Basic concepts of robotics

By
S.VEERAKUMAR
Assistant Professor
Mechanical Engineering Department
Veerakumar.me@srit.org
23-11-2021
1

» Definition and origin of robotics –
different types of robotics – various
generations of robots – degrees of
freedom – Asimov’s laws of robotics –
dynamic stabilization of robots

» Definition
» Origin of robotics
23-11-2021
3

What is Robotics?
• Robotics is the branch of technology that deals with the
design, construction, operation, and application of robots, as
well as computer systems for their control, sensory feedback,
and information processing.
• The design of a given robotic system will often contain
principles of mechanical and electronic
engineering and computer science.
• The word robotics was first used in 1941 by the
writer Isaac Asimov.

23-11-2021
5
 Robotics is an interdisciplinary branch of engineering and science
that includes mechanical engineering, electronic engineering,
information engineering, computer science, and others.
 Robotics deals with the design, construction, operation, and use
of robots, as well as computer systems for their control, sensory
feedback, and information processing.
 Robotics is a branch of engineering that involves the conception,
design, manufacture, and operation of robots.
DEFINITION-ROBOTICS

23-11-2021
6
 Robotics institute of America defines a robot as a
“programmable, multifunction manipulator designed to
Move materials, parts, tools or special devices through
variable programmed motions for the performance of
the variety of task”.
DEFINITION-ROBOTS

The Advantages of Robots
• Perform the defined tasks with speed and accuracy
• Give us information that we can’t
• Don’t get bored
• Work at any time without salary or food
• Can work in dangerous environment
• Can do many tasks at the same time
• Don’t need experience

The Disadvantages of Robots
• Can’t respond in emergencies
• Cost a lot of money
• Replace human workers
• Need a huge power supply

Future of Robotics
• Every person will have a robot at home
• Robots will do all the household tasks
• Robots will take care of children and elderly
• Nanorobots will be made
• The whole army will be composed
of robots
• Robots will perform surgeries
• Robot brains that are based on
computers can be ordered 100
trillion instructions per second
will be made

23-11-2021
10
 Automation is the technique, method, or system of operating or
controlling a process by highly automatic means, as by electronic
devices, reducing human intervention to a minimum. A
mechanical device, operated electronically, that functions
automatically, without continuous input from an operator.
(OR)
 Automation is a technology that is concerned with the use of
electronic, mechanical and computer based system in the
operation control and production. The definition of automation is
the use of machines and technology to make processes run on
their own without manpower.
DEFINITION-AUTOMATION

23-11-2021
11
DIFFERENCE BETWEEN ROBOTICS AND AUTOMATION
The answer to this question is ‘robotics is a form of automation,
so there is no difference.’

23-11-2021
12
The main difference between robotics and
automation is that, robots are a piece of equipment
that can perform a variety of tasks with programming,
whilst be spoke automation is a term that is used for
special purpose machines or systems that are designed
to perform a specific task.

23-11-2021
13

23-11-2021
14
ORIGIN OF ROBOTS

Da Vinci sketched the
first humanoid robot in
1495
George Devol and Joseph
Engelberger formed the
world’s first robot company in
1956
Unimate, the first
industrial robot was
designed in 1961
The Soviet Union
launches the first
artificial orbiting
satellite in 1957
The first artificial robotic arm to
be controlled by computer was
designed at Rancho Los Amigos
Hospital in Downey in 1963
Neil Armstrong became
the first human to land
on the moon in 1969

First mobile robot
controlled by artificial
intelligence was designed
in 1970
Mars Pathfinder’s
sojourner rover landed on
Mars for the first time in
1977
Honda debuts a new
humanoid robot
called Asimo in 2002
Epsom release the
smallest known robot
helicopter in 2004
The Roomba robotic vacuum
cleaner has sold over 2.5
million units in 2008

