Adaptive active control of flexible structures subjected to rigid body displacements

When flexible structures are subjected to rigid body displacements, their dynamic behavior presents a coupling between rigid body displacements and flexible modes. Moreover, if these structures are articulated, their inertia characteristics can vary considerably through time and cause this dynamic behavior to become highly nonlinear. per presents the principle of a new adaptive controller MIMO. making it possible to render nearly constant the dynamic behavior of multi-articulated flexible structures in spite of changes in the geometry of their masses. The principle of this controller is based on the operation in parallel of a number of finite Gaussian quadratic linear controllers calculated before simulations, for the operating points crossed during the motion. The global multivariable command generated by the adaptive controller is the sum of the commands generated by the linear controllers, weighted by functions of rigid body displacements to allow the smoothing of the control actions on the structure. ve control is first applied to a rigid bi-articulated structure, then to mono-articulated and bi-articulated flexible structures equipped with piezoelectric sensors and piezoelectric and electromechanical actuators. After temporal optimization, the results of the proposed adaptive control are compared with those of a linear controller. This is done by using two methods, chosen according to whether the structures are stressed by disturbances or by tracking. case of regulation, the performances of this controller highlight on the one hand, the near-constant dynamic behavior of the controlled structure by eliminating instabilities, in spite of the considerable changes of kinetics and, on the other hand, clearly improved performances when compared to a fixed linear controller. In the case of a set point tracking, performances in terms of rapidity are also appreciably improved compared to those of a linear controller, while guaranteeing stability, significant damping and absolute precision without residual strains when the commands are performed.