Auto Exact

Hi all. I was wondering how some bots have such an exact autonomous. I have seen some that are perfect every time, and I want to know if they use sensors, or what, because I have been in vex for 4 years, and have never seen this. Thanks!

1 Like

For perfect programs I would use distance sensors, shaft encoders for everything that uses a axel that can be off, and a inertial sensor. Color sensors are used for absolute perfection (though have fun coding that)

Ok. Sense we dont have all of that, or the time to do all of that, is there 1 that helps more then the others? or do all of them help equally?

1 Like

The most helpful one by far is the inertial

do you mean inertial?

Also, if you were to use something like an inertial sensor combined with squaring up your robot on walls (just drive into a wall for a certain length of time to get your robot straight) you could make a pretty successful autonomous/programming skills. Our change up robot scored a 116 with only a camera and encoders attached to our drive wheels.

The best sensors are encoders for your drive base, though. If you can successfully program at least a P loop, you will be just fine. Down the line, you can then evolve into a full PID loop on your drive base.


Ok. Thank you!
20 char

1 Like

Sorry if i sound dumb, What is a P loop? I did a quick google, But I dont understand the reason for doing it.

Proportional loop. Helps a robot to drive in a straight line. Pseudocode looks basically like this:

while distance is less than x
_ if left encoder > right encoder
__ left motor = 90
__ right motor = 100
_else if left encoder < right encoder
__ left motor = 100
__ right motor = 90
__ left motor = right motor = 100

If one encoder gets ahead of the other, it slows that wheel down, otherwise they run at the same speed as long as they are in sync.


Ok. thank you!
20 char