Dynamtes of Naval Craft - System Identtficatton 
tering action and identification allows the evaluation of the desired 
parameters to exhibit themselves as functions of time and arrive at 
their final steady value. Similarly the estimation of state variables 
with random disturbances present also evolves as a function of time, 
and the ability of the estimated state variables to ''track'' the measur- 
ed trajectories when using the estimated parameter values in the 
representative system equations is directly exhibited in this proced- 
ure. 
Applications of this technique that allows for the presence of 
"noise'' in the system response have been made for the case ofa 
surface effect ship (SES craft) as well as for a hydrofoil craft (see 
[9] and [1 0} ). The mathematical procedures underlying this par- 
ticular technique, as well as the results obtained in practical appli- 
cations to different seagoing craft, are described in later sections 
of this paper. 
MATHEMATICAL PROCEDURES - ITERATION METHOD 
The iterative technique used for system identification of 
dynamic systems for which transient response data is available is 
described by the following. The dynamical equations representing 
the system are assumed to be given in the form 
Me an bts AOE oEaete Ad) 
where the dot denotes differentiation with respect to time t, a denotes 
the unknown parameter vector and c denotes the initial value of the 
solution vector Y and may or may not be totally known. Measure- 
ments bd, =; bo, > «-.. ofthe state variables “Y, , Y¥>5 <1. St 
times tm are available, and it is required to find an initial vector 
c together with a parameter vector a which minimize the sum of 
the squares of the deviations : 
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