Torque or Speed? For Drive.

What do you guys think? What is a good gearing ratio, keep in mind the weight of these cubes if i want to push them around.

as long as speed is chained then you should be good just don’t push others around:D

What ratio are you thinking? Not 1:1 i suppose?

Yeah 1:1 with motors on speed configuration. Ours was fine but since we didn’t chain them together we overheated a lot. If you chain them together though you’ll be golden.:slight_smile:

Both motors chained together?

Both. :wink:

Though if I were doing a single speed, go as fast as you can go without stalling.

Direct Drive with motors in the High Speed config is referred to as a ratio of 1:1.6, as it is a ratio of 1:1.6 compared to the out of the box high torque 393s.

I was thinking of a slightly faster drive, faster than 1:1. The drive I am currently planning on is a holonomic drive, 4 motor, 2.75inch diameter omni wheels, 160rpm direct drive, and use angle to adjust speed. 45 degree angle on such a holo drive will yield a gear ratio slightly below 1:1.6, comparing to a 100 rpm 4inch wheel drive. But the angle can be adjusted and the speed can be lowered down.

It’s probably a good idea to take into consideration the weight of your robot when you look at designing drives. We had a lot of issues with our drive stalling during the Toss Up season because our robot was considerably heavy, which took it’s toll on the motors(they were geared for speed, 1:1.6). For Skyrise it would probably be much more efficient to speedily traverse the field, but still be able to push through the cubes if they start to become an obstacle. I also think it’s worthwhile to have a drive as precise as possible when dealing with placing skyrise sections and the skyrise base. For that you might even consider going with PID control loops to tighten up the precision of your drive.

Can someone explain how you would use PID for driving, doesn’t PID need a set point to go to? Thanks

Edit: Like in driving wouldn’t any set point change constantly and quickly making PID not as effective?

Say for example you want to place a Skyrise Section on the base, but you’re going at full speed and you might overshoot the base’s exact location, forcing you to go reverse and constantly move your robot around to put the skyrise in. A PID control would allow you to move precisely what you set a sensor value to (like say for example, you press a button on the joystick to move forward 1 tile exactly. you could also set this to 1/2 a tile or whatever distance you need to move) and the PID would ensure that you stop exactly at that point. This could be useful in both autonomous AND teleoperated applications, and you could bind a button on the controller to switch from PID control to regular driver control, if preferred. (At least, that’s how I think it could work)

Ah that makes sense PID with buttons and set points would work

Yeah. As I typed this, I also realized that this might have been what one of my former sister teams did a few years ago in Sack Attack. Go figure! I can definitely see the need for PID this year to increase accuracy on the field, especially when building skyrises.

I honestly prefer torque that is geared or chained to a 3:1 or 2:1 because in the past we had overheating/stalling problems with speed.

I think it will be beneficial to have speed this year to collect and score your cubes quickly because there is no descoring. Once the cubes are on, they’re on for good. Get as many cubes as possible on each post. If someone is guarding that post, move on to the next. No sense wasting time fighting for the spots and burning out your drive.

However, it may be worthwhile to push bots away from the posts. They certainly won’t be locked on the goals like Toss Up. The ideal combination would probably one strong bot and one fast bot.

We’ll see.

My vote is for 1:1



I can’t lie. I want to tinker with the new turbo internal 1:2.4 gearing on the drive at some point.

1:2.4 speed drive might be a challenge.

If you plan to make a omni-functional robot that rises to 50 inches in, say, three seconds, and can effectively hold about three cubes and build skyrise tower, i think the robot is not very light and it will require somewhat a reliable lift. I personally also do desparately want a 1:2.4 direct drive, but that might be kind of risky in skyrise.

I think the turbo gearing could only be used on a drive reliably if you have 8 motors. That’s given that the robots this year will probably be heavier. However, I don’t think it will be very easy to dedicate 8 motors to the drive as obviously lifts are important this year. For college, it shouldn’t be too hard. However, I would rather do an 8 motor 1.6 X drive than an 8 motor regular turbo drive as it’s close to the same speed after you work the geometry out but you get the omni functionality.

Well we are lucky enough to be able to go all aluminum this year, so it won’t be as heavy, but like I said tinker. Mainly I’m just curious to see how quickly turbo will burn out. I’m guessing we’ll end up either with 1:1.6 or a custom gearing of 1:1.8 or 1:2. Idk…it’ll be fun to see where this all goes :slight_smile: