| Research Abstract |
In this project, we designed and prototyped a contorollable n-joint manipulator actuated by only two motors based on a new concept. We also established and verified its nonlineat control thepry for positioning and trajectory control. The idea of controlling a manipulator of an arbitrary number of degrees of freedom with only two motors, had never been developed nor studied in the world before this research. From nonlinear control theory point-of-view, it is a new system that has nonholonomic constraines. In contrast to the fact that nonholonomic systems research had conventionally focused on analysis of various existing mechanisms, we have invented a new mechanism that had never existed, with the knowledge of nonlinear control thepry recently developed for nonholonomic systems. Since hte nonholonomic manipulator locates its two actuators at the base, it is a suitable design of reconfigurable modular robot systems.
We also studied whether we can control a manipulator with more than two joints with only one motor. We specifically discussed a planar two-joint manipulator of which 1^<st> joint is actuated and the 2^<nd> is free to rotate. It is a unique feature that such a system is described as a system with nonintegrable dynamic constraines with respect to acceleration. It is often called a nonlinear system with drift, for which a general theory of control has not yet established. In this research, we analyzed the system from the scope of nonlinear dynamics, and showed that a simple periodic control may exhibits chaotic behavior. Them, we discussed stabilization to periodic trajectories and established simultaneous poritioning of the both joints.
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