It is an introduction to robot technology for engineering, polytechnic, and school students.

1. INTRODUCTION TO
ROBOT TECHNOLOGY
A Presentation by
Prof. Dr. Janak B. Valaki
Associate professor, Mechanical Engg. Dept.,
Government Engineering College, Bhavnagar
janakvalaki@gmail.com, 09913715250

2. Sanjay Patel (CAD/CAM )

3. Robotics Terminology:
• Robot: An electromechanical device with multiple degrees-of-
freedom (DOF) that is programmable to accomplish a variety of
tasks.
• Industrial robot:The Robotics Industries Association (RIA)
defines robot in the following way:
An industrial robot is a programmable, multi-functional
manipulator designed to move materials, parts, tools, or
special devices through variable programmed motions for
the performance of a variety of tasks”
ISO defines a robot as: A robot is an automatically
controlled, reprogrammable, multipurpose, manipulative
machine with several reprogrammable axes, which is
either fixed in a place or mobile for use in industrial
automation application.

4. Definition of Robot
A Robot is a Electro-Mechanical device
with links and joints, guided by sensors,
driven by actuators and controlled
through a programmed software, to
handle and manipulate parts ,materials,
tools, and devices for performing various
tasks in variety of work environments”

5. The study and understanding “Robotics” is interdisciplinary domain
consisting mainly of mechanical and supported by electrical, electronics,
computer streams
Various links and joints are to be designed for strength and rigidity
through static and dynamic force analysis.
Electrical and hydrulic / pneumatic actuators produce various robot
motions.
Required positions are computed through transformations.
The electronics contributes in the types of control system to closely
achieve the desired output with the achieved output.
The computer programs add flexibility for performing the variety of jobs
executed by the robotics manipulators.
The software programs with the developed algorithms , controllers, and
sensing systems make the robot to posses intelligence to carry out jobs
with in the work envelope defined by the movements (degree of
freedom) given to links.

6. Structure of a Robotic system

7. Robotic system
• Manipulator
• Drive system
• Control system
• End effectors
• Sensors
• Vision system
• Computer software and hardware

8. ROBOT PHYSICAL CONFIGURATION
1. Cartesian configuration
2. Cylindrical configuration
3. Spherical/Polar configuration
4. Articulated/Joint-arm configuration

9. Cartesian Configuration
• Robots with Cartesian configurations consists of
links connected by linear joints (L). Gantry
robots are Cartesian robots (LLL).

10. Cartesian Robots
• It consists of three orthogonal
slides.
• Three slides are parallel to x, y
and z axes of the Cartesian
coordinate system
Commonly used for:
• pick and place work
• assembly operations
• handling machine tools
• arc welding

11. 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

12. Cylindrical Configuration
• Robots with cylindrical configuration have one rotary ( R)
joint at the base and linear (L) joints succeeded to
connect the links.

13. Cylindrical Robots
• In this, the robot body is a vertical
column that swivels about vertical axis
• The arm consist of several orthogonal
slides which allow the arm to be moved
up and down and in or out w.r.t. to
body
Commonly used for:
• handling at die-casting machines
• assembly operations
• handling machine tools
• spot welding

14. Cylindrical Robots
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:
• linear axes is hard to seal
• won’t reach around obstacles
• exposed drives are difficult to cover from dust and liquids

15. Spherical/Polar Robots
A robot with 1 prismatic joint and 2
rotary joints – the axes consistent
with a polar coordinate system.
Commonly used for:
•handling at die casting or fettling
machines
•handling machine tools
•arc/spot welding

16. Spherical/Polar Robots
Advantages:
• large working envelope.
• two rotary drives are easily sealed against liquids/dust.
Disadvantages:
• complex coordinates more difficult to visualize, control,
and program.
• exposed linear drive.
• low accuracy.

17. Articulated Robot

18. • Articulated Robots have all the joints of single
axis revolute or rotary type. This chain of
revolute joints provides greater freedom and
dexterity in movement of the articulated
robotic arm. SCARA and PUMA are the most
popularly used articulated robots in assembly
lines and packaging processes.

