robotics conguration and classification overview

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Configuration and
Classification
UNIT 1 CONFIGURATION AND
CLASSIFICATION
Structure
1.1 Introduction
Objectives
1.2 History
1.3 Robot Subsystems
1.3.1 Motion Subsystem
1.3.2 Recognition Subsystem
1.3.3 Control Subsystem
1.4 Robot Configuration
1.5 Classification of Robots
1.5.1 Application Wise
1.5.2 Coordinate System Wise
1.5.3 Actuation System Wise
1.5.4 Control Method Wise
1.5.5 Programming Wise
1.6 Summary
1.7 Key Words
1.8 Answers to SAQs
1.1 INTRODUCTION
Robots are useful for their ability to perform tirelessly, and to do monotonous and
hazardous tasks over a very long period of time. As a result, productivity increases if the
number of pieces to be produced is very large. However, the intelligence of even the
most advanced robot is nowhere near that of a human being. Thus, the introduction of a
robot without real understanding of its benefits will be disastrous and is not adviceable.
Robots can be broadly classified as industrial and non-industrial or special-purpose
robots. A typical industrial robot made by Cincinnati Milacron of the United States of
America (USA) is shown in Figure 1.1.
Figure 1.1 : An Industrial Robot, Cincinnati Milacron, T3 (Koivo, 1989)

6
Robot and Its Applications Industrial robots are intended to serve as a general purpose, unskilled or semiskilled
labourer, e.g., for welding, painting, machining, etc. Alternatively, a special-purpose
robot is the one that is used other than in a typical factory environment. For example, a
robot mounted on a spacecraft is used for the retrieval of a faulty satellite and for
redeploying it after repair. Some other types of special-purpose robots are listed below :
Automatic Guided Vehicles (AGVs)
These are mobile robotic systems commonly used in factories for material
handling purposes. Figure 1.2(a) shows one such AGV with Mekanum or
ommidirectional wheels. These wheels, in contrast to the conventional wheels used
in automobiles, can move sideways. Thus, an AGV with Makanum wheels has
three degrees of freedon (DOF) mobility compared to the two DOF mobility of an
automobile or an AGV with conventional wheels. AGVs are also used in hospitals
for nursing, security and other applications.
Walking Robots
These robots walk like animals or human beings, as shown in Figure 1.2(b). They
are used in military, undersea exploration, and places where rough terrains exist.
Parallel Robots
As the name suggests, these robots have a parallel configuration, compared to the
serial-like structure of an industrial robot shown in Figure 1.1. In this sense, a
walking robot with all its legs touching the ground is a parallel robot. One well
known parallel structure is the Stewart platform. It has a moving platform with a
fixed-base, as shown in Figure 1.2(c), and is used as a flight simulator to train
aeroplane pilots.
In this course, however, only industrial robots will be treated. A robot here will always
mean a serial-type industrial robot unless otherwise stated explicitly. Note that these
robots or the industrial robots are neither as fast nor as efficient as the special-purpose
automated machines. However, they are easily retrained or reprogrammed to perform an
array of tasks, whereas special-purpose machines can perform only a very limited class of
tasks. The question is then to decide whether a human, a robot, or a specialised machine
is to perform a certain job. The answer to this question is not simple and strishtforward.
However, some rules of thumb can help one to decide. They are as follows :
(a) The first rule to consider is what is known as Four Ds of Robotics, i.e. is the
task dirty, dull, dangerous or difficult? If so, a human will probably not be
able to do the job efficiently for hours. Therefore, the job is appropriate for
automation or robotic labour.
(b) The second rule is that a robot may not leave a human jobless. Robotics and
automation must serve to make our lives more enjoyable, not miserable.
(c) A third rule involves asking wheather you can find people who are willing
to do the job. If not, the job is a candidate for automation or robotics. Indeed
this should be a primary reason for the growth of automation and robotics.
(d) A fourth rule of thumb is that the use of robots or automation must make
short-term and long-term economic sense.
As a general starting point, consider the following. A task that has to be done only once
or a few times and is not dangerous probably is best done by a human. After all, the
human is the most flexible of all machines. A task that has to be done a few hundred to a
few hundred thousand times is probably best done by a flexible automated machine such
as an industrial robot. And a task that has to be done one million times or more is
probably best handled by building a special purpose hard automated machine.

