Design of ultrasonic leak location detector based on FPGA for spacecraft based on orbit

Abstract

The research on the ultrasonic leak location technology for the spacecraft on orbit environment is of great significance to ensure the long-term on orbit normal operation, eliminate the leakage in time, maintain the cabin environment and ensure the life safety of astronauts. Taking the leakage of the cabin wall structure and gas pipeline of the space station as the research object, the aerodynamic sound source characteristics of on orbit gas leakage are analyzed, and the acoustic characteristics are analyzed and extracted. Based on the theoretical basis, an ultrasonic on orbit leak detector is developed with non-contact ultrasonic sensor and camera as the probe and FPGA as the core processor. The tests are carried out to simulate the vacuum leakage of the sealed cabin structure and the positive pressure leakage of the sealed pipeline, and the leakage ultrasonic signals under different leakage holes are analyzed and processed. According to the magnitude of Eigen values, the leakage point position is determined by patrol inspection to form the detection process. The results show that the aerodynamic ultrasonic signal of gas leakage to vacuum is weak, and the amplitude of sound source signal increases with the increase of leakage hole. The signal characteristic of leakage ultrasound is that there will be an obvious main peak in the frequency band of 40KHz ± 3kHz. The leakage of more than 0.2mm can be effectively detected through patrol inspection, and the positioning accuracy is better than ± 20mm. The research results lay a foundation for on orbit leak detection and rapid positioning of the space station.