JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III FUNDAMENTALS OF ROBOTICS Previous Question Paper (November/December - 2020 - R16)

Robotic sensors are devices that allow robots to perceive their environment and internal state, categorized primarily into internal and external sensors. Internal sensors monitor the robot's own state, such as joint position, velocity, and force, while external sensors gather data from the surrounding environment.

Common types of sensors include:

• Position Sensors: Measure the linear or angular position of joints (e.g., Potentiometers, Encoders, LVDTs).
• Velocity Sensors: Measure the speed of motion (e.g., Tachometers).
• Force/Torque Sensors: Measure the interaction forces between the robot and the environment (e.g., Strain gauges).
• Proximity/Range Sensors: Detect the presence or distance of objects (e.g., Ultrasonic, Infrared, Laser rangefinders).
• Vision Sensors: Capture visual data for object recognition and navigation (e.g., CCD cameras).
• Tactile Sensors: Detect physical contact and pressure (e.g., Touch sensors, pressure mats).

To measure the position of a robot gripper accurately, an Optical Encoder is the most suitable sensor. Optical encoders convert mechanical motion into digital electrical signals, providing high resolution and precision.

They function by using a light source and a photodetector separated by a rotating disk with slots or patterns. As the disk rotates with the gripper joint, it interrupts the light beam, generating pulses that are counted by a controller to determine the exact angular position. Incremental encoders provide relative position changes, while absolute encoders provide a unique digital code for every position, ensuring the gripper's location is known immediately upon power-up without needing a homing sequence.