Extremely Accurate Autonomous

VEX V5 General Discussion Technical Discussion
1

Hey everyone,

Lately, I have been been focused on trying to make my autonomous extremely accurate and fast. Many people say that going slow is how you make it accurate, but I need to be able to run everything very quickly to get a high score. Currently, I have a P controller(only P, not I or D), along with deadband assist to make sure the bot never stops. It also has autocorrection. My problem, however, is that it is much too slow. It moves quickly, but then it takes a lot of time autocorrecting. This wastes a lot of time.

I have done this with turning functions and drive forward and backward functions. I would appreciate any advice as to how to speed this up.

Robot Specs:
4 motor turbo Drive Base(more motors to be added)
2 motor mobile goal intake
quad encoders
single gyro

2

I know you said more motors are going to be added but you cannot safely run a four motor turbo base.

3

I know that. We just need to get some more turbo gears. However, our robot is extremely light, so we are not worried about it stalling anyway.

4

This sounds like a PID Tuning issue. You can easily achieve a fast and accurate autonomous with a properly tuned PD controller on the base

5

Here’s a really old VEX video (Elevation, 2008-2009), of a robot that used PID logic with line following to go faster the closer it was to the center of a line, and slower when it started to deviate. It used six of the old 3-wire motors geared to 3.6 feet per second. I’m surprised that so few teams try line-following anymore.

On YouTube

6

Seems like you have to tune your PID. I would also recommend using D if you feel like you’re overshooting.

7

I feel like that especially in this year’s game, the lines are not configured in a way that they could be super useful for following.

8

to have an accurate 20 point auton it might, but I see your point.

9

Our Chassis is very light and completely built with Aluminium and still the motors stall with 4 High Speed motors. No issues with running 4 Low Speed with 3:2 gear ratio. But, motors stalling with 4 high speed 3:2 gear ratio. I think you will have issues with Turbo speed motors.

10

A high speed 3:2 would be the equivalent of a 2.4:1 ratio. Which is faster than 4 motor turbo.

11

I agree that the configuration isn’t particularly helpful this year. Last year it was almost meaningless. Both years it looked useful at first glance. It just didn’t hold up.

We did have some early season work both years where we used it. This year when some teams tried it there just wasn’t enough benefit to make up for the problem of how to mount it. To handle changing ambient light conditions it helps to mount the sensors really close to the floor. I think the recommendation what we’ve found is it works well at 1/4 to 1/8 inch off the floor. Turns out that really can get in the way of bouncing over the zone divide bars. It was possible to overcome that, but encoders, gyros, or both together work pretty well to overcome positioning problems.

12

Isn’t this exactly the same as turbo?

13

Turbo is 240 rpm 2.4:1. It shows the rpm of the gear sets at the bottom of this page.

14