Diff: main.cpp

Revision:

0:3cafef4c2519

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Dec 11 01:39:42 2019 +0000
@@ -0,0 +1,198 @@
+#include "mbed.h"
+#include "Motor.h"
+#include "LSM9DS1.h"
+#include "math.h"
+
+#define PI 3.141592653589793
+#define PERIOD 0.001 //NOTE: Max sample rate is 952 Hz
+
+Serial pc(USBTX, USBRX);
+LSM9DS1 imu(p28, p27, 0xD6, 0x3C);
+Motor L(p22, p5, p6); // pwm, fwd, rev
+Motor R(p21, p8, p7);
+DigitalOut myled(LED1);
+
+float angle;
+float gOffset = 0;
+float aOffset = 0;
+
+int kp = 48; //Best performance so far acheived with kp and speedCorrection
+int ki;
+int kd;
+int factor;
+float speedCorrection = 2.0;
+float speed;
+
+void myCalibrate();
+void control();
+void drive();
+void callback();
+
+int main() {
+    //LSM9DS1 imu(p9, p10, 0x6B, 0x1E);
+    imu.begin();
+    if (!imu.begin()) {
+        pc.printf("Failed to communicate with LSM9DS1.\n");
+    }
+    imu.calibrate();
+    imu.setAccelScale(2);
+    imu.setGyroScale(2);
+    pc.attach(&callback);
+    myCalibrate();
+    drive();
+}
+
+void control() {
+}
+    
+void drive() {
+    float accelAngle;
+    float gyroAngle;
+    float pastAccAngle = 0;
+    float pastRawGyro = 0;
+    float pastGyroAngle = 0;
+    float temp;
+    int counter = 0;
+    float alpha = 0.50; // = T/(T+dt) where T is response time
+    float beta = 1; // Decides how much the gyroscope data is trusted. b/t 0.9 & 1
+    float integral = 0;
+    float derivative = 0;
+    float lastAngle = 0;
+    factor = 1000;
+    while(1) {
+        counter++;
+        accelAngle = 0;
+        for (int i = 0; i < 10; i++) {
+            imu.readAccel();
+            imu.readGyro();
+            accelAngle += ::atan2((float) imu.ax, (float) imu.az)*180/PI - 90;
+            //The max we will see for this application is about 16380 (1 G), but max is 2 G's (32767 in 16 bits):
+            gyroAngle += (1/2)*imu.gy + gOffset;
+            wait(PERIOD);
+        }
+        accelAngle = accelAngle/10.0 + aOffset; //Averaging accel to get rid of some noise
+        gyroAngle = (gyroAngle)*PERIOD - pastGyroAngle;         //Sum over a set time (10 ms) and multiply by differential time (1 ms) to integrate angular velocity
+
+        temp = gyroAngle;
+        accelAngle = (1 - alpha)*accelAngle + alpha*pastAccAngle; //Low Pass Filter
+        //gyroAngle = (1 - alpha)*pastGyroAngle + (1 - alpha)*(gyroAngle - pastRawGyro); //High pass filter
+        pastRawGyro = temp;
+        angle = accelAngle*beta + gyroAngle*(1 - beta);
+        angle -= 2; //Attempt to correct for weight distribution bias
+        
+        myled = 1;
+        if (counter % (int) (0.5/(PERIOD*10)) == 0) {
+            pc.printf("Angle by acc: %.3f\n\r", accelAngle);
+            pc.printf("Angle by gyro: %.3f\n\r", gyroAngle);
+            pc.printf("Overall %.3f\n\r", angle);
+        }
+        integral += angle*PERIOD;
+        derivative = angle - lastAngle;
+        speed = (kp*angle + ki*integral + kd*derivative)/factor;
+        speed = abs(angle) > 80 ? 0 : speed;
+        pastAccAngle = accelAngle;
+        pastGyroAngle = gyroAngle;
+
+        if (speed < 0) {
+            speed *= speedCorrection; //Speed Correction attempts to correct weight distribution issue
+        }                             //by driving faster when falling on the heavier side
+        if (speed > 1) {
+            speed = 1;
+        } else if(speed < -1) {
+            speed = -1;
+        }
+        if (counter % (int) (0.5/(PERIOD*10)) == 0) {
+            pc.printf("speed: %.3f\n\n\r", speed);
+        }
+        speed *= -1;        //Had to correct direction after moving accelerometer to opposite side
+        L.speed(speed);
+        R.speed(speed);
+        lastAngle = angle;
+    }
+}
+        
+void myCalibrate() {
+    //Get linear offsets for accelerometer and gyroscope
+    float gSum = 0;
+    for (int i = 0; i < 100; i++) {
+        imu.readAccel();
+        imu.readGyro();
+        gSum += imu.gy;
+        aOffset += ::atan2((float) imu.ax, (float) imu.az)*180/PI;
