This work comprises several parts, the initial part o f which is a review o f the techniques
in use at present for measuring shape and characterising products. The major work
details a ring sensor system, which consists o f a large number o f transmitters and
receivers alternately arranged on the circumference o f a metal annulus. Using a modified
polar co-ordinate system and trigonometric functions, two enveloping spirals o f an
object can be determined. One or both spirals can then be used for further data analysis.
Each spiral consists o f intersections between enveloping chords and parts o f the chords.
The area surrounding the object is segmented and properties such as volume and axis
measurements can be determined. A mode! was developed to simulate artificial objects
o f various shapes. Simulation tests were carried out to determine the limits o f the system
concerning position within the ring, shape and speed o f the object and resolution o f the
ring. A ring was manufactured for actual tests, which were carried out mainly on
potatoes to confirm the possible use in practice and to show the relative merits compared
with existing systems. Interesting side issues are introduced, such as the low number of
primary data, possibilities of further reduction using differential coding, and the
consumption time of the algorithms. Finally, a model for the simulation o f more than
one object in the ring at the same time is introduced and a possible way o f separation is
investigated
