Like I said last post, I found a paper about a new type of non contact sensor for ground vibration tests.

The sensor replaces the accelerometers that need to be placed on the airplane. It’s called a NIRV (noncontact inertia reference velocity) sensor, internally it is the combination of a laser displacement sensor and an accelerometer.


The sensors are mounted on large stands that surround the airplane, the laser displacement sensors in the NIRV sensors determine the distance between the sensor and the airplane. Because the stands are very big, they will wobble a bit themselves. To compensate this wobble of the sensor, he uses the accelerometer and makes the distance measurement more accurate.

During the GVT’s, the displacement of the airplane is registered and is expressed in terms of velocity per unit force, just like the data that the normal accelerometers produce. Because the data is expressed in the same unit, the NIRV measurements can then be compared to the results of normal accelerometers, they concluded that the 2 types give an equally good result.

The NIRV sensors have a big advantage, because the sensors are mounted on the stands, these can be used on most airplanes, so this will make you save time in the setup of a measurement. This because there is no tear down or build up needed between 2 measurements, like with the normal accelerometers.


So guys, see you later and hope you understood everything.