Would 3.25" wheels work?

I think you may have missed this, but I stated that we are already 100% aluminum.

then cut down on your metal.

Or just add a reduction gearbox.

Yeah, called high torque internal gearing…

idk, I think that something else is up with the OP’s problem. It could be the weight, but I dont think 20lbs would cause a problem after only 30 seconds. 5-10 minutes of hard driving, maybe sure, but 30s seems unlikely.
I mean, I used a 2 hs drive in NBN, on a heavy robot. Never had a problem

To answer your question, yes 3.25 inch omni-wheels may be worth it this season if you have a slight torque problem. However, you should realize that the torque added may still not be enough. I would highly recommend that you ensure that there is minimal friction on the axle, as well as making sure that you are using bearings on both sides of the axle. 20lbs is quite a bit of weight this season if you are using aluminium, there may be some unnecessary weight on your bot.

Ok so I retested the base motors for specifics, and basically what happened was after 1:30 of hard driving one side of the base stopped working. It just stopped spinning on the ground. However, when I lifted the robot up the motors worked fine. When I put it back down on the ground it was the same problem. However, if I waited 5-10 seconds all the motors were fine again. Weird.

This was tested using Jpearman’s Smart Motor Library and with a mobile goal w/ one cone on it.

Perhaps it could be something with the Smart Motor Library stopping the motors? I read that it stops the motors if it passes a certain calculated PTC temperature.

There is just too much weight. This problem is very common and not unusual at all. You can either reduce robot weight (post pictures and I or someone else can help), decrease the gear ratio (more torque), add motors (more power), reduce wheel size (more torque), or reduce friction in the bearings/chain (not always good enough). I can tell you that high speed four inch drive can only efficiently handle 18.45 pounds from my math, so 20 plus a mobile goal is way too much. I recommend reducing weight first, then possibly changing gear ratios.

@Bryan R I think we’ll have to just put torque motors on :(. If 18.45 is the max it can handle then we would need to shave off at least 5 lbs from our robot, which I think will be unlikely unless we do a redesign. Our robot has a 3 stage cascading lift with a chainbar on the last stage so it can stack cones, it also has a sideways four bar as a mobile goal lift. The version of our robot before this current one had a lot of steel (it was 24 lbs), and it worked fine with the torque motors. We figured that if we replace everything with aluminum + shave off extra stuff we could do it with 4 high speed motors.

Just out of curiosity, can someone with a dr4b robot post the robot’s weight?

@joshua.lim
I would be curious to see what happens with out the SmartMotor library as well. As to the weight, I have an internal DR4B + chainbar that comes in at right about 15 lbs. However it is pushing weight reduction to the extreme, and might not be feasible for everyone to achieve.

Your weight is not so high that I would immediately say that is the problem, if you can test without the library, try that first.

I calculated how much weight it could handle with 3.25" wheels, and I got 22.6 lbs. I think it could do it efficiently enough, or at least last 2 minutes without breaking. Maybe we will make this change in the future.

If you have your robot as light as 16 pounds 6 motor turbo on 3.25 will not burn out.