Ever notice that the belt inside a van der graaf generator looks a lot like a conveyor? Handling of parts, particularly plastic parts, can create relative motion between the part and the equipment. For example, handling parts sliding down a chute or resting on a moving conveyor could result in a shocking experience for workers, including Baxter. Any individual part may not accumulate a significant charge, but creating stacks of charged parts for packaging creates the potential (pun intended) for a nasty surprise. When the cumulative charge reaches a point where the air gap between the part and the nearest metal – such as the structure of a robot end effector – is no longer enough insulation, an electrostatic discharge (ESD) event can occur, sometimes in the order of several kilovolts!
Proper grounding of equipment and parts can help mitigate ESD as can some other methods of eliminating electrostatic charge such as an air ionizer. Rethink Robotics recommends precautionary measures to protect Baxter if there’s a chance of ESD in excess of 3kV. Protection involves positioning a ground wire on the end effector as close to the part as possible, then running it back down the arm to Baxter’s mounting bolts. This provides a secure ground path for ESD, and a happy robot.