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DeveloperPermalink Reply by Randy on August 24, 2011 at 7:27am

Graham,

     There's no easy way to do this I'm afraid.  It's definitely possible though but you'd need to modify perhaps the AP_IMU_Oilpan.h file in the AP_IMU library or maybe somewhere in the DCM lib when it consumes the accelerometer and gyro data..but I can't tell you exactly what you'd need to change.  If the APM is upside-down I think you need to reverse the pitch gyro values and all three (x,y,z) accelerometer values.

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Permalink Reply by Graham on August 27, 2011 at 9:11am

Thanks for this Randy. I am going to try and see if I can make it work and I'll let you know if I am successful.

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Permalink Reply by Graham on August 27, 2011 at 9:30am

It looks like I found the spot and it is much easier than I had thought. I am planning on changing the signs as needed to compensate for the flip. Does this makes sense? Do you think there will be other places in the code that I will need to correct? Or is it really this easy?

// Sensors: GYROX, GYROY, GYROZ, ACCELX, ACCELY, ACCELZ
const uint8_t AP_IMU_Oilpan::_sensors[6] = { 1, 2, 0, 4, 5, 6}; // Channel assignments on the APM oilpan
const int8_t AP_IMU_Oilpan::_sensor_signs[6] = { 1,-1,-1, 1,-1,-1}; // Channel orientation vs. normal

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DeveloperPermalink Reply by Randy on August 27, 2011 at 7:47pm

Ah nicely done.  Yes, that makes sense and that might very well be enough.  I think normally in the rest of the code we use DCM which has already processed the sensor values.

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Permalink Reply by Graham on August 28, 2011 at 10:35am

I got it working upside down! For the record, this is with the pins facing towards the back and the APM with the components facing down. Here is the line I used:

const int8_t AP_IMU_Oilpan::_sensor_signs[6] = { 1,1,1, 1,1,1}; // Channel orientation vs. normal,

I flipped GYROY, GYROZ, ACCELY, ACCELZ. Perhaps we can add a configuration to make this easier for other people in the future. For now I am going to focus on getting it flying and make sure it all works as I expect.

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DeveloperPermalink Reply by Randy on August 29, 2011 at 5:56am

Congrats!  well done!

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Permalink Reply by Don Megabyte on June 6, 2012 at 9:06pm

Yes, great stuff!  Just made this mod to mount an apm1 under my 3DR frame.  Works tremendously. :)  The filename has changed but grepping on GYROY etc will turn it up.

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