my task is to develop a condition monitoring system of a machine module. For that I am using the vibration sensors placed on the machine housing. I want to focus on only one module of the machine, a rack and pinion system, in which the rack carries out one reciprocating movement (back and forward) per machine cycle. I have carried out some test measurements to see if I see the vibrations corresponding to the cycle of the module. I could not see any clear vibrations that I could trace to rack and pinion module. Here is the qualitative representation (The signal above is the vibration, the curve below is the rotational speed of the rack): The rotational speed curve is just an assumption, since I do not have any speed sensor in place to measure it.
There are many rotating gears in the transmission of the machine and I need to extract only the vibration signal of my module. What I want to do is to install a proximity sensor next to the pinion teeth to be able to measure its rotation. I would then know when exactly does my rotation start and end, and I would be able to differentiate the signal flanks to get the instantaneous rotational speed of the pinion. Once I have this information I would be able to extract the parts of the signal when the cycle occurs and analyse them using STFT or Order Tracking (using the calculated instantaneous speed). My questions are:
- Is this approach correct? Or should I just divide the signal into sections corresponding to the cycle of the whole machine and analyse them?
- Are there some ready methods to deal with this task, that I could read on?
- Can I just cut the signal exactly where the movement of the pinion starts and use it just like that or should I use some windowing function?