Rotating with crab drive

[wildaburk3160]

I had actually thought about this before, but wasn't completely sure it would work.

Okay, that's what we will try to do. It shouldn't be too difficult.

[Ether]

Originally Posted by wildaburk3160

I had actually thought about this before, but wasn't completely sure it would work.

Okay, that's what we will try to do. It shouldn't be too difficult.

If you tell me the length of your trackwidth and wheelbase, I can give you the exact angle you should use for completely scrubless/skipless turning.

trackwidth is the distance between the front (or rear) wheels.

wheelbase is the distance between the front left and rear left wheels (or front right and rear right wheels).

[Ether]

Originally Posted by Ether

If you tell me the length of your trackwidth and wheelbase, I can give you the exact angle you should use for completely scrubless/skipless turning.

... and if you want the center of rotation to be something else than the center of the wheel pattern (like maybe closer to the front of the robot), let me know where and I'll tell you the wheel angles (and speeds) for that.

[wildaburk3160]

Wheelbase: 11.717 in
Trackwidth: 26.626 in

[Ether]

Originally Posted by wildaburk3160

Wheelbase: 11.717 in
Trackwidth: 26.626 in

Are you sure it isn't the other way around? What you've described is what is commonly called a "wide" robot (trackwidth greater than wheelbase).


trackwidth > wheelbase (wide robot):

      front
|--------------|


|--------------|
      back

trackwidth < wheelbase (narrow robot):

front
|---|




|---|
back

[wildaburk3160]

Yes, I messed up the calculations there. Here is the cad drawing showing the distances from the centers of the wheels.


http://i.imgur.com/810iW19.png

The center of our wheelbase is not at the center of the frame, so the distance between the center of the frame and the center of the wheelbase is given.

[Ether]

Originally Posted by wildaburk3160

Yes, I messed up the calculations there. Here is the cad drawing showing the distances from the centers of the wheels.

The wheel pattern is very close to square. Use 45 degrees as mentioned previously.

[wildaburk3160]

Will do.

[wildaburk3160]

We got it working. Thanks for the input.