Validation of loop shaping force feedback controller for nonlinear effective force testing

Abstract

This paper presents an experimental investigation of the loop shaping force feedback controller for the effective force test method with nonlinear test structures. Using loop shaping techniques a force feedback controller is designed to compensate for the control-structure interaction and suppress the oil-column resonance of the hydraulic actuator. A series of effective force tests using historical earthquake ground motions are conducted to assess the performance and robustness of the loop shaping force feedback controller at the Johns Hopkins University, USA. The effective force tests were successfully performed beyond the linear range of the test structures, developing nonlinear hysteresis loops and residual displacements. Experimental results proved that the loop shaping force feedback controller provides robustness despite the nonlinearities of the test structures. However, the investigation also revealed that the loop shaping force feedback controller has limited capabilities to produce accurate force tracking in nonlinear region of the test structure.