Achieving Faster Recovery Times

I have a single Flywheel with 2, 5 inch wheels and the intake mounted at a 45 degree angle using the 45 degree gussets. My hood of the flywheel is mounted on the intake too. I have hardly any compression, but it takes a long time for the wheel to recover. What can i do to achieve a faster recovery time?

How many motors and what’s your gear ratio?

One way to decrease recovery time would be to increase the mass of the flywheel by adding another wheel so that the velocity of the flywheel would not decrease as much after each launch. However, doing so would mean sacrificing the spin-up time of the flywheel.

I am using 4 torque motors with a 1:35 speed ratio

Reducing the gear ratio will help. 35:1 is higher than you need, so by reducing the gear ratio, the motors put more torque into the flywheel. You will require a higher motor power, however.
Also, see the last post in this thread. There is a graph of the formula for recovery time in it, which is explained underneath it. The red curve shows that increasing the flywheel’s inertia helps, but only up to a point.

I am pretty sure ,correct me if I am wrong, that the torque motors have a slower acceleration time because their max turn speed is slower. If you want to use toque motors with better acceleration time you would had more mass to create more inertia on the wheel.

The opposite is actually true. The more torque a system has, the faster it will accelerate. This is why cars have transmissions. When the car is accelerating from a stop, it needs a lot of torque, but it doesn’t need a really high top speed yet. Therefore, it has a low gear ratio to fill this demand. When a car accelerates at higher speeds, such as when merging onto a freeway, it needs that higher top speed, so the gear ratio must be higher. Therefore, there is less torque, and acceleration is lower. This is one of the reasons that car acceleration curves look the way they do, as curves rather than linear equations (there’s also the fact that the forces resisting acceleration, like friction and air resistance, scale with speed, but let’s ignore that for now).

Interesting, I know that if you use flywheel control such as bang bang you can achieve faster acceleration to the desired rpm with faster motors. Which is another way to make your recover time much fast is to use fly wheel control and one of the best ways as well.

Yes, velocity control of some kind does help. Bang bang controllers, since they apply full power until the flywheel reaches the desired speed, are the fastest, but this also causes a lot of inconsistency and oscillation. My team uses this weird combination of PD and TBH (I don’t even think I can explain it very well), and it works really well for us. PID has very little oscillation, but I think TBH recovers speed slightly faster.

if i were to lower the gear ratio what would i lower it too?

how would i make a 28:1?

You would need Turbo motors (2.4:1), than gear it 7:3 x 5:1. This would make it 2.4:1 x 7:3 x 5:1 = 28:1

would a single flywheel with 2, 5 inch wheels running 4 torque motors running 25:1 shoot full court with around 70 motor power? The hood would have very little compression and mounted at a 45 degree angle. Also i need the recovery time to be around a ball per second. Would this be possible?

It is more than possible to achieve that. Most importantly, make sure you have minimal friction.
You might not be able to achieve it at 70 motor power, but should be very realistic if it is at about 80 to 90.

what

What would i do to minimize friction?

My team runs a single 5" flywheel with at 25:1 (2 x 60 tooth to 12 tooth) ratio. They started with four motors and saw a 50% improvement in recovery time when they went to six. They did some testing with eight motors but didn’t see significant results although it looked impressive.

As Meng mentioned, fiction is your enemy.
Here is a link on reducing friction: How To Reduce Unnecessary Friction

If you have been following the 8059A thread (which I do recommend you to… there are lots of discussion on how to reduce friction, etc), you would have notice that my students have already reduced the recovery time to about 0.4 second between (full court) shots, with high accuracy.

And they are using 2x5" single flywheel, with 4 motors as well.

The difference is that they are using internal turbo gear, and not high torque motors.
I do believe it is more efficient to use internal turbo gears, it will reduce certain amount of friction. And of course, other stuff like quality of built, etc…

could u give me a link?

https://vexforum.com/t/8059a-robot-in-1-day-singapore-vex-edition-reveal-more/29897/1