(SEM VIII) THEORY EXAMINATION 2024-25 AUTOMATION AND ROBOTICS

SECTION A – Short Answers (2 Marks Each) – Paragraph Style

a) Define industrial automation and list any three of its advantages.

Industrial automation refers to the use of control systems such as computers, robots, sensors, and information technologies to operate industrial processes with minimal human intervention. It improves productivity by reducing manual effort, enhances product quality through consistent operations, and increases safety by minimizing human exposure to hazardous environments.

b) What is robot time estimation? Why is it essential in CNC and automated systems?

Robot time estimation is the process of calculating the time required by a robot to complete a specific task such as movement, pick-and-place, or machining. It is essential in CNC and automated systems because it helps in production planning, cycle time optimization, cost estimation, and efficient scheduling of operations.

c) What are the basic elements of an automated system?

An automated system consists of three basic elements: power, program, and control. Power provides energy for system operation, the program contains instructions defining the process, and the control system executes the program by regulating machines and devices to perform desired tasks accurately.

d) List and briefly explain the laws of robotics as given by Isaac Asimov.

Isaac Asimov proposed three laws of robotics to ensure safe robot behavior. The first law states that a robot must not harm a human being. The second law states that a robot must obey human orders unless they conflict with the first law. The third law states that a robot must protect its own existence as long as it does not conflict with the first two laws.

e) What is a CNC machine tool? How is it different from a traditional machine?

A CNC machine tool is a computer-controlled machine that performs machining operations using programmed instructions. Unlike traditional machines that rely on manual operation, CNC machines offer higher precision, repeatability, automation, and reduced human error.

f) Explain the D-H parameters used in robotic kinematics.

Denavit-Hartenberg parameters are a standardized method for describing the geometry of robotic manipulators. They include link length, link twist, link offset, and joint angle, which together define the position and orientation of robot links in space.

g) What is meant by forward and inverse kinematics in robotics?

Forward kinematics determines the position and orientation of the robot end-effector when joint parameters are known. Inverse kinematics determines the joint parameters required to achieve a desired end-effector position, which is more complex and computationally intensive.

h) Compare servo motors and stepper motors used in robot drives.

Servo motors provide closed-loop control with high accuracy, smooth motion, and feedback mechanisms, making them suitable for precision tasks. Stepper motors operate in open-loop control, are simpler and cheaper, but offer lower accuracy and torque at high speeds.

i) What is robot cell interference? How can it be avoided?

Robot cell interference occurs when robots, machines, or fixtures collide within a shared workspace. It can be avoided through proper layout design, simulation, path planning, safety zones, and synchronization of robot movements.

j) What are the advantages of using ball bearings in robot joints?

Ball bearings reduce friction, support smooth rotation, improve load handling capacity, increase positioning accuracy, and enhance the operational life of robot joints, making them ideal for high-precision robotic applications.

SECTION B – Descriptive Answers (10 Marks Each) – Paragraph Style

a) Analyze the role of robotics in industrial automation and their advantages over conventional systems.

Robotics plays a crucial role in industrial automation by performing repetitive, precise, and hazardous tasks efficiently. Compared to conventional systems, robots offer higher accuracy, flexibility, and consistency. They can work continuously without fatigue, reduce production time, improve product quality, and enhance workplace safety. Robotics also allows easy reprogramming for different tasks, making manufacturing systems more adaptable to market demands.

b) Design a mixed-model flow line for assembling electronic devices and highlight challenges.

A mixed-model flow line assembles different product variants on the same production line. It requires flexible workstations, modular tooling, programmable robots, and real-time control systems. Major challenges include balancing workloads, managing variation in processing time, ensuring quality control, and coordinating material supply efficiently.

c) Explain coordinate systems and robot configurations with suitable explanation.

Robot coordinate systems define reference frames used to describe motion and position, such as world, base, joint, and tool coordinates. Robot configurations describe structural arrangements like Cartesian, cylindrical, spherical, SCARA, and articulated robots. Each configuration offers unique advantages based on workspace, accuracy, and application requirements.

d) Explain power transmission methods in robot mechanisms and rack-and-pinion motion conversion.

Power transmission in robots is achieved using gears, belts, chains, screws, and hydraulic or pneumatic systems. Rack-and-pinion mechanisms convert rotary motion into linear motion by engaging a rotating pinion gear with a linear rack, commonly used in robotic linear actuators.

e) Explain design considerations for robot layout in warehouse material handling.

Robot layout design for warehouses considers space utilization, payload capacity, path optimization, safety zones, and interaction with conveyors and storage systems. Proper layout minimizes interference, improves throughput, and ensures efficient and safe material handling operations.

SECTION C – Long Answer (10 Marks)

a) Numerical: End-effector position of a 3-DOF robot arm.

Given link lengths and joint angles, forward kinematics is applied to calculate the end-effector position. Using trigonometric relations and transformation matrices, the position is determined by summing vector contributions of each link. This method provides the Cartesian coordinates of the end effector with respect to the base frame.

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b) Derive the D-H parameter table and transformation matrices for a 3-joint SCARA robot.

For a SCARA robot, Denavit-Hartenberg parameters are assigned based on joint axes and link orientations. Transformation matrices are derived using standard D-H conventions, which relate successive coordinate frames. These matrices are multiplied to obtain the final transformation describing end-effector position and orientation.