The digital measurement of low values of angular velocity and acceleration

An algorithm and the microprocessor implementation thereof for the measurement of angular velocity and acceleration of rotating machinery are presented. The speed reference signal is derived from a pulse train at a frequency of only one pulse per revolution. This fact places severe constraints on the resolution and measuring time of the instrument. To detect a rate of change of speed of 1 r.p.m./min, a measuring time of at least 1 min is required. Over a 30-s measuring period it is possible to detect a rate of only 4 r.p.m./min. The resolution, therefore, is dependent on the measuring time, and a fixed relationship exists between these two parameters. The values obtained for either velocity or acceleration/deceleration will be average values for the measuring period. The instrument has been implemented using standard microprocessor components and supporting circuitry. The results obtained so far are highly satisfactory