Use Gyro to turn 90 Degrees

[DavisC]

What are the values of the gyro. Is it 0 - 359 or what?

[mikets]

The gyro actually gives you angular velocity (turn rate), but the FPGA is doing integration for you. If you are calling the GetAngle() method, I believe you will get the accumulated angle. So if you turn several rounds, for example, you could get angle values > 360 or < -360. Remember, it is not a compass. It doesn't give you absolute heading. If only gives you current angle relative to your starting angle.

[DavisC]

So another words, if you were heading a direction recording 0. Then you used "GetAngle() + 90" when the drive is correcting itself it will think the robot turned 90 degrees to the right and will try to correct itself by turning 90 degrees to the left?
(Assuming a positive value turns the robot right and a negative value turns the robot left).

I am trying to accomplish this program without using the Reset() because that causes unpredictable angles at which it reset itself.

[mikets]

Yes, you can do the following, for eample:

float targetHeading = gyro->GetAngle() + 90.0;
while (gyro->GetAngle() < targetHeading)
{
    drive->ArcadeDrive(0.0, 0.5);
}

[DavisC]

Alright I will be testing that tomorrow. I was curious about the value range because we had the bot set up with the following code:

float angle = gyro.GetAngle() + 90;
myRobot.Drive(-0.2, -angle / 30);

The robot went straight before the "+ 90"; the -0.2 is because a negative value is actually forward on the bot.

The result when running this was that the robot would turn right at a medium rate and continue turning after passing 90 degrees.

The other result that seemed odd was that changing "/ 30" to "/ 1" caused a slower turn rate while changing it to "/ 60" caused a faster turn rate.

[mikets]

If you just want a simple turn, don't use myRobot.Drive, just use ArcadeDrive, like this:

#define TURN_TOLERANCE 0.5
void Turn(float angle)
{
    float targetHeading = gyro.GetAngle() + angle;
    while (fabs(targetHeading - gyro.GetAngle()) > TURN_TOLERANCE)
    {
        myRobot.ArcadeDrive(0.0, (angle < 0.0)? -0.5: 0.5);
    }
}

However, if you want to adjust the turn power according to how far you are from your target, then you need to use PID.
BTW, you should really fix your signs by calling myRobot->SetInvertedMotor(), you will benefit from it in the long run.