Lab 3: Localization

ECSE 211 Design Principles & Methods 
Lab 3: Localization
Submission instructions: Students are expected to work in their assigned lab groups.
The lab consists of three components, demonstration, lab report, and code submission.
Instructions on the demonstration can be found in this handout. Lab reports and code
submission must follow the guidelines established in this handout and for the course. For more
information, see the ECSE211SubmissionInstructions.pdf on MyCourses.
Design objectives
1. Design a system to localize the robot using ultrasonic and light sensors, where the robot
should move to a known starting position.
2. Evaluate the design and determine how well the system localizes the robot.
Design requirements
The following design requirements must be met:
● The system must localize the robot to the origin of the tiles grid system.
● Localization must use the ultrasonic sensor and, optionally, light sensors (see bonus).
● The robot must localize approximately to the 0° direction using the ultrasonic sensor.
● The robot must localize to the (1, 1) gridpoint and 0° using the ultrasonic/light sensor.
● The robot must wait for input once completing angle localization and orienting to 0°.
© Instructor and Teaching Assistant generated course materials (e.g., handouts, notes,
summaries, assignments, exam questions, etc.) are protected by law and may not be copied
or distributed in any form or in any medium without explicit permission of the instructor. Note
that infringements of copyright can be subject to follow up by the University under the Code of
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ECSE 211 Design Principles & Methods Updated: 26 January 2020
Demonstration (30 points)
The design must satisfy the requirements by completing the demonstration outlined below.
Design presentation (10 points)
Before demoing the design, your group will be asked some questions for less than 5 minutes.
You will present your design and answer questions designed to test your individual
understanding of the lab concepts. Each person will be graded individually.
You must present your workflow, an overview of the hardware design, and an overview of the
software functionality. Visualizing software with graphics such as flow charts is valuable.
Demonstration procedure
As shown in Figure 1, the robot is placed along the 45° line (thick dotted) inside the bottom-left
tile of the 4x4 field grid. The brown-colored walls represent walls used for the ultrasonic
localization. Please note that the robot could be placed in ANY ORIENTATION and POSITION
along this 45° line. For example, Figure 2 shows another orientation and position of the robot’s
starting position compared to that in Figure 1.
Figure 1. Robot’s Starting Orientation A. Figure 2. Robot’s Starting Orientation B.
Indicate to the TA what version of the ultrasonic localization you would like to use. Upon
completing the angle localization, the robot should orient to its estimated 0° axis and the TA
will measure the orientation error with respect to its true 0° axis. Note that you should have a
© Instructor and Teaching Assistant generated course materials (e.g., handouts, notes,
summaries, assignments, exam questions, etc.) are protected by law and may not be copied
or distributed in any form or in any medium without explicit permission of the instructor. Note
that infringements of copyright can be subject to follow up by the University under the Code of
Student Conduct and Disciplinary Procedures.
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ECSE 211 Design Principles & Methods Updated: 26 January 2020
stopping criterion to ensure that the robot stays still while the error angle is being measured
(e.g. Button.waitForAnyPress() can be used to separate the two procedures).
After the measurement is complete, the robot should then move to the (1, 1) point as shown in
Figure 1 and Figure 2. Once ultrasonic/light localization is performed at this point, two error
quantities are measured by the TA: the Euclidean distance error ϵ between the robot’s actual
position (XF
, YF
) and the (1, 1) point, and the orientation error with respect to the 0° axis.
ε = √(X ) F
2 + (Y ) F
2
Angle Localization (5 points)
● 5 points are given for orienting the robot on its 0° axis within an error tolerance of ±10°. A
penalty of 2.5 points per ±10° is used for angles beyond 10°. Hence, the following points
are awarded for the actual robot’s orientation:
● ± [0, 10] ° → 5 points
● ± (10, 20] ° → 2.5 points
● ± (20, ∞) ° → 0 points
Ultrasonic Localization (15 points)
● 5 points are given for orienting the robot along its 0° axis at point (1, 1) within an error
tolerance of ±5°. A penalty of 2.5 points per 5° is used for angles beyond 5°. Hence, the
following points are awarded for the actual robot’s orientation:
● ± [0, 5] ° → 5 points
● ± (5, 10] ° → 2.5 points
● ± (10, ∞) ° → 0 points
● 10 points are given for reaching point (1, 1) within an error tolerance of 3 cm using a
Euclidean distance. A penalty of 2.5 points per 3 cm is used for distances beyond 3 cm.
Hence, the following points are awarded for the actual robot’s position relative to the point
(1, 1):
● [0, 3] cm → 10 points
● (3 6] cm → 5 points
● (6, 9] cm → 2.5 point
● (9, ∞) cm → 0 points
● BONUS: Light Localization - (10 points) are given for reaching point (1, 1) within an error
tolerance of 2 cm using a Euclidean distance. A penalty of 2.5 points per 2 cm is used for
© Instructor and Teaching Assistant generated course materials (e.g., handouts, notes,
summaries, assignments, exam questions, etc.) are protected by law and may not be copied
or distributed in any form or in any medium without explicit permission of the instructor. Note
that infringements of copyright can be subject to follow up by the University under the Code of
Student Conduct and Disciplinary Procedures.
