[Angel And The Wolf]

OK, I think I have it now.The reason I need a single wheel is that my trailer will taper from hatch and bumper profile down to a 12 inch by 12 inch square tail plate, and I need to keep the wheel within that 12 inch transverse dimension. A standard ball hitch presents a problem in that the trailer is all too likely to fall sideways given the least angular change in forward travel. The U-Joint hitch solves this, but introduces lean steer in the wrong direction when the tow vehicle leans to the outside of a turn at speed. I've added servos where the trailer frame ties in to the tow bar to provide a correctional limited number of degrees opposite to the lean, using input from steering angle sensors on the steering arm of the tow vehicle. Properly calibrated, this should lean steer the trailer to track the tow vehicle in turns, rather than trying to steer the trailer (and push the rear of the tow vehicle) outside the turn circle. When the tow vehicle is traveling in a straight line, the servos will hold the trailer straight up, as if the rotational linkage were locked.

What do you think, Gumby?