REAL-TIME RMS ACTIVE DAMPING AUGMENTATION: HEAVY AND VERY LIGHT PAYLOAD EVALUATIONS

摘要

Controls-Structures Integration Technology has been applied to the Space Shuttle Remote Manipulator System to improve on-orbit performance. The objective was to actively damp the undesired oscillatory motions of the Remote Manipulator System following routine payload maneuvering and Shuttle attitude control thruster firings. Simulation of Active Damping Augmentation was conducted in the real-time, man-in-the-loop Systems Engineering Simulator at NASA's Johnson Space Center. The simulator was used to obtain a qualitative definition of the Remote Manipulator System operational performance improvement from astronaut operators, and to obtain supporting quantitative performance data. Vibratory motions were computed using a three-axis accelerometer simulation model located at the end of the lower boom of the Remote Manipulator System. The "sensed" motions were fed back to an Active Damping Augmentation control law, implemented in the Shuttle General Purpose Computer, which computed the joint servo mechanism commands to reduce the unwanted oscillations. Based on the request of astronaut operators who evaluated Active Damping Augmentation applied to an average (middle) weight payload, active damping of the Remote Manipulator System with attached heavy and very light payloads was demonstrated. Five astronaut operators examined the performance of two Active Damping Augmentation control laws which were implemented following single-joint and six-joint coordinated translational and rotational maneuvers. Active Damping Augmentation disturbance rejection of Shuttle thruster firings was also evaluated. Noticeable improvements in the damping response of the RMS with both the heavy, Hubble Space Telescope, payload and very light, astronaut in Manipulator Foot Restraint, payload were observed. The potential of Active Damping Augmentation to aid in maneuvering payloads close to structure or during other precision tasks was deemed significant.