Dynamics and control of flexible articulated space manipulators with large payloads

Abstract

This thesis studies the dynamics and control of flexible articulated space manipulators
\nwith large payloads similar to the Space Shuttle Remote Manipulator System. For
\ndynamic response analyses an exact analytical method to compute natural frequencies
\nand mode shapes of space manipulator systems with varying degrees of complexity is
\ndeveloped.
\nDynamic response analyses are performed comparing the results obtained using the
\nexact mode shapes with those obtained when using assumed mode shapes for a series
\nof different manipulator slew manoeuvres and Shuttle thruster firings.
\nPossible methods for active vibration damping control of the manipulator are
\ndiscussed, including the methods presented by other researchers. In this thesis it is
\nproposed to use reaction wheels in a closed-loop control scheme, and its advantages
\nand disadvantages compared to other methods are discussed.
\nThe problem of payload capturing and post-capture dynamics are addressed, as well
\nas the dynamics following an emergency braking of the robot. For these cases, a
\nsimple method to estimate upper limits of dynamic responses is developed, and
\nresults obtained with this method for various example cases are compared with results
\ncomputed by professional software.
\nFinally the dynamic responses of a space station to various robot manoeuvres are
\nanalysed. These responses can have detrimental effects on micro-gravity and similar
\nexperiments. The analyses are performed using a simplified model of the
\nInternational Space Station and its Mobile Remote Manipulator System.