EACS 2016 paper - Real Time Control of Shake Tables for Nonlinear Hysteretic Systems
journal contributionposted on 28.03.2017, 15:16 authored by Ki P. Ryu, Andrei M. Reinhorn
EACS 2016 Paper No. 110
Shake table testing is an important tool to challenge integrity of structural and non-structural specimens by imposing excitations at their base. When shake tables are loaded with specimens, the interaction between the tables and specimens influence the system dynamics that result in undesired performance. Open loop feedforward compensation methods have been used successfully in current practice of table controls, assuming that the specimens remain linear. However, unsatisfactory signal performances were observed when flexible and heavy specimens experience nonlinear behavior. While lack of high fidelity might be acceptable for the purpose of exploration of specimens subjected to random excitations, a high fidelity of signal reproduction is necessary for shake table qualification testing where specific target motion is required to challenge the specimens. A nonlinear tracking control scheme based on the feedback linearization method is proposed for the control of shake tables to simulate target motions at specific locations of the test structures having nonlinear hysteretic behavior. A real-time estimator using the extended Kalman filter combined with the controller is adopted in order to account for the changes and uncertainties in system models due to nonlinearities and yielding. The proposed adaptive tracking control method is applied in numerical simulations to a setup of a realistic shake table testing of a nonlinear structure.