An Ultrasonic Angular Measurement System

Abstract

An original design is presented for a system capable of measuring the relative angle of a flat surface using reflected ultrasonic wave pulses. No physical contact with the surface is necessary. The measurement range is from 0 to 54 degrees. Theoretical resolution is 5 minutes of arc, with actual measured resolution of approximately 20 minutes of arc. The system has performed successfully in limited flight tests, is capable of rates up to 80 angle measurements per second, and has a solid-state memory recording capacity of 24,000 bytes. The measurements are time-tagged as they are recorded and may be transferred to a personal computer at a later time over a standard RS-232 serial communications link. The system is small (approx. 6 by 4 by 1.5 inches) and uses two standard 9-volt batteries as its power source.