Robust Control of An Active Precision Truss Structure

Stringent pointing and shape accuracy requirements necessitate advances in the control of flexible structures. These precision truss structures will be flexible in the micron regime, and their vibration modes will be densely spaced throughout the frequency range of interest. Such attributes pose a great challenge for the control design to attenuate vibration in one frequency range while not destabilizing other flexible modes outside this range. The problem is further compounded by the inaccuracy of models which requires the control law to be robust to a variety of modeling uncertainties. This paper describes the efforts in control of an active precision truss structure experiment at JPL. The control objective is to provide vibration suppression to selected modes of the structure subject to a band-limited disturbance and modeling errors. Based on performance requirements and uncertainty description, several control laws using H¿ optimization method are synthesized. These controllers are implemented on the experimental facility. Preliminary experimental results are also presented.