Hi everyone,
My team and I are working on a single flywheel for up against the low goal and midcourt shooting. One of the biggest problems we are having is designing a hood to actually angle the ball into the goal. Does anyone with experience with single flywheel field bots have any advice for things like compression, angle of the ball, hood material, point of entry of the ball (the point in relation to the flywheel the ball actually first contacts)?
I might be able to answer this. You said you’re trying to make it into the low goal from mid court? Don’t stress out too much over it. I would suggest instead of building a hood, angle your ramp at about a 40 degree angle (with respect to the flywheel) , and extend your ball’s path. What i mean is, as the ball goes through the flywheel, don’t stop the ramp there. extend the plate on which the ball rolls on out past the flywheel. That should hopefully get your path straight.
Now, If your ball rolls on TOP of the flywheel, and isn’t getting compressed underneath it and above a plate, then build a hood. Use aluminum, as you can bend it if it doesn’t work out, making it easier than grabbing and screwing in an entirely new plate.
Sorry if I was confusing, I actually meant that I want to be able to shoot into the high goal from both up against the low goal and from midcourt.
Is your flywheel above or below the ball when the ball touches it?
If you think of the flywheel as a clock when looking at it from the side, the ball first touches the flywheel at about 9 o’clock.
Got it. I’ve seen a team use that bendy glass stuff(sorry, I don’t know the name of it) with successful results, but it seems a little risky. I would say to still go with the aluminum hood, because it’s easy to bend and change if it doesn’t work out. I can’t think of anything that would let you shoot at different angles at different parts of the field other than using a potentiometer for the axle that runs through your flywheel, or a motor that changes the angle of the hood. If you end up going with a potentiometer, I would also recommend using an encoder to set up the potentiometer change at the right time.
Hi! I strictly speaking don’t have any experience with outfielding flywheel hoods, but I’m sure the concept is very similar between those and base tile shooting hoods. I have gone through 4 different iterations of my single flywheel hood, improving it each time. It’s still far from perfect, but it is very, very accurate and allows for a pretty decent fire rate. You will want pretty minimal compression, maybe around 0.4-0.5." You will have to adjust the hood many times to make the robot shoot variable squishiness balls accurately, but it’s not too difficult. The actual angle of the hood matters very little, as the hood will release the ball at the last point of contact between the flywheel and the hood. In other words, by changing the angle of the hood, you accomplish nothing. However, by moving the hood closer to the inside of the flywheel, you will make the flywheel shoot more vertically. It is important to have a relatively high trajectory for shooting right up against the goal.
So as for accuracy, there is a process to tweaking the hood. First of all, design the hood so that it can be adjusted up or down, or else build the flywheel such that there are two wheels on the same shaft. If the hood can be adjusted, you can obviously change the compression rate by… (wait for it) adjusting the hood, but you can also change the compression rate by changing the space between the wheels. If the wheels are farther apart, they will compress the ball less. One good way to build a hood is to have the hood simply a long standoff,
like 5327C.
By anchoring the hood a set distance from the chassis, it is quite easy to adjust the compression rate precisely. This in my experience is the best type of hood because it minimized contact between the ball and the flywheel, meaning that the flywheel loses as little energy as possible and is able to get back up to speed faster.
There is a very common problem with single flywheels that can be tremendously reduced but never entirely eliminated. This problem is the issue of balls leaving the flywheel at different angles. Depending on the flywheel setup (I don’t know exactly what causes it) some balls may leave the flywheel with almost vertical trajectories, while others may leave the flywheel with very horizontal trajectories. If this happens, the solution is very simple. Buy
these pieces
And put one on each end of the hood standoff. Said differently, there should be a solid standoff in the middle and these rubber pieces on each end of the standoff connecting to the metal that holds up the hood. I know this is not very well- articulated, but I can’t find a better way to explain it. PM me if you don’t understand it. If done correctly, this will make the hood flexible so that it compresses different balls different amounts. Again, I don’t really know why, but this will solve the issue of balls leaving the flywheel at different angles. If balls are leaving the flywheel at different angles with an already flexible hood, simply make the hood solid by removing the rubber links and this should solve the problem. Even though I don’t understand the cause for this issue, this is definitely the solution.
Remember how I said compression had to be tweaked to perfect accuracy? See this post. The concept is the same regardless of the flywheel setup.
I explain it fully here.
(Sorry, I’m really lazy.)
I hope this helps you. 
My team and I have found that a poly carb hood work extremely well with the single flywheel. With our we have close to 100% accuracy for each match with about a 2 ball a second fire rate. We have found that if the hood has a little bend in it, it will help with the harder balls as the poly carb will have a little bend in it. We use a 45 degree mounting bracket for our angle because we are a tile shooter, but one of our other teams used the brackets where you can adjust to the angle you want and it worked out well for him. I would post pictures but I don’t have any of our current robot.
Edit: Found some pictures of our old robot and our new ones hood.