Biped robots are designed to operate in human-centric environments and perform tasks typically carried out by humans. In complex environments with unpredictable disturbances, maintaining stable walking is particularly important. This paper proposes a reactive control method with an analytical solution for biped robots to maintain stable walking. First, based on the robot's Center of Mass state, the step timing and location are adjusted according to the characteristics of the orbital energy of the Linear Inverted Pendulum (LIP) model. Then, the swing foot trajectory is updated in real-time to meet the adjusted gait parameters. With the proposed method, the robot can recover its normal gait in the next step after being disturbed, ensuring walking stability. The performance of the proposed method is validated through numerical verification using the LIP model and simulation experiments on the biped robot Neubot.
Liu et al. (2025) studied this question.