UNITED INSTITUTE OF TECHNOLOGY, PRAYAGRAJ

INTRODUCTION TO ROBOTICS (MNRB-401)

Unit-1
1. Introduction to Robotics

Robotics is an interdisciplinary field that combines mechanical engineering, electrical engineering, computer
science, and control engineering to design, build, and operate robots. A robot is a programmable machine
capable of carrying out a series of actions automatically, either autonomously or semi-autonomously.

2. Brief History of Robotics

Era Development

Ancient Greek engineer Hero of Alexandria (10–70 AD) designed simple programmable
Times mechanical devices using steam and water.

1495 Leonardo da Vinci sketched plans for a mechanical knight, an early humanoid robot.

18th Automata such as mechanical birds and toys were developed in Europe.
Century

1940s–50s Science fiction by Isaac Asimov popularized the concept of robots and their ethical
implications.

1954 George Devol invented the first programmable robot, called Unimate.

1961 Unimate became the first industrial robot, installed in a General Motors factory.

1980s–2000s Growth of robotic arms, mobile robots, and AI-powered robots in manufacturing, space
exploration, and research.

Present Advanced robots are used in healthcare, military, autonomous vehicles, agriculture, and
domestic settings with AI integration.

3. Basic Concepts of Robotics

Definition of a Robot

A robot is a reprogrammable, multifunctional manipulator designed to move materials, parts, tools, or devices
through variable programmed motions to perform a variety of tasks.

Three Laws of Robotics (Isaac Asimov)

Though fictional, Asimov’s laws provide a philosophical framework:

1. A robot may not injure a human being or, through inaction, allow a human being to come to harm.
 2. A robot must obey the orders given to it by human beings, except where such orders would conflict
with the First Law.

3. A robot must protect its own existence as long as such protection does not conflict with the First or
Second Law.

Modern View of a Robot

Robots can be classified based on functionality:

• Industrial Robots: Used in manufacturing.

• Service Robots: Used in healthcare, cleaning, etc.

• Mobile Robots: Autonomous vehicles and drones.

• Humanoids: Robots resembling the human body structure.

• Collaborative Robots (Cobots): Designed to work alongside humans.

4. Elements of Robotic Systems

a) Robot Anatomy

Refers to the physical structure of a robot:

• Manipulator/Arm: Series of links and joints for movement.

• End-Effector: Tool or gripper attached to the arm’s end.

• Actuators: Motors or engines responsible for movement.

• Sensors: Provide feedback from the environment.

• Controller: Computer system that processes inputs and commands motion.

• Power Supply: Batteries, electric motors, or pneumatic systems.

b) Degrees of Freedom (DOF)

• Indicates the number of independent movements a robot can make.

• Each joint provides one degree of freedom.

• A typical industrial robot has 5 to 6 DOF (e.g., rotation, translation).

• More DOF = Greater flexibility, but also increased complexity.

Joint Type Motion

Revolute (R) Rotational
Prismatic (P) Linear

Example: A robotic arm with 6 joints typically has 6 DOF, similar to a human arm (shoulder, elbow, wrist).
c) Misunderstood Devices (Often Mistaken as Robots)

Device Why it's not a robot

CNC Machine Follows pre-defined tool paths, lacks autonomy or sensor feedback.

Microwave Oven Programmable but no mechanical movement or adaptability.

Automatic Doors Reactive systems with sensors, but not reprogrammable or multifunctional.

Washing Machines Programmed cycle execution, but no task adaptability or learning.

d) Types of Robot Configurations

• Cartesian (Gantry): 3 prismatic joints (X, Y, Z).

• Cylindrical: Rotary base and two linear motions.

• Spherical (Polar): One linear and two rotary motions.

• SCARA (Selective Compliance Articulated Robot Arm): Suitable for horizontal tasks.

• Articulated Robot: Multiple revolute joints (like a human arm).

