JNTU B.Tech IV FUNDAMENTALS OF ROBOTICS Previous Question Paper (September - 2022 - R18)

A robot system consists of several integrated components that allow it to perceive, process, and act upon its environment. The primary components include:

1. Manipulator/Arm: The physical structure consisting of links and joints that provide the necessary degrees of freedom to reach and orient objects.
2. End-Effector: The tool or gripper attached to the wrist of the manipulator, designed to perform specific tasks like grasping, welding, or painting.
3. Actuators: The motors (electric, hydraulic, or pneumatic) that drive the joints to create motion.
4. Sensors: Devices that collect data about the robot's internal state (e.g., encoders for joint position) and external environment (e.g., vision, proximity, or force sensors).
5. Controller: The brain of the system that processes sensor feedback, executes programmed instructions, and sends control signals to the actuators.
6. Power Supply: Provides the energy required for the actuators, controller, and sensors to function.

Diagram description: The system is represented as a closed-loop flow where the Controller sends signals to Actuators (Manipulator), which interacts with the Environment. Sensors provide feedback to the Controller, while the Power Supply feeds the Controller and Actuators.

A wrist force sensor is typically mounted between the robot's wrist flange and the end-effector. It is designed to measure the forces and torques exerted on the tool during interaction with the environment.

The principle of operation is based on the use of strain gauges arranged in a bridge circuit. When an external force is applied to the end-effector, it creates mechanical stress on the sensor's structure. This stress causes minute deformations in the sensing elements, changing the electrical resistance of the strain gauges. These resistance changes are converted into voltage signals, which are then processed by the controller to determine the magnitude and direction of the forces (Fx, Fy, Fz) and torques (Mx, My, Mz).

Key applications include:

• Assembly tasks: Detecting contact forces during peg-in-hole insertions to prevent jamming or part damage.
• Grinding and Polishing: Maintaining a constant contact force between the tool and the workpiece to ensure uniform material removal.
• Force-controlled movement: Enabling the robot to follow a surface contour by adjusting its path based on real-time force feedback.