Revision 6:ffbaca2bd3da, committed 2016-08-03

Comitter:

DanArgust

Date:

Wed Aug 03 07:10:09 2016 +0000

Parent:

5:569a11ffee94

Commit message:

comments and format changes

Changed in this revision

--- a/main.cpp	Fri Jul 15 10:36:00 2016 +0000
+++ b/main.cpp	Wed Aug 03 07:10:09 2016 +0000
@@ -21,60 +21,95 @@
 bool  isSearching;
 int   counter;
 
+/* This function is called every 10 miliseconds
+** Using the two inputs from the sensor
+**
+** It calculates the where a mean value for the track would be
+** between 1 and 2
+** if the track is at 1.5 the buggy will travel straight
+** if the track is at 1.0 the buggy will turn left
+** if the track is at 2.0 the buggy will turn right
+**
+** if both inputs are less than 0.35
+** the buggy will assume it has lost the line and will begin "seaching"
+** while searching the buggy will turn in one direction until it finds a line
+** if it fails to find a line in 600 attempts it will change direction
+** this repeats
+** the theory and algorithm can be found here: 
+** https://www.ikalogic.com/line-tracking-sensors-and-algorithms/
+*/
 void computeMotorSpeeds(float a,float b){
     float inputs[2] = {a,b};
-    const float MAXSPEED = 1.0;
+    const float MAXSPEED = 1.0; // Motor max speed
     lMotor  = 0.0;
     rMotor  = 0.0;
     newLine = 0.0;
-    float lineToSpeedFactor = MAXSPEED / 0.3;
+    float lineToSpeedFactor = MAXSPEED / 0.3; // This is a modifier that will be used to set the motor speeds after calculating the position of the track
+    
+    
+    // CALCULATING THE AVERAGE POSITION OF THE TRACK. LEFT = 1.0 / RIGHT = 2.0
     for (int i = 0; i < 2; ++i) {
         newLine += inputs[i] * (i + 1);
     }
     float sum = 0.0;
     for (int i = 0; i < 2; ++i)
         sum += inputs[i];
-    newLine = newLine / sum;
-    if ((a < 0.35) && (b < 0.35)) {
+    newLine = newLine / sum; // newLine is now set somewhere between 1.0 and 2.0
+    // CALCULATING THE AVERAGE POSITION OF THE TRACK. LEFT = 1.0 / RIGHT = 2.0
+    
+    
+    if ((a < 0.35) && (b < 0.35)) { // if both the sensors are low then the line has been lost
         if (oldLine > 1.5)
-            newLine = 2.0;
+            newLine = 2.0; // if the buggy was turning right before losing the line keep doing so
         else
-            newLine = 1.0;
+            newLine = 1.0; // if the buggy was turning left before losing the line keep doing so
         oldLine = newLine;
-        isSearching = true;
+        isSearching = true; // put the buggy in 'searching' mode
     }
+    
     if (isSearching) {
         if ( oldLine > 1.5)
             newLine = 2.0;
         else
             newLine = 1.0;
-        if (abs(a - b) < 0.2)
+        if (abs(a - b) < 0.2) // if a contrast is not detected (a track) then carry on
             newLine = oldLine;
-        else
+        else                  // if a contrast is detected then turn off searching mode
             isSearching = false;
         counter++;
-        if (counter > 600) {
-            newLine = 3.0 - oldLine;
-            counter = 0;
+        if (counter > 600) {  // every 600 iteratons if searching change direction
+            newLine = 3.0 - oldLine; // if the line is 1.0 then 3 - 1 = 2.0
+            counter = 0;             // if the line is 2.0 then 3 - 2 = 1.0
         }
     }
     oldLine = newLine;
-    lMotor =      newLine * lineToSpeedFactor - 4.0;
-    rMotor = 2.0-(newLine * lineToSpeedFactor - 4.0);
+    lMotor =      newLine * lineToSpeedFactor - 4.0; // see below
+    rMotor = 2.0-(newLine * lineToSpeedFactor - 4.0);// see below
     if (lMotor > MAXSPEED)
         lMotor = MAXSPEED;
     if (rMotor > MAXSPEED)
         rMotor = MAXSPEED;
 }
+/* The motor speeds are calculated by taking the average sensor reading that can be anywhere from 1 to 2
+** if the sensor reading is 1.3:
+** lMotor = 1.3 * 3.333 - 4 = 0.3333
+** Rmotor = 2 - (1.3 * 3.333 - 4) = 1.6667 which gets capped to 1
+**
+** if the sensor reading is 1.2:
+** lMotor = 1.2 * 3.333 - 4 = 0
+** rMotor = 2 - (1.2 * 3.333 - 4) = 2 which gets capped to 1
+** so the left motor is stopped if the average sensor value is less than 0.2
+** this is also true for the right motor if the average sensor value is greater than 1.8
+*/
 
 int main()
 {
     isSearching = false;
     counter = 0;
     while (true) {
-        computeMotorSpeeds(ain0.read(), ain1.read());
-        pwm0 = lMotor;
+        computeMotorSpeeds(ain0.read(), ain1.read()); // set the motor speed variables
+        pwm0 = lMotor; // output the variables to the pwm outs
         pwm1 = rMotor;
-        wait_ms(10);
+        wait_ms(10); // wait 10 miliseconds and start again
     }
 }
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