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For large space structures (LSS), the interaction between control system and structural vibration is a major problem. In this paper, the authors will show a new two Degrees-of-Freedom actuator called “Super precision Positioning Device (SPD)” (1)∗ which converts rotational motion to translational motion without cams or link mechanism, and experimental results of active vibration control to large space structures using the actuator as an active damping enhancer. In the experiment, the SPD is mounted to a rigid base to which a flexible structure model is attached. The structure is a free standing flexible frame type structure and it has multi-dimensional vibration modes to simulate a real structure. The movement of the SPD is controlled to damp three dimensional vibration by sensing moments of the structure. The experimental results in this paper shows that the SPD is capable of reducing multi-dimensional structural vibration.

Dynamic wind tunnel tests using a 5-percent cable-mounted model of the NAL spaceplane have been performed in the NAL low-speed large scale wind tunnel to identify the aerodynamic model including dynamic effects. During the tests performed in March 1991, the lateral-directional motion was excited by aileron and rudder inputs. A flight path reconstruction was applied to the recorded data and a parameter identification study of the reconstructed data was undertaken to extract lateral-directional stability and control derivatives using the least square method. The estimated derivatives were compared with the results of static wind tunnel tests and theoretically estimated dynamic derivatives. They were also evaluated by comparing mathematically simulated time histories calculated using them with the wind tunnel test data. As a result, all major derivatives were estimated well and effectiveness of the dynamic test was shown.