A New Method of Dynamic Modelling and Optimal Energy Distribution for Cooperative Closed Chain Manipulators

Abstract

Cooperative manipulators' capability to perform different tasks rather than single-arm robots, has motivated researchers to develop dynamic models. In particular, cooperative manipulators with a closed kinematic chain become more sophisticated to formulate as the kinematic and dynamic constraints should be satisfied. Moreover, by increasing the number of joints and links, deriving motion equations for the whole system requires more calculations. In this paper, dynamic modeling of rigid cooperative manipulators has been done by the recursive Gibbs-Appell formulation for any degree of freedom. Also, there are numerous answers to the inverse dynamic problem due to the redundancy and torques have been calculated by considering optimum energy distribution. In this method, a cost function has been defined in which load can be distributed by specifying arbitrary coefficients for each joint. This approach helps the designer to predict the optimum motor size or calculate the most optimum inputs to an existing robot's joints regarding its motors' capacity. Finally, in order to validate the accuracy of the model, simulation has been conducted and results compared with a similar modeled system in ADAMS software. The cooperative manipulators with closed kinematic chains are used to performing special missions such as displacement of large or heavy objects, assembling or forming parts and etc.