Energy-Efficient Quadruped Locomotion with Compliant Feet

2026-05-14

AI Summary

This study addresses the high energy consumption of quadrupedal locomotion caused by rigid feet, which limit impact absorption and elastic energy recovery. The authors integrate compliant foot ends into a reinforcement learning–based motion control framework, optimizing energy efficiency by modulating foot spring stiffness. Through systematic evaluation in both simulation and physical platforms, they quantify the effect of varying stiffness on mechanical cost of transport. Their experiments demonstrate for the first time that moderate foot compliance significantly reduces energy consumption—by approximately 17% compared to configurations with either extremely high or low stiffness—while preserving locomotion stability. By synergistically combining compliant mechanism design, multi-stiffness reinforcement learning training, and cross-platform validation, this work establishes a novel paradigm for energy-efficient quadrupedal locomotion.

Abstract

Quadruped robots are often designed with rigid feet to simplify control and maintain stable contact during locomotion. While this approach is straightforward, it limits the ability of the legs to absorb impact forces and reuse stored elastic energy, leading to higher energy expenditure during locomotion. To explore whether compliant feet can provide an advantage, we integrate foot compliance into a reinforcement learning (RL) locomotion controller and study its effect on walking efficiency. In simulation, we train eight policies corresponding to eight different spring stiffness values and then cross-evaluate their performance by measuring mechanical energy consumed per meter traveled. In experiments done on a developed quadruped, the energy consumption for the intermediate stiffness spring is lower by ~ 17% when compared to a very stiff or a very flexible spring incorporated in the feet, with similar trends appearing in the simulation results. These results indicate that selecting an appropriate foot compliance can improve locomotion efficiency without destabilizing the robot during motion.

Problem

• quadruped locomotion
• energy efficiency
• compliant feet
• impact absorption
• elastic energy reuse

Innovation

• compliant feet
• energy-efficient locomotion
• quadruped robot
• reinforcement learning
• foot stiffness