STIFFNESS MAPPING FOR PARALLEL MANIPULATORS

Mechanical systems containing closed-loop kinematic chains can exhibit special types of singularities that result in a loss of controllability of the element of interest (output link or gripper link). Therefore, it is very important for the designer to be able to predict this type of behavior. The approach used here is to establish stiffness or conditioning maps of the workspace of the manipulator. A method for obtaining these maps for planar and spatial parallel manipulators is presented. The maps will reveal the existence of zones where the stiffness is not acceptable and will also help the designer by providing a more accurate representation of the properties of the manipulator. © 1990 IEEE