Research on non-intrusive pressure measurement based on capacitor method

Non-intrusive pressure measurement plays a crucial role in failure diagnosis and detection of hydraulic system. A method based on capacitor is discussed in this paper and a mathematical model based on functional link neural network (FLNN) is established, which establishes the relationship between capacitor and pressure of the oil in a hydraulic system. A test platform of pressure via capacitor measurement was designed. Through experiments, the accurate mathematical relationship between capacitor and pressure of the hydraulic system is obtained. And the qualitative analysis of the relationship between capacitor and temperature of the oil is completed. Simulation and test results indicate that the proposed method is feasible for non-intrusive pressure measurement. It offers a new online pressure measurement method for hydraulic system with pipe diameter less than 15 mm.