PID Control Using MATLAB Simulation

Automatic Control - Matlab lecture4

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PID Control Using MATLAB Simulation

Lecturer: 黃教琪Int. phone #:[email protected]


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Proportional-Integral-Derivative(PID) Control

For control over steady-state and transient errors we can combine all three control strategies we have discussed is PID control.PID combination is sometimes able to provide an acceptable degree of error reduction simultaneously with stability and damping.


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PID by MATLAB Implement Example 1

Consider a system with transfer function

T=10K/[(1*2)s^2+ (1+2)s+1+AK]

Time (sec.)

Am

plitu

de

Step Response

0 0.003 0.006 0.009 0.012 0.015 0.0180

0.5

1

1.5

Change it manually


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PID by MATLAB Implement Example 2


T=(K*S+Ki)/[S^3+ 3*S^2+(2+K)*S+Ki]


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0 1 2 3 4 5 6 7 8 9 100

0.2

0.4

0.6

0.8

1

1.2

1.4

t

y(t)

step response


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Ziegler-Nichols Tuning of PID Regulators

J. G. Ziegler and N. B. Nichols recognized that the step responses of a large number of processes control systems exhibits a process reaction curve like <fig.1>Ziegler & Nichols gave two methods for tuning the controller For a decay ratio of 0.25 Based on a stability boundary


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Fig.1


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Z.-N. Tuning of PID Regulators Method One

For a decay ratio of 0.25For a decay ratio of 0.25


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Sample of MATLAB Implement


T=2/[(S+2)*(0.18*S^2+0.6*S+1)]With L=0.38;R=1;

11


10

2

3

4

5


11

0 1 2 3 4 5 6 7 8 9 100

0.5

1

1.5

t

y(t)

Step Response


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Z.-N. Tuning of PID Regulators Method Two

Based on a stability boundary

Based on a stability boundary


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Homework Assignment

Using Z.-N. method Two to establish the PID regulator using the same transfer function above.Adjusting the P,I,D value manually to establish the most stable output using the same transfer function above.

(Deadline: Nov. 10th)

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PID Control Using MATLAB Simulation