High acceleration motion control based on a time-domain identification method and the disturbance observer

High acceleration motion tends to excite flexible modes of the motion stage to magnify disturbances, causing challenges for control engineers. Among existing control algorithms, the disturbance observer (DOB) is recognized as an effective tool for improving servo performance by suppressing disturbances. Besides external disturbances, the internal interference caused by model mismatches is an important factor which can degrade the servo performances of the DOB-based controllers. Therefore, a more accurate relay-based model identification method is proposed to deal with model mismatches. This method uses the position signal as the input of the relay module. Simulations show that the proposed identification method achieves higher identification accuracy by preventing the amplification of the quantization error during velocity detection. High acceleration point-to-point motions are conducted on a linear-driving stage with a DOB-based controller and experimental results demonstrate that improved servo performance with a maximum tracking error of 2.0 μm at a maximum acceleration of 9.1 g (1 g = 9.806 m/s2m/s2).