"Well, great job at this stage Jack.
I assume you extract euler angles properly, from your computed matrix transform, before applying any correction don't you ?
If so, your remaining problems are an illustration of the jerky behavior because of the 3…"

"Thinking about it again...
In fact it would be nice to produce a new PID function, that could take an additionnal new input value :
the amount of the measured error that has to be imputed to anything else than the PID itself. It would prevent the…"

"In fact it's a big headake, that has to be resolved on the math side to be affirmative.
It's difficult to get a good matrix mental representation : how it rotates and turns, and combines of course.
So I spoke to quick, you're true Jack, I probably…"

"ERRATUM: your gimbal is PITCH last, so inverse roll and pitch in my comments"

"Yes, I think so... It will be possible with 2 potentiometers on 2 first axis Yaw and Pitch (but it's additionnal friction, and not easy to adapt). Other existing solutions are expensive (this is what Zenmuse does at a very competitive price).
No…"

"I'm sorry Roberto, but with 1 IMU on camera, and 1 IMU (or AHRS) on main board, it's impossible.
Actual 2 axis gimbal uses PID to control attitude, because you know that a "pitch action" will act on the "pitch axis only".
But on a 3 axis system, if…"

"It's too bad Roberto, as Jack said, I'm afraid it won't work, even with 1 IMU for each axis, because you'll ever get some misalignment between the 3 attitudes estimation. Even with a very accurate initialization position + the best Kalman + fine…"

"Ok, so it's a kind of DCM fusion algo ? No kalman so ?
Did you compare your fusion algo to DCM implementation ?"

"It appears to be very smooth, congrats Max...
What sensor fusion algo do you use to achieve 800 Hz ?"

"@Emile
What kind of USB tool are you using to download to flash the MCU ? What is the compiled file format to upload with that tool ?"

"I agree with you, I don't see very well the advantage of RTOS : it increases the complexity of reading and writing code by the community.
But porting ardupilot or arducopter on STM32F4 (which is a very powerfull MCU and I think a good choice) will…"

"Hi Robero,
did you write code for PX4 board ? Did you compiled something without Nuttx ?
I'd like to know if there is existing code for this board, but without any RTOS. Just initializing FPU GPIOs, SPI, I2C, Uart (eventually main drivers to…"

"Great board for sure...
To summerize about my tweaking needings :The board require an external regulator to provide 4.3 - 6 V INPUT voltage ?And we can feed the board by the pins 1 and 2 of the expansion connector, or by pin 1 of the multi connector…"

"I will take a closed look at it, tx Bill"

"400 Hz is impressive, but with 40% idle, we can improve that a bit, is that true ?
Is this output driven by an interrupt ? On what source file should I look to understand the structure of this IMU output refresh, please ?"