Article Number: 117 | VC6 | VC5 | VC4 | VC3 | Post Date: December 31, 2025 | Updated: December 31, 2025

For Auto-EES and EES objects, with respect to what part of the vehicle is Delta-V reported?

The Auto-EES and EES objects are data containers that report quantities related to impulse exchanges during rigid body contact interactions governed by the Kudlich-Slibar model. This is the default contact model enabled for simulated vehicle objects (learn more). In the "object 1" and "object 2" menus of EES objects, you can find "Delta-V (impulse / mass)" reported. This value equals the ratio of impulse magnitude to vehicle mass and is therefore defined at the vehicle's center of gravity.

PDOF from Cumulative $\Delta \vec{v}$

As of the Summer 2020 Software Update, VC6, VC5, VC4 users can use the dynamics info tool to report the cumulative $\Delta \vec{v}$. The cumulative $\Delta \vec{v}$ is the change-in-velocity that occurs between two arbitrary moments of time, defined by:

$$ \Delta \vec{v} = \vec{v}(t_f) - \vec{v}(t_i) $$

where $t_i$ is the initial time and $t_f$ final time for the calculation. The cumulative $\Delta \vec{v}$ may be preferable to instantaneous values in cases where contact interactions require numerous impulse exchanges to resolve, cases where tire forces may be non-negligible compared to collision forces, or cases involving joint couplings (such as tractor-trailers).

See this blog post to learn more about accessing the cumulative $\Delta \vec{v}$.

As of the Summer 2025 Software Update, the cumulative $\Delta \vec{v}$ can be displayed in traditional SAE J670 conventions (learn more).

Note the Dynamics Info Tool (learn more) can be linked to the Accelerometer Tool (learn more) to monitor behavior at specific locations within the vehicle frame. The accelerometer-linked Dynamics Info Tool can also be used to estimate cumulative Delta-V vector quantities within a user-specified time interval at any position within the vehicle frame.