Control of flexible-joint underactuated manipulators in task space

Abstract

This paper investigates the problem of controlling flexible-joint underactuated manipulators in task space. A lower number of actuators than degrees of freedom alongside flexibility of joints make this mission a challenging task. Problems may arise such as poor tracking performance due to structured and unstructured uncertainties. Here, a controller with two internal loops comprising a free dynamic PID method improved with a free chattering second-order siding mode control is used. The proposed approach makes it possible to track a trajectory in task space with high accuracy for flexible-joint underactuated manipulators. The main motivations for choosing this controller are precision and lower energy consumption. The experimental results for a two-link flexible-joint underactuated robot ensure efficiency of this new control approach.