Design of adaptive control algorithm for automotive dashboard stepper motor pointer

An adaptive control algorithm is designed in this paper for an automotive dashboard stepper motor which is used for driving an pointer to indicate variety of speed. A subdivision control table for stepper motor coil current changes in sinusoidal form is designed based on the smallest subdivision granularity demand for automotive dashboard applications. A subdivision control of the underlying stepper motor is achieved by adjusting the control table index step. In the pointer´s scheduling control, the scheduling cycle in the form of the variable-length time slot is divided to achieve time-interval control of the pointer. Four phases for pointer rotation way in a single scheduling cycle is designed: accelerating start up, uniform rotation, decelerating stop, eliminating inertia. By design of rotational velocity control, the smooth starting up and stopping of the automotive dashboard pointer are achieved during the time of the pointer position updating, coil current adjustment step, scheduling cycle length, starting up acceleration, stopping deceleration and the inertia elimination ending time. The rapid response to the rapidly changing information is achieved, as well as the smoothing reflects to the slowly changing information. The driver can start quickly and stop smoothly, and also ensure jitter-free at low speed.