Gait planning of a scale-driven snake-like robot for winding and obstacle crossing

Gait planning is an effective approach aiming at the difficulty in locomotion control of a multi-degree-of-freedom snake-like robot. In this article, a gait-generating method is presented with regard to the issue of its locomotion control in the process of winding–crossing variable-diameter cylindrical obstacles involving a P-R-joint scale-driven snake-like robot. The proposed method solves the problem of trajectory discontinuity of variable-diameter helix lines through linear fitting in the process of the obstacle crossing of the robot. The collision/interference between the robot and the obstacle is avoided by adding an extended helix segment to the front and rear ends of the obstacle. For direct linear fitting of the locomotion trajectory curve that will lead to velocity discontinuity, B-spline curves are used for smooth transition on generating the trajectory curve. A simulation experiment analysis is performed to demonstrate that the proposed gait-generating method can enable the snake-like robot to cross variable-diameter cylindrical obstacles.