Lecture 1 Introduction to robotics (1).pptx
- 1. Lecture 1 Introduction to robotics 1:41 PM 1
- 2. Learning Objectives The aim of this lecture is to understand the brief introductions to robotics, actuators and sensors, and manipulators: • Introduction to Robotics – History of robotics – Application of robotics • Actuators and sensors • Manipulators 2 1:41 PM
- 3. Reference textbooks 1. P. Corke (2017). Robotics, Vision and Control (Second Edition). 2. B. Siciliano, L. Sciavicco, L. Villani, G. Oriolo (2010). Robotics: Modelling, Planning and Control. 3. John J. Craig (2005). Introduction to Robotics: Mechanics and Control (Third Edition). 4. R. Siegwart, I. R. Nourbakhsh, D. Scaramuzza (2011). Introduction to Autonomous Mobile Robots (Second Edition). 5. B. Sciliano, O. Khatib (2008). Springer Handbook of Robotics. 3 1:41 PM https://moodle.glos.ac.uk/course/view.php?id=48366
- 4. 1.0: Robot Definition The term robot was first introduced by the Czech playwright Karel Capek in his 1921 play Rossum’s Universal Robots (the word robota being the Czech word for worker). The term automaton had been used since ancient Greek times. 4 Two common definitions are: • An industrial robot is a reprogrammable, multifunctional manipulator designed to move parts, tools or special devices through variable programmed motions for the performance of a variety of tasks. • A robot is an artificial physical agent that perceives its environment through sensors and acts upon that environment through actuators. 1:41 PM
- 5. 1.1: Brief History of Automatons • 1,000 BC Yan Shi (China) creates a humanoid automaton (sing and dance) • 400 BC Archytas of Tarentum (Greece) designed a mechanical bird, "The Pigeon“, which was propelled by steam. • 322 BC Homer's Iliad, Aristotle speculated (Politics book 1, part 4) that automatons could bring about human equality by the abolishing slavery. • 1206 Al-Jazari’s humanoid robot. A boat with four automatic musicians. It had a programmable drum machine with pegs that bump into little levers that operate the percussion. The drummer could play different rhythms and drum patterns by moving the pegs. • 1464 Leonardo Da Vinci’s warrior. Humanoid automaton was dressed in medieval armour, capable of some human-like movements. It was able to sit, wave its arms and move its head and jaw. • 1737 Jacques de Vaucanson’s Digesting Duck. Powered by weights, it could flap its wings (each wing has over 400 parts), eat & digest grain, and defecate by excreting matter stored in a hidden compartment. • 1868 Zadoc P. Dederick's Steam Man inspired many walking machines, and (science) fictional stories (patented, google patents). Robot was designed to pull a cart. 5 1:41 PM
- 6. 1.1: Brief History of Robotics • 1921 The term "robot" was first used in a play published by the Czech Karel Čapek. • 1938 World’s Fair, New York: “Electro” and “Sparko” (Westinghouse Electric Corporation). It could walk by voice command, speak about 700 words, smoke cigarettes, blow up balloons, and move his head and arms. • 1940-45 Small radio-controlled robot tanks in World War 2 (Goliath & teletanks) • 1962 First industrial arm robot (Unimate) installed on a General Motor’s assembly line. Unimation becomes profitable in 1975. • 1966 Stanford “Shakey” first general purpose mobile robot with vision system • 1968 General Electric “walking truck” for the US army. Movements are slaved to an operator. 6 1:41 PM
- 7. 1.1: Brief History of Robotics • 1968 Hydraulic Minsky-Bennett arm developed by Marvin Minsky. (Twelve joints) • 1969 Victor Scheinman (Stanford) created the Stanford Arm • 1970 The Stanford Cart which can follow lines and controlled via radio • 1977 Asea produce a microcomputer controlled range of arms. These will go on to become ABB • 1979 SCARA robot • 1979 Stanford Cart rebuilt to include vision which permits 3D mapping • 1981 Takeo Kanade builds the direct drive arm which is the first to have motors installed directly into the arm joints. • 1986 Honda start a research programme which leads to ASIMO • 1988 Lego and MIT collaborate to create LEGO Logo 7 1:41 PM
