## 3D tractor trailers simulation in medit3D?

Question on HVOSM including 3D Vehicle simulation and other 3D Simulation models (HVOSM clones, etc.)
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### 3D tractor trailers simulation in medit3D?

Q: Do you have the ability to have 3D tractor trailers in medit3D?

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:
We unfortunately haven’t had a budget/time to implement in the medit3D environment and not sure when that will occur

The PHASE4 program was created to model trucks, trucks w/trailers and triples. To simplify the coding the authors of PHASE4 used 'small angle"
assumptions.
• 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.
PHASE4 is the program used in HVE, however they published that they modified the program for "large angles", in other words they extended the many equations for the PHASE4 program to INCLUDE the trigonometric functions instead of the simple angles.
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:
• documentation of EDC changes to PHASE4.jpg (41.58 KiB) Viewed 75 times
Their statement 'completely rewritten' of the code we'd bet is mostly transformation of the code from Fortran code to C++ code which is not required since all codes can communicate and link at the binary/machine level!
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!!
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