LAB 7 STEPPER MOTOR CONTROL
write for me an introduction,material list,procedure. I’ve attached a sample that you can follow,a lab report report,and the lab itself. do report for lap#7
lab07_stepper_motor_control.pdf
example_lab_report_writeup__1_.pdf
lab_report_guide_1_.pdf
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Mechatronics
Spring 2018
LAB 7 STEPPER MOTOR CONTROL
OBJECTIVE
Learn what stepper motors are and how they work.
Learn to interface stepper motors to the Arduino motor shield.
Program in MATLAB to control the stepper motion.
INTRODUCTION
I.
Stepper Motors
Stepper motors are a special kind of motor designed to move in discrete steps. This can perhaps
best be understood by looking at how they are designed. While there are many variations, you
will get the general idea by studying a simple type of stepper called the permanent magnet
stepper. Consider the diagram below. The stepper rotor is the moving part attached to the shaft.
It is a permanent magnet with North (N) and South (S) poles. The stepper stator surrounds the
rotor and is the stationary part of the motor. It consists of several coils of wire wound around
iron laminations, which make up electromagnets that can be turned on and off. Recall that
opposite magnetic poles (i.e. N-S) attract each other while like poles (N-N and S-S) repel. The
magnetic polarity of the stator magnets can be controlled, by controlling the current direction
through the coils.
coil A
coil A
coil B
S
N
coil D
coil D
coil B
S
N
coil C
coil C
Figure 1A: rotor aligned with coil A Figure 1B: rotor aligned with coil B
Fig.1. a. Rotor Aligned with Coil A (left), b. Rotor Aligned with Coil B (Right)
Let us assume that our stepper is set up so that when we turn a coil on it generates a magnetic
N pole closest to the rotor. Then, if we turn on coil A and leave all of the others off, it is clear
that the rotor will try to line itself up with its S pole aligned with coil A, as shown in Figure 1a.
If we leave coil A on, the rotor will come to rest in alignment with coil A and will not move
farther. In fact, it will vigorously resist any attempt to manually move it from this position. The
amount of external torque the motor can resist is called its holding torque.
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Mechatronics
Spring 2018
If we then turn off coil A and turn on coil B, the rotor will turn
¼ rotation to the right and align with coil B, as shown in Figure
1b. Continuing to rotate the magnetic field around the circle
will cause the rotor to align next with coil C then coil D, etc.
Each of these locations is a stable position. That is, as long as
one of the coils is energized, the rotor will attempt to lock itself
in alignment with that coil.
The motors you will use are wound as shown in Figure 2. The
motors have two coils (i.e. two phases), each with a center tap,
allowing you a great deal of flexibility in how the motors are
controlled.
Fig. 2. Stepper Motor Windings
with Center Tap
PROCEDURE
I.
Windings
Your first task is to figure out how the stepper motor used in
the lab (Figure 3) is wired. Use your ohmmeter (digital multimeter) to find which colored wires are connected to each coil in
the stepper motor. You will find that the wires are connected in
groups of three, as you can see from the diagram in Figure 2.
First separate the wires into their groups of three and write
down the colors for Group A-B-C and Group D-E-F. You
should be able to find which wire corresponds to terminal A
and which one is terminal D in Figure 2 by comparing the
resistances between the different wires. The resistance between
Fig. 3. Stepper Motor in the Lab
wire C and wire B will be twice as much as the resistance
between C and A or A and B. The same method works for group D-E-F. Write down the wire
colors for terminals A and D.
Find wires A and D and connect them both to the ground. From coil A-B-C, connect one of the
wires to +5V. The motor will move to an equilibrium position and stop. Label that wire B, and
the other wire from that group C. Now with wire B still connected to +5V, choose one of the
wires from the other group and connect it also to +5V. Note which direction the motor turns
when you do this. For the sake of convention, if the motor turns CCW when you connect the
second wire, call it wire E and if the motor turns CW, call it wire F. Label the remaining wire
accordingly. The stepping sequence will be B, E, C, F for CCW rotation, and B, F, C, E for CW
rotation.
