Matthew Lee
Published © GPL3+

Distance Measurement Vehicle via Websocket

A vehicle measures distance with an encoder on its wheel. It is remotely controlled and transmits the distance via Websocket.

IntermediateFull instructions provided8 hours14,304

Things used in this project

Hardware components

Arduino UNO & Genuino UNO
Arduino UNO & Genuino UNO
×1
PHPoC WiFi Shield for Arduino
PHPoC WiFi Shield for Arduino
×1
DFRobot RB-Dfr-67
×1
Rechargeable Battery AA (3050mAh)
×5
DFRobot RB-Dfr-04
×1
DFRobot 2x2A DC Motor Shield for Arduino
×1

Story

Read more

Schematics

System Diagram

The system diagram
Motor vehicle2 cdsn4tn08p

Code

joystick.php

PHP
PHPoC code which controls the vehicle and monitor the current distance from the vehicle via Websocket.
I have modified it from the joystic application on hackster.io (https://www.hackster.io/iot_lover/arduino-web-based-joystick-02ca54)
<!DOCTYPE html>
<html>
<head>
<title>Arduino - PHPoC Shield</title>
<meta name="viewport" content="width=device-width, initial-scale=0.7, maximum-scale=0.7">
<meta charset="utf-8">
<style>
body { text-align: center; font-size: width/2pt; }
h1 { font-weight: bold; font-size: width/2pt; }
h2 { font-weight: bold; font-size: width/2pt; }
button { font-weight: bold; font-size: width/2pt; }
</style>
<script>
var canvas_width = 500, canvas_height = 500;
var radius_base = 150;
var radius_handle = 72;
var radius_shaft = 120;
var range = canvas_width/2 - 10;
var step = 18;
var ws;
var joystick = {x:0, y:0};
var click_state = 0;

var pos_old;

var ratio = 1;

function init()
{
	var width = window.innerWidth;
	var height = window.innerHeight;
	
	if(width < height)
		ratio = (width - 50) / canvas_width;
	else
		ratio = (height - 50) / canvas_width;
	
	canvas_width = Math.round(canvas_width*ratio);
	canvas_height = Math.round(canvas_height*ratio);
	radius_base = Math.round(radius_base*ratio);
	radius_handle = Math.round(radius_handle*ratio);
	radius_shaft = Math.round(radius_shaft*ratio);
	range = Math.round(range*ratio);
	step = Math.round(step*ratio);
	
	var canvas = document.getElementById("remote");
	//canvas.style.backgroundColor = "#999999";
	canvas.width = canvas_width;
	canvas.height = canvas_height;
 
	canvas.addEventListener("touchstart", mouse_down);
	canvas.addEventListener("touchend", mouse_up);
	canvas.addEventListener("touchmove", mouse_move);
	canvas.addEventListener("mousedown", mouse_down);
	canvas.addEventListener("mouseup", mouse_up);
	canvas.addEventListener("mousemove", mouse_move);
	
	var ctx = canvas.getContext("2d");
	ctx.translate(canvas_width/2, canvas_height/2);
	ctx.shadowBlur = 20;
	ctx.shadowColor = "LightGray";
	ctx.lineCap="round";
	ctx.lineJoin="round";
	
	update_view();
}
function connect_onclick()
{
	if(ws == null)
	{
		var ws_host_addr = "<?echo _SERVER("HTTP_HOST")?>";
		if((navigator.platform.indexOf("Win") != -1) && (ws_host_addr.charAt(0) == "["))
		{
			// network resource identifier to UNC path name conversion
			ws_host_addr = ws_host_addr.replace(/[\[\]]/g, '');
			ws_host_addr = ws_host_addr.replace(/:/g, "-");
			ws_host_addr += ".ipv6-literal.net";
		}
		
		ws = new WebSocket("ws://" + ws_host_addr + "/web_joystick", "text.phpoc");
		document.getElementById("ws_state").innerHTML = "CONNECTING";
		ws.onopen = ws_onopen;
		ws.onclose = ws_onclose;
		ws.onmessage = ws_onmessage;
	}
	else
		ws.close();
}
function ws_onopen()
{
	document.getElementById("ws_state").innerHTML = "<font color='blue'>CONNECTED</font>";
	document.getElementById("bt_connect").innerHTML = "Disconnect";
	update_view();
}
function ws_onclose()
{
	document.getElementById("ws_state").innerHTML = "<font color='gray'>CLOSED</font>";
	document.getElementById("bt_connect").innerHTML = "Connect";
	ws.onopen = null;
	ws.onclose = null;
	ws.onmessage = null;
	ws = null;
	update_view();
}
function ws_onmessage(e_msg)
{
	e_msg = e_msg || window.event; // MessageEvent
	document.getElementById("distance").innerHTML = e_msg.data;
}
function send_data()
{
	var x = joystick.x, y = joystick.y;
	var joystick_range = range - radius_handle;
	x = Math.round(x*100/joystick_range);
	y = Math.round(-(y*100/joystick_range));
	
