Wittmann Robot Systeme GmbH of Gross-Umstadt, Germany, has integrated two new functions into its R8 robot control system. With the SoftTorque function, the ejector now pushes the parts to be removed only approximately into the robot’s grippers. At the same time, the arm of the robot moves while applying minimal force. To achieve this, the robot controls switch to a torque control mode, reacting immediately to externally introduced forces and compensating for them by applying a force in the opposite direction. Previously employed techniques for such applications permitted only deactivation of individual servo axes and possibly the opening of any existing brakes to allow passive retraction of the axis in the automatic mode. Thanks to the SoftTorque function, overloading of the mechanical components and possible damage to the surface of the part being removed are prevented completely. The function compensates automatically for varying ejector strokes and speeds. The R8 control system therefore provides a user-friendly interface for rapid parts transfer.

The PartTrack function permits the position of moving objects to be tracked, e.g. on a conveyor belt. It relies on an incremental encoder interface to transmit the speed of the conveyor belt to the robot’s control system. A sensor gives the start signal to track the desired object. As an alternative, a camera system that evaluates various orientations of the object simultaneously can be employed. PartTrack permits parts to be tracked over the entire permissible speed range of the particular robot axis and adjusts automatically to changes in operating conditions and speeds. For instance, PartTrack can be used to peel packaging items from thermoforming machines. It is also possible to stack finished parts in moving containers. In this case, the conveyor belt can have any orientation and assume any angle with respect to the robot axes.