A SYNTHESIS METHOD FOR PLACING WORKPIECES IN RPR PLANAR ROBOTIC WORKCELLS

A new method is used for determining both a satisfactory location of a workpiece and a suitable mounting-angle of the tool for planar RPR ro bots that can provide dexterous workspace. All three joints of the rob ot have excursion-limits that bound their displacement. For the purpos es of this paper, the third joint, a revolute, permits exactly one ful l turn. Successful locations for the workpiece are those places where the rotations at each task-axis and the third joint are synchronized. For a fixed mounting angle of the tool, the radial location and orient ation of the workpiece are determined by just two 2 pi-rotations of th e tool. When the mounting-angle of the tool is also a variable, the to ol can be rotated a fill turn at three locations on the workpiece. The method is particularly,cell suited to applications in which the task requires large rotations of the end-effector. The results a,are presen ted as coordinates of points in a two-dimensional Cartesian reference frame attached to the workcell. Consequently, a technician or an engin eer can determine the location for the workpiece by laying out these c oordinates directly in the workcell. Example problems illustrate the m ethod. Practical applications include welding and deposition of adhesi ves.