Study On The Self-tuning Strategy Of Control Parameters For AC Servo System

The performance of AC servo system and the control parameters are closely related, so the setting parameters of the servo system must be tuned in order to obtain satisfactory servo performance. Self-tuning is an efficient way to complete the servo system control parameter tuning process to get the satisfactory control parameters quickly, furthermore, it can tune the control parameters on-line in accordance with the changes of the characteristics of the controlled object in the running so that the performance of the servo system can always maintain optimal. Therefore, it is urgent and significant to study the self-tuning strategy of AC servo system control parameters to improve the efficiency and performance of servo systems.This paper, aiming at obtaining the AC servo system control parameter self-tuning strategies, combined with the National Science and Technology major projects "an all-digital high-performance general-purpose drives, AC servo motor and spindle motor",National Natural Science Fund " Study on the control method of Fourier frequency domain of high speed, high precision motion of CNC machine tool " and "Study on control parameters self-tuning strategy of Feature-based CNC machine tool motion ", mainly completes the following studies:1.The transfer function of various components of the servo system was analyzed; corresponding mathematical models of the three control loop namely a current loop,velocity loop and position loop were established respectively according to the control structure of various sectors of the servo system; the process of control parameter tuning was analyzed by using the established mathematical model and theoretical basis for the research of control parameters self-tuning was obtained.2.The three main components of control parameters self-tuning were analyzed respectively:the controlled object feature recognition,system performance evaluation methods,control parameter optimization methods, and theoretical foundation for the research was achieved.3.A series of off-line auto-tuning strategies of servo control parameters were proposed:Auto-tuning of the control parameters of the current loop was realized by obtaining the optimum step response of the q axis current, employing the rotation optimization method; Fast Fourier changes was used to error signal of the speed closed-loop, the notch filter parameters were tuned by the amplitude-frequency characteristics of the error and other relevant parameters; The reconstruction results of nonlinear characteristics of the controlled object of speed loop were used as a reference model in the control parameter tuning process, by optimizing control parameters of the reference model to complete the auto-tuning of the speed loop control parameters; The impact of the error characteristics of position control parameters was used to optimize, successively and independently, the proportional gain and feed forward gain, completing the auto-tuning process of the position loop control parameters.4.A set of servo-system control parameter self-tuning strategies were put forward: The approximation model of the controlled object speed loop was identified on-line, using the identification model to predict the performance of the speed loop, and the speed-loop control parameter was tuned according to the predictions; two types of position loop control performance evaluation index were constructioned, according to the online performance evaluation results of position loop, position loop control parameters were tuned on-line according to the rules of the optimal quadratic.5.Real-time simulation platform was constructed based on dSPACE; the proposed servo system control parameter self-tuning strategy rapid prototype simulation and hardware in the loop simulation were carried out. After the real-time simulation experiments, using the servo system in actual operating conditions as objects to verify the application of the self-tuning strategy which was proved accurate, stable and adaptable.