7
Configuration and
Classification
(a) Automatic Guided Vehicle with Mekanum Wheel
(b) Walking Robot
(c) Parallel Robot
Figure 1.2 : Special-purpose Robots
Objectives
After studying this unit, you should be able to
• define the purpose of robotics,
• decide when to use a robot,
• define a robot formally,
• describe the origin of robotics,
• state the “Laws of Robotics”,
• know the subsystems of robots,
• know the different elements of a robot,
• distinguish between various types of robots, and
• judge advantages and disadvantages of robots.
1.2 HISTORY
A robot is a formally defined by the Robotics Institute of America, as a reprogrammable
multifunctional manipulator designed to move material, parts, tools, or specialised
devices through variable programmed motions for the performance of a variety of tasks.
There exist several other definitions too given by other societies, e.g., by the Japan
Industrial Robot Association (JIRA), British Robot Association (BRA), and others. All
definitions have two points in common. They are “reprogrammable” and
“multifunctional”.

8
Robot and Its Applications The idea of robots however goes back to the ancient times over 3000 years ago in the
Indian legend of mechanical elephants (Fuller, 1999). The first use of the word “robot”
appeared later in 1921 in the play “Rossum's Universal Robots” (RUR) written by the
Czeck writer, Karel Capek (1890-1938). The origin of the word “robot” is traced to the
Czeck word “robota”, which means “forced” or “compulsory labour”. In the play of RUR
(Dorf, 1988), a fictional manufacturer of mechanical creatures, designed robots to replace
human workers. Efficient but totally lacking in emotion, these robots are first thought to
be an improvement over human beings since they do as they are told without question.
These robots eventually turned on their masters. They destroy the human race, except for
one man so that he can continue to produce robots. As a result, hatred towards robots
even exists today. The fear that the robots will take away people’s job might have
resulted in no immediate development in this area. However, Isaac Asimov in his science
fiction stories during 1940s envisioned the robot as a helper of humankind and postulated
three basic rules of robots. These are generally known as the “Laws of Robotics”.
Laws of Robotics
(a) A robot must not harm a human being, nor through inaction allow one to
come to harm.
(b) A robot must always obey human beings that are in conflict with the first
law.
(c) A robot must be protected from harm, unless that is in conflict with the first
two laws.
A fourth law is later introduced in Fuller (1999) as
(d) A robot may take a human being's job but it may not leave that person
jobless!
Figure 1.3 : Microrover “Sojourner” for Mars Exploration
Attempts are being made to adhere to these laws of robotics, but there is no automatic
way to implement them. For instance, the military robot, by its very nature, is likely to be
designed with the intention of breaking these laws. Most industrial robots of today are
designed to work in environments which are not safe and hazardous for human workers.
For example, a robot’s hand can be designed to handle very hot or cold objects that the
human hand cannot handle safely. Inspired by the Asimov’s books on robots,
Joseph F. Engelberger tried to design a working robot in the 1950s. He, along with
George C. Devol, started Unimation Robotics Company in the USA in 1958. The first
Unimate robot was installed in 1961 to tend a die-casting machine. Since then robotics
has evolved in multitude directions, starting from using it in welding, painting, assembly,
machine tool loading and unloading, inspection, agriculture, nursing, medical surgery,
military, security, machine tools, undersea and space exploratations. The latest in the

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Configuration and
Classification
series is the microrover “Sojourner”, which landed on Mars on July 4, 1997, by the
National Aeronautic Society of America (NASA), USA. Figures 1.3 shows the Sojourner
mircrorover.
SAQ 1
(a) What is a robot?
(b) Name few typical applications of an industrial robot?
(c) How does one decide the introduction of a robot for a particular job?
(d) What are the four D’s of robotics?
SAQ 2
(a) What is RUR?
(b) What are the “Laws of Robotics”?
(c) What is the name of robot used for Mars exploration?
1.3 ROBOTS SUBSYSTEMS
As illustrated in Figure 1.4(a), a robotic system consists of mainly three subsystems, i.e. a
motion subsystem, a recognition subsystem, and a control subsystem. Their functions are
described below. The main elements in the subsystems are presented in
Sections 1.3.1-1.3.3.
A Motion Subsystem
The motion subsystem is the physical structure that carries out desired motions
similar to human arms or legs.
A Recognition Subsystem
The recognition subsystem uses various sensors to gather information about any
object being acted upon, about the robot itself, and about the environment. It
recognises the robot’s state, the objects, and the environment from this
information.
A Control Subsystem
The control subsystem influences the robot motion to achieve a given task using
the information received from the recognition subsystem.
(a) Subsystems
(b) Block Diagram

