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Digital Control Systems [MEE 4003] - Kckong.info

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2.1. STATE SPACE REALIZATION OF DYNAMIC SYSTEMS 11<br />

k<br />

M<br />

x<br />

u<br />

x1<br />

2<br />

u1<br />

2<br />

m1<br />

u<br />

k<br />

x<br />

m 2<br />

(a) A mass-spring system<br />

(b) Double mass-spring system<br />

k1<br />

k2<br />

m1<br />

m2<br />

c<br />

c1<br />

2<br />

k 4<br />

m 3<br />

x 1<br />

x2<br />

x3<br />

(c) Complicated mass-spring-damper system<br />

k 3<br />

u<br />

c<br />

k<br />

x 1<br />

u 1<br />

(d) Creeping phenomenon of a steel material<br />

P<br />

x<br />

v<br />

(e) Buckling phenomenon of a rod<br />

Figure 2.1: Dynamic systems<br />

The matrices,M, C, and K, are defined as follows.<br />

• M ii is the mass value of thei th mass.<br />

• M ij,i≠j = 0.<br />

• C ii is the sum of damping coefficients of all dampers connected to thei th mass.<br />

• C ij,i≠j is the negative value of the sum of damping coefficients of all dampers connected<br />

between thei th mass and thej th mass.<br />

• K ii is the sum of spring constants of all springs connected to thei th mass.<br />

• K ij,i≠j is the negative value of the sum of spring constants of all springs connected<br />

between thei th mass and thej th mass.<br />

<strong>Digital</strong> <strong>Control</strong> <strong>Systems</strong>, Sogang University<br />

Kyoungchul Kong

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