Fully Temperature Compensated IMU Calibration
Doing a fully temperature compensated Autoquad IMU is a procedure that requires time, patience and a steady hand.
This is the only calibration method available for AIMU users. DIMU users may also benefit from this method.
Done correctly full calibration procedure will give you a very accurately calibrated IMU with full bias, scale and alignment compensation that will show very little drift over a large temperature range.
But the process can be challenging. And for most normal users a DIMU calibration without temperature compensation will work nearly as good for normal flying conditions in ambient temperatures between 10 and 40C, if the board is allowed a bit of time to settle its own temperature before taking off.
For flying in extreme temperature conditions, (specially near or under the freezing point) or if temperature is expected to change significantly during flight, it is still recommended to do a fully temperature compensated IMU.
For AIMU, it is also still needed to do full temperature compensation, since the Analog sensors are more succeptible to drift, specially at lower temperatures. But in general we recommend to upgrade AQ6 boards to DIMU.
How is it done?
The process basically consists of gathering a static dataset by freezing the board and letting it slowly heat up while logging the sensor data. Then this data is combined with a dynamic dataset that is created by performing a calibration “dance” with your copter.
This dataset is then crunched on a PC to produce temperature scale and bias compensation curves and to correct alignment offsets between individual axises.
The process requires good data quality (especially the dynamic data can be challenging), and because we are trying to correct scale and bias over a temperature range using a large dataset, the calculation process is more prone to errors and can require multiple tries to get right.
Read on to the next pages for more details on gathering static and dynamic data needed to to calculate full temperature compensated IMU parameters for your particular IMU.