» Different types of robotics
23-11-2021
22

Different Branches Occupied in the Development of Robotics:
Robotics in contrast to other branches is a
reasonably new domain of engineering. It is a multi-disciplinary
domain. The different branches occupied in the development of
Robotics are:-
 Mechanical Engineering: Deals with the machinery & structure of
the Robots.
 Electrical Engineering: Deals with the controlling & intelligence
(sensing) of Robots.
 Computer Engineering: Deals with the movement development
and observation of Robots.
BRANCHES INVOLVED IN ROBOTICS
23-11-2021
24

Branches of Robotics
• Artificial Intelligence: the developing of an intelligence of
machine and is a branch of computer science
• Nanorobotics: the field of creating machines that are at a
scale of a nanometre
• Telepresence: the study given to an illusion of being at a
place without being there physically
• Robot Locomotion: the study of the methods that robots
use to transport themselves from place to another

Robots are categorized depending upon
the circuits of the Robots and the variety of application it can
perform. The robots are classified into three types:
 Simple level Robots- These are automatic machines which do not
contain complex circuit. They are developed just to extend human
potential. For Example- Washing Machine.
 Middle level Robots– These robots are programmed but can
never be reprogrammed. These robots contain sensor based
circuit & can perform multiple tasks. For Example- Fully Automatic
Washing Machine.
 Complex level Robots- These robots are programmed and can be
reprogrammed as well. They contain complex model based
circuit. For Example- Laptop or Computer.
CLASSIFICATION OF ROBOTS
23-11-2021
33

Classification by Degrees of Freedom
Degrees of freedom refers to the different
directions a robotic arm can move. They represent the location as
well as the orientation of an object. Basically, such type of robots is
pick and place robots, which pick and place the objects on a location
and with an orientation.
 3 Degrees of Freedom: A robot with 3 degrees of freedom can
only pick up the object and place it anywhere in its workspace,
using the 3 different coordinate axes.
 6 Degrees of Freedom: A robot with 6 degrees of freedom can
pick the object and place it anywhere in its workspace, at any
orientation.
23-11-2021
34

23-11-2021
35
 Japanese Industrial Robot Association (JIRA) :
“A device with degrees of freedom that can be
controlled.”
 Class 1 : Manual handling device
 Class 2 : Fixed sequence robot
 Class 3 : Variable sequence robot
 Class 4 : Playback robot
 Class 5 : Numerical control robot
 Class 6 : Intelligent robot

23-11-2021
36
Classification as per Application
Industrial: Industrial robots are generally fixed manipulators
which perform in various working environments. They perform
various general-purpose tasks like Welding, Painting, machining,
etc. In fact, the first robots were the industrial robots which
were used for simple repetitive tasks.
Non-Industrial or Special Purpose: These are robots which assist
humans in their chores
Medical: There has been an increasing use of robots in the
medical field for surgery, rehabilitation and training. Medical
robots are not meant to replace the surgeons but serve as a
surgical assistant to the surgeon.
Space: With the advent of robotic technologies, exploration of
various celestial bodies has been a reality. Tasks like space
manipulation, surface mobility and scientific experiments are
performed by space robots.
CLASSIFICATION OF -ROBOTICS

23-11-2021
37
Defence Robots: These include bomb disposal robots,
transportation robots and reconnaissance drones. Equipped with
infrared sensors, these robots react more rapidly than humans in
emergency and hazardous situations.
Security: These robots are used for surveillance and guarding
large civilian facilities such as Power generating plants, oil
refineries, etc which are under threat from terrorists. An
example is DRDO’s NETRA (An Unmanned Aerial Vehicle)
Domestic: These robots are used to perform daily tasks at home,
such as robotic vacuum cleaner, cleaning robots.
Entertainment: These robots are used in various entertainment
places like amusement parks, joy rides, sports, etc. Examples include
KUKA Robocoaster (amusement ride robot), Honda’s Asimo, Sony’s
Aibo, etc.

