In a week my new set is likely to arrive, replacing my old set, which was lost, in an airline incident. I was thinking about the drivetrain design. Which type I would use. It was brought to my attention that many teams have used X drive. But the speed ratio and the space efficiency have kept me away from the design. Now I was thinking between using an H drive or mecanum drive. The only information I’m aware of is that H drive can easily get pushed around. While mecanum drive has a wide drivetrain.
I wouldn’t use h drive because it takes 5 motors. We made our mecanums into 7 holes with a gear ratio on them, so only about an inch or 2 wider than a straight omni drive, but you don’t need too much internal ground space in your robot this year, so if you want strafe and a tank drive, use mecanums.
1 Like
You can easily fix the speed ratio by using one of the smaller wheel options. For a strafing drive the X drive is the way to go for this years game.
1 Like
I was prefering the mecanum drive over the X drive, i think that it takes up less space, however does sacrifice, the speed which the robot can move sideways, by half.
That makes sense, but the other disadvantage of mecanum drives, is the weight. Is that an issue which you had? With the motors loosing power, mostly when there is weight bearning?
If I understand what you are saying, the weight of the mechanum wheels aren’t a problem. Mechanum wheels aren’t very heavy when compared to the rest of the robot, and they are definitely not heavy enough to cause the drivetrain motors to stop working.
2 Likes
Yes, but they also don’t turn as fast and don’t strafe quite as well as a x drive. I love mecanum wheels, but considering there’s no climbing aspect this year and climbing is the only weakness of the X drive, I believe it’s worth the sacrifice of space.
2 Likes
That makes sense, I assume there were very few mecanums drives. I despite all this still prefer mecanum drives, realizing that I usually wouldn’t need to go very fast in a cube situation. It would be harder to control the fast sideways movement, and it way lead to flipping. As a first year person, my drivers are likely not going to be very good.
I can see that I guess, but don’t underestimated the importance of a fast drive train. The time you shave off will add up pretty quickly.
no. Mecanums are just a no-no to me. The disadvantages far outweigh the advantages. They slip a lot and have a lot less traction than Omnis.
1 Like
I agree. speed should be valued over torque in drive trains in most cases and as long as your motors do not overheat easily it’s fine.
We didn’t have any problems with this last year.
We were opposed to using mecanum wheels in TP because we were told they were slower than regular omni wheels, so when our sister team decided to try a mecanum drive on their bot, we had a race with them to see how much slower they actually were and found that they were the same speed as out omni drive (both tank). Given that they aren’t slower than other tank drives, I think mecanum drives will at least be used on defensive bots that want to strafe since you have more torque than an x drive.
1 Like
But omnis can get easily pushed unlike mecanum, which if the brake hold is applied cannot be easily pushed around.