- 8. 1.1: Brief History of Robotics • 1992 John Adler developed Cyber Knife which takes x-rays (tumour) and delivers a dose of radiation • 1993 Dante (8 legged walking robot) developed at CMU (falls into a crater in the Antarctic) • 2000 ASIMO unveiled by Honda • 2001 Lego Mindstorms released • 2001 Candaarm2 on the ISS (International Space Station) • 2002 Roomba released by iRobot • 2003 Mars rovers Spirit and Opportunity land • 2006 Big dog (and petman) developed by Boston Dynamics (google) • 2007 HyQ was developed by iit (Italian Institute of Technology) 8 1:41 PM
- 9. 1.1: State-of-the-art Robots • iit HyQ-Max (video) • Boston Dynamics Spot (video) • Boston Dynamics Atlas (video) • iit iCub (video) 9 1:41 PM
- 10. 1.2 Current Robotic Application Sectors • Manufacturing • Surgical • Service • Military • Healthcare • Home • Space • Farming • Security/surveillance • Rescue • Extreme Environments 10 1:41 PM
- 11. Activity You are given 15 minutes to search some content related with robots or their applications, then come back to discuss your findings with classmates. 1:41 PM 11
- 12. 2.1 Actuators Three commonly used actuator types: • Electromagnetic – The most common types of actuators • Hydraulic • Pneumatic 12 1:41 PM
- 13. 2.1.1 Electromagnetic Actuators Brushed DC Motor • Current flowing through armature generates a magnetic field and permanent magnets torque the armature – Advantages: provides variable speeds, low-cost – Disadvantages: Brush wear out, low precision 13 1:41 PM
- 14. 2.1.1 Electromagnetic Actuators Brushless DC Motor • Armature is fixed, and permanent magnets rotate – Advantages: Efficiency, Low noise, Cooling, Water-resistant – Disadvantages: low precision, costly 14 1:41 PM
- 15. 2.1.1 Electromagnetic Actuators Stepper Motor • Brushless, synchronous motor that moves in discrete steps – Advantage: Precise, quantized control without feedback – Drawback: Slow and moves in discrete steps, expensive 15 1:41 PM
- 16. 2.1.2 Hydraulic Actuators Cylinders (linear actuators): • Advantages: – Very powerful that offer very large force capability, but expensive – High power-to-weight ratio • Drawbacks: – Their power supplies are bulky and heavy – Oil leakage 16 1:41 PM
- 17. 2.1.2 Hydraulic Actuators Cylinders (linear actuators): • Force, F, calculation extend & retract: – Cylinder bore diameter: 25 mm – Cylinder rod diameter: 16 mm – Max pressure, P= 21 MPa (210 bar) F = P * A Calculate force for extending the rod with max P: A = π R2 = 490.625 mm2 F = 21 x 490.625 = 10,303 N Retract the rod: A = A1 – A2 =π R2 = 289.665 mm2 F = 21 x 289.665 = 6,083 N 17 A P A1 A2 1:41 PM
- 18. • Motors (rotary actuators): 18 2.1.2 Hydraulic Actuators 1:41 PM
- 19. Integrated Smart Actuator 19 Usual hydraulic actuator-valve configuration: 1:41 PM
- 20. 2.1.3 Pneumatic Actuators • Cylinders (linear actuators) • Motors (rotary actuators) 20 1:41 PM
- 21. Question 1 • What types of actuators have you ever used? • Why have you chosen to use it or them? 1:41 PM 21
- 22. 2.2 Sensors • Motivation, why do robots need sensors? • Robotic sensor classification • Various sensors overview 22 1:41 PM
- 23. 2.2.1 Motivation • A robot would be easily controlled if a complete model of the environment was available for the robot, and if its actuators could execute motion commands perfectly relative to this model. • Sensors only measure a physical quantity 23 1:41 PM
- 24. 2.2.2 Robotic sensor classification • Proprioceptive – Internal state of the robot – Measures values e.g. wheels position, joint angle, battery level, etc • Exteroceptive – External state of the system – Observing environment, detecting objects, etc. • Active – Emits energy (e.g. radar) • Passive – Receives energy, e.g. camera 24 1:41 PM
