Slapshot Disks Getting Too Much Lift

I have been building a flywheel robot, which has an interesting effect happening to it. When the disks get launched, they get a small amount of lift before going down. When i’m closer to the bar when I shoot, they go under because the lift does not raise the disks high enough to hit the bar, but then they all go into the 1 point zone, and if I reduce the rpm of the flywheel, they rapid-fire function does not work as well. When I back up, it would normally be the perfect distance, with rapid fire capabilities and 4 point zone, but when I back up to that distance, the lift makes the disks hit the bar. Help?

It is generally better (and easier) for the person experiencing problems to troubleshoot it themselves. I understand that you are looking for ideas to implement, but those ideas are hard to suggest and can be found scattered around vex forums everywhere. You may find a new way to troubleshoot it, or you may change your system to launch the discs slightly differently. Another way to solve this would be to have a vertically adjustable launcher that lets you counteract the lift. However you solve it is up to you, and I hope you get some outside ideas as well as generating your own. I would be impressed if you posted the final solution here for other people who might also be experiencing this problem. As part of V5, I don’t have to worry about solving this, but my suggestion from experience is that there is probably a fairly simple way to do it that you just don’t see yet. Maybe you could add a hood to keep the discs down, or maybe you could slow down your flywheel and modify your rapid fire system somehow. Good luck troubleshooting!

Lots of teams install hoods to help guide the in motion object, you might want to consider that to help it leave the robot on a more flat trajectory.

1 Like

A couple things:

  1. lift can be changed quickly by changing the shape of your backboard (“reaction surface” would be a more technical term I think). If your flywheel is shooting from the ground and the axle of the wheel is pointing up/down instead of left/right or front/back, try to raise the wheels up by adding spacers so that they hit higher on the disc. If you’re reacting them off a beam or other part of your robot as a backboard, experiment with different shapes and angles of that surface.

  2. If you code a motor to have multiple possible speeds depending on user inputs, you could have a slower speed for shooting close to the bar into the 4 pt. and a higher speed for shooting far into the 4 pt. For extra credit, add a sensor to determine if you’re at the bar or further.

  3. “Rapid fire function” could mean a lot of things, but I’m going to guess that your discs stop clearing the flywheel shooting area as quickly, slowing down your shots per minute, when your flywheel RPM is slowed down. If that’s the case, what changes could you make to the loading area that would get the discs into the flywheel’s most powerful areas faster?

There’s 3 phases of a flywheel launch: A. the object has to be “grabbed” by the flywheel by getting pressed between the wheel and another surface. This usually happens at the place in your shooter where there’s the minimum distance between your wheel and your backboard. Backboards can also be the floor, as mentioned above, but if you’re using two wheels in opposite directions, you have a 2nd wheel in place of that backboard. Same logic applies, the grab happens where the two wheels are closest. B. The flywheel loses some energy as the object gets accelerated. C. The “followthrough” where the object stops touching the flywheel and leaves your robot.

Making changes to any of these steps will affect the object’s final flight path. Figure out where the rapid fire is breaking down and that will tell you how to fix it.