Visual servoing: path interpolation by homography decomposition

In order to successfully perform visual servoing of robot manipulators the control algorithm must account for the physical limitations of the manipulator. These constraints define the robot workspace boundary. Any visual servoing control algorithm must avoid this boundary if stability of motion is to be ensured. In the paper, a method is developed by which a desired object path can be interpolated between two arbitrary object poses based on image feature extraction. This path is defined to be a continuous change in object pose between the initial and final desired poses which avoids the workspace boundary. The development of this method involves the parameterization of the 2-D displacement transformation or homography. By decomposing this homography a set of object path poses can be interpolated in either the image plane or reconstructed in the 3-D workspace. Implementation of a visual servoing procedure confirms the validity of the interpolated path with respect to workspace boundary avoidance.