Motion planning for three-link robot arm manipulators operating in an unknown three-dimensional environment

The authors present a general motion planning strategy for a class of three-link robot arm manipulators operating in an unknown 2D or 3D environment. Each joint of the robot arm manipulator can be either revolute or sliding. Out of eight possible combinations of kinematic linkages, the approach presented applies to those four combinations for which the third joint is sliding; this covers a variety of arm manipulators used in practice. It is shown that the free configuration space of such a robot arm has a 2D deformation retract which allows the reduction of the dimensionality of the motion planning problem. Then, existing 2D motion planning strategies can be appropriately modified to produce algorithms for planning collision-free motion for the whole body of the robot arm in a 3D environment with unknown obstacles of arbitrary shape