Abstract
Inertial navigation systems are being broadly used in
water, ground and aerospace applications to provide the
navigation solutions. The initial alignment is first pace to be
determined for the inertial navigation system (INS). This pace of
alignment plays a vital role for carrying out the diverse navigation
applications. In this respect different approaches have been made
in the navigation research for determination of initial alignment of
SINS by using the inertial accelerometers and gyros sensors. Since
the gyros provide body attitude information where as
accelerometers provide position information in the INS.
This paper describes the three methods of generic investigation of
initial alignment of Strapdown Inertial Navigation System (SINS)
on the stationary state. These methods give the comparative
analysis of SINS initial alignment. In the first method of section
III, only the accelerometers are used to compute the initial
alignment of SINS in north, east and down (NED) frame. This
method uses the information of measured gravity, local gravity in
NED frame and direction cosine matrix (DCM). In this case
derivations for elevation and roll are presented. The required
results of initial alignment are produced from the experimental
and simulated data of SINS on stationary state. In the section 1V,
two more systematic methods called Method 2 and Method 3 are
used for SINS initial alignment. In these both methods, inertial
accelerometers and gyros are used to work out for SINS initial
alignment by using body and local level NED frames. Since on
stationary condition, inertial navigation systems are entirely selfreliant and can align themselves by using measurements of the
local gravity and earth rates in body and navigation frames. From
both methods, DCM is analytically computed which relates the
body frame to the navigation frame.
The techniques of SINS alignment on stationary condition have
great privileges over the SINS on the rotating disc. The size,
heating, computational time and zeroing of rotating disc of SINS
are great dilemma and their consequences are usually reflected in
navigation results. These Initial alignments, on stationary
condition, provide the solution of many questions. These
techniques also provide solution and capability of selecting various
grades of gyros and accelerometers to be used for required
application. The experimental and simulation results have been
presented in the form of numerical tables at the end of each
section which are sufficient to show the comparative analysis and
validity of methods.
Anwar Ali Gaho, Muhammad Shahid Qureshi. (2012) The Generic Investigation of Initial Alignment of SINS, Journal of Space Technology , Volume 2, Issue 1.
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