Blog | Easy EDR Animations
The 2021 Summer Software Update brings Easy EDR Sequence types to the Virtual CRASH 5 Path Animation tool. This sequence type was used to create the video below:
This EDR sequence type allows users to input either speed or acceleration time-series data into the Path Animation tool to quickly generate animated motion. You can even input multiple EDR sequences into the same path. Details of this new feature are given below. Before continuing, we strongly recommend first reviewing the various posts on the Path Animation tool here: https://www.vcrashusa.com/vcrash-academy-path-animations.
To illustrate the Easy EDR Sequence type, we will use the front-to-rear impact scenario shown here:
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Using Speed Data
In this case, the blue (target) vehicle was at rest at the moment of impact. Suppose we have EDR pre-crash data from the bullet vehicle, as well as cumulative longitudinal Delta-V. Here we see the black line indicating pre-crash speed.
Creating an Excel Table from a PDF File
In our Acrobat reader, which we use to read reports, we can simply left-click hold and drag to select all values from the pre-crash speed table, then we press ctrl+c to copy.
In Excel, press ctrl+v to paste the data into a cell.
Next, use the “Text to Columns” feature in the “Data” tab to create a table. Chose “Delimited” and left-click on “Next >”.
Select “Space” and left-click “Next >” then click “Finish”.
If the header doesn’t format properly, simply remove the bad rows and type the header information about the data values, as shown here:
Paste EDR Data into EDR Sequence
With your speed values in spreadsheet format, make whatever adjustments to speed values are necessary according to your analysis. Remember, the Easy EDR sequence type expects estimated ground speed values versus time when the speed option is used. In our data, we’ve made speed adjustments to account for ABS braking just prior to impact.
Next, link your vehicle object to the animation path. Because we’re going to use forward evaluation, we’re starting with “speed change” and “uniform” sequence entries to create some motion prior to the EDR pre-crash speed time window. Here we’ll just do 0.5 seconds of motion before our vehicle enters the EDR pre-crash speed time window. Next, we create a third sequence entry, and switch its type to “EDR”.
Because we have pre-crash speed data, we’ll deselect “use acceleration” and select “use speed”.
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.
You should now see the speed graph updated on the animation path. Note that Virtual CRASH assumes constant acceleration between speed values. Therefore, speed changes that occur from one speed value to the next increase or decrease linearly.
Since our report included the cumulative longitudinal Delta-V data, we insert another EDR sequence using the implied speed values from our analysis.
We use the same procedure for our target vehicle.
Note, any combination of sequences can be used after the EDR sequence entries. In this case, we handoff control of our vehicles back to the simulation engine at the end of our EDR data.
The final visual can be seen here:
Using Acceleration Data
Acceleration time-series data can also be used with the EDR tool, with N time values and N-1 acceleration values (in our example, we have 21 time values and 20 acceleration values). Acceleration is applied as a constant value over a time interval. Note, acceleration input will increase or decrease the vehicle’s velocity vector component tangent to the animation path. Time intervals are determined by the progression of time values in the table’s time column. For example, acceleration[row i] is applied over a time interval of Delta-t[row i] = time[row i+1] – time[row i].
Focusing on the first 0.06 seconds of acceleration on our target vehicle, we see in our graph below how Virtual CRASH will treat acceleration values pasted into the EDR sequence type. Note, the acceleration graph is a step function, where constant acceleration is applied over 10 msec intervals (note the time intervals can be variable as well).
To use acceleration, ensure “use acceleration” is selected. Copy and paste your time values into the diagram window (again, there is always one more time value than acceleration).
Do the same for the acceleration (do not copy the final blank row).
You should now see the speed graph on the animation path.
For more complex, non-constant, acceleration behavior, simply build the speed versus time curve off-line (such as in Excel), subdivided into your preferred time intervals, and import the data as speed versus time data using the EDR sequence type as shown at the top of the post.