2004 38
ROBOT CLASSIFICATION
Classification Based on Physical
Configuration:
– 1. Cartesian configuration
– 2. Cylindrical configuration
– 3. Polar configuration
– 4. Joint-arm configuration

23-11-2021
39
Classification as per kinematic structure
Articulated - This robot design features rotary joints and can range
from simple two joint structures to 10 or more joints. The arm is
connected to the base with a twisting joint. The links in the arm are
connected by rotary joints. Each joint is called an axis and provides
an additional degree of freedom, or range of motion. Industrial
robots commonly have four or six axes.
Cartesian - These are also called rectilinear or gantry robots.
Cartesian robots have three linear joints that use the Cartesian
coordinate system (X, Y, and Z). They also may have an attached
wrist to allow for rotational movement. The three prismatic joints
deliver a linear motion along the axis.
Cylindrical - The robot has at least one rotary joint at the base and at
least one prismatic joint to connect the links. The rotary joint uses a
rotational motion along the joint axis, while the prismatic joint
moves in a linear motion. Cylindrical robots operate within a
cylindrical-shaped work envelope.

23-11-2021
40
Classification as per kinematic structure
Polar - Also called spherical robots, in this configuration the arm
is connected to the base with a twisting joint and a combination
of two rotary joints and one linear joint. The axes form a polar
coordinate system and create a spherical-shaped work envelope.
SCARA - Commonly used in assembly applications, this selectively
compliant arm for robotic assembly is primarily cylindrical in
design. It features two parallel joints that provide compliance in
one selected plane.
Delta - These spider-like robots are built from jointed
parallelograms connected to a common base. The parallelograms
move a single EOAT in a dome-shaped work area. Heavily used in
the food, pharmaceutical, and electronic industries, this robot
configuration is capable of delicate, precise movement.

2004 42
ROBOT CLASSIFICATION
Classification Based on Control Systems:
– 1. Point-to-point (PTP) control robot
– 2. Continuous-path (CP) control robot
– 3. Controlled-path robot

2004 43
Point to Point Control Robot (PTP):
• The PTP robot is capable of moving from one
point to another point.
• The locations are recorded in the control
memory. PTP robots do not control the path to
get from one point to the next point.
• Common applications include:
– component insertion
– spot welding
– hole drilling
– machine loading and unloading
– assembly operations

2004 44
Continuous-Path Control Robot (CP):
• The CP robot is capable of performing movements along
the controlled path. With CP from one control, the robot
can stop at any specified point along the controlled path.
• All the points along the path must be stored explicitly in
the robot's control memory. Applications Straight-line
motion is the simplest example for this type of robot.
Some continuous-path controlled robots also have the
capability to follow a smooth curve path that has been
defined by the programmer. In such cases the
programmer manually moves the robot arm through the
desired path and the controller unit stores a large
number of individual point locations along the path in
memory (teach-in).

2004 45
Continuous-Path Control Robot (CP):
Typical applications include:
– spray painting
– finishing
– gluing
– arc welding operations

2004 46
Controlled-Path Robot:
• In controlled-path robots, the control equipment can
generate paths of different geometry such as straight
lines, circles, and interpolated curves with a high degree
of accuracy. Good accuracy can be obtained at any point
along the specified path.
• Only the start and finish points and the path definition
function must be stored in the robot's control memory. It
is important to mention that all controlled-path robots
have a servo capability to correct their path.

» Various generations of robots
23-11-2021
47

23-11-2021
50
Engineers and scientists have analyzed the evolution of
robots, marking progress according to robot generations.
 First Generation Robots
 Second generation robots
 Third generation robots
 Fourth genrataion robots
GENERATION OF ROBOTS

23-11-2021
53
 A first-generation robot is a simple mechanical arm.
These machines have the ability to make precise
motions at high speed, many times, for a long time.
 Such robots find widespread industrial use today. First-
generation robots can work in groups, such as in an
automated integrated manufacturing system (AIMS), if
their actions are synchronized.
 The operation of these machines must be constantly
supervised, because if they get out of alignment and
are allowed to keep working, the result can be a series
of bad production units
FIRST GENERATION

23-11-2021
58
 A second-generation robot has rudimentary machine
intelligence. Such a robot is equipped with sensors that
tell it things about the outside world.
 These devices include pressure sensors, proximity
sensors, tactile sensors, radar, sonar, ladar, and vision
systems.
 A controller processes the data from these sensors and
adjusts the operation of the robot accordingly.
SECOND GENERATION

