[2021-Vol.18-Issue 6]Biomimetic Quadruped Robot with a Spinal Joint and Optimal Spinal Motion via Reinforcement Learning
Post: 2021-12-23 11:04  View:261

Journal of Bionic Engineering (2021) 18:1280–1290

Biomimetic Quadruped Robot with a Spinal Joint and Optimal Spinal Motion via Reinforcement Learning 

Young Kook Kim1  · Woojin Seol2  · Jihyuk Park3

1 LV R&D Team, Electro-technology R&D Center, LS Electric Co., Ltd, Cheongju 28437, Republic of Korea
2 Digital Innovation Unit, Korea Hydro & Nuclear Power Co., Ltd, 1312-gil Yuseongdaero, Yusung-gu, Daejeon 34101, Republic of Korea
3 Department of Automotive Engineering, College of Mechanical and IT Engineering, Yeungnam University, 280 Daehak-ro, Gyeongsan, Gyeongbuk 38541, Republic of Korea 

Abstract Feline animals can run quickly using spinal joints as well as the joints that make up their four legs. This paper describes the development of a quadruped robot including a spinal joint that biomimics feline animals. The developed robot platform consists of four legs with a double 4-bar linkage type and one simplifed rotary joint. In addition, Q-learning, a type of machine learning, was used to fnd the optimal motion profle of the spinal joint. The bounding gait was implemented on the robot system using the motion profle of the spinal joint, and it was confrmed that using the spinal joint can achieve a faster Center of Mass (CoM) forward speed than not using the spinal joint. Although the motion profle obtained through Q-learning did not exactly match the spinal angle of a feline animal, which is more multiarticular than that of the developed robot, the tendency of the actual feline animal spinal motion profle, which is sinusoidal, was similar. 

Keywords Quadruped robot system · Bioinspired methods · Legged robots · Machine learning · Q-learning


Several legged robots. a MIT Cheetah, b Cheetah Cub, and c Boston Dynamics Wildcat

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