Development Of Portable Retroreflection Coefficient Detector

There is no doubt that improving the visibility of pedestrians and drivers plays a very important role in traffic safety. Many studies have shown that, in case of bad weather with the low intensity of natural light, the pedestrain’s visual range is onethird of the normal vehicle deceleration distance on the highway. And traffic logos made by the retroreflective material can improve the visual range of pedestrians, so the special material is widely used in the production of traffic signs and body logos on vehicles. Adequate retroreflectivity is the major variable affecting the visibility of pedestrians. Therefore, accurate measurement of retroreflective coefficient to ensure the safety of traffic has a very important significance. However, due to t he monopoly of foreign retroreflective coefficient measurement, measuring the retroreflective coefficient is expensive, and the domestic research on measuring instruments mainly in the laboratory research stage, which is difficult to cater to the market demand of retroreflection coefficient detector.Aimed at this status quo, this paper designs a portable detector based on relative measurement method of retroreflection coefficient to measure against the important parameter of retroreflective materials which are used to make the traffic signs and body logos of vehicles. Compared with the detector based on absolute measurement method of retroreflection coefficient, the tester proposed in this paper is more portable and has simpler operation while ensuring meas urement accuracy. Moreover, there are some artificial intelligent designs, such as automatic range selection, self-calibration, POST and so on, to improve user experience.In this dissertation, the project requirement analysis of portable retroreflection coefficient detector is carried out firstly. And the overall scheme of the detector is porposed based on the former analysis. In the design of measuring light path, selecting a measurement method caters to the project requirements via the comparison and analysis of a variety of measurement principles. And establishing a model to select angles that are relevant to retroreflection coefficient measurement based on the minimum traffic safety distance through the anaylsis of important parameters of the optical path, taking into account the impact of visual cognition distance, the impact of the distribution of the retroreflective energy and the requirements of relevant national standards. In the design of hardware circuit, using the chip STM32F103C8T6 as the core of hardware circuit can achieve the aim. In the design of debugger, making full use of customized development tools designed for chips STM32 by third-party development tools Keil MDK and definiting the structure to achieve the implementation of fast variable operations as a whole so that can complete the hardware circuit debugging of the portable retroreflection coefficient detector.In order to ensure the credibility of measurement results of the retroreflection coefficient via the portable detector, in this dissertation, the uncertainty of the test results is analyzed. To analyze prototype manufacturing, debugging and testing process which may introduce errors and to make a classification of these errors so that can conclude the synthesis of the uncertainty of measurement results to improve the reliability of the measurement results of portable retroreflection coefficient detector.