Journal of Bionic Engineering (2025) 22:626–641 https://doi.org/10.1007/s42235-025-00657-0

Whole-Body Hybrid Torque-Position Control for Balancing with a New  Wheeled Bipedal Robot

Yi Xiong1  · Haojie Liu2  · Bingxing Chen1  · Yanjie Chen1  · Ligang Yao1  · Zongxing Lu1

1 School of Mechanical Engineering and Automation, Fuzhou  University, Fuzhou 350108, China 

2 Lenovo (Shanghai) Information Technology Co., Ltd. No,  696 Songtao Road, Pudong District, Shanghai 201203, China

Abstract 

The wheeled bipedal robots have great application potential in environments with a mixture of structured and unstructured  terrain. However, wheeled bipedal robots have problems such as poor balance ability and low movement level on rough  roads. In this paper, a novel and low-cost wheeled bipedal robot with an asymmetrical five-link mechanism is proposed,  and the kinematics of the legs and the dynamics of the Wheeled Inverted Pendulum (WIP) are modeled. The primary balance controller of the wheeled bipedal robot is built based on the Linear Quadratic Regulator (LQR) and the compensation  method of the virtual pitch angle adjusting the Center of Mass (CoM) position, then the whole-body hybrid torque-position  control is established by combining attitude and leg controllers. The stability of the robot’s attitude control and motion  is verified with simulations and prototype experiments, which confirm the robot’s ability to pass through complex terrain  and resist external interference. The feasibility and reliability of the proposed control model are verified. 

Keywords Wheeled Robots Legged Robots Motion Control Mechanism Design