Energy-Efficient Quadruped Locomotion with Compliant Feet
For quadruped robotics, this work shows that selecting appropriate foot compliance can improve locomotion efficiency without destabilizing the robot, addressing the problem of high energy expenditure in rigid-foot designs.
This paper investigates the effect of compliant feet on the energy efficiency of quadruped locomotion. By integrating foot compliance into a reinforcement learning controller and testing different spring stiffness values, they found that an intermediate stiffness reduces energy consumption by ~17% compared to very stiff or very flexible springs, both in simulation and on a real robot.
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.