The document provides an introduction to industrial robotics, including definitions of robots, their basic components, and classifications. It describes the typical components of a robot including the manipulator, end-effector, power supply, and control system. It also discusses robot programming methods, languages, accuracy, repeatability and common applications in material handling, processing, assembly and inspection.

1. UNIT 5
INDUSTRIAL ROBOTICS

2. Introduction to Robots
■ An industrial robot is a reprogrammable, multifunctional mechanical
device designed to manipulate and transport parts, tools, or
specialized devices through variable programmed motions to
perform variety of tasks.

3. Definitions of robot
■ “Robot is a device that performs functions ordinarily ascribed to
human beings, or operates with what appears to be almost human
intelligence”.
■ “An industrial robot is a reprogrammable multifunctional
manipulator designed to move material, parts, tools or specialized
devices through various programmed motions for the performance of
a variety of tasks”.

4. Robot Components
■ The four basic components of an industrial robot are:
– Manipulator
– End-effector
– Power supply
– Control system

6. Manipulator
■ Manipulator is called arm and wrist, is a mechanical unit that
provides motions similar to those of a human arm and hand.
■ The end of the wrist can reach a point in space having a specific set
of coordinates, in a specific orientation.
■ Most robots have six rotational joints.
■ The manipulator is powered by hydraulic or pneumatic cylinders or
rotary actuators and electric or hydraulic motors are used to power
the various axes of motions.

7. End effector
■ The end of the wrist in a robot is equipped with an end-effector, also
called end-of-arm tooling.
■ Depending on the type of operation, conventional end-effector are
equipped with any of the following:
– Grippers, hooks, scoops, electromagnets, vacuum cups and
adhesive fingers for material handling
– Spray guns for painting
– Attachment for spot welding and arc welding and arc cutting
– Power tools such as drills, nut drivers and burrs
– Measuring instruments such as dial indicators

8. Power supply
■ The power supply is the source of energy used to move and regulate
the robot’s drive mechanisms.
■ The energy usually comes from three sources: electric, hydraulic and
pneumatic.

9. Control system
■ Control system also known as controller is the communications and
information-processing system that gives commands for the
movements of the robot.
■ The controller is the brain of the robot, as it stores data to initiate
and terminate movements of the manipulator.
■ It is also the nerves of the robot, as it interfaces with computers and
other equipment such as manufacturing cells or assembly systems.
■ Feed back devices such as transducers, are an important part of the
control system.

10. Basic robot motions
■ There are six basic motions.
■ Wrist motions
– Yaw: It refers to rotation in a horizontal plane through the arm.
– Pitch: It refers to rotation in a vertical plane through the arm.
– Roll: It refers to rotation in a plane perpendicular to end of the
arm.
■ Arm and Body Motions
– Vertical traverse: It refers to up and down motions of the arm
– Radial traverse: It refers to the extensions and retraction of the
arm.
– Rotational traverse: It refers to rotation about the vertical axis.

13. Classifications of robots based on
the type of control
■ Point-to-point control robot
■ Continuous path control robot
■ Controlled path (computed trajectory) control robot

14. Point-to-point control robot
■ A point to point control robot also known as PTP robot, is able to
move from one specified point to another. But it cannot stop at
arbitrary points not previously designated.
■ It is the simplest and least expensive type of control.
■ This type of robot is fast, accurate and inexpensive.

15. Continuous path control robot
■ A robot with continuous path control is able to stop at any specified
number of points along a path.
■ If no stop is specified, the robotic arm may not stay on a straight line
or constant curved path between specified points.

16. Controlled path (computed trajectory)
control robot
■ Control equipment on controlled path robots can generate straight
lines, circles, interpolated curves, and other paths with high accuracy.
■ Path can be specified in geometric or algebraic terms in some of
these robots.
■ Good accuracy can be obtained at any point along the path.

17. Classification of robot based on level of
control involved
■ Sequence robots
■ Playback robots
■ Intelligent robots

18. Sequence robots
■ In sequence robot, the manipulator progresses successively through
the various stages of an operation according to the predetermined
sequence.
■ The sequence robots represent the lowest level of control.

19. Playback robots
■ Playback robots use a more sophisticated control unit in which a
series of positions or motions are ‘taught’ to the robot, recorded into
memory and then repeated by the robot under its own control.

20. Intelligent robots
■ In an intelligent robot, the robot can determine its own
behaviour/conduct through its functions of sense and recognition.
■ The intelligent robots represents the most sophisticated level of
control.

21. Work volume
■ The maximum volume of the space that a robot can reach
mechanically is called the work volume or work envelope or robot
reach or the workspace of a robot.

