EXPERIMENTAL RESULTS OF ACTIVE CONTROL ON A LARGE STRUCTURE TO SUPPRESS VIBRATION

The need to suppress vibration in large space structures is a continuing problem during design. Active control of structural vibration is one method that can be used to achieve lightweight structures with desirable damping characteristics. In this paper three design methods, linear quadratic Gaussian with loop transfer recovery, H(infinity), and mu synthesis, are used to obtain compensators for suppressing the vibrations of a 10-bay vertical truss structure, a component typical of what may be used to build a large space structure. For the design process the plant dynamic characteristics of the structure were determined experimentally using an identification method. The resulting compensators were implemented on a digital computer and tested for their ability to suppress the first bending mode response of the 10-bay vertical truss. For these experiments, the first bending mode is excited and the control system is used to damp the vibration. Time histories of the measured motion are presented, and modal damping obtained during the experiments is compared with analytical predictions. The advantages and disadvantages of using the various design methods are discussed.