mecanum wheels on a heavy robot

VEX V5 General Discussion Technical Discussion
#1

Would those that know the characteristics of mecanum wheels expect that 4 regular (default torque) motors would stall (or burn out)trying to strafe on a very heavy robot (say 32 lbs). If this is clearly a waist of time I’d prefer not even try it. Thanks

#2

I tried mecanums on my Skyrise robot, and it wasn’t a good idea. I used 4 Speed motors, and while forward movement didn’t see a drastic decrease in performance, strafing and turning did. It wasn’t worth the performance loss. Even on torque motors, using mecanums on a robot weighing upwards of 30 lbs isn’t going to be worth your time if you want decent strafing.

#3

Same.

#4

Much appreciated…That’s kind of what I suspected.

#5

In skyrise, with our very heavy robot we used mecanum wheels and had high speed motors geared down a little bit, but that was pretty slow, I would not suggest using them in higher speed games like NBN.

#6

I am currently building a mecanum drive to test out the strafing capabilities and see if it is a design that is worth it for potentially future games as we have not qualified for worlds. Are there any performance disadvantages that are major or any largely detracting features of this system vs. omnis that anyone knows of (speed, stalling, excet.)? I like the idea of being able to strafe because if seems like it would be useful especially in a non- NBN setting.

#7

Some problems that my team has faced in the past are:

  1. Mecannum wheel are slower than omnis.
  2. They seem to be less accurate during autonomous, but that was back when we did not use any sensors.
#8

Mecanum wheels are slower than a tank drive or an X-drive with the same speed, and I’m not sure if that’s just extreme power inefficiency (friction losses not resulting in torque gains) or a sqrt(2) mechanical advantage (more torque, less speed). They are also heavy and wide, so they don’t take up less space than 4" omni wheels rotated 45° (X-drive). Also, the X-drive is harder to mess up, since you just form a diamond (technically, you’re just rotating a rectangle, but a diamond is easier to visualize) with the wheels, rather than the mecanum’s “From the top, the rollers make an X, from the bottom, they make a diamond, and which wheels you use where actually matters.”

#9