"Bill 
thanks very much .
I got it.
that's very helpful.

thanks"

"Dear Bill
"Magnetometer is used for yaw compensation."
I think there is little mentioned about this approach in your DcmDraft paper
would you please give more information about how to compensate the yaw correction by Magnetometer?

Thanks"

"Very sorry to trouble you so many times. I have understood and let me answer some of the question myself.
>question 2: >we take the cross product Z row of estimated DCM with the gravity reference vector
>and if the result is not ZERO, you call it…"

"additional question 
regarding COG and roll-axis, we only need the Z component
while gravity and  Z row of DCM, we nee the whole cross product 
may i know the reason"

"Dear I have new questions
regarding the RollPitchCorrection ,we use the accelerometer to obtain a gravity reference vector
question 1:
when we use it ,is there an assumption made that the plane keep going forward in a horizontal level?
question…"

"Dear I have new questions regarding the RollPitchCorrection we use the accelerometer to obtain a reference vector ( the Z-axis in plane frame) and the assumption is made that the"

"new diagramIMG_20160422_125659.jpg"

"new draft"

"Dear I reviewed the Eqn14~17 which someone feels confused maybe. would it be better if we add some tips or comments about this setction 1. the θ(x/y/z) in the matrix of Eqn 17 stands for the magnitude of the Vector : dt * W(x/y/z) X r(t) not the…"

"Dear
Thanks very much for your elaborate answer.
I can understand it now.


Thanks"

"sorry for the stupid question .
I have known it . 
the sign is negative if exchange the cross product of them"

"Additions:
for example. the x-axis has the whole Centrigual acceleration(Vector C). the Gravity works in z-axis (Vector G)
under this condition. the Accelerometer will output the result  Vetor  A = C + G
so if we want to get the G, we need A-C,but…"

"Dear
Regarding the Eqn 26 in the paper(DcmDraft2)
I think 
the acceleromter is aligned with the plane(body).so its output is the combination result of gravity and centrigual acceleration.
and we only need the gravity acceleration as our reference…"

"Dear  Bill
quote:
the bottom row of the direction cosine matrix should be aligned with the vector produced by the accelerometers


May I know the reason why these two vectors should be aligned ?under what condition?
because,from the earth frame. the…"

"Dear Bill 
I'm reading your perfect paper(DcmDraft2)
please let me ask a problem if I may.
in the paper, we got "a convenient matrix form" in Eqn 17
we know the new "DCM“ is not a definite  DCM for its magnitude is not 1 ,and each vector member is…"