Inertial Sensor malfunction

Programming Support VEXcode Pro V5 Text Tech Support
1

Hi all!

I’m trying to code turning for my auton using the V5 inertial sensor
currently, I’m using

Inertial10.rotation(rotationUnits::deg);

to get the rotation value of the sensor
But whenever I run my program, the sensor’s value (printed to the brain) starts at zero and gradually goes up to -143, then stays put and works like it normally should.
Anyone have any ideas why this might be happening?

2

Do you have it mounted upside down, below the bot? IIRC the sensor does not like reading negative z acceleration.

3

yes, it is upside down, I didn’t think it would be an issue. Thanks for letting me know! ill try mounting it rightside up

4

It should not be an issue.
are you fully updated to vexos 1.0.9, that’s mandatory to use the inertial sensor.

1 Like
5

I just updated everything. The sensor works perfect now when standing still, but it just hovers between -1 and 1 while moving.

6

+/- 1 what ? test the sensor using the dashboard.

1 Like
7

this is inside a loop:

sensorValue = Inertial10.rotation(rotationUnits::deg);
    
Brain.Screen.clearLine(4, black);
Brain.Screen.setCursor(4, 1);
Brain.Screen.print(sensorValue);
8

I’m assuming ± 1 degree, but maybe .rotation() doesn’t work how I thought?

9

Is there sensor working in the dashboard ? does it show 0-360 degrees for heading as you rotate the robot ?
Is sensorValue a double ? Did you give the sensor time to finish calibration before entering the while loop ?

1 Like
10

yes * 4

The only time it doesn’t work is when I spin the wheels to turn towards the target rotation
Even when I lift the robot up and let the wheels spin free, the value of the rotation changes. Could the Inertial10.rotation(); value be linked to the spinning of a motor?

Edit: I heard something about some ports being linked (like 1 & 2). Is that a thing?

11

post all the code or attach the project as a zip file.

1 Like
12 
void inertialTurnForPID(int degrees, double maxVoltage) {
  
  double target = Inertial10.rotation(rotationUnits::deg) + degrees;
  Brain.Screen.newLine();
  Brain.Screen.print("Target:");
  Brain.Screen.print(target);
  Brain.Screen.newLine();

  double iSensorValue = Inertial10.rotation(rotationUnits::deg);

  int allowedRange = 5;

  //the error (Proportional)
  double error = 0;
  double kP = 0.03;

  //Integral
  double integral = 0;
  double kI = 0.00;

  //Derivative
  double derivative = 0;
  double kD = 0.00;
  double previousError = 0;

  //the power to the motor
  double power = 0;

  while(iSensorValue < (target - allowedRange) || iSensorValue > (target + allowedRange)) {
    iSensorValue = Inertial10.rotation(rotationUnits::deg);
    
    Brain.Screen.clearLine(4, black);
    Brain.Screen.setCursor(4, 1);
    Brain.Screen.print(iSensorValue);

    error = target - iSensorValue;

    integral += error;
    //if you reach the goal or cross it, set integral to zero
    if(error == 0 || error * previousError < 0) {
      integral = 0;
    }
    //only use integral at the end
    if(abs(error) > 40) {
      integral = 0;
    }

    derivative = error - previousError;
    previousError = error;

    power = (error * kP) + (integral * kI) + (derivative * kD);

    if(power > maxVoltage) {
      power = maxVoltage;
    }
    if(power < -maxVoltage) {
      power = -maxVoltage;
    }

    LDrive.spin(directionType::fwd, power, voltageUnits::volt);
    LDrive2.spin(directionType::fwd, power, voltageUnits::volt);

    RDrive.spin(directionType::rev, power, voltageUnits::volt);
    RDrive2.spin(directionType::rev, power, voltageUnits::volt);

    task::sleep(20);
  }
  
  LDrive.stop(brakeType::brake);
  LDrive2.stop(brakeType::brake);

  RDrive.stop(brakeType::brake);
  RDrive2.stop(brakeType::brake);

}

in the auton section, I’m calling the function with the values (180, 5)

13

Ok, I got it working by adding an extra calibration section before the auton ran. This shouldn’t be necessary though, right?