The body is a central element in the construction of automobiles. Robot-assisted welding systems for welding bolts guarantee high-strength and durable connections in a joining process. The inductive ring sensors are particularly robust and long-lasting. As a result, they detect the welding bolts in the feeding tube close to the welding tool in robot-assisted welding systems. When parts are being fed very quickly, the integrated pulse stretching generates an output signal that can be safely analyzed.