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Robot and Its Applications Figure 1.4 : Robot Subsystems
Figure 1.4(b) demonstrates the interactions between the three subsystems. It may
be useful to point out here that a person with mechanical engineering background
normally works on the motion subsystem, whereas one with computer science and
electrical engineering knowledge focuses on the recongnition and control
subsystems, respectively. However, robotics is an interdisciplinary area and a
comprehensive knowledge of all three areas will certainly help to design and
develop better robotic systems. As a result, it is not uncommon to see people
crossing their boundary of specialisation. Often a mechanical engineering
specialist is seen working on Artificial Intelligence (Recognition Subsystem),
while one with electrical engineering or computer science background deals with
dynamic simulation and design of robots (Motion Subsystem).
1.3.1 Motion Subsystem
The elements of the motion subsystem are :
Manipulator
This is the physical structure which moves around. It comprises of rigid ‘links’
(also referred to as ‘bodies’) and joints (also called ‘kinematic pairs’) that are
connected in series, as for the PUMA (Programmable Universal Manipulator for
Assembly) robot in Figure 1.5(a). Each link is either made of steel or aluminium.
Other materials can also be used depending on the requirements. The joints are
generally ‘rotary’ or ‘translatory’ types. In the study of robotics and mechanisms,
these joints are referred as ‘revolute’ and ‘prismatic’ joints, respectively. An
example of a revolute joint is hinge of a door or the joints in fingers of a human
being. A prismatic joint, on the other hand, is a pneumatic or hydraulic piston-
cylinder arrangement.
(a) A PUMA Robot (b) Equivalent Human Parts
Figure 1.5 : A Analogs of a Robot with the Human Arm and Wrist
Like the human hand shown in Figure 1.5(b), a robotic manipulator also has three
parts. The first two are the arm and the wrist, as shown in Figure 1.5(a), whereas
the third one is a hand or end-effector. Typical end-effectors are shown in
Figure 1.6. The function of an arm is to place an object in a certain location in the
three-dimensional Cartesain space. The wrist serves to permit placement in a
desired orientation. For a typical six-degrees-of-freedom robot, as in Figures 1.1
and 1.5(a), the first three links and joints from the base form the ‘arm,’ and the last
three joints (with mutually intersecting axes) make up the wrist.
End-effector

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Configuration and
Classification
This is the part attached at the end of the manipulator. Hence, the name follows.
This is equivalent to the human hand shown in Figure 1.5(b). An end-effector is
classified as
(a) mechanical hand that manipulates an object or holds it before they are
moved by the manipulator. These hands, in turn, are of various types,
e.g. a simple two-fingered gripper, Figure 1.6(a), that can hold simple
objects, whereas a multi-fingered hand, as shown in Figure 1.6(b), can
perform complex tasks;
(b) a specialised tool like welding electrode, gas-cutting torch, painting
brush, or grinding wheel, etc.
(a) A Simple Gripper (b) A Three-fingered hand (Angeles, 2003)
Figure 1.6 : Robot End-effectors
Actuators
They form the muscles of the robots that nove the manipulator carrying a suitable
end-effector. Acturators are of different types depending of the principle of their
operations, i.e. hydraulic or electric, as explained in Unit 2.
Transmission
As the term conveys, these elements transmit motion from the acutuators to the
actual links of the manipulator and its hand.
1.3.2 Recognition Subsystem
The most important element in the recognition subsystem is the sensor which is like our
eyes or nose. Inclusion of sensors to a robot changes its dumb nature to an intelligent
one. The recognition subsystem has following two elements.
Sensors
Most of the sensors are essentially transducers. Transducers convert one form of
energy to another. For example, the human eye converts light patterns into
electrical signals. Sensors fall into one of the several general areas, vision, touch,
range and proximity detection, navigation, speech recognition, etc.
Analog-to-Digital converter (ADC)
This electronic device interfaces the sensors with the robot's controller. For
example, an ADC converts the voltage signal due to the strain in the strain gauges
to a digital signal, i.e. 0 or 1, so that the digital robot controller can process the
information. They physically look like any other computer interface and card
inside the Central Processing Unit (CPU) box.

