X-Drive With Speed Motors

So in my teams skills competition we had an x-drive chassis with modded speed motors and during our matches the chassis would stall out so we had to switched to regular motors, any suggestions on how to fix this problem.

The only way you can use speed-geared drive motors is to have a light weight bot, particularly for x holonomic. Your options are to reduce weight (to the 13-15 pound range) or add motors (either two per wheel or two extra on the sides).

I know of teams using turbo-geared motors on tank drive, but only by using 6 motors with a 12-14 pound bot.

The only real motor wheel combinations I’ve found to work are the high speed motors on the 2.75 in omnis or torque motors on the 4in wheels. They provide very similar gear ratios. Any other combinations, without heavy adjustments (like an ultra light robot), will tend to stall out.

Note: Much better to have a consistent, slightly slower drive base than one which sporadically stalls out.

This is very true, at NBN worlds our robot had a high speed 4" omni wheel holonomic drive, and it stalled out about 30 seconds into each match. We replaced all the motors with toque, and even though it was slower, we did better afterwards.

Interesting. The answer to this question may come down to a lot of small things like build quality, weight distribution, and total robot weight. For our first competition this year, we ran a high speed x-drive on 3.25" omni wheels with no issues at all. Our robot is light (12.2 pounds). We may even go higher to turbo on 2.75" wheels.

In general, I think you should be able to run high speed on an x-drive. However, you will need a fairly light robot, as others have mentioned. Also, make sure the build quality is high, meaning the bearings are aligned, the axles are straight, and there isn’t too much pressure on the spacers along the axle.

Our robot has turbo motors with 3.25" inch omni-wheels on an x-drive and our driver has no trouble with tripping the ptc’s. We do have a very minimalistic robot but for this game I think that light simple robots will win in the end.

I know I did not start this post but I have a similar question. Our bot has an x-drive with turbo motors using the 2.75 inch wheels and the bot weighs about 11-12 pounds. the problem is it is twitching out. has anyone had a similar experience.

Keep in mind that an X-Drive is faster than a tank or H-Drive by default. Due to this reason, an X-Drive would lack torque compared to an H-Drive, and making the motors for an X-Drive to be turbo is a very weak solution. I would suggest not having turbo motors and try a not-as-fast gear ratio, or switch to an H-Drive.

We had an x drive with turbo motors and it never stalled out. Our bot must be lighter than i thought :stuck_out_tongue:

Lol. Lighter is better, right? :stuck_out_tongue:
We had a team last year and their x-drive was normal speed, and yet all of their motors’ fuze broke during a competition. If only they had their X-Drive started to work we would’ve beat Disco on that day :L
Their robot was about 30 pounds, RIP.

At the my first season comp. my x-drive was powered by 8 turbo motors, two per wheel, which, first of all, was much faster than any robot needs to drive in a full field game much less this one. We had two problems in competition that we unknowingly avoided while testing it.
1: Turbo motors are fast, so fine turns and other small movements were nearly impossible.
2: While turbo motors work well for driving really fast over flat ground on our light robot, the moment it tried to push through a group of stars on the field, it died.

Personally, I think that, due to field constraints, speed isn’t that much of an advantage unless you can also efficiently move game objects. So I would suggest not using a turbo x-drive for this competition as it gets pretty crowded on the field really quickly. We will probably go for 4 torque motors on our x-drive in the future (we may also try a mecanum drive) for the most power while maintaining our mobility.

I’m kinda glad to hear this real-world assessment of 8 turbo x-holonomic. I’ve been joking with my team about them trying it.

That said, the above problems can be solved with programming.

  1. The turn vector within your motor statement can be reduced. Rather than passing the full joystick value, divide it by 3 or capped it at some low value like 45.
  2. Lots of things can be done to scale the overall speed. You can proportionally scale the joystick value so that low values are reduced by a great amount and high values are not reduced at all, resulting in fine control at low values and warp speed when the joystick is pegged to an end. You could also make a turbo button… reduce all your joystick inputs, but multiply them back to full when some button is pressed.

I did have it capped at 50% power to each motor, so it was manageable to drive, but at about 1:20 into every match it stopped functioning. It would wiggle around a little but it wasn’t reasonably controllable. The driving can be modified for fine movements, but the main problem is the lack of power. With the large amount of objects that pile up around fence, your drive should have some pushing power. After being totally carried through the finals despite our consistent-ish high hang because the motors kept cutting out, we decided to change our drive to 4-torque motors.