【摘要】：在非接觸式測距系統(tǒng)中,超聲波測距在汽車防撞、海底定位、物位檢測、機(jī)器人導(dǎo)航、無人作戰(zhàn)平臺和醫(yī)療探傷等民用、軍事及工業(yè)生產(chǎn)領(lǐng)域應(yīng)用十分廣泛。本文設(shè)計了一種基于有阻尼自由振動的超聲波測距系統(tǒng),能夠準(zhǔn)確測量渡越時間,提高了測距的精確度和穩(wěn)定性。傳統(tǒng)的基于有阻尼自由振動的超聲波測距系統(tǒng)是通過測量超聲波傳播的渡越時間實現(xiàn)超聲波測距的,然而超聲波信號接收完畢后,超聲波接收振子存在有阻尼自由振動現(xiàn)象,振子依然振動使計時器計時延長,渡越時間增加,從而對測距的精確度產(chǎn)生影響。通過對超聲波產(chǎn)生、傳播、接收過程進(jìn)行動力學(xué)分析,針對影響渡越時間測量準(zhǔn)確性的振子有阻尼自由振動進(jìn)行分析和研究,提出了一種通過周期頻率來判別振子做受迫振動還是阻尼振動的方法,使得系統(tǒng)在超聲波信號接收完畢后能夠準(zhǔn)確得出渡越時間,消除振子有阻尼振動現(xiàn)象造成的不利影響�；谟凶枘嶙杂烧駝拥某暡y距系統(tǒng)設(shè)計包括硬件設(shè)計和軟件設(shè)計兩個方面。在硬件設(shè)計上,發(fā)射端設(shè)計了正弦波發(fā)生電路、功率放大電路和超聲波信號發(fā)射電路。接收端設(shè)計了接收放大電路、時間增益補(bǔ)償電路、有源帶通濾波電路、溫度測量電路,通過STM32控制芯片,配合完成超聲波信號的發(fā)送和接收信號的采集。軟件設(shè)計方面,提出一種有阻尼自由振動的超聲波測距系統(tǒng)頻率拐點的判別方法。具體為將A/D采樣后數(shù)據(jù)由DSP數(shù)據(jù)處理器進(jìn)行逐個點的FFT變換,得到每個點的幅度譜和相位譜。根據(jù)幅度譜中某一點和其相鄰點的幅度值所對應(yīng)的頻率的差別,可以明確地得出超聲波信號相鄰兩個點的頻率變化,從而準(zhǔn)確地判別出有阻尼自由振動的超聲波測距系統(tǒng)的頻率拐點。通過該拐點能夠精確地測量渡越時間,提高測距精度。多次實驗表明,本超聲波測距系統(tǒng)的絕對誤差限制在0.30mm范圍內(nèi),與傳統(tǒng)同類技術(shù)相比精確度和穩(wěn)定性都有很大提升。
[Abstract]:In contactless ranging system, ultrasonic ranging is widely used in civil, military and industrial fields, such as automobile collision prevention, seafloor positioning, object level detection, robot navigation, unmanned combat platform and medical flaw detection. In this paper, an ultrasonic ranging system based on damped free vibration is designed, which can accurately measure the transit time and improve the accuracy and stability of ranging. The traditional ultrasonic ranging system based on damped free vibration realizes ultrasonic ranging by measuring the transit time of ultrasonic propagation. However, after the ultrasonic signal is received, the ultrasonic receiving oscillator has the phenomenon of damped free vibration. The vibration of the oscillator still prolongs the timer timing and increases the transit time, which affects the accuracy of ranging. Through the dynamic analysis of the ultrasonic generation, propagation and reception process, the damped free vibration of the oscillator, which affects the accuracy of the transit time measurement, is analyzed and studied. In this paper, a method is proposed to distinguish whether the oscillator is forced vibration or damped vibration by periodic frequency, so that the system can accurately obtain the transit time after the ultrasonic signal is received, and eliminate the adverse effects caused by the damped vibration of the oscillator. The design of ultrasonic ranging system based on damped free vibration includes hardware design and software design. In the hardware design, the sine wave generating circuit, the power amplifier circuit and the ultrasonic signal transmitting circuit are designed at the transmitter. The receiver designs a receiving amplifier circuit, a time gain compensation circuit, an active bandpass filter circuit, a temperature measurement circuit, and a STM32 control chip to complete the transmission of ultrasonic signals and the acquisition of received signals. In the aspect of software design, a method for judging the frequency inflection point of ultrasonic ranging system with damped free vibration is proposed. The amplitude spectrum and phase spectrum of each point are obtained by FFT transformation of A 鈮，

本文編號：2492782