UBC Theses and Dissertations
A study of the flexible space platform based deployable manipulator Marom, Itshak
A relatively general formulation, based on Lagrange's approach, for studying the nonlinear dynamics and control of a flexible, space based, Mobile Deployable Manipulator (MDM) has been developed. The formulation has the following distinctive features: (i) it is applicable to a two-link deployable manipulator translating along a flexible space platform in any desired orbit; (ii) the revolute and the prismatic joints are flexible with finite gear ratio and rotor inertia; (iii) the nonlinear, non autonomous and coupled equations of motion are presented in a compact form which provide insight into the intricate dynamical interactions and help achieve a highly efficient dynamic simulation. Validity of the formulation and the computer code were established through checks on conservation of the system energy, and comparison with test-cases. Results of the dynamical analysis clearly show that under critical combinations of parameters, the system can become unstable. An inverse kinematic technique, accounting for the linear and angular displacements of the flexible platform, has been developed to meet the desired position and orientation requirement of the end effector with respect to the chosen reference frame. A nonlinear control strategy, based on the Feedback Linearization Technique (FLT) has been developed to ensure accurate tracking of a desired trajectory in presence of the system libration as well as the base translation and vibrations. The controller also ensures desired attitude motion in presence of the manipulator's translational and slewing maneuvers. The closed loop simulation results show that a desired degree of system stability and high tracking accuracy can be achieved.
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