Reducing the effects of ball PSI on accuracy of flywheel shooter

[LoganKippnick]

Hi there!

We have noticed that the air pressure of the cargo has a huge effect on the distance our hood shooter shoots them. We are trying to find ways to eliminate this as an issue or reduce the effects enough so that it will not determine whether we make or miss a shot. Should we increase the grip the shooter has on the cargo? What about using a PID controller for flywheel velocity?

Thanks from team 6081.

[A-A-Ron]

if you aren’t using a PID for flywheel velocity, do. I also know our robot shoots a little long.

edit: grammar

[JamesCH95]

Using a second ‘upper’ roller helped us immensely in this regard.

100% use PID (usually just P) control for the shooter wheel(s).

[Tom_Line]

Like James said, additional rollers help. That’s because you get different amounts of slip on different pressure balls, because the friction force on the rollers is different. That can be helped by having the ball accelerated over a longer period, either through pre-shooter acceleration wheels, or by having additional ‘wrap’ around the shooter wheel.

A unique effect we noticed this year is that if you have too much pinch in your shooter, the balls will ‘pop’ out if they are at max pressure and give them that little extra nudge of velocity you really don’t want. In the past with foam balls that really hasn’t been much of an issue. On the flip side, if you don’t have enough compression your shooter will never reach the static friction point with the balls and you’ll be wildly variable.

[LoganKippnick]

Do you know where I can find resources to implement PID control on a REV NEO?

[Emilio]

Here is the WPILIB Documentation explaining how PID works

Here is the Rev Spark max Documentation of Closed loop Control

Here is the Spark max Closed loop Examples page