Lesson Notes By Weeks and Term v4 - SHS 1
Sensors & Actuators
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Sensors & Actuators
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Subject: Robotics
Class: SHS 1
Term: 1st Term
Week: 15
Grade code: 1.1.3.LI.2
Strand code: 1
Sub-strand code: 3
Content standard code: 1.1.3.CS.2
Indicator code: 1.1.3.LI.2
Theme: Principles of Robotic Systems
Subtheme: Sensors & Actuators
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In Ghana, we see technology everywhere, from the traffic lights in Accra to the mobile phones we use to check the weather or send money. How do these devices know what's happening in the world around them? They use sensors. A phone's screen brightens in the sun because of a light sensor. A modern incubator for a poultry farm keeps the temperature just right using a temperature sensor. However, these sensors often give readings in a language computers understand (like voltage or a random number), not a language humans understand (like degrees Celsius or centimetres). This lesson is about becoming a translator.
Concept 1: What is a Linear Sensor?
A sensor is a device that detects and responds to some type of input from the physical environment. The input could be light, heat, motion, moisture, pressure, or any of a great number of other environmental phenomena.
A linear sensor is a special type of sensor where the output changes in direct proportion to the input. If you plot its readings on a graph, you get a straight line. Example: A temperature sensor is linear if for every 10°C increase in temperature, its voltage output increases by exactly 0.5 volts. The relationship is consistent and predictable. Non-Example: A sensor where a 10°C increase from 20°C to 30°C causes a 0.5V change, but a 10°C increase from 80°C to 90°C causes a 1.2V change, is non-linear. Concept 2: What is Calibration and Why Do We Need It?
Most sensors do not output readings in nice, human-readable units like degrees Celsius (°C) or metres (m). Instead, they output a raw electronic signal, often as: Voltage: e.g., 2.35V Resistance: e.g., 5,000 Ohms Analog-to-Digital Converter (ADC) Value: A number, often between 0 and 1023 (for a 10-bit ADC common in Arduino).