A: Currently we can only model tractor-trailers in 2D however can display them in our 3D graphics (we are working on simlification of that process).
We have all the software to do 3D tractor/trailers/triples/etc:
- PHASE4 we modified and used in our FHWA research Task E Comparison of Simulation Models
The PHASE4 program was created to model trucks, trucks w/trailers and triples. To simplify the coding the authors of PHASE4 used 'small angle"
- Small-angle approximations are used as a useful simplification of the basic trigonometric functions which is approximately true in the limit where the angle approaches zero. They are truncations of the Taylor series for the basic trigonometric functions to a second-order approximation. Therefore the PHASE4 program has program STOPS at +/-10 to +/-15 degrees of roll and/or pitch since that is the approximate range where the small angles assumptions as valid.
Their only documentation of the changes they made to the code is in their publication:
- This is the extent of their documentation of that MAJOR endeavor:
Our bet is they simply took out the checks for program STOPS for angles greater than 10 degrees to 'extend beyond small angle assumptions' and they let it fly!!