1. SchedulePage 1
Manual for
ENGR 329
CONTROL SYSTEMS LABORATORY
Web site
Dr. Jim Henry425-4398
College of Engineering and Computer Science
University of Tennessee at Chattanooga
Spring, 2001
Grateful acknowledgment is given to the following for support of this laboratory:
Analog Devices Company
Center for Excellence in Computer Applications at UTC
MicroMotion Instruments
Microsoft Corporation
National Instruments Corporation
National Science Foundation
Plant Engineering Consultants
Contents
1: Schedule2
2: Grading4
3: Objectives & Guidelines5
4: Project Information7
5: Weekly Assignments14
Appendices73
1. SchedulePage 1
1: SchedulePart I -- System Identification
Week 1Introduction, steady-state measurements, statistics,
data acquisition software, cleaning up
Week 2Steady-state operating curves, graphing & word
processing software
Week 3Week 3 Report
Step response measurements
Week 4Week 4 Report
Modeling software
Week 5Modeling -- Approximate FOPDT
Week 6Week 6 Report
Frequency response measurements
Week 7Modeling frequency response
Week 8Week 8 Report
Plant visit
Part II -- Control System Design
Week 9Root locus plotting
Week 10Week 10 Report
Proportional control design
Week 11Proportional control experiment
Week 12Week 12 Report
PI control design
Week 13PI control experiment
Week 14Week 14 Report
If I treat you as you are, I will make you worse.
If I treat you as though you are what you are capable of becoming, I help you become that.
--Goethe
Schedule of Presentations & Reports
Pre-Lab / Present-ation / Report
1
2 / T. & X.
3 / S., V. & P. / All members
4 / All Teams / T., X. & L.
third member in each
5 / F. & L.
6 / T. & P. / All Teams / P., S., V. & F.
first member in each
7 / S., V. & L.
8 / All Teams / T., X. & L.
first member in each
9
10 / T. & L. / All Teams / P., S., V. & F.
third member in each
11 / F. & S., V.
12 / P. & X. / All Teams / T., X. & L.
second member in each
P., S., V. & F.
fourth member in each
13 / F. & X.
14 / All Teams / P., S., V. & F.
second member in each
T., X. & L.
fourth member in each
F=Flow, L=Level, P=Pressure, S=Speed, T=Temperature, V=Voltage, X=Position
Pre-Lab presentation is to be given by 2 students; one from each of the teams indicated in the "Pre-Lab" column.
Presentations of results from all teams will be given on the days indicated in the "Presentation" column.
Reports are scheduled as indicated in the "Report" column. Within your team, you submit reports in order of the team assignment list given in lab. For example, "third member" in week 4 means that the person listed third in the team assignment list submits the Week 4 Report.
2: GradingPage 1
2: GradingThe grading in ENGR 329 will reflect what is observed of your understanding of control systems operation. Evidence of this understanding can be observed in your
• ability to apply the principles to a physical system (performance in the laboratory and quality of results)
• ability to construct models to simulate the physical system (performance in modeling and quality of results)
• ability to interpret, describe and explain experimental and modeling work (reports and presentations)
The weights given will be
35 pointsPhysical laboratory
(attendance, performance)
20 pointsModeling laboratory
(attendance, performance)
20 pointsReports
25 pointsPresentations
Physical and modeling lab will be graded on this scale
points forLeadershipContributions
ParticipationCreativity
CooperationTeamwork
0 pointsAbsent
The semester grade will be determined by your point total
90-upA
80-89B
70-79C
65-69D
0-64F
The following must be completed to receive a passing grade in the lab:
2 reports, 3 presentations, 5 out of the 6 physical laboratories, 3 out of 4 of the modeling laboratories and a submitted report notebook.
All work done will receive credit if it is submitted before the last day of classes for the semester.
3: Objectives & GuidelinesPage 1
3: Objectives & GuidelinesObjectives
The main objectives of the laboratory experiences are to help you sharpen your skill in observing what happens to an engineering system and to accurately and completely describe what you observe.