23-11-2021
59
 These devices came into common use around 1980.
 Second-generation robots can stay synchronized with
each other, without having to be overseen constantly
by a human operator.
 Of course, periodic checking is needed with any
machine, because things can always go wrong; the
more complex the system, the more ways it can
malfunction
SECOND GENERATION

23-11-2021
62
 The concept of a third-generation robot encompasses
two major avenues of evolving smart robot technology:
the autonomous robot and the insect robot.
 An autonomous robot can work on its own. It contains
a controller, and it can do things largely without
supervision, either by an outside computer or by a
human being.
 A good example of this type of third generation robot is
the personal robot about which some people dream.
THIRD GENERATION

23-11-2021
63
 There are some situations in which autonomous robots
do not perform efficiently.
 In these cases, a fleet of simple insect robots, all under
the control of one central computer, can be used.
 These machines work like ants in an anthill, or like bees
in a hive.
 While the individual machines lack artificial intelligence
(AI), the group as a whole is intelligent.
THIRD GENERATION

23-11-2021
66
Fourth generation and beyond
 Any robot of a sort yet to be seriously put into
operation is a fourth generation robot.
 Examples of these might be robots that reproduce and
evolve, or that incorporate biological as well as
mechanical components.
 Past that, we might say that a fifth-generation robot is
something no one has yet designed or conceived.
FOURTH GENERATION

» Degrees of freedom
23-11-2021
69

23-11-2021
70
 Degrees of freedom, in a mechanics context, are
specific, defined modes in which a mechanical device
or system can move.
 The number of degrees of freedom is equal to the total
number of independent displacements or aspects of
motion.
No of degrees of freedom=No of joints
 A machine may operate in two or three dimensions but
have more than three degrees of freedom. The term is
widely used to define the motion capabilities of robots.
DEGREE OF FREEDOM

23-11-2021
71
 Each joint or axis on the robot introduces a
degree of freedom.
 Each DOF can be a slider, rotary, or other type
of actuator.
 The number of DOF that a manipulator
possesses thus is the number of independent
ways in which a robot arm can move.
 Industrial robots typically have 5 or 6 degrees
of freedom.
DEGREE OF FREEDOM

Degrees of Freedom
Degrees of freedom (DOF) is a term used to describe a
robot’s freedom of motion in three dimensional space
—specifically, the ability to move forward and backward,
up and down, and to the left and to the right.
For each degree of freedom, a joint is required.
A robot requires minimum six degrees of freedom to be
completely versatile.
Its movements are clumsier than those of a human hand,
which has 22 degrees of freedom
Fundamental of Robotic Manipulator
72

The number of degrees of freedom defines the robot’s configuration.
For example, many simple applications require movement along three axes: X, Y,
and Z.
See Figure 2-10. These tasks require three joints, or three degrees of freedom
73

23-11-2021
74
MANIPULATOR DEGREE OF FREEDOM

23-11-2021
75
SIX DEGREE OF FREEDOM ROBOT

2004
76
DOF degrees-of-freedom: the number of independent motions a
device can make. (Also called mobility)
five degrees of freedom
ROBOTICS TERMİNOLOGY

2004
77
Manipulator: Electromechanical device capable of interacting
with its environment.
Anthropomorphic: Like human beings.
ROBONAUT (ROBOtic astroNAUT), an anthropomorphic robot with two arms,
two hands, a head, a torso, and a stabilizing leg.
ROBOTICS TERMİNOLOGY

2004
78
End-effector: The tool, gripper, or other device mounted at the
end of a manipulator, for accomplishing useful tasks.
Robotics Terminology

2004
79
Workspace: The volume in space that a robot’s end-effector can
reach, both in position and orientation.
A cylindrical robots’ half workspace

2004
80
Position: The translational (straight-line) location of something.
Orientation: The rotational (angle) location of something. A robot’s
orientation is measured by roll, pitch, and yaw angles.
Link: A rigid piece of material connecting joints in a robot.
Joint: The device which allows relative motion between two links in
a robot.
A robot joint

2004
81
Kinematics: The study of motion without regard to forces.
Dynamics: The study of motion with regard to forces.
Actuator: Provides force for robot motion.
Sensor: Reads variables in robot motion for use in control.

