Analysis of Parameter Transition Effects in CPG-Based Control for Multi-Joint Snake-like Robots 

Snake-like robots require body adaptation during locomotion when creeping through environments with obstacles. Central Pattern Generator (CPG) provides an effective way to generate rhythmic signals through parameter modulation. During body-shape adaptation, the body wave generated by the CPG can be modified by adjusting its parameters. In this paper, a CPG network based on Hopf oscillators is adopted, and the amplitude parameter is used for body-shape adaptation. However, the influence of amplitude variation during the transition process has not been fully understood. More specifically, when the amplitude parameter changes abruptly, the attractor shifts immediately, while the oscillator state cannot follow the new attractor instantaneously. This mismatch produces transient responses and waveform distortion during the transition process. To address this issue, a linear parameter transition method is introduced. The proposed method is subsequently extended to a coupled CPG network for controlling the multi-joint snake-like robots. Simulations are conducted under different parameter transition conditions. The results demonstrate that the parameter transition method strongly affects the transient torque response. Compared with abrupt parameter variation, the proposed linear transition method significantly reduces transient torque peaks. Additionally, the results further show that even a short transition interval is sufficient to achieve most of the torque reduction. Experiment results show that the proposed method can be applied to body-shape modulation and obstacle avoidance during snake-like robot locomotion.