Journal of Bionic Engineering (2023) 20:2108–2122 https://doi.org/10.1007/s42235-023-00362-w

A Unified Trajectory Optimization Approach for Long?Term and Reactive Motion Planning of Legged Locomotion

Yapeng Shi1 · Bin Yu1 · Kaixian Ba1 · Mantian Li2

Yapeng Shi shiyapeng@ysu.edu.cn · Bin Yu yb@ysu.edu.cn

1 School of Mechanical Engineering, Yanshan University, No. 438 West Hebei Avenue, Qinhuangdao 066004, Hebei, People’s Republic of China

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

People’s Republic of China

Abstract：This paper proposes a unified trajectory optimization approach that simultaneously optimizes the trajectory of the center of mass and footholds for legged locomotion. Based on a generic point-mass model, the approach is formulated as a nonlinear optimization problem, incorporating constraints such as robot kinematics, dynamics, ground reaction forces, obstacles, and target location. The unified optimization approach can be applied to both long-term motion planning and the reactive online planning through the use of model predictive control, and it incorporates vector field guidance to converge to the long-term planned motion. The effectiveness of the approach is demonstrated through simulations and physical experiments, showing its ability to generate a variety of walking and jumping gaits, as well as transitions between them, and to perform reactive walking in obstructed environments.

Keywords： Legged locomotion · Motion planning · Trajectory optimization · Bionic robot