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Robot and Its Applications 1.3.3 Control Subsystem
Control subsystem mainly comprises of a Digital-to-Analog convertor (DAC) and a
digital controller.
Digital-to-Analog Convertor (DAC)
A DAC serves the purpose opposite to an ADC, i.e. the digital signal from the
robot controller is converted into an analog signal to activate the actuators, e.g. an
equivalent voltage to be applied to a DC electric motor.
Digital Controller
The digital controller is a special electronic device that has a central processing
unit (CPU), memory, and sometimes hard-disk to store programmed data. It is used
to control the movement of the manipulator and its end-effector. A robot controller
is like the supervisor in a factory. Since a computer processes the user
programmed commands and sends the signals to the actuators through the DAC,
the programming languages can be used as same as that of the computers, i.e.
BASIC, Fortran, C, and C++. However, for commercial robots, company specific
languages are also used. This is to introduce specific features into the robotic
systems so that the products are different.
SAQ 3
(a) What are the subsystems of a robot?
(b) Why sensors are important?
(c) How many joints a wrist should have and Why?
1.4 ROBOT CONFIGURATION
The configuration of a robot is a complete specification of the location of a point on the
robot end-effector and its orientation. The set of all configurations is called the
configuration space. For a given robot, if all the values for the joint variables, i.e. the
joint angle for revolute joints, or the joint translation for prismatic joints, are known, it is
possible to obtain the position of any point on the end-effector and its orientation since
the individual links of the manipulator are assumed to be rigid and the base of the
manipulator is fixed. Therefore, a configuration of a robot can be specified by a set of
values for the joint variables.
If the configuration of an object can be minimally specified by n parameters, the number
of DOF is then equal to n. A rigid object in the three-dimensional Cartesian space has six
DOF : three for positioning and three for orientation. Therefore, a manipulator should
typically possess at least six DOF. With fewer than six DOF the arm cannot reach every
point in its workspace with arbitrary orientation. Certain applications such as reaching
around or behind obstacles may require more than six DOF. A manipulator having more
than six DOF is referred to as a kinematically redundant manipulator.
1.5 CLASSIFICATION OF ROBOTS
There are numerous ways one can specify a robot. This can be best understood if one
looks at the robot specification used by the manufactures. For example, Table 1.1 shows
the specification of a Cincinnati Milacron robot of Figure 1.1. From Table 1.1, the
application of the robot (row 2 and column 2 of Table 1.1) is material handling, i.e. the

