一、前言
閱讀此文前請戳這個視頻觀看使用Arduino超聲波傳感器模擬雷達掃描教程，先了解效果，有直觀感受再來看下文。
二、硬體準備
如圖2所示，需要Arduino主板（最好加上擴展板）1塊、超聲波傳感器1個、伺服電機（舵機）1個，1602液晶顯示屏（可選）。
我將超聲波傳感器的Trig、Echo分別連接在擴展板的4、5號引腳，將伺服電機連接在擴展板的9號引腳上，為了簡化程序，後續我沒有使用液晶顯示屏，請你自行添加相關程序。
三、軟體準備
1、Arduino IDE 1.8.9
2、Processing 3.3.5
備註：
1、上述軟體版本是我自己調試成功的版本，略低版本可能會有兼容問題，請注意你的軟體版本號；
2、如果Processing的程序編輯器內不能輸入、顯示中文，請在「文件」、「偏好設定」裡，選擇「啟用複雜字體輸入」並在「編輯器和控制臺字體」中選擇「宋體」即可顯示或輸入中文；
3、如果Processing的展示界面不能顯示中文，請在程序裡裝載中文字庫，如圖6第5、19、20行代碼所示。
四、編寫程序
程序分兩步實現：
第一步：使用Arduino IDE，編寫伺服電機180度循環搖頭、獲取超聲波傳感器返回值（與障礙物的距離值）、向串口輸出伺服電機轉動的角度和超聲波傳感器的距離值（注意要和Processing中獲取串口值的格式一致），代碼如下（請注意修改超聲波傳感器、伺服電機的引腳號為你自己的實際引腳號）：
#include<stdio.h>#include <Servo.h> Servo mServo; //創建一個舵機控制對象//當前角度int mAngleNum = 0;//當前是正向旋轉還是反向旋轉char mFront = 0;//超聲波測距引腳const int mTrigPin = 4; const int mEchoPin = 5; //當前距離int mDistance = 0;//像串口發送數據 發送到processingvoid sendStatusToSerial();//測距void ranging();void setup() {// put your setup code here, to run once: Serial.begin(9600); mServo.attach(9); // 該舵機由arduino第9腳控制 pinMode(mTrigPin, OUTPUT); // 要檢測引腳上輸入的脈衝寬度，需要先設置為輸入狀態 pinMode(mEchoPin, INPUT); }void loop() { // put your main code here, to run repeatedly: //多角度設置 mServo.write(180 - mAngleNum); //超聲波測距 ranging(); //發數據 sendStatusToSerial(); delay(60); if( mFront == 0 ) { mAngleNum ++; if( mAngleNum > 180 ) { mFront = 1; } } else { mAngleNum --; if( mAngleNum < 0 ) { mFront = 0; } }}//發送當前狀態到串口void sendStatusToSerial(){ char mAngleStr[6]; char mDistanceStr[6]; sprintf( mAngleStr, "%d", mAngleNum); sprintf( mDistanceStr, "%d", mDistance); delayMicroseconds(2); Serial.print(mAngleStr); Serial.print(","); Serial.print(mDistanceStr); Serial.print("."); delay(50);}//測距void ranging(){ // 產生一個10us的高脈衝去觸發TrigPin digitalWrite(mTrigPin, LOW); //低高低電平發一個短時間脈衝去TrigPin delayMicroseconds(2); digitalWrite(mTrigPin, HIGH); delayMicroseconds(10); digitalWrite(mTrigPin, LOW); mDistance = pulseIn(mEchoPin, HIGH) / 58.0; //將回波時間換算成cm }
第二步：使用Processing，編寫一圖7的界面、獲取串口發送過來的角度、距離值，將其轉換旋轉指針的動作、屏幕中間的紅色提示、屏幕下方的文字提示等，具體代碼如下：
import processing.serial.*;import java.awt.event.KeyEvent;import java.io.IOException;PFont font;Serial myPort;String angle="";String distance="";String data="";String noObject;float pixsDistance;int iAngle, iDistance;int index1=0;int index2=0;PFont orcFont;void setup() {size (1200, 700); //這個解析度自己根據你的電腦的配置和顯示屏幕配置進行更改。 smooth(); font = createFont("宋體.vlw",48); textFont(font); myPort = new Serial(this,"COM5", 9600); //這個串口號一定要更改。 myPort.bufferUntil('.');}void draw() { fill(98,245,31); noStroke(); fill(0,4); rect(0, 0, width, height-height*0.065); fill(98,245,31); drawRadar(); drawLine(); drawObject(); drawText();}void serialEvent (Serial myPort) { data = myPort.readStringUntil('.'); data = data.substring(0,data.length()-1); index1 = data.indexOf(","); angle= data.substring(0, index1); distance= data.substring(index1+1, data.length()); iAngle = int(angle); iDistance = int(distance);}void drawRadar() { pushMatrix(); translate(width/2,height-height*0.074); noFill(); strokeWeight(2); stroke(98,245,31); // draws