Classification of Robotic Systems

1. Based on Work Volume / Workspace Geometry

The work volume (or workspace) is the 3D space a robot can reach. It depends on joint types and link
lengths.

Type Work Envelope Shape Description

Cartesian Rectangular/Box-shaped 3 linear axes (X, Y, Z); used in CNC, 3D printing

Robot

Cylindrical Cylindrical 1 rotary + 2 linear axes; suited for assembly and

Robot machine loading

Spherical Spherical 2 rotary + 1 linear; used in die casting, welding

(Polar)

Articulated Irregular/Complex (Human- Multiple rotary joints; highly flexible; most industrial
Robot arm) robots

SCARA Robot 2D work area (cylindrical) Selective Compliance Assembly Robot Arm; fast and
precise; ideal for pick/place

Delta Robot Dome/Parallelogram Parallel arms; extremely fast; used in packaging, sorting

Gantry Robot Large rectangular volume Overhead crane-like; used for heavy-duty, large-scale
operations
2. Based on Type of Drive System

Drive systems are responsible for robot motion and power transmission.

Type of Drive Mechanism Applications / Notes

Electric Drive Servomotors or stepper Most common; precise and clean; used in industrial robots
motors
Hydraulic Pressurized fluid High power; suitable for heavy-duty robots; noisy and
Drive needs maintenance
Pneumatic Compressed air Fast, simple; low power; used in lightweight applications
Drive

3. Based on Motion Control / Kinematics

Describes the type of movement the robot can perform.

Motion Type Description

Point-to-Point (PTP) Moves from one point to another without controlling the path
Continuous Path (CP) Follows a precise path (like welding, painting)
Controlled Path Combines PTP and CP, using trajectory planning

4. Based on Programming Methods

Robots can be programmed in different ways:

Programming Method Description

Manual Teaching Human guides robot physically or via pendant
Offline Programming Program written and simulated on computer before transferring
Teach Pendant Programming Use of a handheld device to manually move and record positions
Lead-Through Programming Physically guiding robot arm through motions

5. Based on Path Control

Type Description
Open Loop No feedback; used in simple operations
Closed Loop Uses sensors for feedback; ensures accuracy

6. Based on Level of Intelligence / Autonomy

Type Description
Manual Fully controlled by human operators
Fixed Automation Repetitive, pre-programmed tasks; no flexibility
Flexible (Programmable) Can be reprogrammed for different tasks
Intelligent Robots Have sensing, reasoning, and adaptive capabilities (AI-based)

7. Based on Application Area

Application Type Examples

Industrial Robots Welding, painting, material handling
Medical Robots Surgery, rehabilitation, diagnostic tools
Service Robots Cleaning, delivery, inspection
Military Robots Drones, bomb disposal, surveillance
Agricultural Robots Crop monitoring, spraying, harvesting
Space Robots Mars rovers, ISS robotic arms
Associated Parameters
1. Resolution

• Definition: The smallest change in position that a robot can detect or move to.

• Units: Millimeters (mm) or degrees (°).

• Importance: Higher resolution enables finer movements and is important in precision tasks like
assembly or surgery.

• Determined by: Encoder sensitivity and control system capability.

2. Accuracy

• Definition: The ability of a robot to reach a specific point in space as commanded.

• Units: Millimeters (mm).

• Example: If a robot is commanded to move to (100 mm, 50 mm) and ends up at (102 mm, 51 mm),
the accuracy error is 2.24 mm.

• Importance: Crucial in tasks where precise positioning is necessary (e.g., PCB assembly).

3. Repeatability

• Definition: The robot’s ability to return to a previously taught position with consistency.

• Units: Millimeters (mm).

• Example: If a robot is told to move to the same position 10 times, and it varies within ±0.05 mm, its
repeatability is 0.05 mm.

• Key Point: Most industrial robots have better repeatability than accuracy.

4. Dexterity

• Definition: The robot’s ability to manipulate objects in its workspace in various directions.

• Depends on: Number of Degrees of Freedom (DOF), joint configuration, and geometry.

