GENERAL ENGINEERING
EG 101 Introduction to Engineering
LABORATORY 3
The Programmable Robot
[Developed by Prof. Donald F. Hunt]
SUMMARY
You will be given a WAO II [pronounced "Wow Two"] Programmable Robot, Model
MV-961, made by OWI Incorporated. The kit comes in two parts.
 A mechanical-electrical portion:
You will assemble the parts with tools to form a working robot -- a simple robot, with
various gears and screws, sensors, wheels, DC motors, and other parts.
 A computer portion:
You will use the small, pre-assembled computer, with a four-bit microprocessor and 26
input keys, to generate a program to control the robot's actions.
You will ASSEMBLE and PROGRAM the robot to follow commands. You are expected to
TROUBLESHOOT as you progress. You will RECORD data in your notebook, PREPARE
a formal written report and ORGANIZE a short oral report for recitation.
PROBLEM STATEMENT
An engineering firm that makes robots for sale for a little less than $100.00 has just hired
you. Your boss has asked you to build and test this prototype, and to make suggestions for
improving both the instructions and the robot itself.
OBJECTIVES

Prepare a report for your boss suggesting improvements (if any) to the assembly
instructions and the robot.

LEARN the critical importance of carefully identifying components BEFORE assembly
and reading and understanding the instructions before beginning.

UNDERSTAND the gear linkages which enable:
 Rotation around an axis that passes through the center of the robot
 Motion in a circular arc about an axis OUTSIDE the robot
 Translation [motion of the robot in a straight line].

LEARN ABOUT ADVANTAGES AND DISADVANTAGES. Warranties; lost parts;
how understanding the function of a device helps avoid error in assembly. (Correcting
failure is an important component of engineering).

TROUBLESHOOT: If the robot doesn't work, try to figure out why.

WRITE AND TEST PROGRAMS to evaluate the performance of the robot. Use this
data to determine the accuracy and the precision of the robot.
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EG 101 Introduction to Engineering
PREPARATION

Read this document carefully before beginning work.

STUDY the assembly instructions and then the programming instructions.

STUDY the information on Pg. 20 about experimental measurements such as
ACCURACY, PRECISION, MEAN, and STANDARD DEVIATION.
MATERIALS

Programmable Robot Kit, WAO II Model MV-961.


The mechanical-electrical portion of the robot contains wheels that operate
independently, drive shafts, a system of gears [crown, spur and pinion gears], a
caster, holders for four batteries, sensor, wires with solder-less connectors and
battery snaps, self-tapping screws, machine screws with nuts and washers, two
DC motors and other parts. [Review the parts list.]
The computer portion of the robot uses four-bit microprocessors with 26 input
keys that will generate a program to control the robot actions. The program may
have up to 24 steps.
(You can preset the robot to follow commands such as Forward, Reverse, LeftTurn, Right-Turn, Left-Pivot, Right-Pivot, Break-Stop, and Beep.)
PROCEDURE
As you work, record data in your laboratory notebook.
1.
ASSEMBLING THE ROBOT
A.
UNPACK the pieces of the ROBOT carefully.
B.
SPREAD OUT the pieces on the workbench, IDENTIFY the pieces referring
to the assembly instructions and official parts list. KEEP all the parts from
each bag together! Are any pieces missing?
C.
LEARN the function of the various parts BEFORE you begin robot assembly
[for example, what does "M2.3 X 8" mean on a screw?].
D.
Using the instructions provided by the manufacturer, ASSEMBLE the robot.
E.
RECORD your observations in your laboratory notebook and be sure to
include suggestions to your boss for improving the directions.
2.
UNDERSTANDING THE ROBOT
SHOW your understanding of how the robot operates by recording your data and
your ideas in your notebook. You are expected to:
A.
UNDERSTAND the POWER GEAR LINKAGES that permit the following.
 ROTATION on an AXIS located in the center of the robot
B.

TURNING [rotation on an axis OUTSIDE of the center of the robot]

TRANSLATION [movement of the robot in a straight line]
DETERMINE the GEAR RATIO for the train of four pairs of gears that link
the motors to the wheels. Estimate the INCREASE in traction force and
torque coupled with a decrease in speed.
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GENERAL ENGINEERING

EG 101 Introduction to Engineering
What is an efficient and accurate way to count all the gear teeth? Can you
use pairings?

