Drive System for Skyrise

I’m a new builder in my team and I would like to consult the experts:

What would be better in drive systems: torque or speed?

At the moment, I am using a 5:3 ratio (I think) that is being driven by a two motors (one per side of the drive). So far, it has successfully driven. However recently, it has stopped working properly. During autonomous, it would stop working about 4 seconds in. We have replaced the battery with a fresh one, and the outcome was the same.

I am currently debating on changing the gear ratio to 3:5 to increase the torque or to make a new gear/sprocket system that uses two motors that is speed-based (I have a design, but I haven’t calculated the gear ratio yet).

If I were to replace my drive system with a new one, I would need to modify my current lift so it uses less motors; however our first scrimmage is on tuesday and I am pressed for time.

I would like some feedback if you guys don’t mind.
ImageUploadedByTapatalk1411183342.358478.jpg

The wheels are hypothetical. They will be replaced by omniwheels in the final build.

Ok. I see your issues here.

  1. Mostly, drives have at least 4 motors. If you can’t spare more motors for whatever reason, then you’d have to make your drive very highly geared for torque which will also make it very slow.

  2. Your base is made of steel which most likely means your robot is heavy. With a heavy robot, you can’t always gear for speed. Again, try more torque or motors.

  3. You are not using any bearing blocks. http://www.vexrobotics.com/276-1209.html . These may seem silly and annoying, but what they are there for is to reduce friction. You should have every single axle going through one of these for each piece of metal. (So you’d have one on the piece of metal on the right side of the wheel and the left to help the axle).

  4. In the future, you should plan to have more motors for your drive. I usually get off fine with allowing there to be 4 motors on the drive, 4 motors on the lift, and 2 motors for the intake(s).

If you need more help feel free to p.m me. I know how frustrating it can be sometimes :slight_smile:

Actually, I planned to have Derlin Bearings in the axles, I was short in times when I made that, so I just focused on testing out the fit of the gear and sprockets.

Also, I should have added that I am doing an H-Drive, leaving me with only 4 on the lift and 1 on the intake.

You need more motors

Not really the forum to post this anyway…

My suggestion would be to convert to a tank drive so that the drive can have 4 motors going forward. This is pretty much a necessity, as you’ll find a 2 motor drive will stall chronically in matches due to the lack of torque.
If you really must have the ability to move sideways, try an X-drive or a mecanum drive. This allows you to use all 4 motors when traveling in any direction except diagonal.

Actually you need both: torque and speed. The 4-seconds-off-problem you are talking about usually means that the motors stall (they have an internal temperature sensor that will prevent them from overheating). Your drive is most likely putting a load on the motors that is to high. The motors will get hot and turn of to prevent damage. I would try it with a different gear ratio or more motors (don’t know if that’s possible or not).