Quote:
Originally Posted by JVN
I will look into posting the sideways CoF. I don't believe we tested that when we did our experimentation last year.
Our omni directional wheels should have very very low CoF Side-Side, since we're pretty happy with how freely the rollers spin. 
Unless I'm missing something, using the locked-wheel test, shouldn't the Mecanum Side-Side be identical to front-back? (Isn't that the simplifying virtue of a 45-degree angle?)
Regarding a method to measure dynamic CoF -- one method I've used in the past is:
Get the robot sliding, using the incline test. Slowly reduce the amount of tilt until it stops moving. Measure the angle and calculate like normal.
Out of curiosity -- what sort of design are you doing for FRC which requires dynamic CoF? |
Conceptually I agree that mecanum should have equal forward and side CoF. I am trying to reconcile why AndyMark specifies 0.7 forward and 0.6 side for their mecanum and 1.0 forward for their Omni. I thought I had it, but more data seems to just make things more confusing.
The dynamic CoF is interesting for two reasons. First, I am trying to predict where the transition to/from traction limited will occur (possibly not of practical importance). Second, many teams seem to depend on the wheels slipping during a pushing match (or drive into a wall) to limit the motor current. Four CIMs each drawing a stall current of 133A will obviously pop the breakers. The question is, what gear ratio gets the current to about 40A per CIM when driving into a wall. I believe we need the dynamic CoF for that calculation. This is true for traction wheels as well as holonomic wheels.