Touch-off: a method to determine the position of an object by means of a sensor-driven robot

Touch-off is a method used by a force sensor-driven robot to accurately determine a reference frame on an object when only the approximate location of the object is known. It yields a precise and repeatable definition of the location of the object relative to the base coordinate frame of the robot. Once this reference frame has been defined, all robot locations can be specified relative to this object frame. If the object is subsequently moved, one needs only to redefine the object frame by using the Touch-off procedure. The calculations necessary for the procedure are presented along with the results of the experimental verification. Although developed for use in performing maintenance of the Sandia Pulsed Reactor (SPR III), the Touch-off procedure is applicable to a wide range of object location and orientation tasks.