Revision 0:67bc01af349e, committed 2016-04-26

Comitter:

mitchelljones

Date:

Tue Apr 26 21:36:34 2016 +0000

Commit message:

Two-motor ground robot controller with ROS coms.

Changed in this revision

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue Apr 26 21:36:34 2016 +0000
@@ -0,0 +1,151 @@
+#include "mbed.h"
+#include "QEI.h"
+#include <cstdlib>
+#include <ros.h>
+#include <geometry_msgs/Vector3.h>
+#include "Sabertooth.h"
+
+Ticker flipper;
+/*Serial pc(USBTX, USBRX);//Serial port*/
+/*Serial xbee(p9, p10); //used to connected the mbed to the xbee over Serial UART comm.*/
+//PwmOut wheel1(p21); //signal for speed/direction to right wheels
+//PwmOut wheel2(p22); //singal for speed/direction to left wheels
+QEI wheelR (p29, p30, NC, 624); // Signal from encoder in right wheel
+QEI wheelL (p27, p28, NC, 624); // Signal from encoder in left wheel
+DigitalOut led1(p20);  // LED for xbee connection verification
+DigitalOut led2(p19);  // LED for W+ verification
+DigitalOut led3(p18);  // LED for W- verification
+
+float L=0.28; //Distance between left and right wheel
+float R=0.03;//Radius of wheel
+int encoderResolution=20000;// This is including the gear ratio
+float vR = 0.00;
+float vL = 0.00; //Due to the type of Pwm input the Sabertooth v1 takes, this is the signal for the robot to not move
+float V=0;//Desired linear velocity of robot
+float W=0;//Desired angular velocity of robot
+int thetaprevR=0; // Prev angular rotation of motor
+int thetacurrR=0; // Current angular rotation of motor
+int thetaprevL=0; // Prev angular rotation of motor
+int thetacurrL=0; // Current angular rotation of motor
+float omegaR=0; // Angular velocity of the motor of right motor
+float omegaL=0; // Angular velocity of the motor of left motor
+float errR=0; // Error
+float errL=0; // Error
+float preverrR=0;//Error in the last time step
+float interrR=0; //Integral of the error
+float differrR=0;//Derivative of error
+float preverrL=0;//Error in the last time step
+float interrL=0; //Integral of the error
+float differrL=0;//Derivative of error
+float Kp=3.0;// Propotional controller constant
+float Ki=0.001;//0.0000000001;//Integral controller constant
+float Kd=0;//0.001;//Differential controller constant
+float Kpw=0.1;// Propotional cotroller for omega
+float Kiw=0.0001;// Propotional cotroller for omega
+float errOmega=0;// Error in angular velocity
+float errOmegaprev=0;// Error in angular velocity in last step
+float interrOmega=0;// Integral of error in angular velocity
+float dt=0.01; // Time step
+float omegaDesiredR=((2*V-W*L)/(2*R*6.28)); // Desired angular velocity of right wheel
+float omegaDesiredL=((2*V+W*L)/(2*R*6.28)); //Desired angular velocity of left wheel 
+float thetaTotal=0;
+char w[32];
+
+
+ void checkVelocity(){
+    
+    thetacurrR=wheelR.getPulses();
+    thetacurrL=wheelL.getPulses();
+    omegaR=(float)(thetacurrR-thetaprevR)/(encoderResolution*dt);
+    omegaL=(float)(thetacurrL-thetaprevL)/(encoderResolution*dt);
+    thetaprevR=thetacurrR;
+    thetaprevL=thetacurrL;
+    errR=omegaDesiredR-omegaR;
+    errL=omegaDesiredL-omegaL;
+    interrR=interrR+dt*errR;
+    interrL=interrL+dt*errL;
+    differrR=(errR-preverrR)/dt;
+    differrL=(errL-preverrL)/dt;
+    errOmega=W-(((omegaL-omegaR)*2*3.14*R)/L);
+    interrOmega=interrOmega+dt*errOmega;
+
+   if((errL>0.01||errL<-0.01)){
+            //vL+=(Kp*(errL)+Ki*interrL);//-Kpw*errOmega);//-Kiw*interrOmega);
+            vL+=(Kp*(errL)+Kd*(differrL)+Ki*interrL);//-Kpw*errOmega);//-Kiw*interrOmega);
+   }
+   
+   
+   if((errR>0.01||errR<-0.01)){
+            //vR+=(Kp*(errR)+Ki*interrR);//-Kpw*errOmega);//-Kiw*interrOmega);
+            vR+=(Kp*(errR)+Kd*(differrR)+Ki*interrR);//-Kpw*errOmega);//-Kiw*interrOmega);
+   } 
+   
+   if(interrR>20){
+    interrR = 20;
+}
+if(interrL>20){
+    interrL = 20;
+}
+if(interrR<-20){
+    interrR = -20;
+}
+if(interrL<-20){
+    interrL = -20;
+}
+    preverrR=errR;
+    preverrL=errL;
+    errOmegaprev=errOmega;
+    
+    
+/* if(xbee.readable()){*/
+        //xbee.scanf("%s\n",w);
+        //pc.printf("%s   ",w);
+        
+        //if((atof(w)/1000.0)>=-0.7 && (atof(w)/1000.0)<0.7)
+        //{W=atof(w)/1000.0;}
+        
+         omegaDesiredR=((2*V-W*L)/(2*R*6.28));
+         omegaDesiredL=((2*V+W*L)/(2*R*6.28));  
+/*}*/
+ 
+} 
+ 
+void cmd(const geometry_msgs::Vector3 &cmd_msg) {
+     V = (float) cmd_msg.x;
+     W = (float) cmd_msg.y;  
+     led3 = 1;
+}
+ 
+ros::NodeHandle nh(p9,p10);
+ros::Subscriber<geometry_msgs::Vector3> sub("cmd_vel_w", cmd);
+Sabertooth sb(p13,129,9600);
+
+
+int main() {
+    
+    nh.initNode();
+    nh.subscribe(sub);
+    sb.InitializeCom();
+
+    //wheel1.period(0.20);
+    //wheel2.period(0.20);
+      
+    flipper.attach(&checkVelocity, dt);
+    while(1){
+        nh.spinOnce();
+    wait_ms(1);
+    if (V>0)
+    {
+    led1 = 1;
+    }
+    
+        sb.SetSpeedMotorA((int)vR);
+    sb.SetSpeedMotorB((int)vL);
+    
+        //wheel1.pulsewidth(vR); //output the current speed value to right motor
+        //wheel2.pulsewidth(vL); //output the current speed value to left motor  
+/*        wheel1.pulsewidth(0.00155);*/
+        //wheel2.pulsewidth(0.001);
+       
+    }
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Tue Apr 26 21:36:34 2016 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/9296ab0bfc11
\ No newline at end of file