Abstract: An improved torque sensor, or relative angular movement sensor, comprises an input member, an output member, LED light sources, a pair of photodetector units adapted to receive light from the LED light sources, and signal processing means, in which said signal processing means is 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 the signal processing means being adapted to process the output signals from the photodetector units so as to produce a modified output signal indicative of the relative angular displacement between, or torque applied between, the input and output member. The improvement comprises the provision of diagnostic means which continuously monitors a sum signal, .SIGMA., which comprises the sum of the output signals from the photodetector units, and which detects any variation in the sum signal due to failure of the sensor.

Abstract: An improved torque sensor, or relative angular movement sensor, comprises an input member, an output member, LED light sources, a pair of photodetector units adapted to receive light from the LED light sources, and a signal processor, in which said signal processor is 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 the signal processor being adapted to process the output signals from the photodetector units so as to produce a modified output signal indicative of the relative angular displacement between, or torque applied between, the input and output member, wherein the improvement lies in the arrangement of photodetectors which comprise the photodetector units.

Abstract: An optical displacement sensor comprises first and second optical fibers which transmit light to and receive light reflected from first and second fixed reflectors. A third optical fiber transmits light to and receives light reflected from a moving reflector on the end of a core which moves in response to the displacement to be measured. The intensities of the light reflected to the fibers allows the displacement to be determined with immunity from variations such as in transmissivity and refractive index of a medium between the fibers and the reflectors.

Abstract: A torque sensor, or a relative angular movement sensor, comprises an LED light source mounted in a fixed position relative to a housing which shines light through an associated fixed collimator plate, the light being detected by a pair of detectors also mounted fixed relative to the housing. Two masks pass between the source and the detector, one of the masks being fixed to an input shaft of the steering system and the other being connected to the output shaft. Each of the masks has a first and second aperture, and the amount of light which is received by detectors depends upon the degree of overlap between associated pairs of apertures in the input and output masks. Signals from each of the detectors is fed to a control microprocessor which provides a signal indicative of differential torque between the input and output shafts. This signal is substantially independent of the intensity of the light source which allows it to compensate for ageing effects in the light source.

Abstract: A vehicle brake has a fixed backplate carrying a pair of friction elements and an actuator operable to urge the elements into braking engagement with a rotary braking surface. An abutment for the elements has a portion which is deflectable by load on the elements arising from braking torque. A radiation input device directs radiation at a surface of the deflectable portion and a device is provided to sense radiation after its impingement on the portion and to transmit the sensed radiation to a device producing a responsive electrical output representing deflections of the portion.

Abstract: A method of monitoring combustion within a cylinder of a reciprocating piston internal combustion engine comprising deriving first and second electrical signals representative of light intensity within the cylinder by means of first and second optical transducers of spaced spectral response, said first and second optical transducers observing the combustion event at a common location, or at closely adjacent locations, and, establishing a signal representing the ratio of said first and second electrical signals, said ratio signal being used as, or to obtain, a control parameter for an engine control system. The invention also resides in apparatus for monitoring combustion in accordance with the above method.

Abstract: An incremental position encoder comprising a first member arranged for movement with a second member the movement of which is to be monitored, a plurality of light transmissive or reflective elements of three distinct colors, said elements being arranged in a row on said first member, and the elements being arranged in the row in a repeating sequence of said three colors, a light source directing light to said elements and a color sensitive light detector for receiving light transmitted by, or reflected from said elements, said color sensitive detector being arranged to produce, at any given instant, one of three distinct outputs dependant upon the color of the three available, of the element which is at that instant transmitting or reflecting light from the source to the detector.