Convert acceleration to displacement

[Cobus]

Hi,
I'm trying to develop a system to evaluate the condition of an oscillator, using a tri-axial accelerometer. The purpose of the exercise is to ensure that oscillation occur in only one direction and to detect any other movement should there be.
Unfortunately i am struggling with the implementation of the conversion from acceleration to displacement. According to all information at my disposal the best way is to double integrate the acceleration signal to obtain displacement. This is good in theory but causes problems during implementation. After the first integral serious drift in the signal is evident and after the second integral it seems that low frequency components is extremely amplified resulting in a misformed waveform. Being a novice in the vibration field i really hope somebody could point me in the right direction.
The parameters of the system is: p-p displacement of 7mm at a frequency ranging from 2 to 6 Hz - (sine waveform).

reply to: cobus.smit@iscor.com

[johnsold]

Look at the thread "vibration analysis" posted by RPJ. It is discussing the same issue.

If your data has any constant (an offset for example) component that will integrate to a linear ramp and then a quadratic growth on the second integration. All practical integrators must deal with this issue. The best way to do so depends on the nature of your system and data and what you plan to do with the results.

Lynn