Design of the velocity measurement system using a heat-source and IR detectors

This thesis reports the design of a system to measure the velocity of moving objects or surfaces. A quartz filament lamp is used to create a hot spot on the moving object and this hot spot is detected by two infra-red detectors at a known distance from each other. The time required for the hot spot to travel this distance is measured to determine the velocity. This scheme of velocity measurement does not require the object to have any leading or trailing edge, as do most of the other velocity measurement systems. Therefore, this velocity measurement system can be used for measuring the velocity of a continuous rope or plastic film being wound on a spindle.

Three approaches are used for the design of the Velocity Measurement System. The shortcomings of the initial design are overcome in the subsequent design approaches. The first approach uses hardware components, mainly CMOS integrated circuits and no software is involved. The second approach is based on the use of bit-slice devices, like the AM2903 four-bit microprocessor slice, the AM2910 sequencer, etc. In the third approach, a Motorola MC68000, 16-bit microprocessor is used. Irrespective of the actual design approach, the basic principle of velocity measurement is the same. Schemes for accurate time measurement, which overcome problems arising from the deformation of the signal at the output of the second IR detector or due to conduction of heat from the hotspot to the rest of the body of the moving object, are implemented using the microprocessor based design.