Lesson 5

• Historical Overview of Robot Development

  • 1801 Joseph Jacquerd invents a textile machine that is operated by punch cards
  • 1892 In the US Seward Babbit designed motorized crane with gripper to remove ingots from a furnace
  • 1921 First reference to the word robot appears in a play opening in London entitled "Rossums Universal Robots". The play was written by Czechoslovakian Karel Capek introduces the word robot from the Czeck robota meaning serf or subservient labor
  • 1939 Isaac Asimovs science fiction writing introduces robots designed for humanity and work safely. He formulates the "Three Laws of Robotics"
  • 1946 George David patents a general purpose playback device for controlling machines
  • 1948 Norbert Wiener, a professor of Massachusetts Institute of Technology(MIT) publishes Cybernetics, a book that describes the concept of communications and control in electronic, mechanical and biological systems
  • 1951 A tele-operator equipped articulated arm is designed by Raymond Goertz for the Atomic Energy Commisison
  • 1954 The first programmable robot is designed by George Devol who coined the term universal automation. Devol is joined by Joseph Engelberger in 1956 and shorten the name to Unimation and form the first successful robot manufacturing company
• Robot


  A reprogrammable, multifunctional manipulator designed to move parts, materials, tools or special devices through variable programmed motions for the performance of a variety of different tasks
• Three Laws of Robotics

  1. A Robot may not injure a human being,or through inaction,allow a human being to come to harm
  2. A robot must obey orders given it by human beings except where such orders would conflict with the first law
  3. A robot must protect its own existence as long as such protection does not conflict with the first and second law
• Components of a robot

  • Communicator
  • Control Computer/Controller (Brain)
  • End Effectors (Hands)
  • Manipulator (Arm)
  • Power Supply
  • Sensor (Eye)
  • Actuator
• Pneumatic Drive


  • Reserved for smaller robots which are limited to simple, fast cycle and pick and place operation
  • Have two to four degrees of freedom
  • Quick response
  • Lower initial and operating cost than a hydraulic system
  • Accurate positioning and velocity control are impossible (requires mechanical stops)
  • Weak force capability
• Hydraulic Drive


  • Used in larger robots
  • Generally heavy and require large floor space and heavy floor loadings
  • Great force capability
  • Great holding strength when stopped (will not sag)
  • Intrinsic safe in flammable environments such as paintings
  • Accurate servo type positioning and velocity control can be achieved
  • Messy-tends to leak oil even in the periods when the robot is not in motion
  • High initial and operating costs
• Electric Drive


  • Good for robots in light duty, precision applications but does not offer the speed and strength of a hydraulic drive
  • Used in electronic assembly where precision is required
  • Clean-no oil leaks
  • Lower initial and operating cost compared as compared to hydraulic and pneumatic drive
  • Less force capability as compared to hydraulic system
• Degrees of Freedom


  Refers to different axes of motion of robotic arm

  The movement about one axis is hardware independent of movement about any other axis
• Degrees of Freedom


  • Waist motion or Arm sweep
  • Shoulder or Vertical Motion
  • Elbow extension
  • Wrist Motion

  Pitch – up and down

  Yaw – side to side

  Roll - \rotation of the wrist about the axis of the forearm
• Pitch Axis


  Describes the wrists rotational movement up and down
• Yaw Axis


  Describes the wrist angular movement from the left side to the right side
• Roll Axis


  Describes the rotation around the end of the wrist
• Robot's Axes Control


  • Non-Servo Control
  • Servo Control
• Non-Servo Control


  Movement of the robots axes is stopped by a hard mechanical stop placed in the travel path

  Non-self correcting and not-self regulating
• Servo Control


  The servo control allows the mechanics of the robot to communicate with the electronics of the controller

  Equipped with the feedback sensors so that the controllers knows the exact position of the end effector at all times

  Self correcting and self regulating
• Classification of Robots According to Control

  • Fixed/Variable Sequence

  Playback Robot

  Numerically Controlled Robot

  Intelligent (Sensory) Robot
• Fixed/Variable Sequence


  Pick and place robots

  Point to point movement
• Playback Robot


  Robots that memorizes and records the path and sequence of motions and can repeat them continuously without the guidance from the operator
• Numerically Controlled Robot


  Programmed and operated much like a numerically controlled machine

  Servo-controlled by digital data
• Intelligent (Sensory) Robot


  Equipped with a variety of sensors with visual and tactile capabilities

  Controlled by powerful computers
• Robots Manipulator Arm Geometry

  • Cartesian Coordinates

  Cylindrical Coordinates

  Polar Coordinates

  Articulate Coordinates
• Work Envelope


  Refers to the space with which the robot can use its wrist
• Cartesian Coordinates


  Uses three perpendicular slides to construct the X,Y and the Z axes

  Rectangular work space or work envelope
• Cylindrical Coordinates


  Cylindrical configurations uses a vertical column and a slide that moves up and down the column

  The work space is approximately a cylinder
• Polar Coordinates


  Uses a telescoping arm that can be lowered or raised about a horizontal pivot which is mounted on a rotating base
• Articulate Coordinates


  This configuration consists of two straight components mounted on a vertical pedestal

  A rotary joint connects one of the straight components to the pedestal while another joins the straight components

  A wrist is attached to the end of the straight component and provides several additional joints
• Classification of Robots According to Movement

  • Rectilinear / Cartesian

  Cylindrical Robot

  Spherical Robot

  Fully Articulated Robot
• Rectilinear / Cartesian


  Works with Cartesian manipulator arm geometry

  Movement is three directions only up/down, left/right, front/back
• Cylindrical Robot


  Robot whose work envelope is cylindrical

  Robot's arm swings around its base in circular or polar motion. (up and down, front end)
• Spherical Robot


  Robot whose work envelope is spherical in shape and obviously is has spherical manipulator arm geometry

  With polar articulation for waist and shoulder and rectilinear motion for reach

  The base moves in circular motion (up to 210 degrees) while its main arm moves up and down and in and out (extension and retraction)
• Fully Articulated Robot

  Robot with polar articulation for all degrees of movement

  One example is the SCARA (Selective Compliance Assembly Robotic Arm) which has six axes therefore increases its degrees of freedom

  Used in welding, painting, laser cutting and water jet cutting
• Classification of Robots According To Program Used

  • Positive Stop

  Point to Point

  Continuous Path
• Positive Stop


  Produces only 2 position motion

  Limited sequence or Bang – bang motion
• Point to Point


  Ability to move a robot axis to any position within its range
• Continuous Path

  Like point to point

  Destination points are very closed together
• Selection of Robots


  • Work Volume

  Speed and acceleration

  Repeatability

  Resolution

  Accuracy

  Economics

  Safety
• Modern Uses of Robots

  • Exploration

  Industry

  Medicine

  Military and Police

  Entertainment
• SCARA Robot


  Selective Compliant Articulated Robot Arm Assembly

  1. axis robot with rotating elements that move in a single plane

  Similar to a shoulder-elbow-wrist combination movement with the addition of an up-down component
• SCARA Robot


  Selective Compliant Assembly Robot Arm

  Applications: Assembly, Packaging, Sorting, Screw driving