Mobile Vibration Measurement by Smartphone

With industrial vehicles, external excitation from driving and day-to-day operations or excitation through engine vibrations cause vibrations in the machine and noise pollution. This is at the expense of the driver, who is usually exposed to vibrations and noise in the driver cab for hours at a time. However, the vehicle itself is also affected by vibrations.

In order to reduce significant vibrations and noise in the driver's cab of a mini-excavator, the operator chose a vibration test. To do this, they used the ContiTech Vibration Control app.

On opening the app, the user was given some advice on how to use it and about the possible risks of taking measurements on devices that are in operation. To improve accuracy, the app measured the calibration of the acceleration sensor. During calibration, the application determined the position of the mobile device to adapt the measurement accordingly. The user could then begin taking the actual measurement. To do this, the smartphone had to be placed on the floor of the mini-excavator's cab. After just ten seconds, the app had completed the measurement and determined the time signal. Using the fast Fourier transform (FFT) principle, the data were converted into the frequency range and visualized. The app highlighted critical excitation frequencies – one of the key factors that ViProtect requires for measurement – on the frequency spectrum and showed the numerical values. Values of 14.03 Hz, 17.45 Hz and 20.95 Hz were in the critical range. For further calculation, the vehicle operator chose 14.03 Hz, which was most similar to the idle speed of the vehicle. As an alternative, at this point, ViProtect also offers the opportunity to enter a known value manually.

The user then entered the mass of the 800 kg vehicle cab and four mounting points for the construction vehicle into the app. Afterwards, the user selected “cab” as the type of application from the menu. At this point, the menu also offers “engine stationary” and “engine mobile” as options. This is the best way to take into account operating conditions when choosing mounting elements.

Finally, using these criteria, the app indicated five suitable ContiTech mounting systems. The suggestions were arranged according to the calculated insulation; in other words, insulating effect of the respective mount. The favorite mount for the mini-excavator was a Schwingmetall flange element, which achieved a degree of insulation of 0.83. This product type is particularly suited to insulating medium-sized masses. In second place was a Schwingmetall conical spring with an insulation effect of 0.55. General advantages of this engine mount are its versatility, high radial stiffness and good lateral stability. The three Schwingmetall hydraulic springs suggested achieved good insulation values of 0.52 to 0.42. Their advantages are generally in their good insulation, which is produced via a hydraulic system inside the product.

On the basis of these data, the user was particularly interested in the Schwingmetall flange element. After choosing, the user was able to display the expected insulation effect within the frequency spectrum as a graphic. Alongside final confirmation in the system, the user received the opportunity to request more information about this product directly from ContiTech. For this purpose, the app then opened an e-mail contact form, in which the recipient address and a boilerplate for the request are provided by default.