• Measured by: Reachability and range of motion.

• Importance: Essential in complex operations such as welding, painting, or surgery.

5. Compliance

• Definition: The ability of a robotic joint or end-effector to yield under force.

• Types:

o Passive compliance: Built-in flexibility (e.g., spring mechanisms).

o Active compliance: Controlled by force sensors and actuators.

• Use case: Handling delicate parts or absorbing misalignments during assembly.

6. RCC Device (Remote Center Compliance)

• Definition: A mechanical device added to the robot's wrist or end-effector that allows slight movement
in response to external forces to correct misalignment.

• Function: Automatically aligns parts during insertion tasks (e.g., peg-in-hole).

• Structure: Uses springs and flexures to allow small translations/rotations.

• Advantages:

o Reduces part damage.

o Improves assembly precision.

o Compensates for position errors.

Comparison Table
Parameter Definition Units Key Impact
Resolution Smallest measurable movement mm / degrees Precision of motion
Accuracy Closeness to desired position mm Final position correctness
Repeatability Consistency of returning to same point mm Stability of motion
Dexterity Range & freedom of motion DOF / Ability to perform varied tasks
geometry
Compliance Yielding capability under force N/m (stiffness) Safety, adaptability
RCC Device Device to correct misalignment during N/A Increases precision in contact
insertion tasks

Introduction to Principles & Strategies of Automation

Automation

Automation refers to the use of control systems (computers, robots, or machines) to perform tasks with
minimal human intervention.

Principles of Automation

1. Integration Principle

Combine systems to work together (e.g., sensors + control + actuator).

2. Automation Continuum

Ranges from manual to fully automated systems.

3. Feedback Control Principle

Use sensors and feedback loops to control process variables.

4. Consistency Principle

Automation improves quality by reducing variability in production.

Strategies of Automation

1. Process Improvement

Optimize existing processes before automating.

2. Automation by Elimination

Remove unnecessary steps.

3. Combined Operations

Merge multiple operations into one setup.

4. Simultaneous Operations

Perform parallel tasks using multiple subsystems.

5. Integration of Operations

Use automated material handling and control systems.

6. Process Reengineering

Redesign the entire process for optimal automation.

Types of Automation
Type Description
Fixed Automation High-volume, low-variability tasks (e.g., car assembly lines).
Programmable Medium-volume, configurable systems (e.g., CNC machines).
Automation
Flexible Automation Low to medium-volume, high-variety systems (e.g., robotic arms with tool
changers).
Integrated Automation Complete automation from raw material to final product (e.g., smart
factories).

Levels of Automation

Level Description
0 No Automation – Fully manual operations
1 Assistive tools – Manual control with mechanical aids
2 Semi-automated – Some operations handled by machines
3 Automated systems – Machines operate independently
4 Flexible automation – Can adapt to changes and feedback
5 Intelligent automation – Uses AI, sensors, data for decision-making
Need for Automation

Reason Explanation

Increase Productivity Automation runs continuously, increasing output.

Improve Quality Reduces human error and variability.

Enhance Safety Robots handle dangerous tasks in harsh environments.

Reduce Labor Costs Fewer workers needed for repetitive or hazardous tasks.

Data Collection & Analysis Automated systems generate data to improve process control.

Competitiveness Allows companies to produce faster, cheaper, and with better quality.

Industrial Applications of Robots

Industry Applications

Automobile Spot welding, painting, assembly line, inspection

Electronics PCB assembly, soldering, semiconductor handling

Pharmaceuticals Dispensing, packaging, sterilization, lab automation

Food & Beverage Packaging, palletizing, pick and place, quality control

Metal Industry Arc welding, die casting, machining, material handling

Aerospace Drilling, fastening, precision assembly, composite material lay-up

Logistics/Warehousing Picking, sorting, transporting goods using AGVs and robotic arms

Medical/Healthcare Robotic surgery, diagnostic tools, rehabilitation devices