【導(dǎo)讀】基于單片機的超聲波倒車雷達設(shè)計。所引發(fā)的事故也越來越多這些事故常常給駕駛員帶來許多的麻煩因此有助于駕。駛員泊車和倒車的倒車雷達應(yīng)運而生。倒車雷達全稱叫倒車防撞雷達也叫泊車輔助裝置是汽車泊車安全輔助裝置。能以聲音或者更為直觀的顯示告知駕駛員周圍障礙物的情況解除了駕駛員泊車。和啟動車倆時前后左右探視所引起的困擾并幫助駕駛員掃除視野的死角和視線。有數(shù)字顯示和聲光報警功能的倒車雷達系統(tǒng)該倒車雷達根據(jù)超聲波測距原理研。管顯示同時進行三級聲光報警駕駛員只需坐在駕駛室就能做到心里有數(shù)極大的。262倒車語音及報警控制程序。通部門的高度重視倒車事故發(fā)生的原因是多方面的倒車鏡有死角駕車者目測距。員后顧之憂大大降低了倒車事故的發(fā)生。方向形狀等只不過由于倒車雷達體積大小及實用性的限制目前其主要功能僅為。通常的倒車雷達主要由感應(yīng)器探頭主機顯示設(shè)備等三部分組成感應(yīng)器發(fā)出。叫提示駕駛員停車根據(jù)感應(yīng)器種類不同倒車雷達可分為粘貼式鉆孔式和懸掛式

　　

【正文】 ntrol the emission of ultrasonic pulses When the 4 pin is low there is oscillation pulse output 555 is high the timer 555 is cleared there is no output Thus the 4 foot connecting with the MCU control signals can control the transmitter To ensure that 555 has sufficient drive capability should adopt the 12 V supply that is 12V 4 feet for the ultrasonic emission control signal input from the microcontroller control Acoustic receivers includes receiving ultrasound probe the signal amplification circuit and waveform converting circuit of three parts Ultrasonic probe must be used with the transmitter probe corresponding models the key is the frequency to be consistent the design uses CSB40R otherwise it will not produce resonance effects due to reception if not impossible to receive As the probe transformed by the very weak sine wave signal it must be amplified by the amplifier Sine wave signal microcontroller can not directly be received waveform must change In accordance with the principles discussed above the microcontroller needs only the first echo of the moment Receiving circuit shown in Figure 36 Ultrasonic wave propagation in the air its energy is proportional to the distance attenuation namely the closer the signal is stronger the greater the distance the weaker the signal usually between 1mV 1V Different receiving the probe output signal intensity is different The larger the scope of the input signal the gain of the amplifier made two requests First to a large amplification gain to meet the needs of smallsignal the second is to enlarge the gain to be able to change to meet the needs of a large range of signal change In addition because the input signal is sinusoidal it is necessary to zoom into the AC amplifier circuit design To reduce the use of negative power single supply amplifier signal amplification and conversion using LM324 op amp general the first three for the amplifier design the latter level for the parator design LM324 dual power supply either or you can singlesupply operation it can meet the requirement To meet the needs of munication signals each level of the amplifier circuits are used RClevel migration which in Figure 36 and capacity are 10μF to achieve single supply conditions exchange of signal amplification For AC signals the capacitor is short so the gain of the first three amplifiers are 10 Close proximity the two have been able to gain amplified output signal of sufficient strength the thirdlevel signal saturation may occur but the distance must be threestage amplification Heres the fourth film as LM324 parator inverting potential the circuit shown in Figure 35 there is a threshold voltage the voltage parator inverting input voltage Threshold voltage adjustment potentiometer available When the time 0 is low when the time is high When the LM324 ultrasonic echo signal is detected it outputs low level signal this time for LM324 input voltage is less than the threshold voltage the LM324 to the output level signal leading to end of data acquisition PC On the contrary the output signal to the PC for the low end of data acquisition This part of the parator adjusted properly if there could be some problems such as the output will be highfrequency output This is because the parator is very sensitive to small changes in the signal causes the output values and the mutual transformation Use of the positive feedback of the parator hysteresis to reduce sensitivity of the parator can reduce the interference Because the amplified echo signal amplitude is large so then by setting the appropriate threshold can be effectively stable signal Use of adjustable potentiometer is a more convenient way Needs the input of the parator reference voltage stability need to add capacitance stability Reasonable adjustment potentiometer select the parison reference voltage allows more accurate and stable measurement 參考文獻 《單片機應(yīng)用技術(shù)教程》 張洪潤 藍清華主編 清華大學(xué)出版社 1997 年 5 月出版 《單片機原理與控制技術(shù)》陳麗芳主編 東南大學(xué)出版社 2020 年 7 月出版 《單片 機應(yīng)用技術(shù)》劉守義主編 西安電子科技大學(xué)出版社 2020 年 8 月出版 《單片微機系統(tǒng)》蔣力培主編 機械工業(yè)出版社 2020 年 2 月出版 《超聲手冊》馮諾主編 南京大學(xué)出版社 2020 年 5 月出版 《超聲波測距儀在汽車安全系統(tǒng)中的應(yīng)用》肖質(zhì)紅主編 萬里學(xué)院學(xué)報出版 2020 年 5 月出版． 《超聲波測距系統(tǒng)的設(shè)計與實現(xiàn) 電子技術(shù)應(yīng)用》徐國華主編 l995 年 12 月出版 《基于超聲波測距系統(tǒng)的溫度補償田勝軍》 秦宣云 何永強主編 2020