Path Following Control of Snake Robots in Cluttered Environments
With respect to control design, this chapter represents the culmination of this book and can be regarded as a fusion of the control efforts reported in the previous chapters. In particular, forward propulsion of snake robots on planar surfaces based on oscillatory body shape changes was studied early in this book. Subsequently, this oscillatory gait pattern was extended with directional control capabilities that enabled the snake robot to track straight paths and paths defined by waypoints. The oscillatory gait pattern was further extended in the previous chapter with environment adaptation capabilities that enabled the snake robot to maintain forward propulsion in environments with obstacles. Directional control was, however, not considered in the previous chapter.
In this chapter, we will employ the knowledge gained from these control design efforts to propose a general framework for motion control of snake robots. The framework allows the motion of the snake robot to be specified in terms of three separate components, namely a body wave component, an environment adaptation component, and a heading control component. The framework is subsequently used to propose a continuous control strategy for straight line path following control of snake robots in cluttered environments. An important feature of the path following controller is the idea of a continuous jam resolution action that is performed in parallel with the cyclic wave motion of the robot to continuously adapt the body shape to the environment and prevent the motion from being jammed. We will also combine the proposed path following controller with a waypoint guidance strategy in order to enable a snake robot to move between waypoints in an obstacle environment. The performance of the path following controller and the waypoint guidance strategy is illustrated with simulation results where a snake robot is successfully steered between waypoints in an environment with obstacles. We will also present experimental results where the snake robot Kulko is successfully propelled through three different obstacle environments with the proposed controller.
KeywordsForward Velocity Snake Robot Cluttered Environment Straight Line Path Reference Angle
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