Determining dynamic load carrying capacity for bipedal robot using torque of actuators, stability and jerk limits constraints

Abstract

The paper refers to deriving dynamic equations of motion and applications to obtain dynamic load-carrying capacity (DLCC) for bipedal robots walking. The governing equations for determining the DLCC of a given end-effector trajectory are presented at the beginning. Then via an algorithm for finding the greatest load value, the DLCC for a specified trajectory is obtained for a biped robot for the curve path.10 degrees of freedom (DOF) biped is used, and a kinematic and dynamic model for this robot was obtained. Under these conditions of research, the main limiting factor to calculating the maximum allowable load for a prescribed dynamic trajectory is the constraint of the torque actuator. At the same time, the biped robot walking dictates the need for additional constraints, that is, the stability constraints of the robot. The actuator torque constraint of the joints was formulated in this study depending on typical (torque-speed) characteristics of DC motors. The study also considers the jerk limits, an important constraint in a robotic system's dynamic motion and trajectory planning. A strategy to calculate DLCC subjected to these limitations above-mentioned is formulated. Given an arbitrary path, a general computational technique for a 10 DOF biped robot case is laid out in detail. The results showed that the value of the maximum allowable load when the end-effector moved in a  curve path was 0.702 kg. The path describes the strategy of dynamic motion by controlling dynamic forces on the robot's joints where the lower values of dynamic forces lead to decreasing energy consumption, which means an increased ability to lift larger loads. Lastly, the simulation results were validated by implementing an experimental biped robot.