19. SCARA
(Selective compliance assembly robot arm)

20. SCARA
• It is a simple articulated robot which can
perform assembly tasks precisely and fast.
SCARA is most adept in pick and place
operations in any assembly line in industries
with speed as well as precision. SCARA is more
or less like a human arm the motion is
restricted horizontal sweeping and vertical
movement, it cannot rotate along an axis
other than vertical.

21. PUMA Robot
(Programmable Universal machine for assembly)

22. PUMA
• PUMA is the most commonly used industrial
robot in assembly, welding operations and
university laboratories. PUMA resembles more
closely to the human arm than SCARA. PUMA has
greater flexibility than SCARA but with the
increased compliance comes the reduced
precision. Thus, PUMA is preferably used in
assembly applications which do not require high
precision, such as, welding and stocking
operations.

23. Basic Motion Systems
Six degrees of freedom
• It provides the robot the capability to move and perform
predetermined task
• These six degrees of freedom are intended to follow the
versatility of movement possessed by the human arm
• The six basic motions consists of three arm and body
motions and three wrist motions

24. Basic Motion Systems
Arm and body motions
• Rotational transverse : Rotation about the vertical axis (right or left
swivel of the robot arm )
• Vertical transverse : Up and down motions of the arm , caused by
pivoting the entire arm about a horizontal axis or moving the arm about
vertical slide.
• Radial transverse : extension and retraction of the arm (in and out
movement)
Wrist motions
4. Wrist swivel (Roll) : Rotation of the wrist
5. Wrist bent (Pitch) : Up and down movement of the wrist , which also
involves a rotational movement
6. Wrist yaw: swivel of the wrist

25. Basic Motion Systems
1
2
3
4
5
6
Back

26. Robot Configurations (Manipulators)
• Robot Configuration:
Cartesian: PPP Cylindrical: RPP Spherical: RRP
SCARA: RRP
(Selective Compliance
Assembly Robot Arm)
Articulated: RRR
Hand coordinate:
n: normal vector; s: sliding vector;
a: approach vector, normal to the
tool mounting plate

27. Robot Joints

28. Other basic joints
Spherical Joint
3 DOF ( Variables - 1, 2, 3)
Revolute Joint
1 DOF ( Variable - )
Prismatic Joint
1 DOF (linear) (Variables - d)

29. ROBOT MOTION SYSTEMS
Classification Based on Control Systems:
1. Point-to-point (PTP) control robot
2. Continuous-path (CP) control robot

30. 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

31. Continuous-Path Control Robot (CP):
• The CP robot is capable of performing movements
along the controlled path.
• All the points along the path must be stored explicitly
in the robot's control memory.
• 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

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

33. Other technical features of robot
• Work volume
• Precision of movement
• Speed of movement
• Weight-carrying capacity
• Type of drive system

34. Robot selection:
• 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.
• The characteristics of robots generally considered in a
selection process include:
• Size or 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

35. Contd…..
1. Size or 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.
3. Velocity: Velocity consideration is effected by the robot’s arm
structure.
Rectangular, Cylindrical, Spherical, Articulated
4. Drive type:
Hydraulic, Pnematic,Electric, Electronics, …

36. 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
7. 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.

37. DOF ( degrees-of-freedom)
the number of independent motions a device can make.
(Also called mobility)
five degrees of freedom

38. Manipulator: Electromechanical device capable of interacting with its
environment.
Anthropomorphic: Like human beings.
• End-Effector: The tool, gripper, or other device mounted at the end
of a manipulator, for accomplishing useful tasks.

39. Figure: Sample gripper designs: (a) pivot action grippe;
(b) slide action gripper; (c) double gripper-pivot action
mechanism; (d) vacuum-operated hand

40. Workspace: The volume in space that a robot’s end-Effector can
reach, both in position and orientation.
• 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.

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

42. 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.
Lift Capacity
The maximum weight-carrying capacity of the robot.
Robots that carry large weights, but must still be precise are
expensive.