the arc lines arc(0,0,(width-width*0.0625),(width-width*0.0625),PI,TWO_PI); arc(0,0,(width-width*0.27),(width-width*0.27),PI,TWO_PI); arc(0,0,(width-width*0.479),(width-width*0.479),PI,TWO_PI); arc(0,0,(width-width*0.687),(width-width*0.687),PI,TWO_PI); // draws the angle lines line(-width/2,0,width/2,0); line(0,0,(-width/2)*cos(radians(30)),(-width/2)*sin(radians(30))); line(0,0,(-width/2)*cos(radians(60)),(-width/2)*sin(radians(60))); line(0,0,(-width/2)*cos(radians(90)),(-width/2)*sin(radians(90))); line(0,0,(-width/2)*cos(radians(120)),(-width/2)*sin(radians(120))); line(0,0,(-width/2)*cos(radians(150)),(-width/2)*sin(radians(150))); line((-width/2)*cos(radians(30)),0,width/2,0); popMatrix();}void drawObject() { pushMatrix(); translate(width/2,height-height*0.074); strokeWeight(9); stroke(255,10,10); // red color pixsDistance=iDistance*((height-height*0.1666)*0.025); if(iDistance<40){ line(pixsDistance*cos(radians(iAngle)),-pixsDistance*sin(radians(iAngle)),(width-width*0.505)*cos(radians(iAngle)),-(width-width*0.505)*sin(radians(iAngle))); } popMatrix();}void drawLine() { pushMatrix(); strokeWeight(9); stroke(30,250,60); translate(width/2,height-height*0.074); line(0,0,(height-height*0.12)*cos(radians(iAngle)),-(height-height*0.12)*sin(radians(iAngle))); popMatrix();}void drawText() { pushMatrix(); if(iDistance>40) { noObject = "檢測範圍外"; }else { noObject = "檢測範圍內"; } fill(0,0,0); noStroke(); rect(0, height-height*0.0648, width, height); fill(98,245,31); textSize(25); text("10cm",width-width*0.3854,height-height*0.0833); text("20cm",width-width*0.281,height-height*0.0833); text("30cm",width-width*0.177,height-height*0.0833); text("40cm",width-width*0.0729,height-height*0.0833); textSize(28); text("對象: " + noObject, width-width*0.875, height-height*0.0277); text("角度: " + iAngle +" °", width-width*0.48, height-height*0.0277); text("距離: ", width-width*0.26, height-height*0.0277); if(iDistance<40) { text(" " + iDistance +"cm", width-width*0.225, height-height*0.0277); } textSize(25); fill(98,245,60); translate((width-width*0.4994)+width/2*cos(radians(30)),(height-height*0.0907)-width/2*sin(radians(30))); rotate(-radians(-60)); text("30°",0,0); resetMatrix(); translate((width-width*0.503)+width/2*cos(radians(60)),(height-height*0.0888)-width/2*sin(radians(60))); rotate(-radians(-30)); text("60°",0,0); resetMatrix(); translate((width-width*0.507)+width/2*cos(radians(90)),(height-height*0.0833)-width/2*sin(radians(90))); rotate(radians(0)); text("90°",0,0); resetMatrix(); translate(width-width*0.513+width/2*cos(radians(120)),(height-height*0.07129)-width/2*sin(radians(120))); rotate(radians(-30)); text("120°",0,0); resetMatrix(); translate((width-width*0.5104)+width/2*cos(radians(150)),(height-height*0.0574)-width/2*sin(radians(150))); rotate(radians(-60)); text("150°",0,0); popMatrix(); }
總之，實現模擬雷達掃描效果，只需要能將角度、距離值發送到串口，然後使用Processing將獲得的數據模擬出來即可，這種方法可以推而廣之，將其他傳感器的返回值也發送給Processing，將返回值圖形化，說不定你也可以做出其他不一樣的創意出來。
好好學習，天天向上，初始化工作室和你一起學習Arduino知識，快去動手做吧，做出不一樣的雷達掃描效果分享給大家。