Improving the energy efficiency of quadruped robots on uneven terrains through bio-inspired elastic design

Abstract

This study demonstrates that bio-inspired elastic leg design significantly enhances the energy efficiency of quadruped robots on uneven terrains. Through a quadrupedal spring-mass model and tunable-stiffness prototype (1.2–5.6 kN/m), we validate that elastic legs reduce the Cost of Transport by 18–37% (p<0.01) across flat, 10° slope, and gravel terrains. Optimal stiffness (k=4.4 kN/m) and landing angle (θ=75°) synergistically achieve 68% impact energy recovery, decreasing actuator work by 53% on slopes while expanding stable speed limits. The design eliminates the "slope penalty" and improves gait stability by 53.1%. Gabrielli-von Kármán analysis confirms a fundamental shift in efficiency-speed regimes, establishing adjustable stiffness as a critical paradigm for field robots with immediate logistics and disaster response applications.