Robot Programming Using an Arduino Controller and Matlab Discussion You will write a draft of the Background section to be turned in before the tech report

Robot Programming Using an Arduino Controller and Matlab Discussion You will write a draft of the Background section to be turned in before the tech report (note below). Your background section of the technical report must include background research in areas process capability. One team member will write that portion The other two members may choose another topic such as use of robots in industrial applications, future of use of robots in home applications, Robots used in entertainment, machine learning, and other topics related to this project. These are guidelines of topics, students are encouraged to expand upon this selection of topics. If you are unsure if a topic is relevant, contact your instructor. The group should determine which topics will be covered by which team member using the guidelines above. Each team member will select and write about a different topic. Engineering 102, Dr. Hamrick, Fall 2019 Project 1
Robot Programming Using an Arduino Controller and Matlab
The Objective is to use the Arduino controller, programmed using Matlab, to study the performance
characteristics of the motors. Most of the project is individual. I expect students to help one another,
but no one should do the project for another student. You may not use another student’s robot for data
collection or use another student’s data.
Part A: Individual Using the separate handout “Robotic Set Up of the Arduino Controller” and the files
provided, configure your Arduino so that it can be controlled by Matlab on your laptop. Build the robot,
interface your computer with the Arduino, command it using Matlab, wire at least three motors (torso,
shoulder, elbow) through the H-bridges and control each independently.
Build the robot using the instructions in the kit. Some words of caution before you start: This will take a
couple of hours, so give yourself a clear space to work and bring a lot of patience. Separate the screws
and account for all before you start. Some are close in size and are easy to confuse. Be careful to “Snugtight” the screws, but do not over-tighten or they may strip out the plastic. When assembling the
transmissions, put in the gears before the nuts, and the nuts must be seated correctly. A wooden
toothpick or non-magnetic tool might help, or you can thread one of the correct bolts through the nut to
use as a temporary “handle.” You will not need the control box with its toggle switches or batteries, but
you are welcome to assemble it, plug in batteries and run the bot manually if you like. If you do, remove
all batteries before the next step. Having batteries in the robot can cause many problems.
I call the motors out by this designation in line with the human body: Torso is the bottom motor that
rotates the arm back and forth, Shoulder is the motor that sits on top of the torso, Elbow is the next one
up, Wrist is the next one that is attached to the two links and tilts the gripper, and Gripper is the two
fingers at the end.
Wire ONE motor through the H-bridge using the instructions. Start with the torso motor. Get that one
working so that you can command it with Matlab, then wire the shoulder and elbow motors. It is
recommended that you use only pins 3-12 for motors, starting with 12-11 for torso, 10-9 for shoulder,
etc. Do not use pins 1,2 or 13 at this time. When you can command all three motors independently, you
are ready for data collection.
Part B: Individual Process capability – Collect data on the accuracy of your robot:
Determine the precision characteristics of one of the motors on your robot. Precision can be thought of
as the ability to hit the same mark in the same place every time. This will allow you to determine the
tolerance that your robot can hit repeatedly within. You may find that electric motors have different
performance characteristics from one to another and when running forward and reverse.
Set your initial point: Position a piece of paper in front of your robot with one corner at the front, the
orientation of the paper is not very important for this data collection. Attach a marker to the gripper of
your robot (rubber bands work well). Position the torso at about a 45 degree angle to the left side of
the base so that the marker is roughly in the center of the paper. Write a program that runs the elbow
or shoulder motor down and then up so that you make a mark on the paper. Jog that same motor so
that the marker is 1/8 inch above the paper. Don’t move that motor any more during this test.
Figure 1 Set up of robot with paper
Collect data for the accuracy of your torso motor: Write a Matlab program that will rotate the torso
motor to the right for 6 seconds, pause for at least ½ second, and rotate back for 6 seconds. Your marker
will probably not return to the exact same position. Measure the distance from the fist dot to the
second dot and record the value. Without making any other adjustments, run the program again and
measure the distance from the second dot to the third dot. Repeat this process, measuring the distance
from one dot to the next until you have 10 data points. If your robot drifts significantly you may have to
start over, adjusting the torso to a different starting angle in order to get enough cycles before it hits its
limit. If 6 seconds is not right for your robot, you may increase or decrease the pause time according to
your needs.
Fourth dot
Third dot
D2
D3
Second dot
First dot
D2
D1
Figure 2 Measuring the distances between dots for data collection.
Try to improve the accuracy by adjusting the time intervals: Repeat the process of making an initial dot
on the paper. Next change the return pause time intervals so that the marker returns to its starting
point. Keep the outbound time the same 6 seconds, but change the return time either longer or shorter
depending on the direction it needs to be adjusted. Remember that the pause command in Matlab can
be any decimal number, and does not have to be and integer. This will be an iterative “guess and check”
process to get the time adjusted so that the marker returns to its starting point. Record your outbound
time (6 seconds) and whatever your inbound time is. Repeat the data collection process to get at least
10 data points.
Record your data in a table such as the one below making it as long as necessary to collect your data.
Note that 0.0 is not valid. If the dots appear to be on top of one another, then you need a measurement
instrument with higher resolution.
Table 1 Data collection Project 1
Torso Motor
Time outbound (sec)
Time inbound (sec)
Distance (in)
Unadjusted
6
6
D1
D2
D3
etc …
Time adjusted
6
(your time)
D1
D2
D3
etc …
Process Capability Analysis: Manufacturers often use statistical analysis to prove that the parts that
they make are within tolerances, and use process capability to determine the tolerance that a process
can hold. In statistical analysis the Standard Deviation is a measure of the scatter of a given set of data.
The higher the Standard Deviation (?) the wider the scatter. In normally distributed data, 6 x Standard
Deviation (6?) will encompass all but 0.0026 % of all data. Process Capability (Cp) is a ratio of the
tolerance range to 6?.
Eqn 1
???? =
(?????????????????? ??????????)
6?
A Cp of 1.66 allows a defect rate of only 1 part per million, and is the generally the accepted minimum
value for what is known in manufacturing as a “Capable Process.” A Cp
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