Want to see how a measured quantity is influenced by two different variables? It is now easy with the point cloud display!
The point cloud display is available in both Simcenter Testlab 2019.1 and Simcenter Testlab Neo 2019.1 and higher.
For example, in the plot below, sound pressure is plotted against both engine RPM and horsepower.
Figure 1: Point cloud display shows pressure as a function of horsepower and RPM.
There are many different uses for the display.
Examples include:
Mapping pressure level versus RPM and power
Mapping vibration levels versus current and voltage
Mapping vibration of a dynamic isolator versus force and displacement
Infinite more possibilities! Essentially the display can display 2D data in a 3D format!
The point cloud display shows results quickly and easily, even if the data is acquired under continuously varying and arbitrary conditions.
The display also works with legacy data; there is no need to acquire new data to use the point cloud display.
Using the Point Cloud:
To create a point cloud display in Simcenter Testlab Neo, click the plus sign at the end of the plot list.
Then, select “PointCloud” (Figure 2, below). It is a similar process to open the display in Simcenter Testlab.
Figure 2: Creating a new point cloud display.
Fill in the point cloud display with data in which a metric is displayed as a function of two parameters. For example, an engine efficiency display (RPM vs torque vs vibration).
Figure 3: Populated point cloud display.
The point display will perform triangular interpolation between points.
It may be valuable to visualize the actual data points being used.
To do so, right click on the display and selection “Options”.
Go to the “Miscellaneous” tab. Adjust the option to turn on markers.
Figure 4: Turn on the option to use Markers.
The same plot as Figure 3 is displayed below, but with markers turned on (Figure 5).
Figure 5: Point cloud with markers.
Why use the Point Cloud?
Application Example: The point cloud is a useful display for any industry/application. Below, an automotive application is highlighted.
Perhaps an automotive engineer wants to evaluate the sound pressure level (SPL) in a vehicle.
However, the sound level at the driver’s right ear is not solely dictated by engine RPM: engine power, throttle percentage, gear, and many other factors are at play.
Perhaps the engineer wants to investigate how both RPM and power affect SPL.
The engineer performs multiple run-ups and run-downs to understand how power, RPM, and SPL are related (Figure 6). Figure 6: Engine RPM and power vs time.
The power does not change proportionally to the engine RPM.
In the figure below, the dotted horizontal line represents 2000RPM. The green dots represent power values at 2000RPM.
The power value fluctuates greatly despite the engine RPM being the same at all green dot locations.
Figure 7: Looking at power values when engine RPM equals 2000RPM.
Below is a table that charts the engine power vs engine RPM for 2000 RPM.
Figure 8: Power for different 2000RPM data points.
Knowing that both power and engine RPM are changing, the engineer wants to see how these two parameters influence sound pressure.
An order cut will track the relationship between RPM and pressure.
To add in the third axis of power, plot the order in a point cloud display.
Figure 9: Right click on an order cursor and select “Processing”. Then, drop the order into a point cloud display.
Change the Z axis of the display to be the desired quantity.
Right click on the Z axis and change the unit to Power.
Figure 10: Selecting which parameter the data should be tracked against.
Note that it is possible to change the Z-axis to any tracking channel.
Now, it is easy for the engineer to see how RPM and power dually influence sound pressure.
Figure 11: Point Cloud (right) shows how RPM and power combine to influence sound power.