Connect wires B, C, E, F to the A+, A-, B+, B- terminals on the Arduino Motor Shield, do not
connect wires A and D to anything, and power the shield with a +5V power supply. Since we are
using the Arduino Motor Shield for motor control, the shields pins, divided by channels are
shown again in the table in the next page:
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Mechatronics
Spring 2018
Function
Direction
Voltage
Brake
Current Sensing
Pins Per Ch. A
D12
D3
D9
A0
Pins Per Ch. B
D13
D11
D8
A1
For example, if we want to switch the terminal A- to high, we need first send a digital output
command to pin D12 to select the proper direction, and then send another digital output
command to D3 to turn it on. This is not a very straightforward process and you might need to
try a few times to get it right. The good news is that there is an LED connected to each of the A+,
A-, B+, B- terminals on the Arduino Motor Shield, so you can try different commands and see if
you can turn on the associated LED in a proper sequence.
To turn the motor CCW four steps would require the following sequence (pseudocode). Note that
this sequence uses only one coil at a time.
1. Set A+ terminal high, all others low; Hint: this step will take three lines of code.
2. pause(0.5)
3. Set A+ terminal low
4. Set B+ terminal high, all others low
5. pause(0.5)
6. Set B+ terminal low
7. Set A- terminal high, all others low
8. pause (0.5)
9. Set A- terminal low
10. Set B- terminal high, all others low
11. pause (0.5)
12. Set B- terminal low
The sequence shown above could be repeated until enough steps had been taken. Each switch of
the coils requires a short pause between steps to allow the rotor to move before issuing a new
step command. Play with the length of pause to see how short you can make it.
II. Forward and Reverse Motion
Determine the number of steps per revolution of your motor, then write a program that will drive
the motor one revolution clockwise and one revolution counterclockwise. Use the full-stepping,
one coil at a time mode. Put a piece of tape on the motor shaft as a flag to help you see how
far the shaft has gone. Start by making a flow chart of your programming logic for making the
program work.
Hint: Do not forget to turn off the coils at the appropriate times. Also, do not forget that it will
take some time for the stepper to move from one point to another, and that it will move much
slower than the computer can run through the program. You must insert some time delay in the
appropriate places or the motor will not be able to keep up. If the motion is erratic or it appears
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Mechatronics
Spring 2018
that steps are being skipped, you either have the coils out of sequence or you need to insert more
time delay.
Demonstrate your program to a TA before going on to the next step.
III. Input from Keyboard
For motion control, we want to be able to tell the motor when to stop and which direction to go
from a program or perhaps from the keyboard. Lets use the keyboard as our input interface.
MATLAB can accept input from the keyboard via the command input(prompt). From
the Matlab command window, type help input for more information on this command.
Modify your first program to prompt the user for a number n between -40 and 40, and use this
number to drive the motor that number of steps in the forward (e.g. n > 0) or reverse (e.g. n < 0)
directions, correspondingly. Hint: its easier to request the input number be a multiple of 4.
Hint: you can set up your code with a structure like this:
numsteps = input(Please enter the number of steps as a multiple of 4,
using positive numbers for CCW and negative numbers for CW:)
if numsteps is a positive number
for j = 1:1:(numsteps/4)
run motor CCW 4 steps
end
elseif numsteps is a negative number
for j = -1: -1: (numsteps/4)
run motor CW 4 steps
end
end
Demonstrate your program to a TA before going on to the next step.
IV. Calibration
In the real world, we deal in engineering units like millimeters and degrees, not in steps.
Modify your program so the user is prompted to enter the number of degrees to move, with the
limit between -180? and +180?. Insert a math statement in the code to convert the input to a
number of steps for your program.
Demonstrate your program to a TA before cleaning up your lab station.
DELIVERABLE
Submit a lab report to eCampus for your stepper motor experiments. Attach your MATLAB code
(properly commented) as Appendix in the report.
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MAE 211 Mechatronics Spring 2018
Laboratory 3: Digital Multi-Meter
Larry Banta (LB) and Yu Gu (YG)
Tuesday Lab Section, Station 19
February 07, 2018
1. Introduction
The objective of this lab is to learn how to use the Digital Multi-Meter (DMM). The lab also
provides instruction in writing up lab reports and presenting data.
Although other
exercises were performed in the lab, only the results of resistor testing will be presented
here in this sample report. In your report, all experiments need to be discussed.
2. Materials List
The lab station was supplied with a DMM and five (5) resistors, each with a nominal value
of 1kO. The lab station had two lab partners, LB and YG. The only equipment used for
this lab was a Cen-Tech Digital Multi-meter, model P37772.
