Week 1: Robotics PDF

EL WEEK 1: ROBOTICS PT PROF. (DR.) DILIP KUMAR PRATIHAR N MECHANICAL ENGINEERING DEPARTMENT, IIT KHARAGPUR 1  EL Topic 1: Introduction to Robots and Robotics...

EL WEEK 1: ROBOTICS PT PROF. (DR.) DILIP KUMAR PRATIHAR N MECHANICAL ENGINEERING DEPARTMENT, IIT KHARAGPUR 1  EL Topic 1: Introduction to Robots and Robotics PT PROF. (DR.) DILIP KUMAR PRATIHAR N MECHANICAL ENGINEERING DEPARTMENT, IIT KHARAGPUR 2  Introduction to Robots and Robotics A Few Questions  What is a robot?  What is robotics? EL  Why do we study robotics?  How can we teach a robot to perform a particular task? PT  What are possible applications of robots?  Can a human being be replaced by a robot?, N and so on. 3 Definitions  The term: robot has come from the Czech word: robota, which means forced or slave laborer  In 1921, Karel Capek, a Czech playwright, used the term: EL robot first in his drama named Rossum’s Universal Robots (R.U.R) PT N  According to Karel Capek, a robot is a machine look-wise similar to a human being 4 Robot has been defined in various ways: 1) According to Oxford English Dictionary A machine capable of carrying out a complex series of actions automatically, especially one programmable by a computer EL 2) According to International Organization for PT Standardization (ISO): An automatically controlled, reprogrammable, multipurpose manipulator N programmable in three or more axes, which can be either fixed in place or mobile for use in industrial automation applications 5 3) According to Robot Institute of America (RIA) It is a reprogrammable multi-functional manipulator designed to move materials, parts, tools or specialized devices through variable programmed motions for the performance of a variety of tasks EL PT Note: A CNC machine is not a robot N 6 Robotics  It is a science, which deals with the issues related to design, manufacturing, usages of robots  In 1942, the term: robotics was introduced by Isaac EL Asimov in his story named Runaround PT  In robotics, we use the fundamentals of Physics, N Mathematics, Mechanical Engg., Electronics Engg., Electrical Engg., Computer Sciences, and others 7 3 Hs in Robotics 3 Hs of human beings are copied into Robotics, such as  Hand EL  Head PT  Heart N 8 Motivation To cope with increasing demands of a dynamic and competitive market, modern manufacturing methods should satisfy the following requirements:  Reduced production cost  Increased productivity EL  Improved product quality PT Notes: N (1) Automation can help to fulfil the above requirements (2) Automation: Either Hard or flexible automation (3) Robotics is an example of flexible automation 9  A Brief History of Robotics Year Events and Development 1954 First patent on manipulator by George Devol, the father of robot EL 1956 Joseph Engelberger started the first robotics PT company: Unimation N 1962 General Motors used the manipulator: Unimate in die-casting application 10 Year Events and Development 1967 General Electric Corporation made a 4-legged vehicle 1969  SAM was built by the NASA, USA  Shakey, an intelligent mobile robot, was EL built by Stanford Research Institute (SRI) 1970  Victor Scheinman demonstrated a PT manipulator known as Stanford Arm N  Lunokhod I was built and sent to the moon by USSR  