SLIP Walking over Rough Terrain via H-LIP Stepping and Backstepping-Barrier Function Inspired Quadratic Program

TL;DR

This paper introduces a novel control approach combining Backstepping-Barrier Function quadratic programs and H-LIP stepping to enable Spring Loaded Inverted Pendulum robots to walk over challenging terrains efficiently.

Contribution

It presents a new control framework that decouples vertical and horizontal control for legged robots, improving robustness and computational efficiency over rough terrains.

Findings

Successful simulation of walking over slopes, stairs, and rough terrains.

Efficient control implementation with closed-form solutions.

Robustness to terrain uncertainties demonstrated in simulation.

Abstract

We present an advanced and novel control method to enable actuated Spring Loaded Inverted Pendulum model to walk over rough and challenging terrains. The high-level philosophy is the decoupling of the controls of the vertical and horizontal states. The vertical state is controlled via Backstepping-Barrier Function (BBF) based quadratic programs: a combination of control Lyapunov backstepping and control barrier function, both of which provide inequality constraints on the inputs. The horizontal state is stabilized via Hybrid-Linear Inverted Pendulum (H-LIP) based stepping, which has a closed-form formulation. Therefore, the implementation is computationally-efficient. We evaluate our method in simulation, which demonstrates the aSLIP walking over various terrains, including slopes, stairs, and general rough terrains with uncertainties.