Which of the following statements are correct? 1. The pair (AB) is controllable implies that the pair (ATBT) is observable. 2. The pair (AB) is controllable implies that the pair (ATBT) is unobservable. 3. The pair (AC) is observable implies that the pair (ATCT) is controllable. 4. The pair (AC) is observable implies that the pair (ATCT) is uncontrollable. where: A, B and C are having their standard meanings
Which of the following statements are correct? 1. The pair (AB) is controllable implies that the pair (ATBT) is observable. 2. The pair (AB) is controllable implies that the pair (ATBT) is unobservable. 3. The pair (AC) is observable implies that the pair (ATCT) is controllable. 4. The pair (AC) is observable implies that the pair (ATCT) is uncontrollable. where: A, B and C are having their standard meanings Correct Answer 1 and 3 only
State space representation:
ẋ(t) = A(t)x(t) + B(t)u(t)
y(t) = C(t)x(t) + D(t)u(t)
y(t) is output
u(t) is input
x(t) is a state vector
A is a system matrix
This representation is continuous time-variant.
Controllability:
A system is said to be controllable if it is possible to transfer the system state from any initial state x(t0) to any desired state x(t) in a specified finite time interval by a control vector u(t)
Kalman’s test for controllability:
ẋ = Ax + Bu
Qc = {B AB A2B … An-1 B]
Qc = controllability matrix
If |Qc| = 0, system is not controllable
If |Qc|≠ 0, system is controllable
Observability:
A system is said to be observable if every state x(t0) can be completely identified by measurement of output y(t) over a finite time interval.
Kalman’s test for observability:
Q0 =
Q0 = observability testing matrix
If |Q0| = 0, system is not observable
If |Q0| ≠ 0, system is observable.
Duality property: The property which says that
- The pair (AB) is controllable implies that the pair (ATBT) is observable
- The pair (AC) is observable implies that the pair (ATCT) is controllable
