Let's Make Robots!

FingerTech Mecanum Wheels

Vendor's Description: 

See our new Mecanum Wheel Set!

• FingerTech's revolutionary new Mecanum Wheels allow any robotics enthusiast to add omni-directional capabilities to their creation.

Link to store page

Link to YouTube Commercial!

• Precision engineered delrin hubs and rubber rollers attach to a customizable mount for any motor shaft size between 3mm and 1/4".

• Kit includes:
• Four Mecanum wheels (two A-style, two B-style)
• Four mounting hubs
• Four 4-40 screws + one 6-32 setscrew per wheel
• One 0.050" hex wrench
• Instructions

 What can they do?
The four mecanum wheels are each connected to a motor for independent control. The robot can move forward, reverse and spin just like four regular wheels. The configuration of rollers at 45° also allows the robot to translate sideways and through a combination of these, in any direction (even while spinning!).

How do they work?
Adjacent corners use mirrored hubs so that the wheels freely roll outward from the center of the robot. This splits the force into two vectors, one forward/backward and one right/left. When the wheels on one side are spun in opposite directions, the forward and backward vectors cancel out while both sideways vectors add up. Doing the reverse with the other two wheels results in four added sideways vectors.

How do I drive?
Control can be accomplished with a microcontroller or simply using an R/C transmitter! When both sticks are pushed in any direction, the robot moves in that direction. Pushing the sticks towards or away from each other makes the robot spin in place.
The easiest way to think of it is that the left stick controls the front two wheels in any direction, and the right stick controls the rear two wheels in any direction. To achieve this control, two of our V-Tail mixers are required. One mixes the front two wheels to the left stick to respond just like a two-wheel-drive robot. The second mixes the rear two wheels to the right stick in the opposite fashion.

Mecanum Hub material: Black Acetal (Delrin)
Roller material: EPDM 50-60D(A) Rubber
Outside wheel diameter: 2.125"
Wheel width at widest point: 1.25"
Customizable mount bore: 3mm (can be drilled to any size up to 1/4")
Weight: 48grams (1.69oz) per wheel

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Oh! Nice!
  I like the idea of rubber for the wheels but still a little pricey for just plastic wheels. I like the idea of varable shaft size options. That does give it a plus.
     I didn't mean to ruffle anyone's feathers. I do like the idea of rubber wheels. They do have silicone coated wheels that may be as good. You have to think industrial and convert. I have no money to invest until Ebay is a little nicer to me. I deal with mostly Parallax stuff and surplus motors beyond the toy stage. Parallax does have fantastic support for their products along with an engineering staff for newbees like me.               http://omniwheel.com/transwheel/transwheel-2000.htm  

If I understand you correctly, you want to use regular omniwheel rollers in a mecanum wheel?  It might work, but it would make for one heckuva bumpy ride.  Our rollers are designed specifically for these wheels and have a particular profile.  If you look at the mecanum wheel sideways, the rollers create a perfect circle.

 I like Parallax too, but I'm not sure what they have to do with this post?

This is primarily directed at FingerTech Robotics, but I suppose anyone can chime in.

Would I be correct in assuming that mecanum wheels are suited to an indoor, or at least a flat hard surface only? 

Also, as I'm in the middle of designing a suspension system, would you advise against using a suspension system with mecanum wheels.

I think I know the answers to both questions, but I thought I'd get an official answer. ; j

I've never seen mecanum wheels operating on anything but hard and flat surfaces.  I would be interested to see how some of the bigger wheels perform on grass or gravel.

As for suspension, I think it is a good idea.  Unless you can be sure that a rigid chassis has all four wheels contacting the ground equally, some flex is desired.
The chassis in the demo video is made from garolite and allows the wheels to spring a bit.  It works great.  A combat robot I made with a thick aluminum chassis did not work well because two corner wheels were a bit lower than the others.  I will be adding some flex to that chassis before I try to use it again.

Thanks, I didn't consider the need to allow some flex in the frame to keep all wheels in good contact. I was more thinking of a suspension with 1.5 to 2.0 cm of travel. I figured that might interfere with the way the wheels interact to get a turn without rotating the body.  Maybe as long as the surface is smooth, mecanum wheels would work.  Think slow rolling hills rather than rocky bumps.

As long as the weight distribution is equal between the front and back wheels of each side, you could have them at any height you desire!

If you tilt the wheels though, you will have a bumpy ride and probably not translate siedways very well.

I just remembered that few months ago i posted a video showing an XL version of that kind of wheels...


is it the speed for four motor is same???....