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For example, imagine a robot equipped with PIR sensors in a room. When a
person enters the room, the PIR sensors detect the changes in the infrared
radiation emitted by the person’s body heat. The sensors then trigger a
response in the robot, such as turning its attention towards the detected
movement or adjusting its behaviour based on the presence of the person.
PIR sensors are commonly used for motion detection in robotics
applications, such as security systems, home automation, or interactive robots. They are particularly useful for
applications where human presence or movement needs to be detected or tracked.
• Optical Encoders: Optical encoders are motion sensors that measure the position, speed, or direction of
rotation of a motor or joint. They consist of a light source, a disk with slots or patterns, and a photodetector.
As the disk rotates, the slots or patterns pass through the light source and are detected by the photodetector,
generating electrical signals that indicate the position or movement of the object.
For example, consider a robot arm equipped with optical encoders on its joints. As the robot arm moves or rotates
its joints, the optical encoders detect the position and speed of each joint. This feedback allows the robot to
precisely control its movements, maintain accurate positioning, or perform tasks requiring coordinated motion.
Optical encoders are widely used in robotics for tasks such as robot arm control, motor control, or precise
positioning. They provide valuable feedback that enables robots to accurately track and control their movements.
Navigation Sensor
A navigation sensor is a type of sensor used in robotics to provide
information about the robot’s position, orientation, or movement
in its environment. These sensors help robots navigate, localize
themselves, and understand their surroundings. Navigation
sensors play a critical role in various robotic applications, including
autonomous vehicles, drones, mobile robots, or robotic mapping.
Let’s explore two examples of navigation sensors commonly used in
robotics: GPS (Global Positioning System) and LiDAR (Light Detection
and Ranging).
• GPS (Global Positioning System): GPS is a widely used navigation sensor that utilises a network of satellites to
determine the position, velocity, and time synchronisation of a receiver. GPS receivers calculate their position by
receiving signals from multiple satellites and analysing the time delays and positions of those satellites.
For example, in autonomous vehicles, a GPS sensor can provide accurate global positioning information. By
continuously receiving signals from GPS satellites, the sensor can determine the latitude, longitude, and altitude
of the robot’s position. This information allows the robot to navigate along predefined routes, track its location,
or plan its trajectory based on the desired destination.
GPS sensors are effective in outdoor environments where they have a clear line of sight to GPS satellites.
However, they may have limitations in terms of accuracy and reliability, especially in urban areas or environments
with obstacles that can block the satellite signals.
• LiDAR (Light Detection and Ranging): LiDAR sensors utilise laser beams to measure distances to objects and
generate detailed 3D maps of the surroundings. They emit laser pulses and measure the time it takes for the
pulses to bounce back after hitting objects. By analysing the returned pulses, LiDAR sensors can create high-
resolution point clouds representing the environment.
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