Using a Parallex 360° with Arduino

Other Hardware Motors, Mechanics, Power and CNC
12

MatMax:
Hi all

For a project where we need to simulate a moving head, we have to use a Parallex 360° High Speed. We need to find a way to control the position of the motor. The idea is that we fill in a certain angle and that the motor changes to that position and stays there until we give it another one. Sadly, both of us don't have a lot of experience with programming.

With the datasheet (https://www.mouser.com/pdfdocs/900-00360-Feedback-360-HS-Servo-v12.pdf) and some examples we found on the internet (including this Forum), we managed to have something that looks good, but doesn't work. (We work with an Arduino Uno)

#include <Servo.h>                           

Servo nek; //Name the Servo
int pinFeedback=9;
int pinControl=10;
int angle, targetAngle;
int unitsFC = 360;                          // Units in a full circle
  int dutyScale = 1000;                      // Scale duty cycle to 1/1000ths
  int dcMin = 29;                            // Minimum duty cycle
  int dcMax = 971;                            // Maximum duty cycle
  int q2min = unitsFC/4;                      // For checking if in 1st quadrant
  int q3max = q2min * 3;                      // For checking if in 4th quadrant
  int turns = 0;                              // For tracking turns
  // dc is duty cycle, theta is 0 to 359 angle, thetaP is theta from previous
  // loop repetition, tHigh and tLow are the high and low signal times for
  // duty cycle calculations.
  int dc, theta, thetaP, tHigh, tLow;
  int errorAngle, output, offset;            // Control system variables

void setup() {
pinMode(pinFeedback, INPUT);
pinMode(pinControl,OUTPUT);
unsigned long tHigh;
unsigned long tLow;

}

void loop() {
  //feedback
  tHigh=pulseIn(pinFeedback,HIGH);
  tLow=pulseIn(pinFeedback,LOW);
  //dutycycle berekenen
  dc=(dutyScale*tHigh)/(tHigh+tLow);
  theta = (unitsFC - 1) - ((dc - dcMin) * unitsFC) / (dcMax - dcMin + 1);
  thetaP = theta;
//while(1){
  int tCycle = 0;                          // Clear cycle time
    while(1)                                  // Keep checking
    {
      tHigh = pulseIn(pinFeedback, HIGH);      // Measure time high
      tLow = pulseIn(pinFeedback, LOW);        // Measure time low
      tCycle = tHigh + tLow;
      if((tCycle > 1000) && (tCycle < 1200))  // If cycle time valid
        break;                                // break from loop
    }     
    dc = (dutyScale * tHigh) / tCycle;        // Calculate duty cycle
   
    // This gives a theta increasing int the
    // counterclockwise direction.
    theta = (unitsFC - 1) -                  // Calculate angle
            ((dc - dcMin) * unitsFC)
            / (dcMax - dcMin + 1);

if(theta < 0)                            // Keep theta valid
      theta = 0;
    else if(theta > (unitsFC - 1))
      theta = unitsFC - 1;

// If transition from quadrant 4 to 
    // quadrant 1, increase turns count.
    if((theta < q2min) && (thetaP > q3max))
      turns++;
    // If transition from quadrant 1 to 
    // quadrant 4, decrease turns count.
    else if((thetaP < q2min) && (theta > q3max))
      turns --;

// Construct the angle measurement from the turns count and
    // current theta value.
    if(turns >= 0)
      angle = (turns * unitsFC) + theta;
    else if(turns <  0)
      angle = ((turns + 1) * unitsFC) - (unitsFC - theta);

thetaP = theta;                          // Theta previous for next rep
  }
//}

//Controle van servobewegingen
   
 
  // servo_speed(pinControl, 0);               
   
    errorAngle = targetAngle - angle;        // Calculate error
    output = errorAngle * Kp;                // Calculate proportional
    if(output > 200) output = 200;            // Clamp output
    if(output < -200) output = -200;
    if(errorAngle > 0)                        // Add offset
      offset = 30;
    else if(errorAngle < 0)
      offset = -30;
    else
      offset = 0;   
    //servo_speed(pinControl, output + offset); // Set output
  delay(20);                                // Repeat after 20 ms
 
}

}





Is there someone here who has an idea how to implement this correctly? Or by any chance has a code that already works and that we could use?

It is part of a project we have at university, in which we have to calculate where a sound source is located based on scattering of sound waves on a sphere. To be able to do this, the 'head' (sphere) should be able to turn. Both of us are Engineering Physics students, so our programming skill is only minimal (and apparently not good enough for this task). It would be stupid that our project doesn't work because of an issue that isn't really something we can work on.

Thanks in advance!

Sincerely,
Matmax

Hey Matmax,

Were you able to get it working? Need an update :slight_smile:
I am working on a similar project with the same code.

Thanks,
Sgowdar