Research On High Performance Servo Control Of Two-phase Hybrid Stepping Motor

Stepping Motor is a kind of electromechanical component which is driven in step angle or line displacement by electric pulse signal, and has the advantages of simple controlling, reliable operation, high-precision orientation, and no stepping accumulated error. As the mainstream product of stepping motors, two-phase hybrid stepping motor is widely and importantly used in servo control fields, such as numerical control machine, robotics, Aeronautics and Astronautics. With the deeper industrial applications and the rapid development of related technologies, higher performance requirements on dynamic and steady characteristics, robustness of hybrid stepping motor servo control system are proposed. Because of low response, out-of-step, existing resonance region and other shortcomings, the traditional open-loop control is not applicable any more, which makes it imperative to study on the closed-loop control of hybrid stepping motor. Research on high performance servo control of two-phase hybrid stepping motor is aimed at searching a control strategy of position closed-loop, which is not only superior to the traditional PID control on the control effect, but also simple and feasible on the algorithm implementation. Therefore, the study is helpful to broaden the range of applications of such motors, and meet the demand of modern industrial development, which has important theoretical and practical significance.This paper gives a detailed introduction and analysis of the structure and working principle of two-phase hybrid stepping motor firstly, and derives its mathematical model in the common coordinate systems based on simplified magnetic network model, which is useful to the vector control of two-phase hybrid stepping motor.Then, according to the mathematical model, this paper applies sliding mode control to the long-distance position control of two-phase hybrid stepping motor, proposes an improved piecewise variable exponent reaching law, and designs the sliding positon controller. To solve the problem of unknown load torque disturbance, an improved reduced-order load torque observer is built. Moreover, passivity-based control is applied its small-angle position control. To solve the problem of nonlinear friction disturbance, this paper combines the robust control technology, and designs robust passivity-based position controller under Hamilton model based on the state error model.Finally, the servo control system’s simulation models of two-phase hybrid stepping motor are built in Matlab/Simulink environment, and compared with traditional PID control under the same conditions. The results show that the position control algorithms proposed are more excellent than PID control in term of dynamic and steady characteristics, robustness. In addition, in order to illustrate the practicability of the algorithms, this paper designs the hardware and software of the servo control system of two-phase hybrid stepping motor based on ARM microprocessor, and completes the corresponding experiments and debugging. The results further validate that the control strategies proposed in this paper are effective and superior in high performance servo control of two-phase hybrid stepping motor.