So on the most recent FUN stream they were talking about team 1102’s 2018 robot. They showed a picture of the robot’s drive train and it had 6 mecanum wheels.
I know in 2017 team 1986 had 8 mecanum wheels in their drive train. I think (don’t quote me on this) they said it gave them more grip and helped them to strafe straighter.
So I am wondering what is the advantage of having 6 mecanum wheels?
What are the disadvantages and any other interesting characteristics of this specific drive train?
1102 had 8 mecanum wheels just like 1986.
Here’s the specific image they were discussing, or rather decided not to discuss the six mecanums:
This is a totally conjectural theory, but a serious one:
The robot was initially designed with four mecanums, on the corners. How would it behave? According to my eyeball estimation, the center of gravity of the robot is about six inches behind* the center of volume. This would cause the rear wheels to carry about 3/5 to 2/3 of the weight. When driving forward, this is a wash, as the strafing forces of the wheels across from each other balance out. However, when strafing, this would cause a slight rotation of the tail towards and nose away from the strafe, and when rotating, this would cause a slight strafe in the opposite direction of the rotation.
For some reason, they decided to re-balance the wheel load by moving the wheels rather than the CoG, but they didin’t want to leave the front end unsupported on unlevel ground such as the cable bumps or the platform slopes. Solution? Two more wheels.
*Assumes the metal bowl is at the front of the robot.
Nah, they had eight mecanum, two are just obscured in that picture. Here’s a still I took from their video showing the eight wheels:
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Where in the stream did they discuss what we did? I have been under a rock…
The third set of wheels from the front was hidden under the cross bar that our climber was mounted to. You can’t see it in the picture you posted.
You can see it on the floor in the video I posted here…
As for why? We ran tests. I wasn’t sure why 1986 did 8 wheel mecanum in 2017…and I saw the general reason they gave was that they did everything mecanum did…just better. (weight penalty aside)
In our drivers opinion the 8WD was smoother, and moved sideways more accurately. Will we do it again? It depends. Maybe, maybe not. It certainly helped in some small ways and definitely didn’t do much for us in others.
As for COG. We had our weight centered as much as we possibly could.
FUN was discussing the GreyT products. Your updated intake was shown. They had a picture of your previous intake and commented on what appeared to be a 6 wheel set up.
David