How fast was the fastest mecaum?

[asid61]

Out of curiosity, has anybody actually geared their mecanum drives for anything above 15-16fps? Generally I see speeds of 10-12fps with mecanums.
I'm asking because I always see the claim that mecanums can't go fast, but I've actually never heard of anybody who has tried. There's nothing that limits it in theory, so I wanted to know the practical limit.

[Jay O'Donnell]

2052 has done a pretty good job of a fast mecanum bot: http://youtu.be/Ogy65hEPIXk

[asid61]

Originally Posted by Jay O'Donnell

2052 has done a pretty good job of a fast mecanum bot: http://youtu.be/Ogy65hEPIXk

That's a really well done mecanum. I can't find the actual speed listed anywhere though, although it definitely looks pretty fast.

[mschwab013]

At 291 we usually have pretty fast mecanum. We build custom gearboxs and see about 13-14 fps

[SpeedFreed]

For a summer project, we built an octanum drivetrain powered off of 4 CIMs and 4 Mini-CIMs, and geared the mecanum wheels to 20.5 FPS free-speed. We saw speeds of about 17 FPS, on the field, and 19 FPS in our school's hallways.

In addition, we used the OLD Vex 6" mecanum wheels (the ones that break), and still had them last well enough for whole off-season competition. We have since switched to the updated versions, and they look like they should be fine (haven't tested through a competition though).

[asid61]

Originally Posted by SpeedFreed

For a summer project, we built an octanum drivetrain powered off of 4 CIMs and 4 Mini-CIMs, and geared the mecanum wheels to 20.5 FPS free-speed. We saw speeds of about 17 FPS, on the field, and 19 FPS in our school's hallways.

In addition, we used the OLD Vex 6" mecanum wheels (the ones that break), and still had them last well enough for whole off-season competition. We have since switched to the updated versions, and they look like they should be fine (haven't tested through a competition though).

WOW see now that's what I'm looking for! That's actually a really fast speed for any drive, especially mecanum.
How did strafing go? Even if it was slower than straight, how fast was it? Did you run a suspension?

[Ether]

Originally Posted by SpeedFreed

geared the mecanum wheels to 20.5 FPS free-speed. We saw speeds of about 17 FPS, on the field, and 19 FPS in our school's hallways

That's 93% "speed loss constant" in the hallway and 83% on the field. Interesting.

How did you measure the actual speed? e.g. video, stopwatch, etc?

Would you be willing to share the raw data?

[Jay O'Donnell]

Here's another one, keep in mind they aren't on carpet. http://youtu.be/O_vvVU4OBT4

[Jay O'Donnell]

Originally Posted by SpeedFreed

For a summer project, we built an octanum drivetrain powered off of 4 CIMs and 4 Mini-CIMs, and geared the mecanum wheels to 20.5 FPS free-speed. We saw speeds of about 17 FPS, on the field, and 19 FPS in our school's hallways.

Was this due to never having enough space/time on the field to accelerate to your full speed? That would be a problem this year since the field will get cramped and there won't be room to accelerate much.

[Ether]

Originally Posted by Jay O'Donnell

Was this due to never having enough space/time on the field to accelerate to your full speed?

He said 20.5 fps free speed, which presumably meant "vehicle speed at motor spec free speed". The reduced actual top speed presumably due to JVN's "speed loss constant".

[Chexposito]

Team Titanium's 2008 robot comes to mind.

[Jay O'Donnell]

Originally Posted by Ether

He said 20.5 fps free speed, which presumably meant "vehicle speed at motor spec free speed". The reduced actual top speed presumably due to JVN's "speed loss constant".

I was asking about the difference between the school tested speed and field speed. I'm assuming with a bigger runway one would have more time to accelerate than on a real field that has obstacles.

[Ether]

Originally Posted by Jay O'Donnell

I was asking about the difference between the school tested speed and field speed.

Pronouns are the cause of many misunderstandings.

The difference in hall vs field speed could be due to the difference in compliance of the flooring (carpeted field vs tiled hallway).

[FrankJ]

In a frictionless physics lab I would expect the free speed between the field (carpet?) & hall wall (tiles of other hard surface?) to be the same. In the world the wheels may not be perfectly aligned. The macanum rollers turns more freely on a hard surface rather than carpet. All this create side forces. The side forces net out to zero but consume energy thus a lower speed.

[silverD]

Originally Posted by asid61

That's a really well done mecanum. I can't find the actual speed listed anywhere though, although it definitely looks pretty fast.

Thanks
Our 2013 robot, Silverfish, used 8" mecanum with a 12.75:1 reduction for a free-speed of 14.53 ft/s (11.77 ft/s adjusted).
Our 2014 robot, Dragonfly, again used 8" mecanum, but with a 10.71:1 reduction for a free-speed of 17.3 ft/s (14 ft/s adjusted).