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Configuration and
Classification
robot is most suitable for this purpose. Thus, one can classify robots based on its
applications. Next, look at the operating space of the arm, rows 6-8 and columns 1-3 of
Table 1.1. They show how far and where the arm can move, and defines a geometric
shape. Thus, another way to specify a robot is based on its geometric work envelope.
Similarly, there are other types of classifications depending on different aspects of a
robot, as explained next.
Table 1.1 : Specification of an Industrial Robot
Manufacturer : Cincinnati Mailacron
Model : T3-595
Country of Origin : USA
Main Applications : Material Handling
Configuration : (Kinematics) : Polar
Maximum Load Capacity : 240 kg
Repeatability : N/A
Accuracy : ± 2.00 mm
Arm Operating Space Speed Wrist Operating Space Speed
Axis 1
Axis 2
Axis 3
240o
90o
120o
635 mm/s
635 mm/s
635 mm/s
Axis 4
Axis 5
Axis 6
−
180o
270o
−
635 mm/s
635 mm/s
Drive System : Electric, 380 V, 50 Hz, 27 kVA, Hydraulic linear piston plus five rotary pistons, 155 bars
Maximum Horizontal Reach : 2590 mm Mounting Position : Floor
Control System : CIP 3200 Mini-computer
Type of Memory : RAM
Standard Memory Size : 64 K, max., 1750 points
Number of Programms : N/A
Sensors : Available
Control Channel : Cassette
Teach Method : Teach box
Operating Mode : Point-to-Point
Language Used for Control Program : Direct
dialogue (English)
Diagnostics : Fitted as standard
Total Robot Weight : 2300 kg
N/A : Data not available.
1.5.1 Application Wise
As more and more robots are designed for specific tasks this method of classification
becomes more relevant. For example, many robots are now designed for assembly work
which are termed as ‘assembly robots’. They are not readily adaptable to other
applications. For seam welding some suppliers now provide complete welding systems
incorporating the robot, the welding equipment, and other material handling facilities
such as turntables, etc. Thus, the robot is termed as a ‘welding robot’. Some robots are
specifically designed for heavy load manipulation, and are lableled as ‘heavy duty
robots’.
1.5.2 Coordinate System Wise
This type of classifications is also referred to as classification by arm configuration or
geometric work envelope. It actually classifies the arm of the robot without considering
the wrist and hand. It tells the volume of the reachable coordinates of an end-effector
point, rather than its orientations. There are four fundamental types, namely,
(a) Cartesian,
(b) Cylinderical,
(c) Spherical, and
(d) Articulated.
Cartesian
When the arm of a robot moves in a rectilinear mode, to the directions of x, y, and
z coordinates of the rectangular right-handed Cartesian coordinate system, as
shown in Figure 1.7(a), then it is called Cartesian or rectangular type. The
associated robot is then called Cartesian Robot. It has three prismatic joints. They
refer to the motion of travel x, height or elevation y, and reach z of the arm. Its
workspace has the shape of a rectangular box or prism, as indicated in
Figure 1.7(b). A Cartesian robot needs a large volume to operate. It has, however,
a rigid structure and provides an accurate position of the end-effector.

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Robot and Its Applications
(a) Arm Configuration (b) Rectangular Box
Figure 1.7 : A Cartesian Arm with its Workspace
Cylindrical
When the arm of a robot possesses one revolute and two prismatic joints, i.e. the
first prismatic joint of the Cartesian type, Figure 1.7(a), is replaced by a revolute
one whose axis is rotated by 90o
about the reach z-axis, the points that it can reach
conveniently be specified by the cylindrical coordinates, i.e. angle θ, height y, and
radius z, as in Figure 1.8(a). A robot with this type of arm is termed as cylindrical
robot whose arm movement, θ, y, and z, are called base rotation, elevation, and
reach, respectively. Since the coordinates of the arm can assume values between
the specified upper and lower limits, its end-effector can move in a limited volume
that is a cut section from the space between two cylinders with a common axis, as
shown in Figure 1.8(b). Note that for the Cartesian arm this is not the case, where
the workspace is a solid box, Figure 1.7(b). The dotted line in the figure just
completes the boundary of the workspace volume for better visualisation. It has no
other purpose. A robot of this type may have difficulties in touching the floor near
the base. Cylindrical robots are successfully used when a task requires reaching
into small openings or working on cylindrical surfaces, e.g. welding pipes.
(a) Arm Configuration (b) Cylindrical Shape
Figure 1.8 : A Cylindrical Arm
Spherical
When the arm of a robot can change its configuration by moving its two revolute
joints and one prismatic joint, i.e. the second prismatic joint arm of the cylindrical
arm is replaced by a revolute joint and rotated by 90o
about its z-axis, the arm
position is conveniently described by means of the spherical coordinates, θ, φ, z.
The arm shown in Figure 1.9(a) is termed as a spherical arm. The arm movements
represent the base rotation, elevation angles, and reach, respectively. Its workspace
is indicated in Figure 1.9(b).

