Abstract: Disclosed is a DC parameter motor tester based on current time response, which tester does not require coupling of the motor (14) to some mechanical device or measuring other noise sensitive parameters taken from only a few discrete data points. As is disclosed, the steady state speed of the motor is determined from the frequency composition of the commutation noise and ripple in the steady state current by performing a fast fourier transform on the steady state current to determine its power-spectral-density which shows the frequency composition of the steady state current waveform by giving the power in the waveform at each frequency. The frequency at which the most power exists is divided by the number or twice the number, depending upon the construction of the motor, of commutation segments in the motor to determine the motor's frequency of rotation or velocity at measured power input.

Abstract: Disclosed is a digital escapement control system in which the motor (DC) control is completely digital requiring no tachometer generation of feed back signal nor any analog to digital convertors. Connected to the DC motor shaft is a code wheel and detector to determine the time between discreet positions of the motor shaft as it rotates. The time between discreet positions is then compared with a desired time, and the difference is stored, as by a register. The difference is then converted to a pulse-width-modulated (PWM) signal which directly controls the rotational velocity of the motor, increasing or decreasing it as necessary. The system operates, in a ramp, open loop start up mode and digital velocity controlled braking mode while in the motional mode with the feed back as described above. At start up, provision is made for inserting the feed back loop when the velocity reaches some predetermined level or percentage of the desired velocity.