Shake table testing is a common technique used to examine the responses of structures under dynamic loads. Shake table is often regulated using linear controller, such as proportional-integral-derivative (PID) controller. However, traditional PID control cannot consider inherent nonlinearities in the structural and control systems.
Dynamics of a unidirectional shake table
In this project, a series of novel backstepping control methods, which consider the nonlinearities in the structural and control systems, have been developed. In addition, high-gain observers, which can provide highly accurate estimation of the shake table displacement, velocity and acceleration, are also developed. The proposed backstepping control methods and high-gain observers are implemented in a hierarchical framework, where the high-level backstepping controller generates the command signal for the low-level controller to execute. A total of four hierarchical backstepping control methods, including the acceleration-based backstepping hierarchical control (ABHC), the ABHC with high-gain observer (ABHCO), the displacement-based backstepping hierarchical control (DBHC) and the DBHC with high-gain observer (DBHCO), have been implemented.
DBHC framework with and without high-gain observer
ABHC framework with and without high-gain observer
Experimental setup
Detailed parameter studies have been conducted to identify the optimized parameters for the proposed hierarchical backstepping control methods. The proposed control method is verified through a series of shake table tests. The experimental results show the ABHC, ABHCO, DBHC and DBHCO can all achieve high-performance shake table control, especially with superior acceleration tracking over the traditional PID control. Overall, ABHCO achieves the best tracking performance for displacement, velocity and acceleration.
Performance comparison between different control methods
Team composition: Yifei Xiao, Xiao Pan and T.Y. Yang
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References:
Xiao, Y., Pan, X., Yang, T. Y. (2022). Nonlinear backstepping hierarchical control of shake table using high-gain observer, Earthquake Engineering & Structural Dynamics.