Dynamics of macro/micro manipulator systems

grantor: University of TorontoThis thesis seeks to provide an effective way for developing the dynamics of a modular manipulator system consisting of a micro manipulator mounted on the tip of a macro manipulator. A modular dynamic formulation method is developed to establish the equations of motion of the macro/micro (M/m) manipulator system. The modular equations of the overall system can be constructed by directly using the equations of individual sub-systems and calculating the couplings between the subsystems. The coupling torques are directly calculated using closed-form coupling equations. The modular formulation method is first applied on a rigid M/m manipulator system, and then extended to flexible M/m manipulators mounted on a flexible base (M/m+B). The kinematic redundancy of the M/m system is solved based on the criterion of peak torque reduction. Instead of minimizing the joint torques or kinetic energy at the current instant of time, the proposed Peak Torque Reduction method uses the current torque to approach an optimum velocity at the next instant of time, which, along with joint acceleration, minimizes the torque at that time, while at the same time keeps the current torque within the limits. To model the flexible M/m+B system, the modes of a flexible beam with a flexible joint are first derived. The obtained modes, called flexible-free modes, incorporate the link flexibility with the joint flexibility. By using the flexible-free modes, the flexible-link, flexible-joint macro manipulator can be treated as a flexible-link, rigid-joint manipulator. As a result, the flexible joint coordinates do not appear in the equations of motion and the order of the equations is reduced, while the accuracy remains unaffected. By applying the modular formulation method and the flexible-free modes, the equations of motion of the system consisting of flexible M/m manipulators mounted on a flexible base are finally established. The resultant equations are modular and order-reduced. Closed-form coupling equations are also obtained, which allow direct calculations of the couplings between the subsystems. Simulation is performed on a 3-DOF model to study the dynamic behavior of the system.Ph.D