Joint location sensor
The location of a joint can easily be detected using a tactile sensor by the robot itself using the end of the welding wire or welding shroud. These are charged with a voltage. When the robot is put into search mode the wire or shroud will make contact with the work piece. The robot stops immediately and registers the position by sending the relevant information back to the robot controller. Searches can be carried out in three directions, X, Y and Z as deemed necessary. Each directional search takes about 1.5 seconds to perform, which is not of too much consequence for a heavy welding application where welding cycle times are long, but for a small assembly it is not cost effective since it increases cycle times too much to search for joint locations. Customers should therefore ensure that the upstream equipment delivers quality sub-components. Other less common methods of location the start position include a mechanical probes or a laser point sensor.