	if(ws != null)
		ws.send(x + ":" + y + "\r\n");
}
function update_view()
{
	var x = joystick.x, y = joystick.y;
	
	var canvas = document.getElementById("remote");
	var ctx = canvas.getContext("2d");
	
	ctx.clearRect(-canvas_width/2, -canvas_height/2, canvas_width, canvas_height);
	
	ctx.lineWidth = 3;
	ctx.strokeStyle="gray";
	ctx.fillStyle = "LightGray";
	ctx.beginPath();
	ctx.arc(0, 0, range, 0, 2 * Math.PI);
	ctx.stroke();
	ctx.fill();
	
	ctx.strokeStyle="black";
	ctx.fillStyle = "hsl(0, 0%, 35%)";
	ctx.beginPath();
	ctx.arc(0, 0, radius_base, 0, 2 * Math.PI);
	ctx.stroke();
	ctx.fill();
	
	ctx.strokeStyle="red";
	
	var lineWidth = radius_shaft;
	var pre_x = pre_y = 0;
	var x_end = x/5;
	var y_end = y/5;
	var max_count  = (radius_shaft - 10)/step;
	var count = 1;
	
	while(lineWidth >= 10)
	{
		var cur_x = Math.round(count * x_end / max_count);
		var cur_y = Math.round(count * y_end / max_count);
		console.log(cur_x);
		ctx.lineWidth = lineWidth;
		ctx.beginPath();
		ctx.lineTo(pre_x, pre_y);
		ctx.lineTo(cur_x, cur_y);
		ctx.stroke();
		
		lineWidth -= step;
		pre_x = cur_x;
		pre_y = cur_y;
		count++;
	}
	
	var x_start = Math.round(x / 3);
	var y_start = Math.round(y / 3);
	lineWidth += step;
	
	ctx.beginPath();
	ctx.lineTo(pre_x, pre_y);
	ctx.lineTo(x_start, y_start);
	ctx.stroke();
		
	count = 1;
	pre_x = x_start;
	pre_y = y_start;
	
	while(lineWidth < radius_shaft)
	{
		var cur_x = Math.round(x_start + count * (x - x_start) / max_count);
		var cur_y = Math.round(y_start + count * (y - y_start) / max_count);
		ctx.lineWidth = lineWidth;
		ctx.beginPath();
		ctx.lineTo(pre_x, pre_y);
		ctx.lineTo(cur_x, cur_y);
		ctx.stroke();
		
		lineWidth += step;
		pre_x = cur_x;
		pre_y = cur_y;
		count++;
	}
	
	var grd = ctx.createRadialGradient(x, y, 0, x, y, radius_handle);
	for(var i = 85; i >= 50; i-=5)
		grd.addColorStop((85 - i)/35, "hsl(0, 100%, "+ i + "%)");
		
	ctx.fillStyle = grd;
	ctx.beginPath();
	ctx.arc(x, y, radius_handle, 0, 2 * Math.PI);
	ctx.fill();
}
function process_event(event)
{
	var pos_x, pos_y;
	if(event.offsetX)
	{
		pos_x = event.offsetX - canvas_width/2;
		pos_y = event.offsetY - canvas_height/2;
	}
	else if(event.layerX)
	{
		pos_x = event.layerX - canvas_width/2;
		pos_y = event.layerY - canvas_height/2;
	}
	else
	{
		pos_x = (Math.round(event.touches[0].pageX - event.touches[0].target.offsetLeft)) - canvas_width/2;
		pos_y = (Math.round(event.touches[0].pageY - event.touches[0].target.offsetTop)) - canvas_height/2;
	}
	
	return {x:pos_x, y:pos_y}
}
function mouse_down()
{
	if(ws == null)
		return;
	
	event.preventDefault();
	
	var pos = process_event(event);
	pos_old = pos;
	
	var delta_x = pos.x - joystick.x;
	var delta_y = pos.y - joystick.y;
	
	var dist = Math.sqrt(delta_x*delta_x + delta_y*delta_y);
	
	if(dist > radius_handle)
		return;
		
	click_state = 1;
	
	var radius = Math.sqrt(pos.x*pos.x + pos.y*pos.y);
	
	if(radius <(range - radius_handle))
	{
		joystick = pos;
		send_data();
		update_view();
	}
}
function mouse_up()
{
	event.preventDefault();
	click_state = 0;
}
function mouse_move()
{
	if(ws == null)
		return;
 
	event.preventDefault();
	
	if(!click_state)
		return;
	
	var pos = process_event(event);
	
	var radius = Math.sqrt(pos.x*pos.x + pos.y*pos.y);
	
	if(radius <(range - radius_handle))
	{
		joystick = pos;
		
		if((Math.abs(pos_old.x - pos.x) > 5) || (Math.abs(pos_old.y - pos.y) > 5))
		{
			send_data();
			pos_old = pos;
		}
		update_view();
		
