Diff: WheelControl/Wheel.h

Revision:

1:813f4b17ae65

Child:

3:01b5e80d842d

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/WheelControl/Wheel.h	Sun Mar 03 00:54:07 2019 +0000
@@ -0,0 +1,101 @@
+class Wheel 
+{
+    private:
+    
+    float distance; //distance traversed by wheel
+    float angularVelocity;
+    
+        float const static gain = 0.6f; //closed loop gain, (amount to amplify the difference) you have to tune this value
+    //but make sure its less than 1.5 otherwise you'll have a really sensitive motor
+    
+    PwmOut Mtr; //connect this pin to the motor driveboard pwm
+    DigitalOut direction; //connected to the direction pin of motor drive board
+    DigitalOut polarity; //connected to the bipolar of motor drive board. 0 = unipolar 1 = bipolar
+    
+    Ticker updater;
+
+    Encoder* enc;
+    
+    P controller;
+    
+    public:
+    
+    float maxAngularVel;
+    
+    float static const wheelDiameter = 0.18; //used in calculation of Linear velocity i.e never
+    
+    Wheel (Encoder* E, PinName M, PinName D, PinName Mode) : Mtr(M), direction(D), polarity(Mode), controller(0.6f)
+        {
+        enc = E;
+        polarity = 0;   
+        direction = 0;
+        distance = 0;
+        
+        Mtr.period_us(200); //frequency of 1KHz determine this constant value based on switching losses+frequency losses
+        //higher freq -> more switching losses lower freq -> more "capacitive losses" need to find a balance
+        updater.detach();
+        
+        controller.setControl(10.0f);
+        controller.setOutputLimits(-1.0f, 1.0f);
+        }
+    
+    float calculateAngularVelocity() //returns a float value which is the angular velocity of the WHEEL
+    {
+        float eTR;
+        eTR = enc->encoderTickRate();
+        angularVelocity = (eTR/256.0f)*2.0f*(float)PI;
+        return eTR;
+    }
+    
+    void setFrequency(int freq) //if you want to adjust the frequency
+    {
+        Mtr.period(1/freq);
+    }
+    
+    float returnAngularVelocity() //as it says
+    {
+        return angularVelocity;
+    }
+    
+    //only called once during initialization to calculate max angular velocity 
+    //dir = direction, do opposite for each wheel just so your buggy doesn't move FORWARD but rather rotates
+    void init(int dir) 
+    {
+      Mtr.write(0); //max speed
+      direction = dir;
+      updater.attach(callback(this, &Wheel::init2),1); //used as a wait preferably put this wait just long enough that the buggy will do a full 360 degree turn so that it hasn't moved
+    }
+    
+    void init2(void) //used as a temporarily wait command for the wheel to spin to max
+    {
+        float temp = enc->encoderTickRate();
+        angularVelocity = (temp/256.0f)*2.0f*(float)PI;
+        maxAngularVel = angularVelocity;
+        controller.setInputLimits(-1.0f*angularVelocity,angularVelocity);
+        updater.attach(callback(this, &Wheel::wheelUpdates),0.1);  //attached the actual update function from now ON
+    }
+    
+    void wheelUpdates(void) //sampling rate the ticker is attached I.E the wheel speed is updated everytiem this function is called
+        {
+            if (angularVelocity >= (controller.returnControl()+1.0f) || angularVelocity <= (controller.returnControl()-1.0f)) //only compute if their is a difference between wanted and current val
+            {
+            float temp = enc->encoderTickRate(); //get the encoder tick rate and store in a value called temp
+            angularVelocity = (temp/256.0f)*2.0f*(float)PI; //use it to calculate the angular velocity of the wheel
+            float temp2 = controller.compute(angularVelocity); //another temporary value to store the computed angular velocity
+            if (temp2 < 0) {direction = 1;} else {direction = 0;} //change direction according to the computed value
+            Mtr.write(temp2); //write the value as a pwm
+            distance += angularVelocity * wheelDiameter;
+            }
+        }
+    void adjustAngularVelocity(float W) // W = angular velocity you want, obviously putting a |w| value that is > max angular velocity will set dutcy cycle to 1
+        {
+        controller.setControl(W);
+        if (W < 0.0f) {direction = 1;} else {direction = 0;} //obvs if you put a negative value -> will get a negative direction i.e 0;
+        };
+        
+    float getDistance(void)
+    {
+    return distance; //distance traversed by wheel
+    }
+    
+};
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