2004
82
Speed
•The amount of distance per unit time at which the robot can
move, usually specified in inches per second or meters per
second.
•The speed is usually specified at a specific load or assuming
that the robot is carrying a fixed weight.
•Actual speed may vary depending upon the weight carried by
the robot.
Load Bearing Capacity
•The maximum weight-carrying capacity of the robot.
•Robots that carry large weights, but must still be precise are
expensive.

2004
83
Accuracy
•The ability of a robot to go to the specified position without
making a mistake.
•It is impossible to position a machine exactly.
•Accuracy is therefore defined as the ability of the robot to
position itself to the desired location with the minimal error
(usually 25 mm).
Repeatability
•The ability of a robot to repeatedly position itself when asked
to perform a task multiple times.
•Accuracy is an absolute concept, repeatability is relative.
•A robot that is repeatable may not be very accurate, visa
versa.

» Structure or Block diagram or Basic
components of robot
» Robotic Joints
23-11-2021
85

2004 87
BLOCK DIAGRAM OF ROBOT

2004 88
THE ROBOTIC JOINTS
 The Robot Joints is the important element in a
robot which helps the links to travel in
different kind of movements.
 A joint in an industrial robot is similar to that
in a human body.
 It provides with a relative motion between
two parts.
 Most have industrial joints have mechanical
joints which can be classified into five types.

2004 89
THE ROBOTIC JOINTS
A robot joint is a mechanism that permits
relative movement between parts of a
robot arm.
The joints of a robot are designed to
enable the robot to move its end-effector
along a path from one position to another
as desired.
They include two types that provide linear
motion and three types that provide rotary
motion

2004 90
Classification of Robotic Joints
 These degrees of freedom, independently or in
combination with others, define the complete
motion of the end-effector.
 These motions are accomplished by movements
of individual joints of the robot arm.
 The joint movements are basically the same as
relative motion of adjoining links.
 Depending on the nature of this relative motion,
the joints are classified as
1. Prismatic/Translational motion
2. Revolute/ Rotational motion

2004 91
PRISMATIC JOINT
In a prismatic joint, also known as a
sliding or linear joint (L), the links are
generally parallel to one

2004 92
Revolute joints
Revolute joints permit only angular
motion between links. Their variations
include:
– Rotational joint (R)
– Twisting joint (T)
– Revolving joint (V)

2004 93
TYPES OF ROBOTIC JOINTS

2004 94

2004 95
There are five types of joints in robots. They are
1. Linear Joint (Type L)
2. Orthogonal Joint (Type O)
3. Rotational Joint (Type R)
4. Twisting Joint (Type T)
5. Revolving Joint (Type V)

2004 96

2004 97
1. LINEAR JOINTS (Type L)
Linear joint (type L joint)
• Linear joint can be indicated by the letter L
– Joint.
• The relative movement between the input
link and the output link is a translational
sliding motion, with the axes of the two
links being parallel.

2004 98
1. LINEAR JOINTS (Type L)
 This type of joints can perform both
translational and sliding movements.
 These motions will be attained by several
ways such as telescoping mechanism and
piston.
 The two links should be in parallel axes for
achieving the linear movement.

2004 99
2. ORTHOGONAL JOINTS (Type O)
• Orthogonal joint can be indicated by the letter
O– Joint.
• This is also a translational sliding motion, but
the input and output links are perpendicular
to each other during the move.
• The only difference is that the output and
input links will be moving at the right angles.

2004 100
3.ROTATIONAL JOINT (Type R)
• A rotational joint (R type) is identified by its
motion, rotation about an axis perpendicular to
the adjoining links.
• Here, the lengths of adjoining links do not
change but the relative position of the links with
respect to one another changes as the rotation
takes place.

2004 101
4. TWISTING JOINT (Type T)
A twisting joint (T type) is also a
rotational joint, where the rotation takes
place about an axis that is parallel to both
adjoining links.