+        wait(PERIOD);
+    }
+    aOffset = - aOffset/100 ;
+    gOffset = - gSum/100 ;
+    pc.printf("Accelerometer offset: %.3f \n\r", aOffset);
+    pc.printf("Gyroscope offset: %.3f \n\r", gOffset);
+    wait(2);
+}
+
+//This function is a revised version of that from:
+// https://os.mbed.com/teams/ECE-4180-Spring-15/code/balance2/
+void callback()
+{
+    speed = 0;
+    char val;                                                   // Needed for Serial communication (need to be global?)
+    val = pc.getc();                                            // Reat the value from Serial
+    pc.printf("%c\n", val);                                     // Print it back to the screen
+    if( val =='p') {                                            // If character was a 'p'
+        pc.printf("enter kp \n");                               // Adjust kp
+        val = pc.getc();                                        // Wait for kp value
+        if(val == 0x2b) {                                       // If character is a plus sign
+            kp++;                                           // Increase kp
+        } else if (val == 0x2d) {                               // If recieved character is the minus sign
+            kp--;
+        } else if (val == '(') {
+            kp-= 10;
+        } else if (val == ')') {
+            kp += 10;                                           // Decrease kp
+        } else {
+            kp = val - 48;                                      // Cast char to float
+        }
+        pc.printf(" kp = %d \n",kp);                            // Print current kp value to screen
+    } else if( val == 'd') {                                    // Adjust kd
+        pc.printf("enter kd \n");                               // Wait for kd
+        val= pc.getc();                                         // Read value from serial
+        if(val == '+') {                                        // If given plus sign
+            kd++;                                               // Increase kd
+        } else if (val == '-') {                                // If given negative sign
+            kd--;                                               // Decrease kd
+        } else {                                                // If given some other ascii (a number?)
+            kd = val - 48;                                      // Set derivative gain
+        }
+        pc.printf(" kd = %d \n",kd);                            // Print kd back to screen
+    } else if( val == 'i') {                                    // If given i - integral gain
+        pc.printf("enter ki \n");                               // Prompt on screen to ask for ascii
+        val= pc.getc();                                         // Get the input
+        if(val == '+') {                                        // If given the plus sign
+            ki++;                                               // Increase ki
+        } else if (val == '-') {                                // If given the minus sign
+            ki--;                                               // Decrease ki
+        } else {                                                // If given some other ascii
+            ki = val - 48;                                      // Set ki to that number
+        }
+        pc.printf(" ki = %d \n",ki);
+    } else if( val == 'o') {
+        pc.printf("enter factor \n");
+        val= pc.getc();
+        if(val == '+') {
+            factor=factor+1000;
+        } else if (val == '-') {
+            factor=factor-1000;
+        } else {
+            factor=(val-48)*1000;;
+        }
+        pc.printf(" factor = %d \n",factor);
+    } else if (val == 'a') {
+        pc.printf("enter speed correction \n");
+        val= pc.getc();
+        if(val == '+') {
+            speedCorrection += 0.1;
+        } else if (val == '-') {
+            speedCorrection -= 0.1;
+        }
+         pc.printf("speedCorrect = %f \n",speedCorrection);
+    }
+    wait(1);
+}
\ No newline at end of file