Enabling steep slope walking on Husky using reduced order modeling and quadratic programming

TL;DR

This paper introduces a control method combining reduced order modeling and quadratic programming to enable steep slope walking in legged robots like Husky, inspired by bird wing-assisted inclined running.

Contribution

It proposes a novel control approach using a modified VLIP model and QP MPC to optimize forces for slope walking, extending capabilities of legged systems.

Findings

Simulation demonstrates stable slope walking at 40 degrees.

Thruster and leg forces collaboratively enable inclined maneuvering.

Insights into posture manipulation for thruster-assisted locomotion.

Abstract

Wing-assisted inclined running (WAIR) observed in some young birds, is an attractive maneuver that can be extended to legged aerial systems. This study proposes a control method using a modified Variable Length Inverted Pendulum (VLIP) by assuming a fixed zero moment point and thruster forces collocated at the center of mass of the pendulum. A QP MPC is used to find the optimal ground reaction forces and thruster forces to track a reference position and velocity trajectory. Simulation results of this VLIP model on a slope of 40 degrees is maintained and shows thruster forces that can be obtained through posture manipulation. The simulation also provides insight to how the combined efforts of the thrusters and the tractive forces from the legs make WAIR possible in thruster-assisted legged systems.