	}
}

function clear_distance()
{
	if(ws != null) ws.send("c\r\n");
}
window.onload = init;
</script>

</head>

<body>

<p>
<h1>Arduino - Web-based Joystick</h1>
</p>

<canvas id="remote"></canvas>

<h2>
<p>
Distance: <span id="distance">null</span>
</p>

<h2>
<p>
<input type="button" value="Clear Distance" id="ClickMe" onclick="clear_distance();" />
</p>

<p>
WebSocket : <span id="ws_state">null</span>
</p>
<button id="bt_connect" type="button" onclick="connect_onclick();">Connect</button>
</h2>

</body>
</html>

distance_measuring_machine

Arduino
This is C source code for Arduino Uno
#include "SPI.h"
#include "Phpoc.h"

#include "TimerOne.h"

volatile long encoder1 = 0, encoder2 = 0;
unsigned long encoder1_old = 0, encoder2_old = 0;
unsigned long uptime_old = 0;

//Arduino PWM Speed Control
int EL = 5;  
int ML = 4; 
int ER = 6;                      
int MR = 7;     

int amr, aml;

float max_speed;

bool state_old = 0;
int filter_count = 0;
int filter_threshold = 10;

PhpocServer server(80);



void setup() {
  Serial.begin(9600);
  while(!Serial)
    ;

  Phpoc.begin(PF_LOG_SPI | PF_LOG_NET);
  //Phpoc.begin();

  server.beginWebSocket("web_joystick");

  Serial.print("WebSocket server address : ");
  Serial.println(Phpoc.localIP());
  
  pinMode(ML, OUTPUT);   
  pinMode(MR, OUTPUT);
  digitalWrite(ML, LOW);
  digitalWrite(MR, HIGH); 

  pinMode(2, INPUT);
  digitalWrite(2, HIGH); // pull-up
  
  encoder1 = 0;
  encoder2 = 0;
  encoder1_old = 0;
  encoder2_old = 0;

  //attachInterrupt(digitalPinToInterrupt(2), ISR_di1, FALLING);
  Timer1.initialize(100); // 0.1m second
  Timer1.attachInterrupt(ISR_Timer1);
}

void loop() {
  double distance1;
  String str;
  char ch[32];
  
  // wait for a new client:
  PhpocClient client = server.available();

  if (client) {
    String data = client.readLine();

    if(data){
      if(data.substring(0, 1) == "c") 
      {
        Serial.println("Clearing encoder1...\r\n");
        encoder1 = 0;
        encoder1_old = 0;
        server.write("0");
        return;
      }
      int pos = data.indexOf(':');
      long x = data.substring(0, pos).toInt();
      long y = data.substring(pos+1).toInt();

      if(y < 0)
      {
        analogWrite(EL, 0);
        analogWrite(ER, 0);
        return;
      }
      else
      {
        max_speed = sqrt((float)x*(float)x/10000+(float)y*(float)y/10000);
        max_speed *= 255;
        //Serial.print("Max Speed: ");
        //Serial.println(max_speed);

        //Serial.print("encoder1 = ");
        //Serial.println(encoder1);
      }

      if(x == 0)
      {
        aml = (int)max_speed;
        amr = (int)max_speed;
      }
      else if(x > 0)
      {
        aml = (int)max_speed;
        amr = (int)(max_speed*(100-abs(x))/100);
      }
      else if(x < 0)
      {
        aml = (int)(max_speed*(100-abs(x))/100);
        amr = (int)max_speed;
      }
      
      analogWrite(EL, aml);
      analogWrite(ER, amr);
      
    }
  }
  if(encoder1 >= (encoder1_old + 10))
  {
    distance1 = (double)encoder1 * 0.0103;
    str = String(distance1, 2);
    str.toCharArray(ch, str.length());
    server.write(ch);
    Serial.print(encoder1);
    Serial.print(":");
    Serial.println(ch);
    encoder1_old = encoder1;
  }

}

void ISR_Timer1()
{
  bool state = 0;
  
  state = digitalRead(2);
  if(state != state_old)
  {
    filter_count++;
    if(filter_count > filter_threshold) 
    {
      state_old = state;
      encoder1++;
    }
  }
  if(state == state_old && filter_count > 0)
  {
    filter_count--;
  }
}

/*
void ISR_di1()
{
  unsigned long uptime_now;
  uptime_now = mills();
  if(uptime
  encoder1++;
}
*/

Credits

Matthew Lee

Matthew Lee

2 projects • 22 followers
Hardware Engineer
Contact

Comments