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Configuration and
Classification
(a) Arm Configuration (b) Spherical Shape
Figure 1.9 : A Spherical Arm
Articulated
When an arm consists of links connected by only revolute joints, i.e. the third
prismatic joint of the spherical type is also replaced by another revolute joint
whose joint axis is rotated by 90o
about the z-axis, it is called an articulated or a
revolute jointed arm. It is described schematically in Figure 1.10(a) whose
sphere-looking workspace is shown in Figure 1.10(b). Its actual surface is,
however, difficult to determine.
(a) Arm Configuration (b) Workspace Shape
Figure 1.10 : An Articulated Arm
Table 1.2 depicts how one type of robot can be obtained from the other type,
whereas Table 1.3 shows the advantages and disadvantages of those basic arms.
Some literature also make classifications like Gantry and SCARA (Selective
Compliance Assembly Robot Arm), as shown in Figures 1.11 and 1.12,
respectively. This is not required as the Cartesian type placed up-side down
becomes gantry robot. This robot is versatile in its operation, but expensive. The
SCARA, on the other hand, is a cylindrical type, whose reach is obtained using a
revolute, instead of a prismatic joint (compare Figures 1.8(a) and 1.12). SCARA is
very good for assembly task and, therefore, it is extensively used by industries.
Table 1.2 : Transformation of Robot Arms
Joints Type
P : travel x
↓ − P + R + 90o
@ z
R : rotation θ
↓
R : rotation θ
↓
P : height y
↓
P : height y
↓− P + R + 90o
@ z
R : angle φ
↓
P : reach z
↓
P : reach z
↓
P : reach z
↓ − P + R + 90o
@ z
Cartesian
↓
Cylindrical
↓
Spherical
↓

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Robot and Its Applications R : rotation θ R : angle φ R : angle ψ Revolute
− P : Remove prismatic joint, + R : Add revolute joint; + 90o
@ z : Rotate the joint axis by 90o
about
z-axis.
Table 1.3 : Comparison of Four Basic Robot Arms
Configuration Advantages Disadvantages
Cartesian
(3 linear axes)
x : basic travel
y : height
z : reach
(a) Easy to visualise
(b) Rigid structure
(c) Easy off-line programming
(d) Easy mechanical stops
(a) Reach only front or back
(b) Requires large floor space
(c) Axes are hard to protect from
dust, etc.
Cylindrical (1 rotating
and 2 linear axes)
θ : base rotation
y : height
z : reach
(a) Can reach all around
(b) Rigid y, z-axes
(c) θ-axis is easy to seal
(a) Cannot reach above itself
(b) Less rigid θ-axis
(c) y, z-axes are hard to seal
(d) Won’t reach around obstacles
(e) Horizontal motion is circular
Spherical
(3 rotating axes)
θ : base rotation
φ : elevation angle
z : reach
(a) Can reach all around
(b) Can reach above or below
obstacles
(c) Large work volume
(a) Cannot reach above itself
(b) Short vertical reach
Articulated
(3 rotating axes)
θ : base rotation
φ : elevation angle
ψ : reach
(a) Can reach above or below
objects
(b) Largest work area for least
floor space
(a) Difficult to program off-line
(b) Two or more ways to reach a
point
(c) Most complex robot
Figure 1.11 : A Gantry Robot [Courtesy : Koivo (1989)]

