In this study, a 400-1000nm hyperspectral camera was applied, and FS13, a product of Hangzhou Color Spectrum Technology Co., LTD., could be used for related research. The spectral range is 400-1000nm, the wavelength resolution is better than 2.5nm, and up to 1200 spectral channels can be reached. The acquisition speed can reach 128FPS in the full spectrum, and the maximum after band selection is 3300Hz (support multi-region band selection).
Brake fluid, also known as brake oil, is used to transfer pressure in the vehicle hydraulic brake system. Automotive brake fluid can be divided into alcohol brake fluid, mineral oil brake fluid and synthetic brake fluid. Alcohol brake fluid is made of refined castor oil and ethanol or n-butanol, which is cheap, but has poor high and low temperature performance. Mineral oil brake fluid is made of refined diesel distillate as base oil, adding viscosifier, antioxidant and anti-rust agent. It has good temperature adaptability, but it has swelling effect on natural rubber. The synthetic brake fluid is composed of ethylene glycol ether, diethylene glycol ether, triethylene glycol ether, water-soluble polyester, polyether, silicone oil, etc. as solvent, adding lubricant and additives. The operating temperature range is wide, and the corrosion effect on rubber and metal is small. Different brands of brake fluid have great differences in formula, price and quality.
The quality of brake fluid is directly related to the driving safety of the vehicle, and the use of fake and shoddy brake fluid will lead to brake failure or brake failure due to the occurrence of high temperature air resistance and low temperature brake delay, resulting in safety accidents and injuries to vehicles and people. According to the sampling results of 47 enterprises in 2005 by the State Bureau of Quality and Technical Supervision, the qualified rate of brake fluid is only 45.9%, which has great safety risks. Brake fluid is a colorless and transparent liquid, and it is difficult to distinguish different brands of brake fluid from the appearance, and special analytical instruments are needed to identify it. At present, in addition to the OTC3890 brake oil analyzer of OTC Company in the United States, there is no equipment for the rapid detection of brake fluid parameters.
Rapid identification of brake fluid is very important to ensure the safety of motor vehicles. Using vision-near-infrared spectroscopy to identify different brake fluid has the characteristics of rapid, non-destructive and low cost. In this study, the vision-near-infrared spectrum information of five brands of brake fluid between 400 and 1000 nm was obtained by spectrometers. Through principal component analysis, the cumulative confidence of the first six principal components reached 98.55%. Based on the first 6 principal component data of 225 samples, the identification model was established by stepwise discriminant analysis. The prediction results of 75 unknown samples showed that the prediction accuracy of the model was 94.67%, which realized the rapid and accurate identification of brake fluid brands by using near-infrared spectroscopy, and provided a new method for rapid identification of brake fluid.