43. Spatial resolution:
The spatial resolution of a robot is the smallest increment of
movement into which the robot can divide its work volume.
It depends on the system’s control resolution and the robot's
mechanical inaccuracies.
Accuracy:
Accuracy can be defined as the ability of a robot to position
its wrist end at a desired target point within its reach. In
terms of control resolution, the accuracy can be defined as
one-half of the control resolution. This definition of accuracy
applies in the worst case when the target point is between
two control points. The reason is that displacements smaller
than one basic control resolution unit (BCRU) can be neither
programmed nor measured and, on average, they account
for one-half BCRU.

44. Repeatability:
It is the ability of the robot to position the End Effector to the
previously positioned location.
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x
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x
x
x
x
x
x xx x
x x
x x
x
++
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+ ++
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A
B
C

45. There are basically three types of power sources for robots:
Hydraulic drive
• Provide fast movements
• Preferred for moving heavy parts
• Preferred to be used in explosive environments
• Occupy large space area
• There is a danger of oil leak to the shop floor
Electric drive
• Slower movement compare to the hydraulic robot.
• Good for small and medium size robots.
• Better positioning accuracy and repeatability.
• stepper motor drive: open loop control
• DC motor drive: closed loop control
• Cleaner environment
• The most used type of drive in industry
Pneumatic drive
• Preferred for smaller robots.
• Less expensive than electric or hydraulic robots.
• Suitable for relatively less degrees of freedom design.
• Suitable for simple pick and place application.
• Relatively cheaper

47. Robot Sensors
1. Tactile and proximity sensors
2. Voice sensors
3. Vision sensors
sensors provide feedback to the control systems and
give the robots more flexibility. Sensors such as visual
sensors are useful in the building of more accurate
and intelligent robots. The sensors can be classified
as follows:

48. Robot Sensors
sensors
tactile or contact sensors
touch sensors force sensors
position and
displacement
sensors
external
sensors
non contact
sensors
proximity
and range
sensors
robot vision
system
voice
synthesizers
internal
sensors

49. Tactile sensors provide the robot with the capability
to respond to contact forces between itself and other
objects within its work volume. Tactile sensors can be
divided into two types:
1. Touch sensors
2. Stress sensors (also called force sensors)
Touch sensors are used simply to indicate whether
contact has been made with an object. A simple micro
switch can serve the purpose of a touch sensor.
Stress sensors are used to measure the magnitude of
the contact force. Strain gage devices are typically
employed in force-measuring sensors.

50. • Proximity sensors are used to sense when one
object is close to another object. On a robot, the
proximity sensor would be located on or near the
end effector. This sensing capability can be
engineered by means of optical-proximity devices,
eddy-current proximity detectors, magnetic-field
sensors, or other devices.
• In robotics, proximity sensors might be used to
indicate the presence or absence of a workpart or
other object. They could also be helpful in
preventing injury to the robot’s human coworkers in
the factory.

51. Position sensors:
Position sensors are used to monitor the position of joints.
Information about the position is fed back to the control systems that are
used to determine the accuracy of positioning.
Range sensors:
Range sensors measure distances from a reference point to
other points of importance. Range sensing is accomplished by means of
television cameras or sonar transmitters and receivers.
Velocity Sensors:
They are used to estimate the speed with which a manipulator is
moved. The velocity is an important part of the dynamic performance of
the manipulator. The DC tachometer is one of the most commonly used
devices for feedback of velocity information. The tachometer, which is
essentially a DC generator, provides an output voltage proportional to
the angular velocity of the armature. This information is fed back to the
controls for proper regulation of the motion.

52. Voice sensors
voice sensing or voice programming
Voice programming can be defined as the oral communication
of commands to the robot or other machine. The robot
controller is equipped with a speech recognition system
which analyzes the voice input and compares it with a set of
stored word patterns. When a match is found between the
input and the stored vocabulary word, the robot performs
some action which corresponds to that word.
Voice sensors would be useful in robot programming to speed
up the programming procedure, just as it does in NC
programming. The robot could be placed in the hazardous
environment and remotely commanded to perform the repair
chores by means of step-by-step instructions.

