The current beta PicoScope 6 Automotive software 6.11.7 has a new feature that has been requested by users all over the world and one which I have hinted about in previous posts!
The current generic NVH kit utilises a 3 axis accelerometer capable of measuring vibration in 3 directions X, Y, and Z or to put this another way, X axis = vibration Fore/Aft, Y axis = vibration Vertical, and Z axis = vibration Lateral.
However all 3 axis are summed together inside the single output NVH interface box in such way as to give the end user an overview (average) of all 3 axis . Here then there is no rejection of a particular vibration in a specific axis/direction, everything is accounted for.
The real beauty of such a feature is that with one scope channel, the end user will pick up a vibration present even when the direction of vibration is unknown.
Mounting the accelerometer vertically on a chassis member will detect all vibrations in all axis/directions, as will mounting the accelerometer horizontally on the same chassis member.
What you may experience is a reduction or an increase in the amplitude of a particular vibration, but the frequency will remain the same and this is what we need to identify. (The frequency of a vibration)
Limitations with the current generic NVH kit include:
1. Only a single accelerometer or microphone can be attached to the PicoScope (No option for multiple accelerometers or a combination of accelerometer and microphone)
2. A phenomena may exist in a vehicle where specific vibrations are present in a “equal and opposite axis” resulting in the “cancelling out” or reduction in the measured vibration during the “averaging” calculations. This can reduce the amplitude of displayed vibration to a point of no concern to the operator when in reality, the vibration indicated may well be the offending vibration. Only the average vibration can be displayed, therefore we cannot identify the offending vibrations resultant effect upon the vehicle.We do not know if the resultant vibration is Fore/Aft, Vertical or Lateral
3. Using the 3 axis “average” principle it is very time consuming to identify the transfer path of a vibration as we cannot easily identify the direction of vibration (axis responsible)
4. Only the accelerometer or the microphone can be installed, not both devices at the same time.
3 Axis individual measurement/Multiple accelerometer option
Often a fundamental requirement of vibration analysis is to identify not only the frequency and amplitude of vibration but the direction of vibration.
Here is where the new beta software excels.
All 3 axis can now be measured and displayed individually from the existing 3 axis accelerometer (current NVH kits) in conjunction with the new 3 output interface box
Any combination of accelerometers and microphones can now be attached to PicoScope to measure the transfer path of a vibration or to locate the source of vibration/sound
1 x 3 axis accelerometer (measuring all 3 axis individually) and a single / 3 axis accelerometer to measure vibration in a specific axis/direction
A maximum of 4 accelerometers consisting of any combination of accelerometers (single/3 axis)
A Combination of any accelerometer (single/3 axis) and any number of microphones (Max 4)
A maximum of 4 x microphones
N.B The combination of microphone and accelerometer and multiple microphones is functioning only in the signal history at present and will be incorporated into the frequency display in a future release.
The new beta NVH software can be used in the identical fashion to the original generic version as a 3 axis “average” device (or single microphone) allowing for very simple and effective diagnosis accompanied with maintenance/monitoring measurements or overview testing.
In effect, with the new beta NVH software, we have features that can be configured by the user with a multitude of options to suit any application
Measuring all 3 axis individually using 1 x 3 axis accelerometer allows the user to quickly identify all vibrations applicable to the vehicle in all axis. Here very quickly we can reveal the frequency of vibrations, the amplitude of vibrations and the direction of vibrations.
Once we know the direction of vibration we can use an additional single or 3 axis accelerometer to locate the transfer path of vibration replicating a stethoscope application
We now have multiple mounting options for the accelerometer “pre-set” in the software. Here we can label the location and denote the orientation of each accelerometer/microphone for easier identification and location during data review.
The new beta 3 axis accelerometer measurement ensures all vibration axis are visible to the user ensuring total visibility so reducing diagnosis time
Microphone application for both the new beta and current generation NVH software programs remain identical, however the new beta NVH software will soon see combined multiple accelerometer and microphone applications.
To view the above NVH file you will need to download and install the new beta version 6.11.7 at https://www.picoauto.com/downloads
I hope this very brief introduction into the new 3 output NVH interface box, software and the multiple mode options is of some help. Any questions or feedback are most welcome.
A big thank you to the software development team here at Pico for their continued hard work and persistence with this NVH software which presents more possibilities for diagnosis of such challenging symptoms