Sensor-based motion planning in three dimensions for a highly redundant snake robot

A strategy is described for real-time motion planning for a highly redundant snake-like robot manipulator operating in a three-dimensional (3D) environment filled with unknown obstacles of arbitrary shape. The robot consists of many (say 30 or 50) links serially connected by universal joints (such a joint allows a 3D rotation of one link relative to the other). The robot's sensors allow it to sense objects in the vicinity of any points of its body. The task is to move the robot's tip point (its head) from its starting position to a specified target position, collision-free for the whole robot's body. To achieve the efficiency necessary for real-time computation, an iterative procedure is proposed which makes use of a unit motion for a single link based on the tractrix curve. This choice also results in automatically achieving a motion that is 'natural' (in that the joint displacements tend to 'die out' in the direction from head to tail) as well as locally optimal.