Dynamic Analysis and Synthesis of Geared Robotic Mechanisms

Abstract

The objective of this research is to develop a systematic approach for dynamic analysis of geared robotic mechanisms and to establish systematic and rational methodologies for the determination of gearing configuration and gear ratios.<P>First, a systematic methodology is developed for the dynamic analysis of geared robotic mechanisms. The formulation of dynamic equations is based on the concept of an equivalent open-loop chain. It is shown that reaction force analysis of such mechanisms can be efficiently carried out by a forward evaluation along its transmission lines followed by a backward evaluation along the equivalent open-loop chain.<P>Then, two methodologies are developed for the determination of gearing configuration and gear ratios. The first methodology considers the design from both kinematics and dynamics points of view. It is shown that, through proper choice of gear ratios, certain gear-coupled manipulators can be designed to possess kinematic isotropy and maximum acceleration capacity (KIMAC) conditions at a given reference point while individual-joint drive manipulators can not be designed to possess such conditions. The train values of those gear-coupled manipulators can be thought of as a product of two- stage gear reductions. The second-stage gear reduction is used to define the kinematic isotropic condition while the first- stage gear reduction is used to optimize the acceleration capacity. The second methodology considers the design from just the dynamics point of view. It is shown that, to achieve a maximum acceleration capacity (MAC), the mass inertia matrix of the input links reflected at the joint-space should be equal to that of the major links. It is also shown that the maximum acceleration capacity is independent of the gearing configuration.<P>The methodologies developed in this research provide an efficient and systematic approach for the dynamic analysis and synthesis of geared robotic mechanisms.