To keep myself on the center platform how would I lock the gears to the drive train of my robot at the press of a button?
hmmmm… well, you’d need a motor dedicated to the task. The best way to do it would be to jam something to stop it from moving. You could have something side between the spokes on the wheels. You could stick a piece of antislip in between external gears to jam those. If your driven wheel shaft is on a lock bar, you could jam that the same way you’d jam your wheels. You could employ a dual ratchet.
Brakes on cars use friction on the drive shaft. You could put a high-torque arm over your wheels with antislip to press down on them. Or maybe your driven shaft, which I don’t see working out well.
I don’t know that there is a mechanically sound way to do it. Without the V5 “Brake Mode,” you’d need to do it mechanically… Unless you do have V5, but I think I saw in another thread that you don’t.
There are a bunch of other threads about ways to stay on the platform. Locking your wheels doesn’t seem like the best possible way to do this. Unless you come up with a super cool system that revolutionizes how we think about brakes. That’d be pretty awesome.
You can do this in software with a PID. Here is a good explanation if you need it. If your drive PID is tuned correctly, you should be able to set the target to the current position on a button press and turn it on. It will hold its position reasonable well. This is a good way to add a brake, as it doesn’t require any extra motors or hardware (except for encoders, which I would recommend having anyway). We have had great success with this in ITZ (when doing driver loads) and parking this year. Just remember that this will use motor power, if you are pushed VERY hard, it may burn out your PTCs. However, this should not happen unless you are being pushed by something ridiculous, like a 6 motor V5 drive- you should generally be fine.
This type of brake will also not prevent you being pushed from the side (assuming you are using all omnis). To protect against that, you should either use locked omnis (see the attached photo- credit to team 240P) or a vertican brake that pushes into the floor (non-destructively of course). These are generally implemented with pneumatics, although it is possible with motors. If you use this type of brake, a PID brake will be mostly unnecessary.