2004 102
5. REVOLVING JOINT (Type V)
• This joint also provide rotational motion.
• Here, the output link axis is perpendicular to the
rotational axis, and the input link is parallel to the
rotational axes.
• As like twisting joint, the output link spins about the
inputlink

» Robot Anatomy
» Robotic configuration
23-11-2021
10
3

Robot Anatomy
 Manipulator consists of joints and links




Joints provide relative motion
Links are rigid members between joints
Various joint types: linear and rotary
Each joint provides a “degree-of-
freedom”
 Most robots possess five or six
degrees-of-freedom
 Robot manipulator consists of two
sections:
 Body-and-arm – for positioning of
objects in the robot's work volume
 Wrist assembly – for orientation of
objects
Base
Link0
Joint1
Link2
Link3
Joint3
End ofArm
Link1
Joint2

2004 105
ROBOT MANIPULATORS
 Industrial Manipulators or robotics manipulators are
machines which are used to manipulate or control
material without making direct contact.
 Originally it was used to manipulate radioactive or bio-
hazardous object which can be difficult for a person to
handle.
 But now they are being used in many industries to do
task like lifting heavy objects, welding continuously with
good precision etc.
 Other than industries they are also being used in
hospitals as surgical instruments.
 And now a day’s doctors extensively use robotics
manipulators in their operations.

2004 106
ROBOT MANIPULATORS
 An industrial robot is comprised of a robot manipulator,
power supply, and controllers.
 Robotic manipulators can be divided into two sections,
each with a different function:
1. Robot Arm
2. Body
 The arm and body of a robot are used to move and
position parts or tools within a work envelope.
 They are formed from three joints connected by large
links.

2004 108
ROBOT MANIPULATOR
CONFIGURATION
Classification Based on Physical
Configuration:
– 1. Cartesian configuration
– 2. Cylindrical configuration
– 3. Polar configuration
– 4. Joint-arm configuration
– 5. SCARA configuration

111
ROBOT CONFIGUARTIONS
1. CARTESIAN CONFIGURATION (LLL)
 Robots with Cartesian configurations consists of links
connected by linear joints (L).
 Gantry robots are Cartesian robots (LLL) or (PPP).
 In this industrial robot, its 3 principle axis have prismatic
joints or they move linear thorough each other.
 Cartesian robots are best suited for dispensing adhesive
like in automotive industries.
 The primary advantage of Cartesians is that they are
capable of moving in multiple linear directions.
 And also they are able to do straight-line insertions and
are easy to program.
 The disadvantages of Cartesian robot are that it takes
too much space as most of the space in this robot is
unused.

CARTESIAN GANTRY ROBOT ARM
robots with Cartesian configuration consist of links
connected by linear joints (L).
 Thus the resulting configuration is (LLL).
The three joints corresponds to the notation for the moving
the wrist up and down, in and out, and back and forth.
Thus the work envelop/ work volume generated by this
robot is a rectangular box.
example: the gantry robot
Uses 3 perpendicular slides
to construct x , y , z axes.
Hence called xyz/rectilinear
robot.
e.g. IBM RS-I robot
11
2

Cartesian Gantry
Robot Arm
(LLL)
APPLICATIONS:
1. for pick and place work
for heavy loads
2. assembly operations
3. handling machine tools
4. arc welding operations
11
3

2004 114
CARTESIAN ROBOTS
A robot with 3 prismatic joints
– the axes consistent with a
Cartesian coordinate system.
APPLICATIONS
•pick and place work
•assembly operations
•handling machine tools
•arc welding

2004 115
CARTESIAN ROBOTS
Advantages:
• ability to do straight line insertions into furnaces.
• easy computation and programming.
• most rigid structure for given length.
Disadvantages:
• requires large operating volume.
• exposed guiding surfaces require covering in corrosive
or dusty environments.
• can only reach front of itself
• axes hard to seal