Here is a diagram of the experiments and modeling to be done during the semester. Generally, in the first half of the semester, you will be conducting experiments and making observations on your system so that you can build a good linear FOPDT model of the system. A "good" model is one in which the results of the model calculations are in agreement with the experimentally observed results.
Observations on Laboratory System / Modeling to Approximate the SystemWeek 1-2
Observations at steady state
System
Identification / Week 3
Observations of dynamic response to a step input / / Week 4-5
Build a model to describe the system
Week 6
Observations of dynamic response to a sine input / / Week 7
Improve a model to describe the system
Control
System / Week 11
Verify & fine tune the design of the controller / / Week 9-10
Use a model to design a proportional controller
Design
Week 13-14
Verify & fine tune the design of the controller / / Week 12
Design a proportional-integral controller
In the second half of the semester, you will use this linear FOPDT model that you have built to design a control system to give a response of your system under certain operating scenarios. Then you will conduct experiments to see if your designs were valid and useful.
Guidelines on Safety, Cleanliness, Conservation, Citizenship
We have had years of experience with no lost-time injuries in this lab. Let's all do our part to make this year another one. In the event that someone is injured in the lab and is bleeding, before you help them, put on latex gloves that are available in the lab. Have someone show you where they are.
These labs are not routinely cleaned by the custodial workers. We have to keep them clean ourselves. Always leave the lab cleaner when you leave than when you arrived. If the trash cans are full, set them in the hall to be emptied. If an empty trash can is outside the door, bring it into the lab.
Around the computer workstations, do not have food or drink. If you have food or drink elsewhere, please clean up your stuff. Recycle aluminum cans. Rinse them first if there's grunge in them.
Conserve resources and money by printing only what is necessary for effective learning. If you print something that you don't need, place the paper in the "one-side-good" recycle stack to be reused. (Put the good side up.) If you are printing a draft, please use paper from the "one-side-good" stack.
Printers are not instantaneous. This lab has one printer and many users. During heavy use times, plan twice and print once. This will reduce frustrations. In the event you don't get a printout instantly, re-read this paragraph.
If you have any suggestions to improve this lab, pass it on to an instructor or assistant.
4. Project InformationPage 1
4: Project InformationXRC/248
The position control system consists of a cart on rails coupled to a DC electric motor. The torque of the motor is manipulated by the pulse width modulating power supply under the table. The input signal (0-100% of 10 volts DC) to the power supply comes from the computer. The torque moves the cart via a chain.
The position of the cart is detected by potentiometer ("pots" are variable resistors) that has 10 volts DC across the ends. The voltage on the wiper of the pot is sent to the computer.
Computer Hardware
ComputerDell
RAM128 meg
ProcessorIntel Pentium II
Speed450 MHz
Disk13.4 giga
Data Aq. BoardMIO-16-10E
SRC/249
The motor speed control system consists of a 3-phase, 5 hp electric motor that is coupled to a DC generator. The speed of the motor is manipulated by the variable-voltage, variable-frequency power supply on the wall. The input signal (0-100 % of 10 volts DC) to the power supply comes from the computer. The generator produces about 85 volts which can be connected to one or two banks of light bulbs to provide a load for the generator.
The speed of the motor-generator set is detected by a photocell and chopper wheel. The pulses from the photocell are converted to a voltage (0-10 volts DC) that is sent to the computer. The computer converts this to RPMs for display & recording.
Operation
The Plexiglas lid for the motor-generator set must be closed for the motor to run.
To operate the pulse-to-voltage converter, its power must be turned on. The power switch for the converter is the little toggle switch on the aluminum box.
Computer Hardware
ComputerDell
RAM128 meg
ProcessorIntel Pentium II
Speed450 MHz
Disk13.4 giga
Data Aq. BoardMIO-16-10E
VRC/272
The voltage control system consists of a 3-phase, 5 hp electric motor that is coupled to a DC generator. The speed of the motor is manipulated by the variable-voltage, variable-frequency power supply on the wall. The input signal (0-100 % of 10 volts DC) to the power supply comes from the computer. The generator produces about 85 volts which can be connected to one or two banks of light bulbs to provide a load for the generator.
