Off-line programming of an industrial robot in a virtual reality environment

Industrial robots need to be programmed quickly in order to be practically deployable in the production of small batches. In programming by teaching or demonstration, when most of the program’s content involves handling tasks, gesture recognition or other multimodal interfaces may be exploited. However, when the main task concerns manufacturing processing, typically tracing an edge in seam welding, deburring or cutting, then positioning and orienting the tool to considerable accuracy are required. This can only be achieved, if suitable tracking sensors are used. The current work employs a 6 degree-of-freedom magnetic sensor, but any other equivalent sensor could be used, too. The sensor is attached to a suitable hand-held teaching tool that is constructed in accordance with the real end-effector tool, enabling continuous tracking of its position and orientation interactively. A virtual reality platform records this stream of data in real time, making it possible to exploit it primarily in off-line programming of the robot. In this mode both the robot and the manufacturing cell are virtual, inverse kinematics allowing for calculation of joint coordinates from end-effector coordinates. Collision and clearance checks are also straightforwardly implemented. An edge-tracing application in 3D space was programmed following this paradigm. The resulting curves of the tool tip in the virtual and the real environment were close enough when compared by using photogrammetry. If required, the VR environment also allows for remote on-line programming, without any major modifications.