The Circuit Research Of Long Distance Ranging SystemBased OnHigh-FrequencyLaser

Real-time distance detection technology is the key technology of vehicle rear-ends collision avoidance system. In real-time distance detection, high-frequency pulsed laser ranging technology has great advantage over other ranging techniques. According to the characteristics of automobile electronics, application of pulsed laser ranging principle, and based on integrated components, the circuit and the software of the high frequency distance measuring system were designed. In addition, the performance of circuit is tested and the measurement error was analyzed. The whole system, small size and high frequency, is highly integrated. Measuring distance can reach100m, the highest frequency is up to5kHz, and precision is within±0.3m.The main researches are as follows:1.According to a large amount of data, the principle and characteristics of several commonly used distance detection technology were analyzed, and the pulsed laser ranging was chosen.2.A mathematical model was built based on energy transfer law of pulsed laser during the flight. According to laser ranging performance equation, related parameters of laser ranging performance were analyzed.3. Mainly composed of integrated circuit chip, the pulsed laser transfer circuit and receiver circuit were designed. Compared with circuit designed by discrete components, this circuit is highly integrated, and it has compact size and strong anti-jamming capability.4.According to constant fraction discriminator method, and the negative pulse constant fraction discriminator circuit, a constant fraction discriminator circuit without transmission delay line was designed to improve the identification accuracy of the pulse time.5.Several common timing methods were analyzed. The TDC-GP2and ATMEGA16micro-controller were used to design high-precision timing circuit. Micro-controller controls the timing chip via the serial peripheral interface (SPI). The timing accuracy of the circuit can achieve65ps. 6.A communication circuit, combined with the characteristics of automotive electronic system, was designed with CAN bus, and the timing data could be transmitted to the vehicle electronic system in real time. System power was supplied by DC power in the vehicle system, and the boost circuit and stable power management module were designed to ensure that the circuit works.