Design of EM Sensor for Non-Contact Detection of Defective Wire Harness in Conveyor System

For a non-contact detection of defective wire harness in conveyor system, a new method using the electromagnetic (EM) sensor is proposed in this paper. A dual-feed and multi array microstrip patch antenna operating at 5.8 GHz is utilized to design the EM sensor. When the wire harness is located above patch antenna, the equivalent circuit of each patch antenna and wire harness can be modeled as shunt resistor, capacitor, and inductor. Moreover, a capacitive coupling between the patch antenna and the wire harness is generated. Next, the shunt resistor of wire harness increases due to the defect of the wire so that the reflection coefficient of the patch antenna is lower than that of the wire without defect; thus, the defect of wire harness can be detected by magnitude of reflection coefficient at resonant frequency. The performances of the designed EM sensor are verified and compared by the equivalent circuit modeling, full-wave simulation, and measurement.