on the at least one array at said any instant of time, is processed by a processor to derive the relative angular deflection of the first and second torque input members, and hence provide a measure of the magnitude of the torque in the shaft.