Locomotion Control of Head Orientation Strategies Based on Hopf Oscillators for a Snake Robot

Abstract The multi-redundant degrees of freedom (DoF) in snake robots present substantial challenges in attaining oriented movement towards target directions. Under the coupled influence of various factors, these systems progressively deviate from desired trajectories, thereby diminishing locomotion precision. This paper systematically investigates head orientation strategies and their effects on orientation control and stability during the snake robot's serpentine locomotion. First, through biomechanical analysis and mechanistic simplification of biological snakes' orientation mechanisms, a dynamic model of the snake robot and a CPG control network based on Hopf oscillators are established. Building on this foundation, we implement head orientation algorithms under different strategies and propose a multi-metric evaluation framework. The methodology comprises three steps: (1) formulation of distinct head orientation strategies considering the characteristics of signal continuity and joint angular patterns; (2) definition of state variables for serpentine locomotion and corresponding orientation evaluation metrics; (3) parametric investigation of control parameters' impacts on head orientation accuracy through the proposed framework. Finally, comprehensive simulations and prototype experiments demonstrate the approach's effectiveness. This work provides theoretical and practical guidance for achieving precise orientation control of snake robots in complex operational scenarios.