(15C) Ziegler-Nichols PID tuning

[Dwight Sturrock]

Ziegler-Nichols Proportional Integral Deriviative controller tuning program for the HP15C. PID controllers are commonly used in industry to provide feedback for a process.

LBL A
STO 0
ROLL DN
STO 1
ROLL DN
STO I
GTO I

LBL 1
RCL 1
2
/
RTN

LBL2
RCL 1
.
4
5
*
ENTER
1.2
*
RCL 0
/
X<>Y
RTN

LBL 3
RCL 1
.
6
*
STO 3
2
*
RCL 0
/
ENTER
RCL 3
*
8
/
X<>Y
RCL 3
RTN


INPUT:
T-
Z- type of loop: 1=Proportional only; 2=Proportional Integral; 3=Proportional Integral Derivative
Y- Ku
X- Pu

OUTPUT:
T-
Z- Kd
Y- Ki
X- Kp


Increase P only on the PID controller until the output of the loop begins to oscillate: this number is "Ku". "Pu" is the period of that oscillation.

EXAMPLE- We want a PI loop- type 2. Ku is 5, period of oscillation is 1 min.

2
ENTER
5
ENTER
1
f A

Result:

T-
Z-
Y- 2.7
X- 2

Set your controller to proportional, 2; integral, 2.7

EXAMPLE- We want a PID loop- type 3. Ku is 2.5, period of oscillation is 50 sec= 5/6 min.

3
ENTER
2.5
ENTER
.83
f A

Result:

T-
Z- .67
Y- 3
X- 1.5

Set your controller to proportional, 1.5; integral, 3; derivative, .67