Overview of Models and Methods for Control of Stepper Motors

A review of models and algorithms for control of a stepper motor (SM) is presented. Due to high accuracy, improved power density, economy and reliability compared to other synchronous motors, stepper motors are widely used in various practical applications and scientific equipment. In aviation and space technology, step motors are actively used in actuating systems, such as drives for the movement of elements of large-sized structures, guidance, and stabilization systems, etc. The article describes some existing stepper motor control algorithms, which are both based on the knowledge of the parameters of the stepper motor model, and on the absence of this or that information. Of the many described algorithms, four were selected (PID controller, exact feedback linearization algorithm, adaptive control with partially unknown parameters and adaptive control with completely unknown parameters), which showed the best results of transient processes in tracking the angle of the rotor of the SM behind the reference value. A comparative numerical analysis among these four algorithms is also given, which showed that the best results of transients are demonstrated by adaptive controllers (in the sense of the smallest error in steady state), while the worst results are demonstrated by the PID controller. It is noted that the studied PID controller contains much fewer feedback loops compared to other algorithms, which simplifies the choice of adjustable parameters and reduces the dynamic order of the closed system, however, the design is based on knowing the exact parameters of the drive and is also sensitive to external disturbances. On the contrary, adaptive approaches successfully solve the problem of estimating parametric and functional perturbations, but their implementation is associated with significant difficulties.