Application Cases

Experiment Title: Position Detection and Control Technology in Electrostatic Levitation

Testing Purpose:According to Earnshaw's theorem, a static electric field cannot have a minimum three-dimensional electrostatic potential, so stability of the sample must be achieved in combination with a negative feedback control system. To conduct material property studies, it is also necessary to heat and measure the temperature of the material sample, thus requiring heating and temperature measurement equipment. Therefore, the following sections introduce the position detection and control, as well as heating and temperature detection technologies in the electrostatic levitation experimental setup.

Testing Equipment: High Voltage Amplifier, Position Controller, Detector, etc.

Experiment Process:

Figure 1: Schematic Diagram of Electrostatic Levitation Position Detection and Control Structure

The structure of the electrostatic levitation position detection and control is shown in Figure 1. The system includes a position detection unit, a processing and control unit, a high voltage amplifier, and an electrode structure. The position detection unit uses a PSD (Position Sensitive Detector) as the sensor to obtain the position signal of the levitated sample. The processing and control unit filters the measured position signal and performs PID control calculations based on the processed position signal. The output control signal is then transmitted to the high voltage amplifier. The high voltage amplifier controls the output high voltage according to the input signal. The output high voltage is applied to the upper and lower electrodes of the electrode plate. By changing the electric field force experienced by the charged sample, the motion of the levitated sample is adjusted, achieving control of the levitated sample.

The position detection unit employs the shadow method to measure the position of the levitated sample. A parallel light with uniform energy illuminates the entire photosensitive surface of the PSD. If the object to be measured is in front of the PSD, then the shadow of the object will be cast on the PSD. If the light spot energy distribution is uniform, then the position of the light spot centroid is linearly related to the shadow position. By inversely amplifying the measurement signal of the PSD, the position information of the levitated sphere can be obtained. To obtain the three-dimensional position information of the levitated sample, two PSDs need to be placed parallel to the z-axis and perpendicular to each other. As shown in Figure 2, one PSD detects the (x, z) coordinates of the levitated material, while the other detects the (y, z) coordinates. When both PSDs detect simultaneously, the (x, y, z) coordinates of the levitated material can be obtained.

Figure 2: Schematic Diagram of Position Detection Structure

Experimental Results:

The position detection and control technology in the electrostatic levitation experimental setup is a key aspect of the levitation experiment. The experimental setup uses a Position Sensitive Detector (PSD) for sample position measurement and a PID control algorithm to adjust the high voltage applied to the electrode plate to achieve stable levitation of the sample. Based on the experimental conditions of the levitated material and space experiments, the shortcomings of using PSD for position measurement are introduced, and a method for using a CCD (Charge-Coupled Device) for sample position measurement is proposed.

High Voltage Amplifier Recommendation: ATA-7050

Figure: Specifications of the ATA-7050 High Voltage Amplifier

This material is compiled and released by Aigtek Antai Electronics. For more case studies and product details, please continue to follow us. Xi'an Aigtek Antai Electronics has become a widely recognized supplier of instruments and equipment with a broad product line and considerable scale in the industry. Sample machines are available for free trial.