Computer Science
Grade 7
20 min
Lesson 5: Basic Robot Movements: Controlling Motors and Actuators
Learn how to control basic robot movements using programming commands (e.g., move forward, turn left, stop).
What you'll learn
- Identify the function of at least three different types of actuators (e.g., motors, servos, solenoids) commonly used in robots and explain how they convert electrical energy into mechanical motion.
- Apply a block-based programming language (e.g., Scratch, Blockly) to program a robot to perform three basic movements: forward, backward, and turn, with at least 80% accuracy based on pre-defined distance/angle parameters.
- Explain the relationship between motor speed, motor direction, and the resulting movement of a robot, providing at least two examples of how changing these parameters affects the robot's path.
- Solve a simple obstacle course challenge by programming a robot to navigate around at least two obstacles within a 5-minute time limit using controlled motor movements and without direct physical intervention.
Tutorial Preview
1
Introduction & Learning Objectives
Learning Objectives
Define the terms 'motor' and 'actuator' and explain their role in a robot.
Write a program to turn a DC motor on and off using code.
Control the speed and direction (forward/reverse) of a robot's wheels.
Program a robot to move for a specific duration of time.
Design and use a simple function to create a reusable movement command (e.g., `moveForward()`).
Program a sequence of movements, such as moving forward and then turning.
Explain the difference between a pivot turn and a swing turn.
Ever wonder how a robot vacuum cleaner knows how to move around your room, or how a rover explores Mars? 🤖 It all starts with telling its 'muscles' what to do!
In this lesson, we'll learn how to be the 'brain' for our...
2
Key Concepts & Vocabulary
TermDefinitionExample
ActuatorA component of a robot that is responsible for moving or controlling a mechanism. It's the 'muscle' of the robot.A motor that spins a wheel is an actuator. A small arm that opens and closes a gripper is also an actuator.
DC MotorA common type of motor that spins continuously in one direction when power is applied. Reversing the power makes it spin the other way.The motors that spin the wheels on your robot are DC motors. They are great for driving and continuous motion.
Servo MotorA special type of motor that can rotate to a specific angle (like 0, 90, or 180 degrees) and hold that position.Used for a robot's arm to raise it to a precise height, or for a steering mechanism in a robotic car.
PortA physical socket on the robot's control...
3
Core Syntax & Patterns
Single Motor Control
motor.run(port, speed)
This is the fundamental command to control one motor. You must specify which `port` the motor is connected to (e.g., 'A', 'B') and the `speed` you want (e.g., from -100 for full reverse to 100 for full forward). A speed of 0 stops the motor.
Timed Movement Pattern
motor.run(port, speed)
wait(seconds)
motor.stop(port)
To make a robot move for a specific amount of time, you must (1) start the motor, (2) tell the program to wait for a set duration, and then (3) explicitly command the motor to stop. This is the most common pattern for creating predictable movements.
Movement Function Design
function moveForward(speed, duration):
leftMotor.run('A', speed)
rightMotor.run('B', speed)
wai...
4 more steps in this tutorial
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Challenging
The right motor on Port 'B' was accidentally wired backward. To fix this in the code for a `moveForward(speed)` command without touching the wires, what change must be made?
A.The code should be `leftMotor.run('A', speed); rightMotor.run('B', speed);`
B.The code should be `leftMotor.run('A', -speed); rightMotor.run('B', -speed);`
C.The code should be `leftMotor.run('A', speed); rightMotor.run('B', -speed);`
D.The code should be `leftMotor.run('A', 0); rightMotor.run('B', speed);`
Challenging
Given the functions `moveForward(duration)` and `pivotRight(duration)`, which sequence of calls would make the robot trace a path resembling the letter 'L'?
A.moveForward(2); pivotRight(0.5);
B.moveForward(2); moveForward(2); pivotRight(0.5);
C.pivotRight(0.5); moveForward(2); pivotRight(0.5);
D.moveForward(2); pivotRight(0.5); moveForward(2);
Challenging
A robot's pivot turn is not precise. Sometimes it over-turns, sometimes it under-turns, even with the same code. What is the most likely cause and best solution?
A.The code is wrong; rewrite the turn function from scratch.
B.The motors are broken; they need to be replaced.
C.The battery level is fluctuating, causing motor speed to vary; use a sensor to make turns more reliable instead of relying only on time.
D.The floor surface is too slippery; the program cannot be fixed.
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Start Practicing FreeMore from Chapter 5: Robotics: Building and Programming Autonomous Machines
Lesson 1: What is a Robot? Defining Autonomous Machines
Lesson 2: Robot Components: Sensors, Actuators, and Controllers
Lesson 3: Types of Robots: Exploring Different Designs and Applications
Lesson 4: Introduction to Robot Programming: Giving Robots Instructions
Lesson 6: Robot Sensors: Using Sensors to Interact with the Environment
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Lesson 5: Basic Robot Movements: Controlling Motors and Actuators is a Grade 7 Computer Science lesson on ExcelOS.
What will I learn in Lesson 5: Basic Robot Movements: Controlling Motors and Actuators?
You'll be able to: Identify the function of at least three different types of actuators (e.g., motors, servos, solenoids) commonly used in robots and explain how they convert electrical energy into mechanical motion; Apply a block-based….
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This lesson includes 27 practice questions across multiple difficulty levels, each with instant feedback and explanations.