IMU dampening


A few days ago my colleague pulled a log to check the vibrations on a newly build drone using a Cube Black. In general VIBE.VibeX, VIBE.VibeY and VIBE.VibeZ seems all good (well below 20). Clipping for X and Y also stays at 0 but for Z it seems to steadily increase, which as we understand is not good.

Looking at IMU3.AccZ we could see that it might be the culprit as it has much higher vibrations than IMU1.AccZ. Now according to the Cube specs and HW ID in Mission Planner both IMU1 and IMU3 are of type MPU9250. We believewe read that the Cube’s System Features also mentions that only 2 of the 3 IMU’s are vibration-isolated. So I guess this is why when I overlay IMU1.AccZ and IMU3.AccZ there is such a huge difference, IMU3 must then be the non-isolated one.

Below we have Z clipping in blue and the two AccZ plots in green (IMU3) and red (IMU1):

So we are not sure what to make of this, is it a serious problem or not?
Could it generate a EKF warning above a given value?

Thank you,