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Chapter 4 Discription of Computer- Controlled System. Contents. 4.1 Description of Linear Discrete Systems 4.2 Pulse Response Function 4.3 Pulse Transfer Function 4.4 Open/closed-loop Pulse Transfer Function 4.5 Response of the CCS 4.6 Performance Specifications of the CCS
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Chapter 4 Discription of Computer- Controlled System
Contents 4.1 Description of Linear Discrete Systems 4.2 Pulse Response Function 4.3 Pulse Transfer Function 4.4 Open/closed-loop Pulse Transfer Function 4.5 Response of the CCS 4.6 Performance Specifications of the CCS 4.7 State Space Description of the CCS
4.1 Description of Linear Discrete Systems The system considered in the class is the linear time-invariant system, i.e. the relation between the output and input is unchangeable over time. r(kT)→y(kT); r(kT-iT)→y(kT-iT), k=0,1,2,…; i=…,-2,-1,0,1,2,…
y(t) x(t) x*(t) G(s) y*(t) 4.2 Pulse Response Function • Pulse response function is the basis for studying pulse transfer function. Fig. 4.1 Continuous system with impulse sampling signal input
X(z) Y(z) G(z) 4.3 Pulse Transfer Function Fig. 4.2. Diagram of Pulse Transfer System
y(t) x(t) x*(t) G(s) Y(s) X(s) X*(s) 4.4 Open/closed-loop Pulse Transfer Function 4.4.1 Laplace transform of the sampled signal
4.4 Open/closed-loop Pulse Transfer Function 4.4.2 Properties of X*(s)
y(t) x(t) x*(t) G(s) y*(t) 4.4 Open/closed-loop Pulse Transfer Function 4.4.3 How to get pulse transfer function (1) System with sampler Fig. 4.3 system with sampler
x(t) y(t) G(s) X(s) Y(s) 4.4 Open/closed-loop Pulse Transfer Function (2) System without sampler Fig. 4.4 system without sampler
y(t) x(t) x*(t) G(s) y*(t) 4.4 Open/closed-loop Pulse Transfer Function (3) The methods to get pulse transfer function
4.4 Open/closed-loop Pulse Transfer Function 4.4.4 Pulse transfer function and difference equation • Pulse transfer function can be converted to the difference equation, and vice versa.
4.4 Open/closed-loop Pulse Transfer Function 4.4.5 Pulse transfer function of the system with ZOH The transfer function of the zero order holder is The transfer function of the system with zero order holder is
G(z) T (s) R(s) R*(s) C(s) C*(s) C1(s) G1(s) G2(s) R(z) C(z) 4.4 Open/closed-loop Pulse Transfer Function 4.4.6 Open loop pulse transfer function of the system (1) Pulse transfer function of cascaded elements without sampler between them Fig. 4.5 cascade connection without sampler
G(z) T R(s) R*(s) C1(s) C1*(s) C(s) C*(s) G1(s) G2(s) R(z) C1(z) C(z) 4.4 Open/closed-loop Pulse Transfer Function (2) Pulse transfer function of cascaded elements with sampler between them Fig. 4.6 cascade connection with sampler
Y1(s) U*(s) G1(s) Y*(s) Y(s) U(s) U*(s) G2(s) Y2(s) 4.4 Open/closed-loop Pulse Transfer Function (3) Pulse transfer function of parallel elements
Y1(s) U*(s) G1(s) Y*(s) Y(s) U(s) G2(s) Y2(s) 4.4 Open/closed-loop Pulse Transfer Function
Ф(z) R*(s) C*(s) R(z) C(z) E*(s) R(s) E(s) G(s) C(s) E(z) - B(s) H(s) 4.4 Open/closed-loop Pulse Transfer Function 4.4.7 Closed-loop pulse transfer function of the system (1) Sampler is located after the comparator Fig. 4.7 sampler is located after the comparator
R*(s) C*(s) R(z) C(z) R(s) E(s) G(s) C(s) - B(s) H(s) E*(s) 4.4 Open/closed-loop Pulse Transfer Function (2) Sampler is located at the feedback channel Fig. 4.8 Sampler is located at the feedback channel
4.4 Open/closed-loop Pulse Transfer Function (3) Sampler is located at the forward channel T R*(s) R(z) C*(s) E*(s) R(s) E(s) G(s) E(z) - C(z) B(s) H(s) Fig. 4.9 sampler is located at the forward channel
E(s) E*(s) U(s) R(s) G2(s) G1(s) C(s) - 4.4 Open/closed-loop Pulse Transfer Function
Gh(s) G1(s) Gp(s) x(t) x*(t) y*(t) H(s) 4.5 Response of the CCS (1) System response at sampling instant Fig. 4.10 Open loop sampling system
4.5 Response of the CCS The response of the open-loop control system