ODEX 1 was built by Odetics 11 Year Events and Development 1973 Richard Hohn of Cincinnati Milacron Corporation manufactured T3 (The Tomorrow Tool) robot EL 1975 Raibart at CMU, USA, built a one-legged hopping machine, the first dynamically PT stable machine N 1978 Unimation developed PUMA (Programmable Universal Machine for Assembly) 12 Year Events and Development 1983 Odetics introduced a unique experimental six-legged device 1986 ASV (Adaptive Suspension Vehicle) was EL developed at Ohio State University, USA PT 1997 Pathfinder and Sojourner was sent to the N Mars by the NASA, USA 13 Year Events and Development 2000 Asimo humanoid robot was developed by Honda 2004 The surface of the Mars was explored by Spirit EL and Opportunity PT 2012 Curiosity was sent to the Mars by the NASA, USA 2015 N Sophia (humanoid) was built by Hanson Robotics, Hong Kong 14 A Robotic System Various Components 1.Base 2.Links and Joints 3.End-effector / gripper EL 4.Wrist 5.Drive / Actuator PT 6.Controller 7. Sensors N 15  Interdisciplinary Areas in Robotics Mechanical Engineering  Kinematics: Motion of robot arm without considering the forces and /or moments EL  Dynamics: Study of the forces and/or moments PT  Sensing: Collecting information of the environment N 16  Interdisciplinary Areas in Robotics (Cont.) Computer Science  Motion Planning: Planning the course of action  Artificial Intelligence: To design and develop suitable brain for the robots EL Electrical and Electronics Engg. PT  Control schemes and hardware implementations N General Sciences  Physics  Mathematics 17 Connectivity / Degrees of Freedom of a Joint It indicates the number of rigid (bodies) that can be connected to a fixed rigid body through the said joint EL Joints with One dof Revolute Joint (R) PT N 18  Joints with One dof Prismatic Joint (P) EL PT N 19  Joints with two dof Cylindrical Joint (C) EL PT N 20  Joints with two dof Hooke Joint or Universal Joint (U) EL PT N 21  EL PT Joints with three dof N Ball and Socket Joint / Spherical Joint (𝑺𝑺𝑺) 22 Representation of the Joints Revolute joint (R) EL Prismatic joint (P) PT Cylindrical joint (C) N 23 Representation of the Joints Spherical joint (𝑺𝑺𝑺) EL Hooke joint (U) PT Twisting joint (T) N Kinematic Diagram 24 Degrees of Freedom of a System It is defined as the minimum number of independent parameters / variables / coordinates needed to describe a system completely Notes EL  A point in 2-D: 2 dof; in 3-D space: 3 dof  A rigid body in 3-D: 6 dof PT  Spatial Manipulator: 6 dof  Planar Manipulator: 3 dof N 25 Redundant Manipulator Either a Spatial Manipulator with more than 6 dof or a Planar Manipulator with more than 3 dof EL Under-actuated Manipulator PT Either a Spatial Manipulator with less than 6 dof or a Planar Manipulator with less than 3 dof N 26 Mobility/dof of Spatial Manipulator Let us consider a manipulator with n rigid moving links and m joints 𝑪𝑪𝒊𝒊 : Connectivity of i-th joint; i = 1, 2, 3,………, m No. of constraints put by i-th joint = (𝟔𝟔 − 𝑪𝑪𝒊𝒊 ) EL PT Total no. of constraints = ∑𝒎𝒎 𝒊𝒊=𝟏𝟏(𝟔𝟔 − 𝑪𝑪𝒊𝒊 ) N Mobility of the manipulator 𝐌𝐌 = 𝟔𝟔𝟔𝟔 − ∑𝒊𝒊=𝟏𝟏 𝒎𝒎 (𝟔𝟔 − 𝑪𝑪𝒊𝒊 ) It is known as Grubler’s criterion. 