Operation
The Plexiglas lid for the motor-generator set must be closed for the motor to run.
Computer Hardware
ComputerDell
RAM128 meg
ProcessorIntel Pentium II
Speed450 MHz
Disk13.4 giga
Data Aq. BoardMIO-16-10E
TRC/303
The temperature control system consists of a reservoir of water which can be heated or cooled by two copper coils in the reservoir that have hot or cold water running through them. A video is available that shows the inner construction of the reservoir.
The hot water comes from an ordinary hot water heater. The flow rate of the hot water is varied by changing the speed of two pumps. The speed of the pumps' 3-phase motors are manipulated by variable-voltage, variable-frequency power supplies on the wall.
The input signal (0-100% of 10 volts DC) to the power supply comes from the computer. The cold water flow rate is varied with a manual valve; the cold water is simply tap water.
The temperature of the reservoir is determined by a "resistance temperature device" or RTD. An RTD is a 100Ω platinum resistor that changes resistance when it changes temperature. The RTD is connected to an Analog Devices signal conditioner that converts the resistance to a voltage (0-5 volts) for the computer to read.
Operation
Make sure the water heater is plugged in. The circulating water pump must be operating for the experiment to function; plug it in and turn it on with the push-button switch. Adjust the cooling water supply to the desired flow rate by observing the rotameter on the wall.
Computer Hardware
ComputerTangent
RAM128 meg
ProcessorIntel Pentium-Pro
Speed200 MHz
Disk3 GB
Data Aq. BoardAT-MIO-16E-10
LRC/307
Reference: Smith & Corripio, pp. 135-142, 168-172
The level control system consists of a water tank. The water entering the tank is supplied through a manual valve and a rotameter flowmeter. The tank also has a variable-speed pump connected to the bottom that receives a signal from the computer telling it how fast to pump the water out. The computer sends a voltage (0-100% of 10 volts DC) to an Analog Devices signal conditioner that converts it to a 4-20 ma signal that the pump recognizes.
The level of water in the tank is detected by an air bubbler that is connected to a pressure transducer. The pressure required to push a bubble into the tank is the hydrostatic head due to the depth of the water. The pressure is converted by the transducer into a voltage (0-10 volts DC) that is read by the computer.
Computer Hardware
ComputerDell
RAM128 meg
ProcessorIntel Pentium II
Speed450 MHz
Disk13.4 giga
Data Aq. BoardMIO-16-10E
PRC/308
The pressure control system consists of a air blower powered by a 3-phase electric motor. The speed of the motor is manipulated by the variable-voltage, variable-frequency power supply on the wall. The input signal (0-100% of 10 volts DC) to the power supply comes from the computer.
The air goes into one or more of the outlet ducts. The pressure in the first manifold is detected by a pressure transducer. The pressure is converted by the transducer into a voltage (0-10 volts DC) that is read by the computer.
Computer Hardware
ComputerDell
RAM128 meg
ProcessorIntel Pentium II
Speed450 MHz
Disk13.4 giga
Data Aq. BoardMIO-16-10E
FRC/309
Reference: Smith & Corripio, pp. 268-270
The flow control system consists of a water pump powered by a 3-phase electric motor. The speed of the motor is manipulated by the variable-voltage, variable-frequency power supply on the wall. The input signal (0-100% of 10 volts DC) to the power supply comes from the computer.
The water goes into one or more of the outlet pipes. The flow in the first pipe is detected by a MicroMotion mass flow meter. The MicroMotion sends out a signal of 4-20 ma that is fed through a 500 resistor to convert it to a voltage (1-5 volt DC) that is read by the computer.
Computer Hardware
ComputerDell
RAM128 meg
ProcessorIntel Pentium II
Speed450 MHz
Disk13.4 giga
Data Aq. BoardMIO-16-10E
5.1 Weekly AssignmentsPage 1
5: Weekly AssignmentsWeek 1Introduction
Objectives
To get an overview of the course. To receive assignments of a project and project team. To understand how to operate the data acquisition station. To understand what the input function and the output function are for the system. To observe steady-state performance of the system. To begin to make measurements on the system and analyze your data.
