My setup is Ardupilot 2.6, IMU, Ublox, Xbee pro 900 mhz, kyosho calmato 60 sport trainer (aprox 8 lb) 4 stroke saito 100 and 24 oz fuel tank. previosly I been flying with IR sensors (ardupilot 2.4) everything were ok, since I've changed to IMU things get messy, basicaly the IMU is affected by engine vibrations, I 've tried different shock absorbers but they didnt help, any attempt to run the engine above 5000rpm will cause IMU health drop to 0. in the IMU manual I find the gyro adjustments, can I reduce the shock sensibility through Gyro_gains ?
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Rafael - sorry, no, the gyro gains will not help with the vibration problem. You are running in to a limitation of the hardware. If the gyro health is hitting 0 you have a real problem. The gyro health is a metric that I just made up and it only has a loose correspondence to the pitch/roll drift correction time constant. I fly an electric plane and only see the gyro health drop from the maximum value when I do aerobatics or violent maneuvers, but not at all during normal flight at any throttle setting. I do not have a real feel for how far you can push the hardware with respect to vibration, but I would say that you probably need to get the airframe so that vibration has minimal impact on gyro health if you are going to use ArduIMU.
I'm sorry to hear you're having that problem, and I hope an Ardupilot user can step in and help you. Harsh environments with vibration are the reason the ADXRS450 MEMS gyro (with a differential quad sensor design - to cancel vibration) exists. Here's an excerpt:
"The new quad-sensor design rejects the influence of linear acceleration, enabling the ADXRS450 to operate in exceedingly harsh environments where shock and vibration are present and can cause measurement errors in less capable gyros. The ADXRS450 is the most stable, vibration-immune MEMS gyro available, with sensitivity to linear acceleration specified at only 0.03 °/sec/g, acceleration rectification of only 0.003 °/sec/g2, a noise-rate density specification of 0.020°/sec/√Hz, and power consumption of only 6 milliamps under typical conditions. Other features include internal temperature compensation over an extended industrial temperature range and an optional ceramic vertical-mount package that uniquely enables three-axis sensing on a single PCB without daughterboards."
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Also is your prop balanced? Are you mounting your engine with shock absorbers as well?
"The new quad-sensor design rejects the influence of linear acceleration, enabling the ADXRS450 to operate in exceedingly harsh environments where shock and vibration are present and can cause measurement errors in less capable gyros. The ADXRS450 is the most stable, vibration-immune MEMS gyro available, with sensitivity to linear acceleration specified at only 0.03 °/sec/g, acceleration rectification of only 0.003 °/sec/g2, a noise-rate density specification of 0.020°/sec/√Hz, and power consumption of only 6 milliamps under typical conditions. Other features include internal temperature compensation over an extended industrial temperature range and an optional ceramic vertical-mount package that uniquely enables three-axis sensing on a single PCB without daughterboards."