Originally Posted by Nick.kremer (Post 1526475)

I have seen you posting the same thing in a few other threads. I was wondering if you have a minute to explain/have a link to a thread that explains how operating voltage is tied to using control loops, to someone who knows very little about such things?

Originally Posted by GeeTwo (Post 1526487)

The control works by varying the voltage supplied to the motor. The motor controllers cannot put out a higher voltage than they take in from the battery. Without getting into PID theory, essentially if it's going too slow, the voltage is increased; if it's going too fast, the voltage is decreased. If you're running the motor at top speed (giving it full voltage), you can only adjust down. Far better to have your nominal operating speed at say 75% of top speed, especially later in the match when the battery voltage is reduced.

Originally Posted by Ether (Post 1526301)

Reading between the lines, it sounds like you are not planning to control wheel speed, is that right?

Originally Posted by roystur44 (Post 1526755)

Since the target is a hole in the wall and not a hoop. I think getting your shooter to have a fairly straight trajectory is needed. Let the motor rip and throw a fastball into the hole. It's all about aiming.


Roy

Originally Posted by CalTran (Post 1526757)

So what's your plan if your battery runs low, or (hopefully not) you forget to switch it between rounds? Pray that it still makes it?

Originally Posted by Mike Schreiber (Post 1526572)

For a shooter it really doesn't matter too much. The main thing that matters is your RPM and compression, I'm not convinced torque has a large impact on the shot as much as it has on spin up time / slow down after a ball is shot (which doesn't matter in this game). You want to get the wheels going at a specific repeatable speed to get an accurate shot - generally between 3000-8000 RPM with a 4" wheel(s) and depending on the distance / angle etc.

The advantage to a Mini CIM is that you can direct drive and be at around the right RPM, the disadvantage is that you can't really go any faster than free speed unless you gear up - which is silly. The Bag, 775, or 550 all have high free speeds and require some gearing down, but a versa planetary box makes that really easy. 550s are a little weird this year since you can't get them from VP or AM. Also consider packaging and where your motor / shooter will live inside the robot.

Originally Posted by Mike Schreiber (Post 1526572)

550s are a little weird this year since you can't get them from VP or AM. Also consider packaging and where your motor / shooter will live inside the robot.

Originally Posted by popnbrown (Post 1526521)

We're also looking at using a 775pro at a 3:1 but I'm having trouble figuring out how to attach a longer shaft to the VersaPlanetary Gearbox shaft.

Originally Posted by popnbrown (Post 1526521)

We're also looking at using a 775pro at a 3:1 but I'm having trouble figuring out how to attach a longer shaft to the VersaPlanetary Gearbox shaft.

I figure in order to gain efficiency it would be better to drive the shooter wheels directly from the gearbox, without adding a second set of gears, belt/pulley or sprocket/chain set-up. We don't have a lathe, so is our only option to not directly drive the shooter wheel?

Originally Posted by carpedav000 (Post 1527221)

We are using a miniCIM to power a ratcheting shift-to-freefall gearbox.

Originally Posted by carpedav000 (Post 1527221)

We are using a miniCIM to power a ratcheting shift-to-freefall gearbox.

Originally Posted by Monochron (Post 1527259)

Can you describe your reasoning for this? What is the pupose of a ratchet on your shooter? And why the need to shift to neutral?

Originally Posted by CalTran (Post 1527267)

Catapult?

Originally Posted by carpedav000 (Post 1527461)

Close, spring-powered linear puncher. :yikes: