Enhancing jumping ability with clutched parallel elastic actuators for large-scale quadruped robots

Abstract

Abstract Advances in actuation technology have enhanced the flexibility and mobility of quadruped robots. Numerous quadruped robots with diverse configurations specialize in walking and trotting, whereas very few achieve high-performance jumping due to limited torque density. Here, we propose a clutched parallel elastic actuator (CPEA) to enhance the jumping ability of quadruped robots. The CPEA primarily comprises three magnetorheological fluid bearings that serve as a clutch mechanism to regulate energy flow within the actuation system, coupled with a torsional spring for energy storage and release. The CPEAs are installed at the knee joints of large-scale quadruped robots, operating in parallel configuration with the leg linkages. When the torsional springs are engaged, energy is accumulated during the leg’s squat phase and subsequently released to augment the propulsion during the takeoff phase. When disengaged, the system allows for unrestricted leg movement, enabling natural motion patterns during standard locomotion. To validate the feasibility and enhanced performance of the proposed CPEA, we conducted simulations and experimental evaluations. Single-leg vertical jump experiments were performed using two distinct counterweight configurations (6.2 kg and 11.3 kg) to evaluate system performance under varying load conditions. Compared to the baseline jumps without CPEA, the energized CPEA resulted in center of mass height increases of 93.9 mm and 83.3 mm, respectively, corresponding to performance improvements of 13.44% and 12.67%. Furthermore, jump simulations of the prototype demonstrated a 15.07% increase in height and a 7.82% increase in distance. Additionally, the demonstrations of the quadruped robot prototype clearly illustrated its capabilities for flexible walking and high-performance jumping. The advantages of our augmentation method make it particularly useful in demanding tasks, where quadruped robots can benefit from increased actuation torque and speed.