Page 115 - Toucpad robotics C11

The sensor’s electronic circuit then converts this detected light intensity into an electrical signal (often a voltage or
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digital signal), which the robot’s microcontroller can read to determine the presence of an object or estimate its
approximate distance.
Applications in Robotics
Proximity Detection/Obstacle Avoidance: Detecting if an object is very close to the robot, commonly used in robotic
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vacuum cleaners to avoid bumping into furniture.
Line Following: Used in line-follower robots to detect a black line on a white surface (or vice-versa) to guide their
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movement.
Edge Detection: Sensing the edge of a table or ramp to prevent a robot from falling off.
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Remote Control Receivers: Used in television remotes, but also in some simple robotic control systems to receive
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commands.

Advantages
Inexpensive: Relatively cheap and easy to integrate into robotic projects.
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Fast Response Time: Can detect objects quickly.
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Compact Size: Small and lightweight.
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Low Power Consumption: Generally consumes little power.
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Disadvantages
Limited Range: Typically effective only for short distances (a few centimetres to tens of centimetres).
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Susceptible to Ambient Light: Strong sunlight or other infrared sources can interfere with their readings.
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Affected by Surface Colour/Material: Dark, matte, or transparent surfaces absorb infrared light, making them
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difficult to detect reliably. Highly reflective surfaces can cause false readings.
Less Accurate for Distance Measurement: Provides a rough estimate of distance rather than highly precise
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measurements.

Ultrasonic Sensors
Description

An Ultrasonic sensor is a device that uses sound waves, specifically ultrasound
(sound waves with frequencies higher than the upper audible limit of human
hearing, typically above 20 kilohertz), to measure distance to an object or detect
its presence. They are similar to how bats or dolphins navigate.

Working Principle
The sensor contains two main parts: a transmitter (or transducer) that emits
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ultrasonic sound waves and a receiver that detects reflected sound waves.
The transmitter emits a short burst of ultrasonic sound waves.
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These sound waves travel through the air. If they encounter an object, they reflect off its surface and travel back
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towards the sensor.
The receiver listens for the echoed sound wave.
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The sensor’s internal circuitry measures the time elapsed between sending the sound wave and receiving its echo.
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Since the speed of sound in air is known (approximately 343 meters per second at room temperature), the sensor can
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calculate the distance to the object using the formula:
Distance = (Speed of Sound × Time Elapsed)/2 .
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Electrical and Control Systems