A holdsite method for parts acquisition using a laser rangefinder mounted on a robot wrist

The acquisition of parts by a robot is an important problem industrially. The parts may be of various types and can be separate or jumbled together. We have mounted a laser rangefinder on the wrist of a robot and use the profile data it gives to determine a location, called a holdsite, at which to grasp the part. The laser rangefinder is lightweight and collects data quickly with more than sufficient accuracy for this application. The parts are not recognized, instead the best holdsite according to the criteria of stability and safety is chosen using methods from the field of spatial planning. The method has been tested on a variety of parts, from screws to rings and works well. The time required to acquire a part is approximately one minute but we believe this time can be decreased substantially to about ten seconds per part.