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ECSE 211 Design Principles & Methods Updated: 26 January 2020
distances beyond 2 cm. Hence, the following points are awarded for the actual robot’s
position relative to the point (1, 1):
● [0, 2] cm → 10 points
● (2, 4] cm → 5 points
● (4, 6] cm → 2.5 point
● (6, ∞) cm → 0 points
Provided materials
Sample code
No sample code is provided for this lab. Instead follow the guidelines given below:
● Create a UltrasonicLocalizer class that performs the ultrasonic localization routine.
● Optional: Create a LightLocalizer class that performs the light localization routine.
Physical material
In the lab, tiles with grids will be provided which will have walls for localization.
Implementation instructions
1. Using the class definitions above, implement the ultrasonic localization versions.
a. For more information see the tutorial provided.
2. Using the class definition above, implement the localization routine(s).
3. Create a main class that:
a. First, corrects the angle of the robot and then waits for input by the user before
moving to the grid intersection.
b. Second (if you choose to do the bonus), your robot must pause after the angle
localization and wait for user input before continuing to light localization.
© Instructor and Teaching Assistant generated course materials (e.g., handouts, notes,
summaries, assignments, exam questions, etc.) are protected by law and may not be copied
or distributed in any form or in any medium without explicit permission of the instructor. Note
that infringements of copyright can be subject to follow up by the University under the Code of
Student Conduct and Disciplinary Procedures.
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ECSE 211 Design Principles & Methods Updated: 26 January 2020
Report Requirements
The following sections must be included in your report. Answer all questions in the lab report
and copy them into your report. For more information, refer to
ECSE211SubmissionInstructions.pdf. Always provide justifications and explanations for all
your answers.
Section 1: Design Evaluation
You should concisely explain the overall design of your software and hardware. You must
present your workflow, an overview of the hardware design, and an overview of the software
functionality. You must briefly talk about your design choices before arriving at your final design.
Visualizing hardware and software with graphics (i.e. flowcharts, class diagrams) must be
shown.
Section 2: Test Data
This section describes what data must be collected to evaluate your design requirements.
Collect the data using the methodology described below and present it in your report.
Test localization (10 independent trials)
1. Place the robot in a tile corner along the 45° line (Figure 1), where two walls are present.
2. Choose a random orientation for the robot.
3. Run the ultrasonic localization routine.
4. Note the ultrasonic angle of the robot.
5. Compute the ultrasonic angle error using the ultrasonic angle and the expected value.
6. Continue the localization using the ultrasonic sensor to center at (1, 1) and 0°.
7. Note the final position and final angle of the robot.
8. Compute the Euclidean distance error and final angle error.
9. Report in a table: ultrasonic angle error, Euclidean distance error, and final angle error.
Section 3: Test Analysis
For each test, compute the mean and standard deviation of the ultrasonic angle error, Euclidean
distance error, and final angle error. Be sure to show general formulas and sample calculations.
Section 4: Observations and Conclusions
1. Describe other possible localization techniques and explain why you chose yours.
2. Was the final angle impacted by the initial ultrasonic angle?
3. What factors do you think contributed (positively and negatively) to the performance of your
method?
© Instructor and Teaching Assistant generated course materials (e.g., handouts, notes,
summaries, assignments, exam questions, etc.) are protected by law and may not be copied
or distributed in any form or in any medium without explicit permission of the instructor. Note
that infringements of copyright can be subject to follow up by the University under the Code of
Student Conduct and Disciplinary Procedures.
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ECSE 211 Design Principles & Methods Updated: 26 January 2020
4. Do you think that the ultrasonic sensor or the light sensor method performs better? (If you
did not do the bonus answer based on the reliability/quality of the readings of the light
sensor vs. ultrasonic sensor). In future labs which one do you plan to use for navigating?
Section 5: Further Improvements
1. Propose a software or hardware way to minimize errors in the ultrasonic sensor.
2. Propose another form of localization.
3. Discuss how and when light localization could be used outside of the corner to correct
Odometry errors, e.g. having navigated to the middle of a larger floor.
4. How could the robot quickly localize given two light sensors?
Frequently asked questions (FAQ)
1. Do I need to implement my robot’s localization routines using the same 0° axis shown
in Figure 1 and Figure 2 (that is, along +y axis)?
Yes.
2. Do I need to move to another position within the angle localization procedure?
No, you should only rotate about your starting position. Once the orientation error in part 1 is
measured, the robot should then move to the (1, 1) point for ultrasonic localization.
3. What is meant by “design presentation”?
Before a lab demo, you and your partner will briefly present your design. This can include a
basic visualization of how your code functions, such as a flow chart. You will then be asked
a series of questions. These could be related to the lab tutorial and the initial lab code. For
this part, a grade of 10 signifies full understanding, 5 signifies satisfactory understanding,
while 0 shows no understanding at all. Note that memorized answers are discouraged and
both partners should be responsible for understanding the design and their associated code,
even if one of them did not write all of it.
© Instructor and Teaching Assistant generated course materials (e.g., handouts, notes,
summaries, assignments, exam questions, etc.) are protected by law and may not be copied
or distributed in any form or in any medium without explicit permission of the instructor. Note
that infringements of copyright can be subject to follow up by the University under the Code of
Student Conduct and Disciplinary Procedures.
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