Dynamics of Naval Craft - System Identification 
Table 1 
Results of System Identification of Surface Ship 
True cco 2% 5% Analog 
Values Data Noise Noise Data 
Gyiy = 10° eee 03 =e 20? +1071 eeeliai 
Gs ir Ties : his . 109 -. 589 -1.64 
Co 10° =j.gh2 114, suas -. 164 -.091 
Chen 10° =optlAs -.149 -. 185 ae lag 
C, -. 334 oe = a0 -.415 =, 342 
feeveilOnk ens 10 PSB 942 796 ae 
C, x 10° 323 bi PRD 321 .318 
e7 10° Beuie2 ee: OT =.O12 2Aets 
ae Wor 1 397 391 =. 360 JygoM Lalgey 
ce 24.120 =e -. 097 -. 070 
one ae 10° -. 584 -. 583 -. 586 -.591 
In order to assess the accuracy requirements, the input was 
contaminated by adding Gaussian noise of 2 and 5% error magnitudes, 
where this error is based on the indicated percentage of the maximum 
value of the variable. The results of identification with these inputs 
are also shown in Table 1. It is seen that as the noise level is in- 
creased some coefficients remain close to their true values while 
others drift away and still others lose all significance. The coeffi- 
cients C, and C» are seen to deteriorate the most rapidly. These 
coefficients have been shown in [11] to be of minor importance, and 
the present results support the relative ordering given in fi] 
1641 
