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Unread 26-10-2016, 22:35
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Re: [FTC]: Is this Mecanum wheel configuration acceptable?

Quote:
Originally Posted by GeeTwo View Post
Can you increase the brightness and contrast? I can see what I assume is a mecanum wheel because you mentioned it, and a couple of other shapes before I enhance it.

After doing both adjustments, there are a couple of questions that come quickly to mind:

First, is this picture inverted? If not, you will have VERY little ground clearance, and the bolts securing the gearboxes to the c-channel will be in tension rather than compression. Don't worry so much about the robot holding the wheels up as that the wheels hold the robot up.

Second, consider whether the gearbox can handle the shear force of supporting its share of the robot weight. In the very best case, 1/4 of the robot weight will be applied at the center of the wheel to the axle. In a more realistic low-impact case, it will be more like 1/2 of the robot weight. In a high-impact case (e.g. something similar to STRONHOLD, where you are hitting vertical walls and catching air), you will want to multiply by another factor of 3 or 4 or more. As I look at the NeveRest40 (picked one at random), I do not see what sort of lateral torque it will support. If the gearbox is not up to supporting this torque, the simplest solution is to place another support member and bearing at the end of the shaft, past the wheel, and support a significant portion of the robot weight on those members.
Sorry about the weird image, still familiarizing with SolidWorks, I will attached a non rendered image.

Yes, the model is flipped, so the wheels will and motor will be on the bottom side of the structure.

I believe we will be using a NeveRest 20, or possibly a Matrix motor to drive Mecanum wheels. I wasn't really concerned with the weight impacting the motors too much -- well not until you mentioned it (: I think we may end up supporting the other side of the wheel, like you suggested. It doesn't seem favorable given the limited time, however it most likely will happen!
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