Computer Science
Grade 9
20 min
Robot Obstacles: Navigating a Maze
Students program their robot to navigate a simple maze.
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1
Introduction & Learning Objectives
Learning Objectives
Define what an algorithm is in the context of robotics and maze navigation.
Explain the role of sensors in detecting obstacles for a robot.
Implement a simple 'wall-following' algorithm using pseudocode.
Use conditional statements (if/else) to make decisions based on sensor input.
Use a `while` loop to repeat navigation steps until a goal is reached.
Debug a simple maze-solving program by tracing the robot's path and logic.
Represent a simple maze using a 2D grid data structure.
Ever wonder how a robot vacuum avoids your furniture or finds its way back to the charging dock? 🤖 Let's teach a virtual robot to solve a maze!
In this lesson, you will learn the fundamental programming concepts needed to guide a robot through a maze full o...
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Key Concepts & Vocabulary
TermDefinitionExample
AlgorithmA step-by-step set of instructions or rules for a computer (or robot) to follow to solve a problem or complete a task.A simple robot algorithm could be: 1. Move forward. 2. If you sense a wall, turn right. 3. Repeat.
SensorA device on a robot that detects or measures something in the environment and sends that information to the robot's controller.An ultrasonic distance sensor can tell the robot how many centimeters away a wall is, just like a bat uses sound to 'see' in the dark.
Conditional Statement (If/Else)A programming structure that performs different actions depending on whether a condition is true or false.`if (isWallInFront == true): turnLeft() else: moveForward()` This tells the robot to turn only if a wall is detected.
Loop (While L...
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Core Syntax & Patterns
The Wall-Follower Algorithm (Right-Hand Rule)
1. If the path to the right is open, turn right and move one step.
2. Else, if the path forward is open, move forward one step.
3. Else, turn left.
This is a simple but powerful algorithm for solving any maze that is 'simply connected' (i.e., all walls are connected together). By consistently 'hugging' one wall, the robot guarantees it will explore every possible path and eventually find the exit. This logic is placed inside a loop that runs until the goal is found.
Sensor-Based Decision Logic
`if (sensor_condition):
action_A
else:
action_B`
This is the fundamental pattern for making a robot react to its environment. The `sensor_condition` checks data from a sensor (e.g., `distanceToWall < 10`). Base...
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Challenging
The Wall-Follower algorithm can fail in mazes where the goal is on an 'island' not connected to the outer wall. Why does this happen?
A.The robot's sensors cannot see the island from the outer wall.
B.The algorithm is designed to follow one continuous wall, so it will circle the outer perimeter and never find the path to the island.
C.The robot runs out of battery before it can explore the entire maze.
D.Islands in mazes cause the robot's `while` loop to terminate prematurely.
Challenging
A robot using the Right-Hand Wall-Follower algorithm approaches a T-junction from the south (bottom). Paths are available to the West (left), North (forward), and East (right). Which path will it take?
A.It will go North (forward) because that is the simplest path.
B.It will go West (left) because it is at a junction.
C.It will stop because it has too many choices.
D.It will go East (right) because that is the first rule of the algorithm.
Challenging
To prevent a robot from getting stuck in an endless loop by visiting the same grid cell multiple times, a programmer wants to store every 'state' (e.g., position AND orientation) the robot has been in. Which data structure would be efficient for quickly checking if a state has been visited before?
A.single integer variable to count the states.
B.simple list where the robot appends each state, then searches the whole list every time.
C.hash set or dictionary, which provides very fast lookups of previously visited states.
D.2D grid that only stores the robot's last position.
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