Journal of Bionic Engineering (2025) 22:1249–1264https://doi.org/10.1007/s42235-025-00687-8

Snow Leopard-inspired Lower Limb Exoskeleton for Adaptive Multiterrain Locomotion: Design and Preliminary Experimental Evaluation

Yi Long1,2,3 · Xiaofeng Luo1  · Tianqi Zhou1  · Xiaopeng Hu4  · Long He3  · Wei Dong5

1 Faculty of Robot Science and Engineering, Northeastern University, Shenyang 110000, China 

2 Foshan Graduate School of Innovation, Northeastern University, Foshan 528000, China 

3 Zhiyuan Research Institute, Hangzhou 310013, China 

4 School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China 

5 State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China

Abstract 

To overcome the limitations of traditional exoskeletons in complex outdoor terrains, this study introduces a novel lower limb exoskeleton inspired by the snow leopard’s forelimb musculoskeletal structure. It features a non-fully anthropomorphic design, attaching only at the thigh and ankle with a backward-knee configuration to mimic natural human knee movement. The design incorporates a single elastic element at the hip for gravity compensation and dual elastic elements at the knee for terrain adaptability, which adjust based on walking context. The design’s effectiveness was assessed by measuring metabolic cost reduction and motor output torque under various walking conditions. Results showed significant metabolic cost savings of 5.8–8.8% across different speeds and a 7.9% reduction during 9° incline walking on a flat indoor surface. Additionally, the spring element decreased hip motor output torque by 7–15.9% and knee torque by 8.1–14.2%. Outdoor tests confirmed the design’s robustness and effectiveness in reducing motor torque across terrains, highlighting its potential to advance multi-terrain adaptive exoskeleton research. 

Keywords Lower limb exoskeleton · Bionic structure · Multi-terrain adaptive structure · Backward-knee configuration · Non-exhaustive anthropomorphism