High Precision Pulsed Laser Ranging System For Automobile

Nowadays, safety-driving of the car has been more attention, the research of intelligent transportation is to prevail and laser ranging plays an important role in this system. Accurate measuring distance is useful for the reversing radar and collision avoidance system. This article is based on the intelligent collision avoidance system to developed the high-precise pulsed laser ranging system. This paper focuses on the design of the relative circuits of ranging system, such as, laser emitting circuit, echo receiving circuit, time measurement module and the power circuit.In the laser emission module, chose the laser diode of SPLPL90₃ as the light source and designed its schematic and PCB of drive circuit. When designing the PCB, use the Hyperlynx software to simulate the key signal to ensure that the laser energy concentration. Finally, the emitting circuit can provide the pulsed laser of 20ns pulsed width and 8ns rising time.In the echo receiving module, chose the avalanche photodiode（APD） to receiving the echo light wave, analyzed the best working status for the APD. Designed the pre-amplification electric circuit, which is composed by two triode cascade, and the first of this two triodes is common-collector and the other is common-base. Then, the main amplifier was designed which gain is almost 300, the purpose of this idea is used to insure the amplification echo is saturated when the target in the place of farthest. And finally, chose the simple way of identifying the frontier moment to obtain the cut-off time, based on the characteristic of amplification echo.In the module of time measure, realized the high-precise time measure module and the control circuit based on the TDC-GP2. At the same time, designed the power board for the whole system which provide the clean voltage to the relevant circuits.Finally, set up the experiment platform, do some related experiments, and collect and correct data, analyze the error source. The experimental result demonstrated that the high-precise pulsed laser ranging system can measure the distance more the 150m with its precision is 0.1m. which is more than enough to satisfy the intelligent collision avoidance system.