Journal of Bionic Engineering (2023) 20:2570–2589 https://doi.org/10.1007/s42235-023-00412-3

Design and Experiments of a Human-Leg-Inspired Omnidirectional Robotic Leg

Yuze Xu1 · Zirong Luo1 · Xiangjuan Bai1 · Huixiang Xie2 · Yiming Zhu1 · Shanjun Chen1 · Jianzhong Shang1 

Zirong Luo luozirong@nudt.edu.cn * Jianzhong Shang jz_shang_nudt@163.com

1 College of Intelligence Science and Technology, National University of Defense Technology, Changsha 410073, China 

2 PLA Rocket Force University of Engineering, Xi’an 710025, China

Abstract：Bionic-based robotic legs enable the legged robots with elegant and agile mobility in multi-terrain environment, just like natural living beings. And the smart design could efficiently improve the performance of a robotic leg. Inspired by the simplified human leg structure, we present a 3-DOF robotic leg—OmniLeg, that is capable of making omnidirectional legged locomotion while keeping constant posture of the foot. Additionally, the concentrated drive mode, in which all the motor

actuators are installed in the torso and do not move with the leg, minimizes the inertia of the robotic leg. In this paper, the modular design, the kinematics model, the structural analysis, the workspace, and the performance evaluation of the Omni-Leg are discussed. Furthermore, we build a prototype based on the proposed design, and the precision of it is verified by the error calibration experiment which is conducted by tracking the trajectory of the prototype’s endpoint. Then, we present

an OmniLeg-based single legged mobile robot. The capability of omnidirectional legged locomotion of the OmniLeg is demonstrated by the experiments.

Keywords： Human leg · Robotic leg · Omnidirectional legged locomotion · Spatial dual-parallelogram-linkages · Spatial closed-loop four-bar