116
2. CYLINDRICAL CONFIGURATION (TLL)
 Robots with cylindrical configuration have one rotary ( R) joint at the
base and linear (L) joints succeeded to connect the links.
 It is basically a robot arm that moves around a cylinder shaped pole.
 A cylindrical robotic system has three axes of motion – the circular
motion axis and the two linear axes in the horizontal and vertical
movement of the arm.
 So it has 1 revolute joint, 1 cylindrical and 1 prismatic joint.
 Today Cylindrical Robot are less used and are replaced by more
flexible and fast robots but it has a very important place in history as
it was used for grappling and holding tasks much before six axis
robots were developed.
 Its advantage is that it can move much faster than Cartesian robot if
two points have same radius.
 Its disadvantage is that it requires effort to transform from Cartesian
coordinate system to cylindrical coordinate system.

CYLINDRICAL CONFIGURATION
Notation : TLO or TLL


Consists of a vertical column,
relative to which an arm
assembly is moved up or down
The arm can be moved in or out
relative to the column

2004 118
CYLINDRICAL ROBOTS
A robot with 2 prismatic joints
and a rotary joint – the axes
consistent with a cylindrical
coordinate system.
APPLICATIONS:
1. handling at die-casting
machines
4. spot welding

2004 119
Advantages:
• can reach all around itself
• rotational axis easy to seal
• relatively easy programming
• rigid enough to handle heavy loads through large working
space
• good access into cavities and machine openings
Disadvantages:
• can't reach above itself
• linear axes is hard to seal
• won’t reach around obstacles
• exposed drives are difficult to cover from dust and liquids
CYLINDRICAL ROBOTS

120
3. POLAR CONFIGURATION (TRL)
 It is also sometimes called as Spherical robots.
 Polar robots have a work space of spherical shape.
Generally, the arm is connected to the base with a
twisting (T) joint and rotatory (R) and linear (L) joints
follow.
 These are stationary robot arms with spherical or near-
spherical work envelopes that can be positioned in a
polar coordinate system.
 They are more sophisticated than Cartesian and SCARA
robots but its control solution are much less complicated.
 It has 2 revolute joints and 1 prismatic joint to make near
spherical workspace.
 Its main uses are in handling operations in
production line and pick and place robot.

Polar Coordinate
Body-and-Arm Assembly
 Notation TRL:
 Consists of a sliding arm (L joint) actuated relative to the
body, which can rotate about both a vertical axis (T joint)
and horizontal axis (R joint)

2004 122
POLAR CONFIGURATION (TRL)
 The designation of the arm
for this configuration can be
TRL or TRR.
 Robots with the designation
TRL are also called
spherical robots.
 Those with the designation
TRR are also called
articulated robots.
 An articulated robot more
closely resembles the
human arm.

2004 123
SPHERICAL/POLAR ROBOTS
A robot with 1 prismatic joint
and 2 rotary joints – the axes
consistent with a polar
coordinate system.
APPLICATIONS:
1. handling at die casting or
fettling machines
3. arc/spot welding

2004 124
4. JOINTED ARM CONFIGURATION (TRR)
The jointed-arm is a combination of
cylindrical and articulated configurations.
The arm of the robot is connected to the
base with a twisting joint.
The links in the arm are connected by
rotatory joints.
Many commercially available robots have
this configuration.

JOINTED-ARM
ROBOT
 Notation TRR:

2004 127
5. SCARA CONFIGURATION (VRO)
 The SCARA acronym stands for Selective Compliance Assembly
Robot Arm or Selective Compliance Articulated Robot Arm.
 SCARA robots have motions similar to that of a human arm.
 These machines comprise both a 'shoulder' and 'elbow' joint along
with a 'wrist' axis and vertical motion.
 SCARA robots have 2 revolute joints and 1 prismatic joint.
 SCARA robots have limited movements but it is also its advantage
as it can move faster than other 6 axis robots.
 It is also very rigid and durable.
 Its disadvantages are that it has limited movements and it is not very
flexible
 They are mostly used in purpose application which
require fast, repeatable and articulate point to point
movements such as palletizing, DE palletizing,
machine loading/unloading and assembly.