53. Vision sensors
Computerized visions systems will be an important technology in future
automated factories. Robot vision is made possible by means of a video
camera, a sufficient light source, and a computer programmed to
process image data.
The camera is mounted either on the robot or in a fixed position above
the robot so that its field of vision includes the robot’s work volume.
The computer software enables the vision system to sense the presence
of an object and its position and orientation.
Vision capability would enable the robot to carry out the following kinds
of operations:
Retrieve parts which are randomly oriented on a conveyor.
Recognize particular parts which are intermixed with other objects.
Perform visual inspection tasks.
Perform assembly operations which require alignment.
It is merely a matter of time and economics before vision sensors
become a common feature in robot applications.

54. Robot Grippers:
Grippers are generally used to grasp and hold an
object and place it at a desired location.
 mechanical grippers
 vacuum or suction cups
 magnetic grippers
 adhesive grippers
 hooks, scoops, and so forth

55. Robot Kinematics:
• Forward Kinematics (angles to position)
What you are given: The length of each link
The angle of each joint
What you can find: The position of any point
(i.e. it’s (x, y, z) coordinates
• Inverse Kinematics (position to angles)
What you are given: The length of each link
The position of some point on the robot
What you can find: The angles of each joint needed to obtain
that position

56. Programming with Robot
1. Manual method
2. Walk through method
3. Lead through method
4. Off- line programming

57. Manual method
• It is more like setting machine rather than
programming
• It involves setting mechanical stops, cams,
switches, or relays in the robot’s control unit
• Used for short work cycles (e.g. pick-and-
place operations )

58. Walk through Method
• In this programmer manually moves robots arm and
hand through the sequence of the work cycles.
• Each movement is recorded into memory for
subsequent playback during the production
• Speed is controlled independently
• Appropriate for spray painting, arc welding robots

59. Lead Through Method
• Uses teach pendent to power drive the robot
through its motion sequence
• Teach pendent is device, consists of switches and
dials to control the robot’s physical movements
• Each motion is recorded into memory for future
playback during the work cycle
• Popular because of its ease and convenience

60. Off-line Programming
• It involves the preparation of robot program off-line ,
in a manner similar to NC part programming
• It is accomplished on computer terminal
• After preparation it is entered into the memory of the
computer for use during the work cycle.
• The advantage is that production time of robot is not
lost to delays in teaching the robot a new task

61. Robot Applications
• Machine loading,
• Pick and place operations
• Welding,
• Painting
• Inspection
• Sampling
• Assembly operations
• Manufacturing
• Surveillance
• Medical application
• Assisting disabled individuals
• Hazardous environment
• Underwater, space and remote locations

62. Advantages of Robots
• Robotics and automation can, in many situations, increase productivity, safety,
efficiency, quality, and consistency of products.
• Robots can work in hazardous environments without the need for life support,
comfort, or concern about safety.
• Robots need no environmental comfort, such as lighting, air conditioning,
ventilation, and noise protection.
• Robots work continuously without experiencing fatigue or boredom, do not get
mad, do not have hangovers, and need no medical insurance or vacation.
• Robots have repeatable precision at all times, unless something happens to
them or unless they wear out.
• Robots can be much more accurate than humans. Typical linear accuracies are a
few thousands of an inch. New wafer-handling robots have microinch
accuracies.
• Robots and their accessories and sensors can have capabilities beyond that of
humans.
• Robots can process multiple stimuli or tasks simultaneously. Humans can only
process one active stimulus.

63. Disadvantages of Robots
• Robots replace human workers creating economic problems,
• Robots lack capability to respond in emergencies, This includes:
• Inappropriate or wrong responses
• A lack of decision-making power
• A loss of power
• Damage to the robot and other devices
• Human injuries
Robots, although superior in certain senses, have limited capabilities in
• Degrees of freedom
• Dexterity
• Sensors
• Vision systems
• Real-time response