Thesis - Leigh Moody.pdf - Bad Request - Cranfield University

Chapter 2 / Target Modelling
_ _
Target motion is defined in the Alignment frame using a Cartesian state
vector (XT) comprising 3D position, velocity and acceleration states.
Sufficient flexibility has been provided so that the user can construct target
trajectories from a number of target models. The target models provided are
the basic building blocks that can be characterised by the user, either in
isolation, or to create more complex trajectories. This Simulator contains a
number of pre-programmed trajectories IMM_*_TEST, controlled by
TG_IMM_TEST, each designed to tune the separate IMM target tracking
filters. An important feature is the activation the Target Simulator in
conjunction with the target tracking sensors so that their corrupted
measurements can be assessed against reference target kinematics. The
reference target data listed in §22.2.3 is computed directly from the target
state vector in module TG_GEOMETRY.
Initially default target data is loaded by module D_TARGET for a constant
velocity flypast trajectory using Target Trajectory 2 and Target Model 1 that
are described in §2.3.2 and §2.2.4 respectively. The program then reads the
users target control and characterisation data provided from external files.
This data contains TGT_SEL, used to select one of the Target Trajectories
described later. Target initialisation is then completed in I_TARGET.
TG_SELECTOR provides the generic target type sequence and peak
acceleration profiles for each of the pre-set trajectories identified by
TGT_SEL. The target demanded and actual accelerations are transformed
into the Alignment frame by TG_DYNAMICS at the simulation reference
rate of 4 kHz. If the acceleration demand filter bandwidths are set to zero
the aircraft “stick” to acceleration dynamics are by-passed.
2.1.1 Target Default Parameters
The default target type TG_TYPE in the range [1(1)6] for the wire frame
model is set to 1 representative of a MiG-29 (Fulcrum). The initial target
class described in §2.2.1 is a head-on aspect. For glint modelling, an
important element in the ground radar and missile seeker measurement error
models, the physical dimensions of a typical air superiority fighter along its
Target Body axes are loaded,
TB
t
l : =
( ) T
19 , 13 , 5
2-4
Equation 2.1-1
The dimensions of modern military aircraft vary greatly depending on their
role and design. From published data the following are typical:
• Trainers/light strike Fighters ( ) T
TB
l : = 13 , 10 , 4
• Attack Helicopter (incl. main rotor) ( ) T
TB
l : = 12 , 11 , 3
• Transport Helicopter (incl. main rotor) ( ) T
TB
t
t
l : =
t
18
,
20
,
5