[DanL]

How's this for some brief thinking? (Disclaimer: probably requires a physics class under your belt, preferably one with some calc)

1. Measure wheel rotational velocities (eg wheel encoders).
2. Assume no-slip condition, and calculate force vectors exerted by each wheel. Estimate robot-trailer CoM, and use vector arithmetic to calculate assumed torque around the CoM.
3. Using a gyro (needs to be right on the CoM?), calculate actual angular acceleration.
4. Compare actual angular acceleration to predicted angular acceleration (derived from torque in step 2) -- this is your traction control system's wheel-slip-error measurement. If actual A_angular < predicted A_angular, you're slipping and you need to cut power.

Does this sound legit to you more mechanically-inclined people out there? It's an approximation since we're ignoring all the friction forces created by the the robot/trailer wheels sliding, but will it be close enough?

How about the process of combining linear traction control with angular traction control? Do people predict any weird dependencies, or can we just use good ol' superposition?