L5 — Light, Sound & the Robot Claw

Lesson 5 of 6

Light, Sound & the Robot Claw

Sensors, event-driven responses, and EdBuild physical construction

Year 9 · Robotics with Edisons

Learning Objectives

1Program Edison to follow a line using Ed.ReadLineState() or respond to claps using Ed.ReadClapSensor()

2Construct the EdBuild robot claw attachment and connect it to Edison's servo port

3Write a program that controls the claw servo in sequence with movement commands

Prior Knowledge: Lessons 1–4 — movement, loops, obstacle detection, while True. Students should be confident with EdPy download process.

Prep: Distribute EdBuild claw kits and printed instructions (EdBuild EdRoboClaw Instructions.pdf from Existing Store). Print a line-following track — thick black tape on white A3 paper works well. Have a small object (cotton reel, block) for claw testing.

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Key Vocabulary

Sensor types and event-driven programming

⚫

Line Tracking Sensor

Two IR sensors on Edison's underside that detect whether they are above a dark or light surface. Returns LINE_ON_LEFT, LINE_ON_RIGHT, or LINE_ON_NEITHER.

👏

Clap Sensor

Edison's built-in sound sensor detects sudden loud sounds (claps). Activated with Ed.ReadClapSensor(Ed.CLAP_SENSOR_ON). Returns Ed.CLAP_DETECTED.

🦾

EdBuild / Servo

EdBuild is Edison's LEGO-compatible construction system. The robot claw uses a servo motor — a motor that moves to a specific position (0–100). Controlled with Ed.SetServoPosition().

⚡

Event-Driven Programming

Code that responds to events (sensor readings, inputs) rather than just running sequentially. The while True + sensor check pattern is a simple form of event-driven programming.

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Line Following & Clap Detection

Two sensor-response programs — students choose one

Option A — Line Follower

Value	Meaning
`Ed.LINE_ON_LEFT`	Left sensor over line → turn left
`Ed.LINE_ON_RIGHT`	Right sensor over line → turn right
`Ed.LINE_ON_NEITHER`	Both off line → drive straight

while True:
    line = Ed.ReadLineState()
    if line == Ed.LINE_ON_LEFT:
        Ed.TurnLeft(Ed.SPEED_2, Ed.TURN_SPOT)
    elif line == Ed.LINE_ON_RIGHT:
        Ed.TurnRight(Ed.SPEED_2, Ed.TURN_SPOT)
    else:
        Ed.Drive(Ed.FORWARD, Ed.SPEED_3,
                 Ed.DISTANCE_UNLIMITED)

Option B — Clap Control

Note: Must enable clap sensor first with Ed.ReadClapSensor(Ed.CLAP_SENSOR_ON) before the loop.

Ed.ReadClapSensor(Ed.CLAP_SENSOR_ON)
driving = False

while True:
    if Ed.ReadClapSensor() == Ed.CLAP_DETECTED:
        if driving:
            Ed.StopDriving()
            driving = False
        else:
            Ed.Drive(Ed.FORWARD, Ed.SPEED_3,
                     Ed.DISTANCE_UNLIMITED)
            driving = True

Boolean variable pattern: driving = False — a True/False flag that tracks robot state. Important concept for the final challenge.

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The EdBuild Robot Claw

Physical construction + servo control code

Construction Steps

1Attach the base plate to the front underside of Edison — clip into the front two locking slots

2Clip the two claw arm pieces onto the axle on the base plate — one per side

3Thread the servo cable through the clip and plug into Edison's servo port (right side, 3-pin connector)

4Test the connection is firm — gently tug the claw arms to ensure they do not detach

Refer to: EdBuild EdRoboClaw Instructions.pdf for detailed diagrams. Print one per pair.

Servo Control Code

import Ed
Ed.EdisonVersion = Ed.V3
Ed.DistanceUnits = Ed.CM
Ed.Tempo = Ed.TEMPO_MEDIUM

# Servo: 0 = fully closed, 100 = fully open
open_pos = 100
closed_pos = 0
wait_ms = 1000

# Open claw
Ed.SetServoPosition(open_pos)
Ed.TimeWait(wait_ms, Ed.TIME_MILLISECONDS)

# Close claw (grip)
Ed.SetServoPosition(closed_pos)
Ed.TimeWait(wait_ms, Ed.TIME_MILLISECONDS)

Ed.PlayBeep()  # signal done

Grip position: Servo position ~30–40 usually gives a gentle grip. 0 is fully clenched — may slip on smooth objects.

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Student Task

Two-part challenge — sensor response AND robot claw

Direct students to: student.html → L5 Light, Sound & the Robot Claw. Steps 1–3.

1Step 1: Choose line follower or clap control. Code and test it. Upload code screenshot.

2Step 2: Build the EdBuild claw. Use the instructions sheet. Take a photo once built and upload it.

3Step 3: Write a sequence program: drive → open claw → wait → close claw → reverse → beep. Test on a small object. Upload claw code screenshot.

🥉 Bronze

Working sensor program (line or clap). Claw opens and closes on command.

🥈 Silver

+ Combined sequence: movement + claw in one program. Named variables for all positions and timings.

🥇 Gold

+ Use obstacle sensor to trigger the grab — drive until obstacle detected, then open/close claw to grab it.

Timing: Step 1 (~12 min) → Step 2 construction (~10 min) → Step 3 coding + testing (~15 min). Move construction to start of lesson if EdBuild kits are complex for your cohort.

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Plenary

Consolidate and preview the Final Challenge

Exit Ticket — Think → Pair → Share

"Name one similarity and one difference between the line follower program and the obstacle avoidance program from Lesson 4. Consider the structure of the code, not just what the robot does."

✅ Today we covered

Line tracking sensor values and line follower logic
Clap detection and boolean state variables
EdBuild robot claw construction
Ed.SetServoPosition() for gripper control
Combining movement + claw in sequence

⏭ Next Lesson

Lesson 6: Edison Final Challenge

Students design and build their own Edison program. They must use movement, a loop, and a condition. Ends with PDF portfolio export. Remind students to bring their ideas.

Exit ticket model answer: Similar — both use while True + sensor read + if/elif/else. Different — obstacle uses rear IR sensors; line uses bottom IR; obstacle reverses on detection; line steers to correct.