Vex Flywheel Launcher Accuracy

VEX Robotics Competition Discussion VRC > Nothing But Net (15/16)
#1

Hey guys, so after finishing my first nothing but net robot for the season
(video in the link below)


We had a lot of success within testing the robot, although the accuracy was quite bad. Despite the conditions of the balls, it seamed to be inconsistent in height and side to side. We can shoot at a distance of over 30+ feet, So that being said does anyone have any tips to improve accuracy?

( p.s its a 35:1 gear ratio, 4 Stock motors 1:1 internally geared)

#2

possibly cut down on power because the more power put in, the less stable the robot and balls are during the launch. Also, better horizontal stabilizers will provide for better horizontal accuracy.

#3

Is it possible that the system you use for feeding balls up to the flywheels is feeding the balls at inconsistent angles? If you have access to an iPhone with the slow-motion capability, perhaps you can observe the feed in action? Otherwise, maybe just add some bar or something to ascertain that the feed angle stays good.

#4

Make sure and use this suggestion, if a ball is not consistent in the feed to the launcher you are spinning your tires (Pun intenended lol) in trying to solve consistency. That has been the biggest area to address on our robots so far.

#5

Yes you don’t need that much power.

#6

Due to manufacturing tolerances, no two motors are the same, so your two flywheels will produce slightly different amounts of torque, which will cause them to react differently when different balls are fed into the launcher. Mechanically linking your flywheels would solve this, however, this has downsides, most notably, more friction.

A single flywheel design will be more accurate, since it does not have this problem. Additionally, your gear ratio is much better suited (actually very well suited) to a single flywheel design. 1:35 is much too high for a double flywheel design, but very good for a single flywheel design. If you adjust your angle to be about 45 degrees, and remove one of the flywheels, this should be a very good launcher.

This will help with distance accuracy. In terms of horizontal accuracy, I’m not quite sure since I haven’t had any experience with double flywheel designs. The omni wheels may be a factor, although I have seen a single flywheel launcher with omni wheels that was very accurate. Keeping the robot stable and making sure all of the parts are aligned at right angles may help.

This post I made about single flywheel launchers should also be helpful if you choose that route.

Good luck!

#7

Thank you all for your suggestions. Today I removed the intake and tested it with a more natural and constant feeding angle and the accuracy went from 2% to 50%. I’ll be continuing to tweak it until it’s 100% accurate.
Thank you all.

#8