Hi, I’ve been noticing that some people are thinking about using an X-Drive for this year’s challenge, and I don’t find it strange, since when I saw the challenge the first thing that came to my mind was to use an X-Drive type of drivetrain due to the large amount of free space on the field.
The thing is that I have been hearing that an X-Drive has 41% more speed and 41% less torque than a tank drive. I’ve seen people mention an aura resource or something like that. But apparently it doesn’t exist anymore.
If anyone knows about it and knows of a resource that explains it I would really appreciate it.
And finally I ask you all what you think is the best option for this year, X-Drive or Tank Drive.
I sincerely opted for a PTO of 6 motors in a tank drive, but since I saw the 41% more speed made me doubt, that’s the reason for this topic.
At the end of the day its what your driver and team prefer.
I personally came to the conclusion that x drive would not be a good choice due to its lack of torque, and I belive that goalrush would become meta, so a 360-480rpm 6m drive tank bot would be perfect, I recommend looking back at tipping point worlds matches to see what worked best, I would say roundup but apart from being the early days of vex, I cant seem to find worlds footage of that year
If you look at the image below you can see that when the red and blue wheels both move forward then the resulting vector is √2 or 1.41 times further forward than the black vector representing a tank drive. The opposite is true of torque because only the y values of the vectors add and a tank drive has 2 units of torque and the x drive has 1.41.
In terms of viability, this year the optimal speed was ≈60 inches per second, and a direct driven x-drive on 200 rpm motors goes 59 in/s. This combined with the change in torque essentially makes the x-drive a gear ratio that adds the ability to strafe.
I am planning on using an X-drive but that might change after the manual comes out tonight and a couple more early revels happen in the next week. The main issue is whether most people end up using 66-watt drivetrains or not because, with an x drive, it is almost impossible to make an effective 66-watt drivetrain.
As for a PTO, it is possible to connect one to an x-drive with the universal joint or just have the other mechanism at 45 degrees.
Thank you very much for everything, now I understand better the fact that the X-Drive go faster. So for the time being I’ll stick with the tank drive idea.
If you are planning on 200rpm x drive, 66w is not so crazy. So, if you want to be beaten to the rush and pushed around by all the inline drives, don’t let the 66w thing stop you
Seriously, x-drive has no push. Opponent comes at you at all obliquely and you effectively have half your drive motors eliminated.
An X-drive is not “faster” than a tank drive. The speed boost that an X-Drive gives you is essentially just a gear ratio due to the geometry. You are still sacrificing torque in the forward direction. You could make a tank drive go just as fast, or an X-drive just as slow as a tank drive using a gear ratio. This: “Seriously, x-drive has no push. Opponent comes at you at all obliquely and you effectively have half your drive motors eliminated.” from @DougMoyers (sorry, don’t know how to quote you properly) is why an X-drive gets pushed around really easily, not just a lack of torque.
as someone who has run in nearly every competition in spin up and over under, i can say with confidence that no one has ever managed to push the drive at a diagonal. it’s simply too difficult with a tank drive since the x drive tends to just rotate (although i suspect a mecanum might have more success…)
