Wireless ESD Event Locator Systems in Hard Disk Drive Manufacturing Environments

Abstract

This paper presents two wireless systems, namely, an electromagnetic interference (EMI)-strength-based system and a received signal strength indicator (RSSI)-based system, that locate electrostatic discharge (ESD) events in hard disk drive (HDD) manufacturing environments. The EMI-strength-based system is composed of four EMI detectors and estimates an ESD event position using an enhanced trilateration method. The RSSI-based system consists of three stationary wireless sensor nodes and one mobile wireless sensor node. The stationary nodes provide reference positions, whereas the mobile node is equipped with an EMI detector, which is used to detect an ESD event throughout the manufacturing line. Subsequently, the ESD event position is estimated by an RSSI-based localization method. In this RSSI-based system, a new method is also introduced to compensate the attenuated RSSI values by using a neural network and various transmission powers. Both systems were evaluated in a real HDD setting, and their advantages and disadvantages are discussed here. The evaluation results indicate that both systems worked well. However, the RSSI-based system can support a larger area compared with the EMI-strength-based system.