Unified Force and Motion Adaptive-Integral Control of Flexible Robot Manipulators

TL;DR

This paper introduces a unified adaptive control method for flexible robot manipulators that seamlessly switches between force and motion control modes in contact scenarios, ensuring stability and robustness with low computational cost.

Contribution

It presents a novel unified control framework that combines force and motion control without switching, using adaptive laws and Lyapunov stability for flexible manipulators.

Findings

Successful experimental validation on a 3-joint flexible manipulator

Achieved robust control with low-cost sensors and microcontroller

Demonstrated stability and adaptability in mixed contact scenarios

Abstract

In this paper, an adaptive nonlinear strategy for the motion and force control of flexible manipulators is proposed. The approach provides robust motion control until contact is detected when force control is then available--without any control switch--, and vice versa. This self-tuning in mixed contact/non-contact scenarios is possible thanks to the unified formulation of force and motion control, including an integral transpose-based inverse kinematics and adaptive-update laws for the flexible manipulator link and contact stiffnesses. Global boundedness of all signals and asymptotic stability of force and position are guaranteed through Lyapunov analysis. The control strategy and its implementation has been validated using a low-cost basic microcontroller and a manipulator with 3 flexible joints and 4 actuators. Complete experimental results are provided in a realistic mixed contact scenario, demonstrating very-low computational demand with inexpensive force sensors.