An angular position encoder utilizes Moire fringes formed by illuminating regions of coded images arranged circumferentially on wheels rotatable in accordance with angles to be encoded. Movement of the Moire fringes from a reference position is detected and used to determine the angular movement. All non-rotating movements of the coded wheel are compensated by the encoding process and do not effect the output.

An optical motion sensor is provided for monitoring movement of a mechanical device, particularly such as an infusion pump of the type used for controlled delivery of medication to a patient. The motion sensor includes a disk member mounted upon a selected mechanical output component driven by the infusion pump, such that the disk member undergoes displacement during normal pump operation. The disk member defines a pattern of reflective and substantially nonreflective surface zones which are alternately illuminated by a light source during normal pump operation. A light detector responds to the level of reflection from the disk member to provide an output signal which varies according to disk member displacement. This output signal is connected to a controller for comparison with drive signals supplied to the infusion pump, to verify proper mechanical output operation of the pump.

In a preferred embodiment, a shaft sensor for a machine, the shaft sensor including: first and second disks, fixedly orthogonally attached to a portion of a shaft of the machine, the portion of the shaft being subject to torsion, and the first and second disks being operatively attached to the portion of the shaft at spaced apart locations along the portion of the shaft; and a sensor assembly, including first and second sensors, disposed in sensing relationship with the first and second disks to sense relative position of the first and second disks resulting from torsion of the portion of the shaft and to output a signal representative of at least one parameter related to torsion of the shaft. In another preferred embodiment, the shaft is discontinuous and the first and second disks are attached, respectively, to first and second portions of the shaft and have a resilient member disposed therebetween.

A torque transducer comprises a rotating shaft having first and second torque input members connected by a torsionally compliant coupling thereby enabling angular deflection of the torque input members relative to each other as a function of the magnitude of the torque in the shaft. The transducer has an EMR source and an array of EMR sensitive detectors. Each of the torque input members has a grating zone with alternating regions of high and low transmissibility to the EMR. The grating zone resides in the transmission path communicating EMR from the source to the array. A pattern is produced by incident EMR on the array resulting from the alternating regions of high and low transmissibility of the grating zones residing in the transmission path to the array. The pattern on the array is processed to derive the relative angular deflection of the torque input members and provides a measure of the magnitude of the torque in the shaft.

The invention relates to a device or arrangement for measuring the angle of rotation of the rotor of a rotary machine. Markings are applied circumferentially to a part of the rotor that is enclosed by the housing and a passage is provided in the housing which has an opening adjacent the markings. A sensor arrangement disposed at least partly in the housing passage has one end thereof adjacent the markings in a position for detecting the rotational movement of the markings. The snesor arrangement may have electrical, magnetic or optical capabilities.