27 Mobility/dof of Planar Manipulator Let us consider a manipulator with n rigid moving links and m joints 𝑪𝑪𝒊𝒊 : Connectivity of i-th joint; i = 1, 2, 3,………, m No. of constraints put by i-th joint = (𝟑𝟑 − 𝑪𝑪𝒊𝒊 ) EL PT Total no. of constraints = ∑𝒎𝒎 𝒊𝒊=𝟏𝟏(𝟑𝟑 − 𝑪𝑪𝒊𝒊 ) N Mobility of the manipulator 𝐌𝐌 = 𝟑𝟑𝒏𝒏 − ∑𝒊𝒊=𝟏𝟏 𝒎𝒎 (𝟑𝟑 − 𝑪𝑪𝒊𝒊 ) It is known as Grubler’s criterion. 28  Numerical Example Serial planar manipulator 𝒏𝒏 = 𝟒𝟒, 𝒎𝒎 = 𝟒𝟒 𝑪𝑪𝟏𝟏 = 𝑪𝑪𝟐𝟐 = 𝑪𝑪𝟑𝟑 = 𝑪𝑪𝟒𝟒 = 𝟏𝟏 EL Mobility/dof: PT 𝒎𝒎 𝑴𝑴 = 𝟑𝟑𝟑𝟑 − 𝟑𝟑 − 𝑪𝑪𝒊𝒊 = 𝟑𝟑 × 𝟒𝟒 − 𝟖𝟖 = 𝟒𝟒 N 𝒊𝒊=𝟏𝟏 29 Parallel planar manipulator 𝒏𝒏 = 𝟕𝟕, 𝒎𝒎 = 𝟗𝟗 𝑪𝑪𝒊𝒊 = 𝟏𝟏, 𝒘𝒘𝒘𝒘𝒘𝒘𝒘𝒘𝒘𝒘 𝒊𝒊 = 𝟏𝟏, … , 𝟗𝟗 EL Mobility/dof: 𝒎𝒎 PT 𝑴𝑴 = 𝟑𝟑𝟑𝟑 − 𝟑𝟑 − 𝑪𝑪𝒊𝒊 = 𝟑𝟑 × 𝟕𝟕 − 𝟏𝟏𝟏𝟏 = 𝟑𝟑 N 𝒊𝒊=𝟏𝟏 30 Parallel spatial manipulator 𝒏𝒏 = 𝟏𝟏𝟏𝟏, 𝒎𝒎 = 𝟏𝟏𝟏𝟏 EL Mobility/dof: 𝒎𝒎 PT 𝑴𝑴 = 𝟔𝟔𝟔𝟔 − 𝟔𝟔 − 𝑪𝑪𝒊𝒊 = 𝟔𝟔 × 𝟏𝟏𝟏𝟏 − 𝟕𝟕𝟕𝟕 = 𝟔𝟔 𝒊𝒊=𝟏𝟏 N 31 Classification of Robots  Based on the Type of Tasks Performed 1. Point-to-Point Robots Examples: EL Unimate 2000 PT T3 N 32 2. Continuous Path Robots Examples: PUMA CRS EL PT N 33  Based on the Type of Controllers 1. Non-Servo-Controlled Robots  Open-loop control system Examples: Seiko PN-100 Less accurate and less expensive EL 2. Servo-Controlled Robots PT  Closed-loop control system Examples: Unimate 2000, PUMA, T3 N More accurate and more expensive 34  Based on Configuration (coordinate system) of the Robot 1. Cartesian Coordinate Robots  Linear movement along three different axes  Have either sliding or prismatic EL joints, that is, SSS or PPP  Rigid and accurate PT  Suitable for pick and place type of operations N  Examples: IBM’s RS-1, Sigma robot 35 2. Cylindrical Coordinate Robots  Two linear and one rotary movements  Represented as TPP, TSS  Used to handle parts/ objects in manufacturing EL  Cannot reach the objects lying on the floor PT  Poor dynamic performance  Examples: Versatran 600 N 36 3. Spherical Coordinate or Polar Coordinate Robots  One linear and two rotary movement  Represented as TRP, TRS  Suitable for handling EL parts/objects in manufacturing  Can pick up objects lying on the PT floor  Poor dynamic performance N  Examples: Unimate 2000B 37 4. Revolute Coordinate or Articulated Coordinate Robots  Rotary movement about three independent axes  Represented as TRR  Suitable for handling EL parts/components in manufacturing system PT  Rigidity and accuracy may not be good enough  Examples: T3, PUMA N 38  Based on Mobility Levels 1. Robots with fixed base (also known as manipulators) Manipulators EL Serial Parallel PT PUMA, CRS Stewart platform N 39  Based on Mobility Levels (contd.) 2. Mobile robots Mobile robots EL Wheeled robots Tracked robots Multi-legged robots PT N 40  Based on Mobility Levels (contd.) 2. Mobile robots EL PT Wheeled Robot N Six-legged Robot 41 Workspace of Manipulators It is the volume of space that the end-effector of a manipulator can reach Workspace EL PT N Dextrous Reachable 42 Dextrous Workspace It is the volume of space, which the robot’s end-effector can reach with various orientations Reachable Workspace It is the volume of space that the end-effector can reach with one EL orientation PT Note N Dextrous workspace is a subset of the reachable workspace 43 Workspace of Cartesian Coordinate Robot EL PT N 44 Workspace of Cylindrical Coordinate Robot EL PT N 45 Workspace of Spherical Coordinate Robot EL PT N 46 Workspace of Revolute Coordinate Robot EL PT N 47