The precise modeling and active disturbance rejection control of voice coil motor in high precision motion control system

In this paper, the improved active disturbance rejection control (ADRC) method is discussed firstly. This method is applied to the high precision positioning table, which is driven by the voice coil motor (VCM). Compared with the conventional ADRC, the proposed ADRC has been improved for its tracking differentiator (TD) is replaced by the reference trajectory optimization (RTO), which is based on 5 order S-shaped curve (FOS). An extended state observer (ESO) of the ADRC can observe disturbances and uncertainties of the system, and cancel them dynamically. Secondly, the hybrid cascaded H-bridge (HCHB) seven-level inverter topology structure is proposed to make sure that the current could possess high power and low ripple at the same time. However, the HCHB inverter has its own drawback that its current flows backwards in it. Therefore, the hybrid frequency carrier-based PWM (HFPWM) modulation method is put forward to solve this problem. Thirdly, the mathematical model of VCM is established accurately, which takes the air damping, eddy current damping and elastic stiffness into consideration. Finally, the experimental and simulation results show that the improved ADRC control method can effectively improve positioning accuracy and robustness; the FOS curve can reduce the impact of shocks and residual vibration; the HCHB inverter resolves the contradiction between high power and low ripple.