Experiment 8 Closed loop pressure control

Objectives:

1. Compare the performance of the system when using the P, PI and PID controllers. 2. Obtain the best performance for the system by tuning the gains of the PID

controller

Introduction: The automatic pressure control is much used in industry and its basic structure is the same of an automatic control of other physical variables such as temperature, speed, luminosity, etc. Usually, the kind of regulation implemented by these controls is PID, designed in a way to obtain best characteristics in terms of stability, response speed and steady state error. The board mod. G35/EV together with the external unit mod. TY35/EV enables the: • Analysis of pressure transducers and related conditioning circuits; • Automatic pressure control with PID regulator with variable coefficients. The pressure process consists of unit mod. TY35/EV provided with: • Compressor with air tank. • Piezoresistive transducer. • Load variation device. • Indication pressure gauge. • Proportional valve. The closed loop pressure control block diagram The closed loop pressure control of the pressure process shown in Figure 2.

Figure 2: Closed loop pressure control.

Figure 1 : Pressure control process.

Procedure: 1- Connect the circuit as shown in Figure 3 to build a closed loop pressure control

with Proportional controller.

Figure 3: Closed Loop Pressure control.

2- Used the DMM to determine the set point voltage and set it (e.g. 5 Volt).

3- Connect the two terminal of the oscilloscope; the first one on the set point and the second on the output of the pressure sensor.

4- Fill the table below by read the response from the oscilloscope. Take a screenshot

of the oscilloscope for each step and compare the result with the desired output.

Table 1: System output response with different gains of Proportional controller.

Proportional Gain

Rise time Overshoot Settling time SSE

min ½ max max

5- What is the best value of the proportional gain, and keep the proportional on this

value ………………………………………………

PI Controller

6- Build a PI controller by adding a wire to connect the Integral part in the PID controller section.

7- Fill the table below by read the response from the oscilloscope. Take a picture

from the oscilloscope for each step and compare the results for different gains.

Table 2: System output response with different gains Proportional and Integral controller.

Proportional Gain

Integral gain

Rise time Overshoot Settling time SSE

-------------

C4 C5 C6

PD Controller

8- Build a PD controller by connecting the derivative amplifier in the PID controller section.

9- Fill the table below by read the response from the oscilloscope. Take a screenshot of the oscilloscope for each step and compare the results for different gains.

Table 3: System output response with different gains of Proportional and Derivative controller.

Proportional Gain

Derivative Gain

Rise time Overshoot Settling time SSE

-------------

C1 C2 C3

PID Controller

10- Build a PID controller by connecting the derivative amplifier in the PID controller

section.

11- Fill the table below by read the response from the oscilloscope. Take a screenshot of the oscilloscope for each step and compare the results for different gains.

Table 4: System output response with different gains of PID controller.

Proportional Gain

Integral Gain

Derivative Gain

Rise time Overshoot Settling time SSE

------------- C4

C1 C2 C3

------------- C5

C1 C2 C3

------------- C6

C1 C2 C3

12- Which is the best gains of the PID controller

waraydah

Sticky Note