McHenry Forum - Crash Reconstruction & Simulation

The Coordinate Sign Convention for Vehicle Dynamics as follows:

• X forward,
• Y to the right,
• Z down (towards the earth as in Positive Gravity)

The msmac3D, HVOSM and SMAC programs ALL use the same conventions.
When HVOSM was first developed in the late 60s space travel was on the rise so they wanted a general purpose program that could simulate in near zero gravity (HVOSM & msmac3D can still do that! since Gravity is an optional input)
So Raymond R McHenry used flight conventions for the simulation coordinate system.
Flight conventions:

• This was from book Dynamics of flight, originally published in 1959 and used by Ray McHenry in his graduate studies at the Chrysler Institute of Engineering and then in the formulation for HVOSM, SMAC etc.
  The sign convention also adopted by SAE in 1994 as sign convention for Sign Convention for Vehicle Crash Testing J1733_201811

  

  Sign Conventions.png (113.06 KiB) Viewed 18361 times

  Here is the HVOSM Coordinates:

  

  HVOSM Coordinates.jpg (36.89 KiB) Viewed 20858 times

  NOTE: Some simulation programs use Cartesian Coordinates.
  • Like the screen you are reading this on.
    • X goes + across to right,
    • Y goes + UP, and
    • Z goes + coming out at you.

    

    Cartesian Coordinates.jpg (11.17 KiB) Viewed 20858 times