Embedded Files
What Are Sensors?
What Are Sensors?
Sensors are devices that detect changes in the environment and convert these changes into electrical signals that can be processed by electronic circuits. They act as the "senses" of a mechatronic system, allowing it to perceive and respond to its surroundings.
In our everyday lives, we encounter sensors constantly:
The automatic doors at a supermarket use motion sensors.
Your phone's screen brightness adjusts based on ambient light sensors.
Thermostats in buildings use temperature sensors to control heating and cooling systems.
In mechatronics, sensors play a crucial role in gathering data about the system's state and its environment, enabling the system to make decisions and take actions based on this information.
Common Types of Sensors in Mechatronics
Common Types of Sensors in Mechatronics
Let's explore some common types of sensors used in mechatronic systems:
Motion Sensors
Motion Sensors
Accelerometers: Measure acceleration forces and can detect orientation.
Gyroscopes: Measure angular velocity and help determine orientation.
PIR (Passive Infrared) Sensors: Detect motion by measuring changes in infrared radiation.
Light Sensors
Light Sensors
Photoresistors: Change resistance based on light intensity.
Photodiodes: Generate current when exposed to light.
Phototransistors: Similar to photodiodes but with higher sensitivity.
Temperature Sensors
Temperature Sensors
Thermistors: Change resistance based on temperature.
Thermocouples: Generate voltage based on temperature difference.
RTDs (Resistance Temperature Detectors): Change resistance linearly with temperature.
Proximity Sensors
Proximity Sensors
Ultrasonic Sensors: Use sound waves to measure distance.
Infrared Sensors: Use infrared light to detect nearby objects.
Capacitive Sensors: Detect nearby objects by measuring changes in capacitance.
Pressure Sensors
Pressure Sensors
Piezoresistive Sensors: Change resistance when pressure is applied.
Capacitive Pressure Sensors: Change capacitance with pressure variations.
Force Sensors
Force Sensors
Strain Gauges: Measure deformation to determine applied force.
Piezoelectric Sensors: Generate voltage when force is applied.
Sensors on the BBC micro:bit
Sensors on the BBC micro:bit
The BBC micro:bit is equipped with several built-in sensors, making it an excellent platform for learning about sensor technology:
Accelerometer: Measures acceleration forces and can detect tilt, free fall etc
Magnetometer: Measures magnetic fields and can be used as a compass.
Light Sensor: Uses the LED display to measure ambient light levels.
Temperature Sensor: Measures the temperature of the micro:bit's processor.
Touch Sensors: The micro:bit's pins can be used as capacitive touch sensors.
Buttons: While not traditional sensors, the two buttons (A and B) can be considered simple input sensors.
Analogue vs. Digital Sensors
Analogue vs. Digital Sensors
Sensors can be categorised as either analogue or digital based on the type of output they produce:
Analogue Sensors
Analogue Sensors
Produce a continuous range of values.
Output is proportional to the measured quantity.
Examples: thermistors, photoresistors, potentiometers.
Digital Sensors
Digital Sensors
Produce discrete, binary outputs (usually 0 or 1).
Often used for detecting the presence or absence of something.
Examples: push buttons, reed switches, some infrared sensors.
Analogue-to-Digital Conversion (ADC)
Analogue-to-Digital Conversion (ADC)
Many sensors capture analogue data, but computers and microcontrollers work with digital data.
This is where Analogue-to-Digital Conversion (ADC) comes in:
The Process:
The Process:
The continuous analogue signal is sampled at regular intervals.
Each sample is quantized to a specific digital value.
Resolution:
Resolution:
ADCs have a fixed resolution, often expressed in bits.
Common resolutions are 8-bit (0-255) or 10-bit (0-1023).
Why 0-255 or 0-1023?
Why 0-255 or 0-1023?
8-bit ADC: 2^8 = 256 possible values (0-255)
10-bit ADC: 2^10 = 1024 possible values (0-1023)
Example:
Example:
If a temperature sensor's range is 0-100°C and we're using an 8-bit ADC:
0°C would be represented by 0
100°C would be represented by 255
50°C would be approximately 127 or 128
Page updated
Report abuse