Enhancing Vertical Jumping Performance in Wheel-Legged Robots: An Aerial Leg-Swing Jumping Scheme for Energy and Torque Reduction

The jumping motion of wheel-legged robots (WLR) is of great significance to their obstacle-crossing ability. In existing studies, a Vertical Jumping (VJ) scheme that mimics human-like jumping has been realized in WLRs. However, the capacity limit of the actuator severely restricts the height of the wheel off the ground that VJ can reach, that is, the effective jumping height which directly affects the ability to cross obstacles. To enhance the effective jumping height within the actuator’s capacity, this paper proposes the Aerial Leg-Swing Jumping (ALSJ) scheme. By analyzing the take-off and flight phases from an energy perspective, the ALSJ scheme is designed to reduce peak torque and energy consumption. The implementation framework of the proposed scheme includes a vertical reachability map, a phased optimization planning method, and an offset-free whole-body control strategy. Simulation results show that, compared to the VJ scheme, the proposed scheme increases the maximum achievable effective jumping height by about 31.03% within actuator constraints. Additionally, these two schemes are compared in hardware experiments under a test condition with a desired jumping height of 0.15 m, and the flight time constraint of 0.32 s is introduced in ALSJ scheme to enhance the practical significance of the jump. Using the ALSJ scheme, the energy consumption during take-off phase is reduced by 16.23%, the total energy consumption throughout the entire jumping process is decreased by approximately 9.78%, and the peak knee joint torque is decreased by 32.57 Nm, further validating the effectiveness of the proposed scheme. Note to Practitioners—This paper addresses a pressing challenge in the wheel-legged robot jumping filed: energy-effecient and lower-torque jumping a desired height. Current studies achieved vertical jumping motions like humans in which the joint angles remain constant during the flight phase, resulting in the need to accumulate a large amount of kinetic energy during take-off to achieve the desired jumping height. This paper analyzes the robot jumping process from the energy perspective and proposes the Aerial Leg-Swing Jumping (ALSJ) scheme that can effectively reduce the energy consumption and peak torque requirements during the take-off phase, improving the jump height within the actuator limitations. However, applying this scheme to the obstacle jumping of wheel-legged robots requires further integration of obstacle information and driving speed. Future research will focus on this application problem.