基于超声波的汽车防撞系统设计

摘要

随着中国工业经济的不断高速发展，汽车行业成为了促进中国经济发展的不可或缺的一部分，近年来我国高速公路追尾碰撞事故频繁发生，而车载追尾碰撞预警系统在解决高速公路行车安全中具有良好的前景，科学技术的快速发展使得超声波技术在汽车领域中的应用越来越广泛。本文对超声波汽车防撞系统进行了理论分析，利用模拟电子、数字电子、微机接口技术、超声波换能器、以及超声波在介质中的传播特性等知识，采用以stc89c51单片机为核心的低成本、高精度、微型化数字显示超声波测距的硬件电路和软件电路设计方法在此基础上设计了系统的总体方案，最后通过硬件个软件实现各个功能模块。

该设计由超声波发射模块、信号接收模块、单片机处理模块、数码显示以及声光告警显示模块等部分组成，文中详细介绍了测距器的硬件组成、检测原理、方法以及软件结构。超声波发射模块中采用555定时器构成的时基电路，接收电路使用SONY公司的CX20106A红外检测专用芯片，该芯片常用于38kHz的检波电路，文中通过对芯片内部电路的仔细分析，设计出能够成功对40kHz超声波检波的硬件电路，并且增益可调，与传统超声波检波电路相比，电路变得精简，调试变得相对容易。测距器使用数码管显示目标物的距离。

为了保证超声波汽车防撞系统的可靠性和稳定性，采取了相应的抗干扰措施。就超声波的传播特性，超声波换能器的工作特性、超声波发射装置、接收装置、超

声微弱信号放大、波形整形、速度变换电路及系统功能软件等做了详细说明.实现障碍物的测距、显示和报警，超声波测距范围0.6-2.0米，精度在10厘米左右。关键词：汽车防撞报警系统、STC89C51、传感器、LED显示、测量距离

Abstract

With the rapid development of China industrial economy, the automotive industry has become an indispensable part of China promote economic development in recent years, the rear end collision accidents occur frequently in China, and the vehicle rear end collision warning system in the settlement of expressway traffic safety has a good prospect, the rapid development of science and technology makes the ultrasonic technology applied in automotive more widely in the field of. This paper analyses the theory of ultrasonic wave automotive collision avoidance system, the use of analog electronics, digital electronics, computer interface technology, ultrasonic transducer, and the ultrasonic propagation in the medium of knowledge, using low cost, using

STC89C51 microcontroller as the core of the hardware circuit and software design method of the circuit of high precision, miniaturization digital display ultrasonic ranging in on the basis of the overall system design, the hardware software implementation of each functional module.

The design is composed of ultrasonic transmitting module, the signal receiving module, microcontroller module, digital display and sound and light alarm display module and other components, this paper introduces in detail the range of hardware devices, measuring principle, method and structure of software. The time base circuit module 555 timer used a special chip CX20106A, ultrasonic, infrared detection receiving circuit using the SONY company, the chip used in the detector circuit 38kHz, careful analysis of the internal circuit in this paper, the hardware circuit design can successfully 40kHz ultrasonic detection, and adjustable gain, compared with the traditional ultrasonic detection circuit, the circuit is simplified, the debugging easier. The range finder using digital tube display distance of object.

In order to ensure that the ultrasonic wave automotive collision avoidance system reliability and stability, take the corresponding anti-interference measures. On the ultrasonic propagation characteristics, job characteristics, the ultrasonic transducer ultrasonic transmitting device, receiving device, ultrasonic signal amplification and waveform shaping, speed converter circuit