Adaptive Control Of Real-time Substructure Experiments Based On Ultra-stable Theory

Real-time substructure testing (RST) is a new modern experimental method which integrates the advantages of the traditional structural seismic tests and can evaluate the performance of speed related structure or device. The character about "real time" of RST puts forward higher requirements on stability, accuracy and respond speed of loading control process. Adaptive control method is mainly used for the systems whose parameters cannot be determined or change with time, so it is very suitable for nonlinear load control of the specimens in geotechnical structure seismic experiment. In this paper, the model-reference adaptive control (MRAC) method based on hyperstable theory is applied to the controller design of hydraulic servo actuator to achieve target steady, timely, fast in loading control process of RST. The research contents mainly include:(1) The design method of hyperstable MRAC of RST is presented. With numerical simulation of second degree system in step orders, the adaptive gains' influence on the loading control is analyzed. Through comparing and analyzing the simulation results of super stable MRAC, Lyapunov adaptive control and PID control under step signal with changing step signals and stiffness coefficients, the hyperstable MRAC is proved to have good adaptability and be able to achieve loading goals steadily and fast.(2) The hyperstable MRAC is applied to second-order system in RST under different seismic loads and the overlaps between hyperstable MRAC's output and exact solution are studied. Numerical simulations of RST with hyperstable MRAC and MIT control are carried out under various integration step-sizes. The results show that the hyperstable MRAC has good stability under multi-step orders and can implement the output displacement of system quickly and accurately.(3) The hyperstable MRAC system for RST is designed for case of linear experimental structures. Numerical simulations of hyperstable MRAC, Lyapunov adaptive control and PID control are carried out and compared under the same conditions. The results show that the stability of hyperstable MRAC is better than Lyapunov adaptive control and PID control. With better accuracy and faster response speed, hyperstable MRAC is a reasonable control method.(4) The hyperstable MRAC system for RST is designed for case of nonlinear experimental structures. Numerical simulations of RST with the hyperstable MRAC and PID control are carried out. The results show that the control accuracy and robustness of hyperstable MRAC are better than that of PID control.