An Overview of Energy-Optimal Impedance Control of Cooperative Robot Manipulators

TL;DR

This paper presents an energy-efficient impedance control scheme for cooperative robot manipulators handling a load, balancing tracking accuracy, stability, and minimal energy use through optimization of impedance parameters.

Contribution

It introduces a novel energy-optimal impedance control framework with a virtual control strategy and stability guarantees for cooperative manipulators.

Findings

Energy consumption is minimized through optimized damping and stiffness gains.

The control scheme maintains stability with time-varying impedance parameters.

Numerical example demonstrates effectiveness of the proposed method.

Abstract

An impedance-based control scheme is introduced for cooperative manipulators grasping a rigid load. The position and orientation of the load are to be maintained close to a desired trajectory, trading off tracking accuracy by low energy consumption and maintaining stability. To this end, the augmented dynamics of the robots, their actuators and the load is formed, and an impedance control is adopted. A virtual control strategy is used to decouple torque control from actuator control. An optimization problem is then formulated using energy balance equations. The optimization finds the damping and stiffness gains of the impedance relation such that the energy consumption is minimized. Furthermore, L2 stability techniques are used to allow for time-varying damping and stiffness in the desired impedance. A numerical example is provided to demonstrate the results.