An Inverse Dynamics Approach to Control Lyapunov Functions

TL;DR

This paper introduces an inverse dynamics control method using control Lyapunov functions for underactuated bipedal robots, improving convergence and behavior regulation, demonstrated in simulation and real-time hardware tests.

Contribution

It presents a novel inverse dynamics control approach with control Lyapunov functions that enhances convergence and allows for more behavior regulation in underactuated robots.

Findings

Successful simulation of walking behavior

Real-time hardware control of dynamic crouching

Improved convergence properties of the controller

Abstract

With the goal of moving towards implementation of increasingly dynamic behaviors on underactuated systems, this paper presents an optimization-based approach for solving full-body dynamics based controllers on underactuated bipedal robots. The primary focus of this paper is on the development of an alternative approach to the implementation of controllers utilizing control Lyapunov function based quadratic programs. This approach utilizes many of the desirable aspects from successful inverse dynamics based controllers in the literature, while also incorporating a variant of control Lyapunov functions that renders better convergence in the context of tracking outputs. The principal benefits of this formulation include a greater ability to add costs which regulate the resulting behavior of the robot. In addition, the model error-prone inertia matrix is used only once, in a non-inverted form. The result is a successful demonstration of the controller for walking in simulation, and applied on hardware in real-time for dynamic crouching.