CASTOR Active Damping Experiment, Preliminary Flight Results

Abstract

The experiment "'CASTOR" (French acronym for Characterization of Structures in ORbit) is dedicated to the analysis of the structural dynamic modes of the MIR station, and to the investigation of the dynamic behaviour-in zero g conditions-of a truss mock-up with various damping technologies. This project has been developed under CNES management in less than three years. The work in orbit was performed by a French cosmonaut within the frame of the CASSIOPEE mission in MIR at the end of August 1996. This paper is dedicated to the active damping systems for CASTOR's truss structure. They consist essentially of three piezoelectric members, and one reaction mass actuator. Both systems use collocated sensors and actuators. Their development and flight tests are part of CNES' general activities whose aim is to improve, demonstrate the efficiency, and prepare the application of active control techniques for future space missions. Typical applications include optical systems with high stability requirements, large antennas, sensitive microgravity payloads, spacecrafts with flexible appendages, and large orbital infrastructures. In Bonus (1995), we presented the motivations behind the test in zero g conditions, and a full description of the equipment. In this paper, we briefly recapitulate upon the design of the active systems, before summing-up the recent development activities. The operations in flight are then presented. A few zero-g measurements are shown without much interpretation considering the short time available between flight and conference. The active systems exhibited excellent performances in flight. Preliminary conclusions are drawn with respect to the CASSIOPEE mission and to further activities.