24. Joint drive system
■ Hydraulic drive system
■ Pneumatic drive system
■ Electrical drive system

25. ■ Its sophisticated for robots
■ Associated in large robots
■ This drive is only for rotational drive or linear drive
HYDRAULIC DRIVE

27. ■ It do not provide as much speed & power
■ Associated in small robots
■ Accuracy & repeatability is better
■ Actuated by dc motor or stepper motor
■ This drive is only for rotational drive, by drive train & gear systems
■ Perform linear systems by pulley systems
ELECTRIC DRIVE

29. ■ For smaller systems with less DOF
■ Performs pick & place operations only with fast cycles
■ This system having compliance or ability to absorb some shock
■ This is only for rotary operations.
PNEUMATIC DRIVE

31. ■ The controller act as a brain of the robot
■ This is a information processing device.
■ The inputs are both desired and measured positions.
■ Velocity (or) other variables in a process whose o/p systems are drive
signals to control the motors or actuators.
■ Types of robot control systems:
– Non-servo (open loop) control
– Servo (closed loop) control
Robot control

32. Non-servo (open loop) control
■ Non servo robots do not have a feedback capability and their axes
are controlled through a system of mechanical stops and limit
switches.

34. Servo (closed loop) control
■ The servo controlled robots are controlled through the sensors that
automatically monitor the robots axes and associated components
for position and velocity.
■ This feed back is compared to pre-taught information which has
been programmed and stored in the robot’s memory.

36. Hierarchical control structure of a
robot controller

37. TYPES OF ROBOT CONTROL
■ Limited sequence control
■ Playback with point to point control
■ Playback with continuous path control
■ Intelligent control

38. Limited sequence control
■ Limited sequence robot do not use servo control to indicate relative
positions of the joints. Instead, they are controlled by setting limit
switches and/or mechanical stops together with a sequencer to
coordinate and time the actuation of the joints.
■ Thus the limited sequence robots use pick and place motion.
■ These type of robots are normally pneumatically actuated.

39. Playback with point to point control
■ Point to point robots are the most common of the four classifications
and can move from one specified point to another but cannot stop at
arbitrary points not designated previously.

40. Playback with continuous path
control
■ Continuous path motion is an extension of the point to point method.
The difference is that continuous path involves the utilization of more
points. Its path can be an arc, a circle, or a straight line.
■ Greater storage capacity
■ Interpolation calculations

41. Intelligent control
■ The intelligent control robot is capable of performing some of the
functions and tasks carried out by human beings. It can detect
changes in the work environment by means of sensory perception.

42. Robot End Effectors
■ End effector is attached to the end of the wrist arm to make
intentional contact with an object or to produce the robot’s final
effect on its surroundings by performing a particular task.
■ Depending on the type of operation, conventional end-effector are
equipped with any of the following:
– Grippers, hooks, scoops, electromagnets, vacuum cups and
adhesive fingers for material handling
– Spray guns for painting
– Attachment for spot welding and arc welding and arc cutting
– Power tools such as drills, nut drivers and burrs
– Measuring instruments such as dial indicators

43. Classification of End Effectors
■ Grippers
■ End-of-arm tooling (EOAT)

44. Grippers
■ A gripper is like the arm of an operator that establishes the
connection between the work piece and robot.
■ The functions of the gripper mechanism is to translate some form of
power input into the grasping action of the fingers against the part.
■ The mechanism must be able to open and close the fingers and to
exert sufficient force against the part to hold it securely.

45. Types of Grippers
■ Mechanical grippers
■ Magnetic grippers
■ Vacuum grippers
■ Other types
– Adhesive grippers
– Piercing grippers
– Hooks, scoops and other miscellaneous devices

46. Mechanical grippers
■ A mechanical gripper is an end effector that uses mechanical finger
or clamp actuated by mechanism to grasp an object that actually
make contact with the object.
■ Two groups
– Internal gripper
– External gripper

49. Types of Mechanical grippers
■ Single grippers
■ Dual grippers
■ Interchangeable grippers
■ Multiple fingered grippers
■ Standard grippers
■ Sensory grippers

51. Dual grippers
■ Two gripping devices attached to the wrist.

52. Interchangeable grippers
■ The interchangeable grippers consist of interchangeable fingers that
can be used on single gripper mechanism.

53. Vacuum Grippers
■ In vacuum grippers, the suction cups are used to create negative
pressure and thus the vacuum to parts so that they adhere to the
grippers.

55. Magnetic Grippers

56. Other Type of Grippers
■ Adhesive Grippers
– Adhesive substance (sticky tape) performs the grasping action.
■ Piercing grippers
– The component to be handled are pierced
– This method is only used where slight damage to the component
is acceptable.
■ Hooks, Scoops & Ladles and other devices
– Hooks can be used as end effector to handle containers of parts
and to load and unload parts from overhead conveyors
– Scoops and ladles can be used to handle certain materials in
liquid (chemicals and molten metals) or powder form (food
materials)
– Inflatable bladder or diaphragm is expanded to grasp the object.

