Moving Forward

I am doing some simple programming my vex cortex. I built the Clawbot with motors in port 1 (left) and port 10 (right-then reversed).

When I use robot C 4.52 to program it to go forward, it will not work for rotations or degrees. If I pick seconds, the cortex robot will move forward or backward.

Why will the motors not respond to rotations or degrees?

Our team uses time as a value; we can control speed and time. Assuming a perfectly frictionless world, you can run a calculation to find rotations from this

Do you have encoders on your wheels?
You will need either optical shaft encoders or integrated motor encoders if you want to move using rotations or degrees. Without any sensors, the only way to move is using time (seconds).

You need encoders to track distance. The motors do not have them out of the box and can’t track rotation themselves. You’ll either need the optical shaft encoders or the integrated motor encoders, which are sold separately. If you don’t have them installed on your robot, you need to put them on.

OK so here’s THE DEAL.

All you get as a programmer on this platform is the ability to tell the motors what direction to go, and how “fast.” Unfortunately the “fast” part will be relative to the battery voltage, so what you really have is “go forward/backward with x% of the current battery voltage.”

If you want to travel say a certain distance forward, you’ll need some feedback, an encoder or accelerometer can provide this. You’ll need to relate the way the sensor you choose measures the world to the actual performance of the motors and the easy quick and dirty way to do this involves control loops.

Which is a whole other discussion which you should start by watching this: