Javad JNSGyro-4T, Operator'S Manual

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3-4 JNSGyro-4T Operator’s Manual www.javad.com
S E T U P A N D M E A S U R I N G
How to Work with JNSGyro-4T
3
set,att/procmode,<mode>
,
where mode = [delay|extrapolation] (the default value is “delay”).
If the mode is set to “delay”, the extrapolation is off and the unit works with
delays in time tags between the positions and attitude. In the extrapolation
mode, the filtering is applied to attitude angles. The time tags between
positions and angles are aligned owing to the extrapolation (note that the
side effect of the filtering is the smoothing of the results).
Reference point determination
The Master receiver determines position of the antenna Master1 . In many
applications, the users are interested in the position of a different point,
which cannot be determined directly because there is no antenna at this
point. This point will be referred to as a reference point. This point can be,
for example, the center of mass, or another point important from the
standpoint of a certain application.
The vector directed from the point of the antenna Master 1 to the reference
point will be referred to as the lever arm vector. That is, it is supposed that
the user knows components of this vector in the body frame. This vector can
be measured directly by measurement tools different from GPS. To set the
coordinates of the lever arm, the following command is used:
set,att/arm,{n,r,b}
where {n,r,b} are the nose, right, and belly components of the vector,
respectively. Their default values are {0,0,0}. Each component belongs to
the range [-10000, 10000].
The position of the reference point is calculated as
P
γ
=P
M1
+Q*L ,
where P
γ
is the reference point position, P
M1
is the position of the antenna
M1, Q is the rotation matrix, and L is the lever arm vector in the body
frame.