3. Procedure
The five resistors were laid out on the table in order so they could be distinguished from
each other by position. They were labeled A, B, C, D, and E for data recording
purposes. With the DMM on the 2kO scale, LB measured each of the resistors three
times and recorded the data. Measurements were made by placing the resistor on the
lab table and touching each end of the resistor with the meter probes, as shown in Figure
1.
Figure 1: Resistance measurement method 1
1
A second set of measurements was then made by another person (YG), using a different
method. He squeezed the resistor leads between his fingers and the meter probes, as
shown in Figure 2. Three measurements were taken for each resistor.
Figure 2: Resistance measurement technique #2. Finger pressure was used on both resistor leads
Following those measurements, a different DMM was obtained by trading with another
lab group. The purpose was to determine the influence of the meter on the readings. The
same procedure was used with the second meter. Data from the experiments are
presented in the next section of this report.
4. Results
Data are presented below for each of the measurements taken. Table 1 presents data
taken with Meter #1, and includes the data for both measurement methods. Table 2
presents the data taken using Meter #2. Table 3 is a summary of the data, and is
constructed by taking the mean value for each set of three measurements on each
resistor.
2
Table 1: Meter 1 Measurements
Resistor
Meter 1 LB (Ohms)
Meter 1 YG (Ohms)
mean
sigma
A
985
985
985
983
983
982
984
1.33
B
993
992
993
991
991
991
992
0.98
C
982
982
982
980
980
980
981
1.10
D
984
984
983
983
982
982
983
0.89
E
985
984
985
983
984
983
984
0.89
mean
986
985
986
984
984
984
sigma
4.21
3.85
4.34
4.12
4.18
4.28
mean
sigma
Table 2: Meter 2 Measurements
Resistor
Meter 2 LB (Ohms)
Meter 2 YG (Ohms)
A
983
983
983
979
979
980
981
2.04
B
991
992
991
987
987
988
989
2.25
C
980
981
980
977
977
978
979
1.72
D
983
982
983
979
979
979
981
2.04
E
984
984
985
980
980
980
982
2.40
mean
984
984
984
980
980
981
sigma
4.09
4.39
4.10
3.85
3.85
4.00
Table 3: Data Summary from Tables 1 and 2
A
Meter 1
LB
Average
985
Meter 1
YG
Average
983
Meter 2
LB
Average
983
Meter 2
YG
Average
979
B
993
991
991
987
C
982
980
980
977
D
984
982
983
979
E
985
983
984
980
mean
986
984
984
981
sigma
Overall
Average
Overall
sigma
4.12
4.18
4.17
3.89
Resistor
984
4.20
3
5. Conclusions
Although all five resistors were nominally 1,000 Ohms, the mean value of our
measurements was 984 Ohms, as shown in Table 3. While this is within the ±5%
tolerance of the resistor, it is interesting that all five of our resistors were less than the
nominal value by a substantial amount. Four of the five resistors were within one standard
deviation of the mean value. For a given meter, measurement method and resistor, there
was very little variation in the measured values among the three measurements made in
each trial. This indicates that there was not significant random electrical noise present in
the readings. We wish to investigate the error mechanisms and the relative importance
of several types of error on the measurements.
We can model a single measurement as follows:
Rm = Rt + ßm + ßp + e(t)
(1)
Where Rm is the measured value, Rt is the true value, ßm is bias due to the meter
(constant), ßp is bias due to the measurement technique (assumed more or less constant,
or at least containing a constant component) and e(t) is a random error that changes with
each measurement and/or with time. In the absence of specific knowledge about e, we
will assume that the random error is normally distributed with zero mean.
We would like to estimate the bias terms, so that we can correct the measured data and
develop an estimate of the actual resistance for each resistor. For the meter bias, we see
that there is a difference in the readings between meter 1 and meter 2 of about 1.27 Ohms
for LB and about 3.27 Ohms for YG. The person/method bias between LB and YG is
about 1.73 Ohms for Meter 1 and about 3.73 Ohms for Meter 2.
Similarly, the
person/method bias is also dependent on the meter. Table 4 summarizes the calculations
for the two bias errors.