57. End-of-Arm-Tooling
■ In many applications, the robot is required to manipulate a tool
rather than a work part. In such applications, the tool is used as the
end-effector, which is attached directly to the robot wrist.
■ Examples
– Spot welding guns
– Arc welding torch
– Spray painting nozzle
– Rotating spindles
– Heating torch
– Water jet cutting tool

58. Sensors in Robotics
■ Sensors are the sensory system of a robot (must like the five senses
that human system have – touch, sight, sound, smell and taste) and
the sensors measure environmental data (such as touch, distance,
light, sound, strain, rotation, magnetism, smell, temperature,
inclination, pressure, altitude, etc.).
■ A robot sensor is a device or transducer that detects information
about the robot and its surrounding, and transmits it to the robot’s
controller.

59. Type of robotic sensors
■ Classification of sensors on the basic of their location.
– Internal sensors
– External sensors
■ Classification of sensors on the basic of their physical activation
– Contact sensors
– Non-contact sensors

60. ■ Internal Sensors
■ Internal sensors use feedback information internally to ascertain
their present condition.
■ Examples:
– Potentiometers and optical encoders
– Tachometers
■ External Sensors
■ External sensors are physically mounted on the robot or on process
equipment in the robot cell so that they can be usually seen.
■ Examples:
– Micro switches
– Touch or tactile sensors
– Photoelectric devices
– Proximity sensors

61. ■ Contact sensors
■ Contact sensors are devices used in robotics to obtain information
associated with the physical contact between a manipulator hand
and objects in work space.
■ Types of contact sensors
– Touch sensors
– Force sensors
■ Non contact sensors
■ Non contact sensors measure the condition of an object without
physically touching the part.
■ Examples
– Range sensors
– Proximity sensors
– Acoustic sensors
– Vision sensors

62. Industrial Robot Applications
■ Hazardous or uncomfortable work environment for human beings.
■ Repetitive tasks.
■ Difficult handling for humans.
■ Multi shift operation.
■ Infrequent changeovers
■ Part position and orientation are established in the work cell

63. Categories of industrial robot
applications
■ Material handling applications
– Pick and place operations
– Palletizing and/or depalletizing
– Machine loading and/or unloading
– Stacking and insertion operations
■ Processing operations
■ Assembly operations
■ Inspection operations

71. Robot Programming
■ A robot program can be defined as a path of movements of its
manipulator, combined with peripheral equipment action to support
the work cycle.
■ The process of robot programming involves ‘teaching’ it the task to
be performed, storing the program, executing the program, and
debugging it.

72. Methods of robot programming
■ Manual programming
■ Teach pendent programming
■ Walk through programming
■ Computer terminal programming
– Online programming
– Off-line programming

73. Manual Programming
■ In this manual programming, the operators set-up program by fixing
limit switches, stop, cams etc.
■ The manual programming method is adequate for limited sequence
pick and place robots.

74. Teach pendant programming
■ Teach pendent programming, also known as lead through
programming, uses a teach pendent to instruct a robot to move in
working space.
■ Teach pendent is a small hand held device with toggle switches and
dials to control the robots physical movements.

76. Walk through programming
■ In this method, the programmer or the operator physically grasps the
end effector and manually moves it through the motion sequence,
recording the path into the memory.

77. Computer terminal programming
■ The computer terminal programming, uses an English-like language
to establish the logical sequence of a work cycle.
■ Online programming
■ The online programming method requires the availability of a robot.
It gives the programmer the ability to see the motions of the robot
actually executing the program as it is being developed.
■ Offline programming
■ Off-line robot programming is typically accomplished on a remote
computer terminal. After the program has been prepared, it is
entered into the robot memory for use during the work cycle.

78. Robot programming Languages
■ All robots are programmed with some kind of programming
language. These programming languages command the robots to
more to certain locations, to signal outputs, and to read inputs.
■ Three basic categories
■ Specialized robot language
■ Robot libraries for a new general purpose language
■ Robot libraries for an existing computer language

79. Some commonly uses robot
programming languages and their
sources
■ AML-IBM
■ HELP- General Electric
■ VAL & VAL II – Unimation, Adept
■ RAIL – Automatrix
■ MCL – McDonnel Douglas
■ AL – Standford University

80. Robot Accuracy and Repeatability
■ Three measures of precision of the robot’s movement are
– Control resolution
– Accuracy
– Repeatability

81. Control resolution
■ Control resolution is defined as the capability of the robot’s
positioning system to divide the range of the joint into closely spaced
points, called addressable points, to which the joint can be moved by
the controller.

83. Accuracy
■ Accuracy is defined as the robot’s ability to position and orient the
end of its wrist at a defined target point within the work volume.

87. Repeatability
■ Repeatability is the ability of the robot to a position to which it was
previously commanded or taught.