Delayed Closed-Loop Scheme for Stepping Motor Control

An efficient method for control of stepping motor speed and position, the delayed closed-loop (DCL) mode, is described. The new technique permits control of high-speed motor motion by means of a programmed speed-displacement characteristic. The method combines the static-speed control characteristic of the open-loop mode with the stable dynamic behavior of the closed-loop mode. Unlike other schemes for delayed closed-loop control, the present configuration features an extension of delay time to more than one step duration, significantly improving the velocity control. The phase angle can also be varied to ±180°, permitting adequate control of deceleration as well as acceleration. A stability analysis is made of the DCL control method. In an illustrative example, the technique is applied to control of the carriage drive on an experimental high-speed line printer.