Systematic Evaluation of Soft Failures in System-Level ESD Transient Events

A system such as a human-assisting robot consists of many subsystems such as sensors, display, motors, and control. When an electrostatic discharge (ESD) occurs, it can disrupt the normal operation of any subsystem. This paper analyzes such events beginning at the tribo-charging down to the sensor disruption. The rolling wheels charge the robot, and a discharge occurs when it reaches the charging station. Based on the charge voltage, the discharge current is simulated using a simple switch model along with the loop impedance which limits the current. In multiple steps, the discharge current couples to the sensor. This coupling is represented as S-parameters obtaining the noise voltage at the sensor. This noise voltage is compared to the sensor's noise sensitivity threshold to reproduce the disruptive event. The model is validated with measurements. The simulation model can help system designers assess ESD risks without damaging hardware as well as efficiently design filtering components and effective on-board ESD protection.