Integrating Structure and Controller Design to Mechanical Systems via Decentralized Control Techniques

The overall performance of the mechanical system can be significantly improved by concurrently optimizing the plant and the controller. This paper proposes a new integrated design method via decentralized control techniques to concurrently optimize the structure and the controller, which aims at minimizing the system H2 norm from the disturbance to the system cost. The integrated design problems have been formulated in the cases of a full state feedback controller and a full order output feedback controller respectively. Inspired by noticing that the control techniques are capable of optimizing both the parameters of passive springs and dampers and the controller for the mechanical system, we extend the current LTI control system to a more general framework suitable for the integrated design needs, where the structure design is treated as the passive control optimization tackled by decentralized control techniques with static output feedback, while the active controller is optimized by solving the modified Riccati equations. With the extended system framework, we transfer the original non-convex integrated optimization problem to an unconstrained optimization problem by introducing Lagrange multipliers and a Lagrange function. The gradient-based optimization method is employed to effectively find the optimality solution of the integrated design. Two design examples including an active-passive vehicle suspension system and an active-passive Tuned Mass Damper (TMD) system are designed by the proposed integrated design method. The improvement of the overall system performance due to the integrated design is also presented in comparison with the conventional design methods.Copyright © 2015 by ASME