C.
D.
E.
3.
What does a crown gear do that a spur gear doesn't?
What are the two identical springs for?
DETERMINE the following: where is friction used for assembly rather than
plastic cement (examine the tire rim, for example). Which is the plastic piece
that appears to be a single piece, yet is composed of two pieces cemented
together; why was this not made in a single mold? What is the mechanical
principle that makes the solderless connector work?
RECORD the results you find for parts B-D and any other comments in your
notebook and include this in your report as part of the Data and Observations
section.
TESTING THE ROBOT
Designing and testing various control programs for the robot (including loops) is
necessary for a purchaser to determine if the robot fulfills its specs (specifications).
You are required to perform three tests as indicated below.
Note: The data you record for these tests will also be used in your Excel
Proficiency Test due later in the semester.
MEASUREMENTS
Mean (or Average)
Take a number (N) of distinct measurements of a parameter (P) and compute the average
as follows:
AP 
P1  P2  P3  ...  PN
N
Accuracy (or Error)
The difference (+ or -) between the standard value and the mean. Accuracy may be a
Primary (Atomic Clock) or Secondary (Ruler) standard (see fig. 1).
Precision (or Repeatability)
The difference (+ or - half the difference) between the high reading (Pn - high) and the
low reading (Pn - low) in a set of repeated measurements of a parameter.
Standard Deviation
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GENERAL ENGINEERING
EG 101 Introduction to Engineering
Distance Test:
Fig. 1
For this test you must first determine the distance per unit time of the robot. Have the robot
run in a straight path (see Fig. 1) for one “robot” unit of time and measure the distance
traveled. It is then expected that the robot must travel twice that distance if two units of time
are chosen, etc. Determine the expected distance the robot must travel for five units of time.
This is your “Standard Value”. Now, run the robot in a straight-line path for the 5 units
of time and measure the actual distance traveled. Repeat this trial 10 times. Using the data
collected, find the accuracy and precision of the distance traveled in a straight-line path.
Angle Test:
Fig. 2
When the robot is sent in a straight-line path there will be some deviation from the expected
destination point (see Fig 2). Draw the expected straight-line path. Using the same data from
the Distance Test, draw straight lines from the origin to the end points you recorded. Then,
measure the angle of deviation () for each line. Using this data find the accuracy and
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GENERAL ENGINEERING
EG 101 Introduction to Engineering
precision of the angle of deviation from the straight line path. What is your standard value
in this case?
Robot Time Unit Test:
Fig. 3
Set the robot to run in a straight-line path for an extended amount of time (see Fig. 3).
Measure the time that it takes for the robot to travel a specified distance. Repeat this trial 10
times and record your findings. Using this data find the accuracy and precision of the time
response of the robot.
A.
Determine variability in angle, distance, and time response resulting from
repeated trials. Determine accuracy and precision from these tests. Answer
the following questions clearly: What tests did you make? What do the tests
determine (accuracy, precision)? What were the results? Were the results
repeatable? Are the specs met or not? What changes would you request from
the manufacturer? What are the average values and maximum deviation from
average for your repeated trials? What additional features, not promised by
the specs, would you recommend?
B.
What conclusions can you draw about the performance of the robot? (Avoid
meaningless comments like "I think this is a very good robot". Be specific,
honest, and constructive.) In essence, is this device well designed? What
other tests should have been done?
C.
In both the construction and analysis, you may seek assistance from your
instructor in lab, or work by yourself -- but you must show the results to the
instructor. Record all results and comments on parts A and B in your
laboratory notebook.
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GENERAL ENGINEERING
4.
EG 101 Introduction to Engineering
Advantages and Disadvantages.
A.
Warranties -- learn what they do and don't do.
B.
Parts which are lost (i.e. they take flight as you try to install them); some
extras may be available.
C.
Can we assemble without error? No, but if we examine the function of the
part as we assemble the kit, we can reduce our errors, and also correct
misleading statements in the directions. And, more importantly, we can begin
the long process of learning how to design.
D.
The psychology of failure in engineering: You learn from failure. The greater
the failure, the better your chance to learn from the failure and the greater
your chance for distinction, promotion, and salary increases.
Note: No writing required for this part (Part 4) in your lab report.
REPORT

Team report

Use a WORD PROCESSOR to write text, a SPREADSHEET to summarize and
calculate data, if appropriate.

Make sure all questions have been answered.
RECITATION DISCUSSION TOPICS

Discuss the assembly instruction for the WAO II. Are they clear? If so, explain what is
clear. If not, what changes would you make to the assembly instructions.

Discuss your findings for the gear ratio.

Discuss the components of the WAO II and their functions.

Discuss the testing methods that you employed. Explain the terms mean, accuracy and
precision as they relate to the WAO II.
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