A Nonlinear Method for Improving the Active Control Efficiency of Smart Structures Subjected to Rigid Body Motions

Smart components are commonly used for their compactness and ability to control the vibrations in an embedded flexible structure. Their relative actuation capabilities can limit the active control efficiency. This paper introduces a nonlinear method to improve their action using independent controllers for flexible modes and for rigid body modes. The nonlinear control of each flexible mode uses fuzzy logic controllers designed to improve the mechanical work of smart actuators by taking into account their actuation capabilities. The control law parameters are iteratively adjusted by taking into account the estimated disturbance levels until obtaining the desired compromise between efficiency and spillover. In addition, an independent fuzzy control for rigid body motions is then developed and adjusted in order to reduce the vibrations of the structure without decreasing the tracking efficiency. These two independent nonlinear strategies are described, implemented, and experimentally tested to control an articulated smart structure.