Music by Touch: Programming Robot Tactile Sensors to Play Sounds

Touch (tactile) sensors are key components of many devices we use every day. For instance, the touch sensors in keyboards and keypads tell computers which keys you are pressing. Similarly, you can open a car door using a touch sensor that generates an infrared signal that goes to the car's computer informing it to unlock the door. Phone and tablet touchscreens on phones enable even more exquisite communication between people and machines. The use of touch sensors has exploded into the engineering design of all sorts of devices.

Computer programming is a key component of many modern engineering designs. As students create robot programs in this activity, they must have a "goal" or "concept" of what the program solution needs to do and how, before they begin writing the code. Then, the process of working on the code and "debugging" it inherently constitutes "revising and improving their designs based on the results of testing." Hence, the thought processes required to code programs that meet problem constraints are very similar, if not identical, to those required for traditional engineering design of physical objects and products.

After this activity, students should be able to:

• Program a LEGO robot to take input from touch sensors to play music and activate a motor.
• Explain how the program and the touch sensors work.
• Relate the program (robotic response to touch sensor information) to human responses to touch.

• Experience using and programming the LEGO MINDSTORMS EV3 robot and intelligent brick (computer) so that it takes input from sensors for decision making.
• An understanding of how touch sensors work, both human and robotic, as presented in the associated lesson.
• Completion of the Our Bodies have Computers and Sensors unit and the What Is a Sensor? lesson.

We have learned how the human sense of touch works from the previous lesson. Now how do we implement the "stimulus-sensor-coordinator-effector-response" framework in a LEGO robot?

In today's design challenge activity, you will carefully program a LEGO robot to alter how some music is played and how a wheel is turned, depending on which touch sensors are activated. Let's get started!

Before the Activity

• Gather materials so each group has a LEGO MINDSTORMS EV3 intelligent brick, motor and two touch sensors, and cables for connecting them, as well as a computer with the LEGO EV3 software installed.
• Make copies of the Music by Touch Pre-Quiz (PDF) and Music by Touch Post-Quiz (PDF), one each per student. The quizzes are provided as separate attachments, and also embedded in the presentation so they can be presented to the class as a whole, if desired.
• Perform the activity prior to doing it with students. Make sure you are familiar with the design challenge and answers, which are provided in detail on slides 4-7 of the presentation.
• Use the 13-slide Music by Touch Presentation (PPTX), a Microsoft^® PowerPoint^® file, to teach and conduct the activity. Set up a computer/projector to show the presentation to the class.
• Divide the class into groups of three students each.

With the Students

1. Administer the pre-quiz by handing out paper copies; the quiz is also on slide 2. The answers are provided for the teacher on slide 3 for discussion after students have completed the quiz.
2. As a quick review, remind students of the similarities between human and robot designs (slide 4). Your hand is commanded by your brain. Similarly, the LEGO intelligent brick commands its motor to move.
3. Then introduce the activity's design challenge. Slide 5 provides a description and diagram of the equipment setup and explains the program requirements. Have students write the program on paper and check them as completed. Program requirements:

• If one touch sensor is touched, play a piece of music and keep rotating the wheel (attached to the motor) slowly.
• If the other sensor is also touched, play the music faster and make the wheel turn faster.
• Do this in a loop, continuously, until the program is stopped.

4. Review with students how the LEGO EV3 motor works:

• The EV3 motor is an electric motor that works by converting electricity into motion, and is similar to many other motors that you see around you daily.
• The EV3 motor has a built-in wheel rotation sensor that helps it control its motion, that is, it can move precise distances using this rotation sensor.

5. Hand out to each group a LEGO brick, motor and two touch sensors.
6. Assist students as they work through the challenge. Make sure to check each group's plans and provide encouragement and suggestions so that they develop successful programs. Slides 6-9 provide the programming solution for the teacher.
7. Have each group demonstrate that its program works successfully.
8. At activity end, lead a class discussion about the activity, as described in the Assessment section.
9. Administer the post-quiz by handing out paper copies; the quiz is also on slide 10. The answers are provided on slides 11-12. Slide 13 contains vocabulary terms and definitions.

Pre-Activity Assessment

Pre-Quiz: Before starting the activity, administer the Music by Touch Pre-Quiz (PDF) (also on slide 2) to assess students' base understanding of the stimulus-to-response framework and touch sensors. Answers are provided on the Music by Touch Pre-Quiz Answer Key (PDF) (and slide 3).

Activity-Embedded Assessment

Button Check: As students are conducting the activity, check to see if students understand what each of the individual programming buttons mean, whether they can follow the logic of the program step-by-step and explain their programs (refer to the programming answer for the teacher on slides 6-9).

Post-Activity Assessment

Concluding Discussion: At activity end, lead a class discussion about the activity, asking students to share their experiences and lessons learned. Ask students:

• Describe the challenges you faced.
• What issues or difficulties did you encounter?
• What are examples of how touch sensors are used in real-world devices? (Example answers: Remote control devices that open car and garage doors, turn on/off ceiling fans, etc.).
• What might you now want to learn about touch sensors?

Post-Quiz: Administer the Music by Touch Post-Quiz (PDF) (also on slide 10) to assess students' understanding of the stimulus-to-response framework, touch sensors and programming. Answers are provided in the Music by Touch Post-Quiz Answer Key (PDF) (and slides 11-12). Review students' answers to assess their understanding of the concepts explored in the activity.