SCARA
ROBOT



Notation VRO
SCARA stands for Selectively
Compliant Assembly Robot
Arm
Similar to jointed-arm robot
except that vertical axes are
used for shoulder and elbow
joints to be compliant in
horizontal direction for vertical
insertion tasks

2004 129
SCARA (Selective Compliance
Articulated Robot Arm) Robots
A robot with at least 2 parallel
rotary joints.
APPLICATIONS:
1. pick and place work

2004 130
Advantages:
• high speed.
• height axis is rigid
• large work area for floor space
• moderately easy to program.
Disadvantages:
• limited applications.
• 2 ways to reach point
• difficult to program off-line
• highly complex arm
SCARA (Selective Compliance
Articulated Robot Arm) Robots

2004 131
ARTICULATED CONFIGURATION (RRR)
A robot with at least 3 rotary
joints.
APPLICATIONS:
1. Assembly operations
2. Welding
3. Weld sealing
4. Spray painting
5. Handling at die casting or
fettling machines

2004 132
Advantages:
• all rotary joints allows for maximum flexibility
• any point in total volume can be reached.
• all joints can be sealed from the environment.
Disadvantages:
• extremely difficult to visualize, control, and program.
• restricted volume coverage.
• low accuracy
ARTICULATED ROBOTS

To establish the orientation of the object, we
can define 3 degrees of freedom for the
robot's wrist. The following is one possible
configuration for a 3 d.o.f. wrist assembly:
•Roll. This d.o.f. can be accomplished by a T-
type joint to rotate the object about the arm axis.
•Pitch. This involves the up-and-down rotation of
the object, typically done by means of a type R
joint.
•Yaw. This involves right-to-left rotation of the
object, also accomplished typically using an R-
type joint.
134

Joint Notation Scheme


Uses the joint symbols (L, O, R, T, V) to designate joint
types used to construct robot manipulator
Separates body-and-arm assembly from wrist assembly
using a colon (:)
 Example: TLR : TR
 Common body-and-arm configurations …

» Asimov’s laws of robotics
» Selection of robot
23-11-2021
13
8

The Laws of Robots
Three laws were introduced by the writer Isaac
Asimov in 1942 which are:
1. Robot may not injure a human being or through inaction, allow a
human being to come to harm
2. Robot must obey orders given by human beings unless they
conflict with the first law
3. Robot must protect its own existence unless it conflicts with the
first or second law

2004 140
 In a survey published in 1986, it is stated that there are
676 robot models available in the market.
 Once the application is selected, which is the prime
objective, a suitable robot should be chosen from the
many commercial robots available in the market.
ROBOT SELECTION

2004 141
The characteristics of robots generally considered in a selection process include:
 Size of class
 Degrees of freedom
 Velocity
 Drive type
 Control mode
 Repeatability
 Lift capacity
 Right-left traverse
 Up-down traverse
 In-out traverse
 Yaw
 Pitch
 Roll
 Weight of the robot
ROBOT SELECTION

2004 142
1. Size of class: The size of the robot is given by the
maximum dimension (x) of the robot work envelope.
Micro (x < 1 m)
Small (1 m < x < 2 m)
Medium (2 < x < 5 m)
Large (x > 5 m)
2. Degrees of freedom. The cost of the robot increases with
the number of degrees of freedom. Six degrees of freedom is
suitable for most works.
ROBOT SELECTION

2004 143
3. Velocity: Velocity consideration is effected by the robot’s
arm structure.
Rectangular
Cylindrical
Spherical
Articulated
4. Drive type:
Hydraulic
Electric
Pneumatic
ROBOT SELECTION

2004 144
5. Control mode:
Point-to-point control(PTP)
Continuous path control(CP)
Controlled path control
6. Lift capacity:
0-5 kg
5-20 kg
20-40 kg and so forth
ROBOT SELECTION

» Dynamic Stabilization of robots
23-11-2021
14
5

Basic concepts of robotics

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to Basic concepts of robotics

Similar to Basic concepts of robotics (20)

More from Veerakumar S

More from Veerakumar S (6)

Recently uploaded

Recently uploaded (20)

Basic concepts of robotics