A Field High Resolution Measurement Method for Irregular Surface Electrostatic Potential

Characterized by noninvasiveness and high sensitivity, the noncontact electrostatic testing technology has been widely used in scientific research and engineering practices such as electrostatic charge imaging, high-voltage insulator analysis, biological sensing, and gas—solid two-phase flow parameter measurement. However, in many practical applications, scanning electric potential microscope (SEPM) technologies focusing on high spatial resolution cannot meet the testing requirements of charged objects with irregular 3-D structures and flexible activities. Based on the principle of direct inductive electrostatic potential measurement and a six-axis robot arm, a 3-D scanning method for noncontact electrostatic potential measurement is proposed in this article. A low-noise electrostatic potential sensor with both high sensitivity and high accuracy was designed via positive feedback circuit technology. A calibration system was built, which has an adjustable excitation signal, progressive spatial accuracy, and variable 3-D attitude. The experimental data verify the effectiveness of this method. The correlation between the signal characteristics and the physical size of the calibration device was statistically analyzed. The effects of parameters such as the amplitude and frequency of the excitation signal, speed, and normal distance of the robot arm scanning on the resolution of the test results were investigated. The testing results show that the 3-D spatial resolution of dc and low-frequency ac potential distribution reached 200 $\mu \text{m}$ .