Heuristic dynamic programming for semi-active control of vibration isolation

Vibration isolation controllers are used to suppress undesirable disturbance in order to guarantee better performance in many industrial and scientific domains. To overcome the drawbacks of the conventional passive systems, a novel design based on the action dependent heuristic dynamic programming (ADHDP) is addressed in this paper for the semi-active vibration isolator. ADHDP, derived from dynamic programming, is adopted in the design of a nonlinear optimal vibration controller. This approach is the simplest category of adaptive critic designs (ACDs) which are very efficient to solve a class of nonlinear optimal control problems. Only two subnetworks are involved in ADHDP, namely the action network and the critic network. Least mean square (LMS) algorithm with variable learning rate is applied to the adaptation of these two networks. A single-stage training process is also demonstrated as a useful training strategy. Two types of vibrations are utilized to verify the effectiveness of this control design. Simulation results show that the semi-active vibration isolator is able to reduce the influence of the vibration excitation to the payload significantly in comparison with the passive system.