The physics of pushing

[Ken Streeter]

Originally Posted by Ether

Nice catch. In my haste I labelled "h" as the vertical distance from the force to the ground. It should be the vertical distance from the force to the horizontal witness line through the center of the rear wheels.

See corrected diagram in original post.

Oops! I actually liked where you had it the first time -- changing the diagram has now gone and made my earlier post invalid -- except it now agrees with my calculations! Whew!

[Ether]

Originally Posted by Ken Streeter

Oops! I actually liked where you had it the first time -- changing the diagram has now gone and made my earlier post invalid -- oh well!

Ah, I didn't consider that. I re-attached the original diagram to provide context for your post.

What I think I was probably missing in my calculation from the earlier diagram and might have been why you had included "tau" in the equations was considering the rotational torque of the wheels on the floor. Is that it?

Yes, the rotational reaction torque on the robot due to the torque on the wheels.

In that case, though, it would be necessary to consider the radius of the wheels (which is not necessarily the same as "h").

Yes. I think you posted this while I was busy wordsmithing my previous post It now explains the role of "r", the wheel radius.