Table 4: Individual and Average Bias Errors (Ohms)
LB Meter 1 - Meter 2 bias
1.27
YG Meter 1 - Meter 2 Bias
3.27
Average meter Bias
2.27
Meter 1LB - YG Bias
1.73
Meter 2 LB - YG Bias
3.73
Average User Bias
2.73
4
Our conclusion is that both the meter used and the measurement method used can have
a measurable impact on the measured values of the resistors. It can be shown that the
numbers given in Table 4 do not represent the actual biases, but rather the difference in
bias errors between the two meters or the two methods. That is, the difference between
the bias for meter 1 and for meter 2 is approximately +2.27O. But we do not know the
absolute value of the bias for either meter. To determine the bias explicitly, we would
need to compare the meter readings against a calibrated source.
The person/method bias is also not known precisely, but the situation is slightly different
in this case. We could declare one method or the other as the standard method, and
so long as the standard is followed in all subsequent experiments, the results should be
consistent.
5
MAE 211 Mechatronics
Spring 2018
MAE 211 Mechatronics Lab Report Guide
A. Introduction
The purpose of this document is to illustrate for you the basic principles of report writing for the
MAE 211 course. The instructions in this handout, if properly followed, will allow you to become
proficient with what can be the challenging task of writing reports. Be aware that proficiency in
technical writing is a critical capability for your future professional life.
B. General Guidelines
Some labs require that the overall format of the lab report be applied to several experiments. It is
important to read over the lab guide to make sure your lab report contains all specified requirements
designated for the lab report.
It is important to note that when grading lab reports, length or wordiness of reports is not
considered. As you are writing a technical report, it is imperative that your writing be complete,
concise, and accurate, not necessarily lengthy. Each of your reports should fall somewhere between 37 pages, depending on the lab experiments and requirements. Font and paragraph formatting will not
be limited, though it is important that your reports look professional and have reasonably-sized fonts
and layouts.
Your lab reports should be written to a person who is an engineer, but who is not familiar with the
particular lab you are doing. Include enough detail that the reader can visualize your setup, assess your
methods and understand clearly what you discovered. The write-ups are to demonstrate that you
understand the objectives, methods, and outcomes of the experiments and should be done in your own
words. Do not copy and paste sections of the lab instructions into your report.
Generally, a laboratory report for MAE 211 should have the following sections. Exceptions will
occur, but for most you should use the following outline as a template for your report.
1. Cover Page
The cover page should be neatly formatted and include the name, number, and date of the lab, the
lab section (e.g. Tuesday, Wednesday morning/afternoon, or Thursday), lab station number, and the
names of all lab partners.
2. Introduction
This should be a brief introduction to the lab or a particular lab experiment. It should have a concise
statement of the objective of the experiment as well as any other pertinent information about the lab.
3. Materials List
This section should be a listing of all the materials needed to complete the experiment.
4. Procedure
This part of the report should lay out the procedure followed through the lab experiments, in your
own words. You should also include drawings, schematics, or photographs as appropriate to tell the
story. It is acceptable to write this section in either bullet/list format or paragraph format, as long as it
completely recalls all steps taken during the lab.
5. Data Collected/Results
This section should include all data collected in the lab as well as any results or findings of each
experiment. This is where any questions asked during the lab or required results should be answered
1
MAE 211 Mechatronics
Spring 2018
or explained. It is also important to state any reasons for your results not matching theoretical results
or any inconsistencies with your data and possibly reasons for these inconsistencies. Illustrations or
pictures taken during lab should be included here to help explain any setups created or results from
experiments, and may be embedded directly in the text or referenced to an Appendix.
6. Conclusion
This should be a conclusion stating the overall findings of the lab and how they relate to the lab
objectives. Do not just report the values that we can all read in the Results section and do not
introduce new results here. The Conclusions is where you interpret the data and provide your best
explanation of what it all means. This could include some observations on how the experiment could
have been improved, or some suggestions for additional measurement that could be taken in a later
experiment. This does not have to be a book, but it does have to represent some thought and exhibit
that you understand the principle involved.
7. Question
In this section, answer with details any questions asked at the end of the lab guide.
8. Bibliography
If references to external documents are used, they must be cited properly using End-note style
and a bibliography must follow the Conclusions section. All lab reports must have a reference
section.
9. Appendices
Some lab reports may include significant amounts of data that would clutter the main body of the
report, or lengthy computer programs that would detract from the flow of the document. Unless the
program is the main deliverable for the lab, it should be placed in an Appendix. Voluminous data
should be summarized by presenting graphs or statistics and the original data should be provided in an
Appendix.
In the report, pages must be numbered starting after the cover page. Figures/pictures must include
captions with the number and title of the figur ...
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