Background
Each system has some "input function" and some "output function." The input function is called M(t), it is usually a function of time. The output function is called C(t), it also is usually a function of time. The names of the functions come from the fact that later they are called the Manipulated variable and the Controlled variable. A diagram that shows the input-output relation is in Figure 2.
Figure 2. Single-Input, Single-Output system diagram
This week and next week, you are to make measurements on your system, learn about the variability of the measurements and find the steady-state operating curve (SSOC) for your system.
Variations in Measured Quantities
(ENGR 322)
Every time an experimental measurement is taken, there is some error associated with the measurement. Today you are to determine the error in measurements in your system. Do this by taking steady-state measurements of the output function, C(t), for a number of data points. Find the mean and standard deviation of the measurements you make. Report your results as mean±2x(standard deviation). This range will include the true value of the function at a confidence level of 95%. Be aware that the standard deviation may be different at different operating points. Software packages like Excel or Kaleidagraph can help a lot with the statistics.
The following graph shows how this statistical analysis could look. This graph is the measured output for a steady input.
Figure 3. Output data varying with time
System Operating Curve
For each value of a constant value of the input function, there will be a value of the output function; this is called the steady-state value of the output for that value of the input. A graph of the output function (on the ordinate) versus the input function (on the abscissa) is called a steady-state operating curve.
An example of what steady-state operating curves look like is in Figure 4.
Figure 4. Example of a Steady-State Operating Curve
An example of what the steady-state operating curve (SSOC) looks for the Position system is in Figure 5. (Friction is the apparent cause of the hysteresis observed in the SSOC of the Position system.)
Figure 5. An example of Steady-State Operating Curve for the Position system
Lab Assignments
248 Position Control
Take data on the position of the cart. Make estimates of the error in measuring position at several points.
249 Speed Control
Take data on the motor RPM. Make estimates of the error in measuring RPM at several speeds.
272 Voltage Control
Take data on the generator's voltage. Make estimates of the error in measuring voltage at several input values.
303 Temperature Control
Take data on the temperature of the water in the reservoir. Make estimates of the error in measuring temperature at several temperatures.
307 Level Control
Take data on the height of the water in the tanks. Make estimates of the error in measuring height at several heights.
308 Pressure Control
Take data on the pressure of the air in the tube. Make estimates of the error in measuring air pressure at several pressures.
309 Flow Control
Measure the flow of the water going through the flow meter. Make estimates of the error in measuring water flow rate at several flow rates.
Data Acquisition Program - LabVIEW
LabVIEW stands for "Laboratory Virtual Instrument Engineering Workstation." It is used in this lab for control of the experiments and data acquisition, analysis and presentation. If you want to know more, the LabVIEW manuals are in room 213, Grote Hall. LabVIEW works by utilizing data acquisition boards that are installed inside the computers.
LabVIEW Tutorial
Bring the "LabVIEW" window to the top by clicking on the "LabVIEW" box at the very bottom of the screen. Open the program for your system by choosing the name you wish to use. Today, you'll want the one that has the word "Manual" in the name.
You'll get a screen similar to the one in Figure 6, on the next page.
At the top of the window is the name of the controller program.
At the top of the Window is the "RUN" button. Click on it when you want to take data.
On the left is the "controller."
The manual slide control: this directly controls the "input" of your system
Next to it is a slide indicator: it indicates the value of the "output" of your system
Below it is a meter labeled "Controller Output (%)." It is the "output" of the controller. In terms of the diagrams in section 4 of this manual, it is the symbol "M" (for manipulated variable) for your system. (It is not the "output" of your system.)
On the right is a rectangle that is a strip chart recorder. The fact that this "controller" has a recorder connected to it is why the "RC" is in the nickname.
Above the recorder is a little box labeled "points" that tells you how many data readings have been made and recorded.