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Configuration and
Classification
Figure 1.12 : A SCARA Arm
1.5.3 Actuation System Wise
Robots are driven by either electric power or fluid power. The latter category being
further subdivided into pneumatic and hydraulic. Today, the most common drive method
is electric with various types of motors, e.g., stepper, DC servo, and brushless AC servo,
etc.
1.5.4 Control Method Wise
Here the word control means two things. One is motion control strategy, i.e. whether a
robot is servo controlled or not, and the other one is how the motion or path is achieved,
i.e. point-to-point or continuous.
Servo/Non-servo Control
Robots are either servo controlled (closed-loop) or non-servo controlled
(open-loop). To gain full advantage of the digital or microprocessor control to
achieve good precision under heavy load conditions, and to carry out complex
tasks with confidence, full servo control is necessary. In this method of control,
commands are sent to the arm drives to move each axis. The actual movement is
monitored for both the displacement and velocity, and compared with the
command signals. The difference between the command and the action is the error.
This value is used as feedback to the controller to enable further commands to be
modified accordingly. Most electric and hydraulic robots are servo controlled.
Pneumatic robots usually non-servo controlled. In this case, a command signal is
sent and it is assumed that the robot arm reaches its intended position, usually a
fixed or programmable mechanical stop. Non-servo control is adequate where
position control of light loads is required. However, if velocity, acceleration, and
torque are to be controlled or if movement against heavy loads is necessary then
non-servo control is usually not possible. The majority of the industrial robots
today use servo control.
Path Control
In point-to-point control, the robot arm moves from one desired point to the next
without regard to the path taken between them. The actual path taken may be the
result of a combination of arm link movements calculated to provide the minimum
travel time between the points. Point to point control is widely used for
assembling, palletising, and machine tool loading/unloading.
In continuous path control, the robot moves along a continuous path taught with
specified orientations. For example, in spray painting the signal from the sensors
of the joints are constantly monitored by the robot controller.
1.5.5 Programming Wise
Industrial robots can be programmed by various means. For example, they can be
programmed either on-line or off-line. On-line methods require direct use of the robot
and will utilise teach pendant for point to point programming, and slave arms with pistol
grip attachments for continuous path programming. Present day robots have the provision
to be programmed off-line, i.e. the robot can continue working on a particular task while
a program for a new task is prepared on a computer terminal using a programming
language.
SAQ 4
(a) What are the ways of classifying a robot?
(b) What kind of robot is suitable of painting a shaft? Why?
(c) What is the shape of the workspace of SCARA robot (Figure 1.12)?
Draw it.
(d) What type of arm PUMA robot is?
(e) Name few robot manufacturers and their robot programming languages?

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1.6 SUMMARY
Robots, their usefulness, definitions, configurations, types and applications are presented
in this unit. A brief history is given in Section 1.2, where the laws of robotics are also
introduced. These laws should be strictly adhered to avoid any unemployment. The
different subsystems and elements of a robotic system is presented in Section 1.3.
Classifications of robots, along with their relative advantages and disadvantages are also
presented in this unit.
1.7 KEY WORDS
Articulated : ‘Jointed’ like in human arm.
CPU : Central Processing Unit.
Manipulator : Mechanical motion provider of a robot.
PUMA : Programmable Universal Manipulator for
Assembly.
Robot : ‘Reprogrammable’ and ‘multifunctional’ machine
controlled by a digital controller or computer.
RUR : Rossum’s Universal Robot.
SCARA : Selective Compliance Assembly Robot Arm.
Sensor : A device that detects a robot’s status.
1.8 ANSWERS TO SAQs
Check your answers of all the SAQs that are not provided below with the respective
preceding text to each SAQ.
SAQ 3
(c) Three. This is because the purpose of a wrist is to orient an object in the
three dimensional Cartesian space, e.g. rotations about three mutually
perpendicular axes.
SAQ 4
(b) Cylindrical because the shape of a shaft is cylindrical.
(c) Cylindrical, as shown below.
(d) Articulated

19
Configuration and
Classification
Figure
(e) The answer to this question is tabulated below :
Sl. No. Manufacturer Country Programming Language
1 Cincinatti Milacron USA MCL
2 Unimation Inc. (PUMA) USA VAL
3 IBM USA AML
4 GM (Allegro) USA HELP
5 Fanuc Japan Karel
6 Sankyo Japan SERF
7 Olivetti Italy SIGLA
8 Scemi France LM
FURTHER READING
Angeles, J., 2003, Fundamental of Robotic Mechanical Systems : Theory, Methods, and
Algorithms, Spring-Verlag, New York, 2nd
Edition.
Cugy, A., and Page, K. (1984), Industrial Robot Specifications, Kogan Page, London.
Dorf, R. C. (1988), International Encyclopedia of Robotics, John Wiley and Sons,
New York.
Fuller, J. L. (1999), Robotics : Introduction, Programming and Project, Prentice Hall,
New Jersy.
Koivo, A. J. (1989), Fundamental for Control of Robotic Manipulators, John Wiley and
Sons, New York.
Mair, G. M. (1988), Industrial Robotics, Prentice Hall, New York.
Todd, T. J. (1985), Walking Machines, Kogan Page, London.

20
Yoshikawa, T. (1990), Foundation of Robotics, The MIT Press, Massachusetts.

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