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MotionFX in problem

Question asked by Lemjee on Sep 2, 2017

Hi all,


I have a problem using the motion fx library. Here is the descriptoin of my setup:

  • X-NUCLEO-IKS01A2 (inertial units),
  • NUCLEO-L476RG (MCU),
  • MotionFX200_CM4F_IAR (motion fx library version 2.0). Configure in 6x mode. We won't have the magneto on our product.


When I work in my office, everything works well. I got all axis (X, Y and Z) when the baord is moved manually. The problem begin when we install the device in a boat (the final product will be installed in boat). As soon as we increase the speed of the baot, the vibration is also increased (not that much, but increase). At this moment, the pitch and roll are still good BUT the yaw (Z axis) is turning crazy. The is 3 differents behaviors (not desired) observed.


1) In straight line, at high speed (with vibration), the yaw is continiously changing. We can observe 1-2 degrees per second in the same direction. Ex. If we are at 0 deg, the yaw angle will increase non-stop from 0 to 360 deg, rollover and continue increasing. The boat is always in straight line.


2) With a sharp turn at high speed, the yaw change rapidly (normal). When we come back in straigth line, the yaw continue to change rapily (much faster that case describe in 1).


3) At low speed but sharp turn, the yaw sometimes do not change. We do a 180 deg with the boat at 20km/h (12miles/h). We see the yaw updating but the angle doesn't change of 180 deg.


Without vibration (at the office) it's ok. If we reduce the vibration with little bumpers the result of the yaw seams to be better (not perfect but better).


The motion fx library is at version 2.0 (the lastest).


Do you have any suggestions to have a good yaw value? Is that another library that can give me the yaw?