Frequency Modulation Based on Hyperbolic Tangent Function for Position Closed Loop Control of Stepper Motor

Generally, the position closed-loop control of stepper motors requires high-precision models, however stepper motors are complex nonlinear systems, and high-precision models are difficult to obtain. In order to solve this problem, a variable frequency controller based on hyperbolic tangent function is proposed. Similar to the proportional integral (PI) control method, this method does not require an exact model of the plant. The experimental results show that when tracking the sinusoidal signal ${180^ \circ }\sin (0.628t)$ , the tracking error of the Tanh control algorithm is reduced by nearly 60% compared with the PI control algorithm, which provides a new idea for the position closed-loop control of stepper motor.