Blog | Fall 2021 Software Update
With the start of Fall, the Virtual CRASH team brings the Virtual CRASH 5 family of users another great (and free) software update. Read on to learn more about the latest software update.
Momentum Solver + EDR pre-impact Speed Data
Before continuing we recommend you familiarize yourself with the Momentum Solver tool introduced in the User’s Guide (VC5). It’s also worth reviewing the EDR feature of the Path Animation tool since the control workflow is identical.
Use case 1: Known pre-impact speed for a single vehicle (1-D)
Let’s suppose we’ve set up our Momentum Solver for a 1-D collision. Let’s further suppose we wish to specify vehicle 1’s pre-impact speed behavior by using our EDR pre-crash speed data. First, left-click on the linear momentum object in the project. Next, expand the “vehicle 1-inputs” menu. Enable the “pre-impact EDR” toggle. Note, by doing this, Virtual CRASH automatically removes the “known value” input option in the “method” menu of the Momentum Solver. Since we wish to import speed data, we’ll also disable the “use acceleration” toggle, and enable the “use speed” toggle.
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The time column and the speed column are pasted in separately from our Excel table. First, we paste the time values. Note, the absolute time value is not important here. Virtual CRASH uses the implied time increments from the time data column. Left-click on the box to the right of “time”, then left-click on “data” from the dropdown.
With the graph window open, lasso the values in the time column from your Excel data and press ctrl+c. Next, in the graph window, left-click on “paste text data”.
You will now see the time values graphed versus row number. Scroll through the values displayed on the left side of the graph and confirm the correct values have been pasted.
Next, left-click on the box to the right of “speed”.
In Excel, lasso the speed values and press ctrl+c. In the diagram window, left-click on “paste text data”.
You should now see the speed values graphed as a function of row number. Again, confirm that the speed values have been entered correctly.
The Momentum Solver’s calculations will update using the final speed value in the EDR data as the known impact speed value.
Use case 2: Known pre-impact speeds for both vehicles (1-D)
If you wish to use EDR pre-impact speed data for both vehicles when using “method: collinear 1-D”, be aware that the system will be overdetermined. The pre-impact speeds for both vehicles will be set by the EDR input speed data (not derived based on COLM). The post-impact (departure) speeds are determined by work-energy. Therefore, care must be taken to ensure that your scenario is not implying a violation of Newton’s 3rd law.
Use case 3: Known pre-impact speed for one or both vehicles (2-D)
If you wish to use EDR pre-impact speed data for one or both vehicles when using “method: linear 2-D”, be aware that the system will be overdetermined. The pre-impact speed(s) for one (both) vehicle(s) will be set by the EDR input speed data (not derived based on COLM). The post-impact (departure) speeds are determined by work-energy. Therefore, care must be taken to ensure that your scenario is not implying a violation of Newton’s 3rd law.
Use case 4: Known acceleration versus time
If the “use acceleration” option is enabled, the user can specify pre-impact acceleration behavior for the given vehicle. As with speed data, acceleration data can be pasted into from a spreadsheet application. The implied speed versus time is then calculated, evaluated backward, starting with the pre-impact speed determined Momentum Solver tool. This option may be preferred for complex pre-impact acceleration and deceleration sequences leading to impact.
New Pan and Rotate Controls
Now when the mouse cursor is linked to a polyline, curve, animation path, or dimension line 3D, you can pan by pressing the Ctrl key on your keyboard. You can rotate by pressing Ctrl+Shift. Prior to this update, the only way to pan with mouse cursor linked was to zoom out and zoom in with the mouse scroll wheel. This feature is demonstrated below.
TFW (“World File”) Parsing for Rotated Orthos
If you use a photogrammetry app that exports rotated orthomosaics (such as Reality Capture), you can now use the Smart Alignment Tool in Virtual CRASH to automatically import, scale, and align your orthomosaic imagery with point cloud, total station, or RTK GPS assets. Just follow the standard workflow described here.
Kinematic Wheel Rotation for Reversing Vehicles
For vehicles assigned to a Kinematics Tool, wheel rotation will now reverse for backward vehicle motion.