I have tried using the sample prrograms for basic turn but I can't seam to understand it since the robot does a 90 degree turn and then keeps on turning. So can some one tell me how to do a 90 degree turn?

What gyro? Does it provide raw data or euler angles? (http://en.wikipedia.org/wiki/Euler_angles)

It takes some math, to turn 90 degrees using the encoders. Code for this is included in my lib at http://www.spiked3.com/?p=410

The more common basic way to do it is to simply wait an amount of time previously determined by trial and error.

So an example might be;


with a gyro is a whole new model In theory, you read the turn rate sample, multiply that by elapsed time, accumulate to an actual amount turned variable, (optionally fuse with compass heading and encoder data), lower power to 0 as you approach 90 degrees. That's the theory anyhow. I have that as an upcoming project as well. Please let me know if you find something else.

The gyro is the vex yaw gyro. http://www.vexrobotics.com/276-2333.html

There are sample programs include with ROBOTC for use with the VEX Gyro Sensor.

You can find these in the C:\Program Files (x86)\Robomatter Inc\ROBOTC Development Environment\Sample Programs\VEX2\Gyroscope folder.