- 25. 2.2.2 Robotic sensor classification 25 Application Sensors PC/EC A/P Tactile sensors (physical contacts, distance estimation etc) Bumpers, contact switches Optical barrier Proximity sensors EC EC EC P A A Wheels and Motors sensors Detecting speeds and position Brush encoders Potentiometers Optical, magnetic, inductive capacitive encoders PC PC PC P P A Heading Sensors Orientation of robot and alignment Compass Gyroscopes Inclinometer EC PC EC P P A/P Ground based beacons (localisation) GPS RF, ultrasonic, reflective beacons EC EC A A Active ranging (reflectivity, time-of-flight, geometric triangulation) Ultrasonic, laser, reflective sensors Optical triangulation (1D) Structured light (2D) EC EC EC A A A Motion and speed sensors (relative to a fix or moving object) Doppler radar Doppler sound EC EC A A Vision-based sensors (visual ranging, segmentation, object detection etc) CCD/CMOS cameras (ranging, tracking, etc packages) EC P 1:41 PM
- 26. 2.2.2 Robotic sensor classification • Real-world Characteristics of sensors – Sensitivity: Ratio of output change to input change. – Error/Accuracy: Difference between the sensor’s output and the true value. • Systematic/Deterministic Error: Caused by factors that can be modelled (in theory), e.g., calibration of a laser sensor. • Random Error: e.g., hue instability of camera, black level noise of camera. – Reproducibility: Reproducibility of sensor results. 26 1:41 PM
- 27. 2.2.3 Various sensors overview • A simple On/Off switch • Tilt sensor (mercury title) • Dual axis inclinometer 27 1:41 PM
- 28. 2.2.3 Various sensors overview • Potentiometer • Bumpers – Mechanical switches 28 1:41 PM
- 29. 2.2.3 Various sensors overview • Light sensors • Photoresistors, light dependent resistors (LDR) • Phototransistors 29 1:41 PM
- 30. 2.2.3 Various sensors overview • Thermal sensor • Thermal resistor • Temperature sensors – Analogue – Digital 30 1:41 PM
- 31. 2.2.3 Various sensors overview • Proximity sensors • Non-contact • Devices that can be used in areas that are near to an object to be sensed • Different types of Proximity Sensors: – Infrared – Ultrasonic – Inductive – Capacitive 31 1:41 PM
- 32. 2.2.3 Various sensors overview Position Sensors (for angle) • Potentiometer • Resolver • Optical Encoders – Relative position – Absolute position Measure position, speed, direction of revolution of the wheel. 32 1:41 PM
- 33. 2.2.3 Various sensors overview Heading sensors: • Heading sensors can be proprioceptive (gyroscope, inclinometer) or exteroceptive (compass). • Used to determine the robots orientation and inclination Compass • The magnetic compass was invented by Chinese (more than 2000 years ago), suspended a piece of natural magnetite from a silk thread and used it to guide a chariot over land. • Absolute measure for orientation based on Earth magnetic field o Mechanical magnetic compass o Direct measure of the magnetic field, Hall-effect Drawbacks: Easily disturbed by magnetic objects or other sources 33 1:41 PM
- 34. 2.2.3 Various sensors overview • Accelerometer • Acceleration is the change in velocity over time, based on Newton’s 2nd law (F = ma) a sensor may be made to sense acceleration by simply measuring the force on a mass. 34 1:41 PM
- 35. 2.2.3 Various sensors overview Gyroscope • Heading sensors for measuring and to keep the orientation to a fixed frame • Two methods: – Mechanical (flywheel) – Electronic 35 Gyroscope was invented by Jean Bernard Léon Foucault, a French physicist, in 1852. 1:41 PM
- 36. Question 2 • What types of sensors have you ever used? • Why have you chosen to use it or them? 1:41 PM 36
- 37. Components used for Manipulators • Components in a joint: – Motors (electric or hydraulic) – Motor Encoders • Angle (joint angle) • Displacement sensor – Gearbox 37 1:41 PM
- 38. 3.1: Robotic Manipulators A wide range of robotic manipulators exist. Typically, all manipulators represent a different price, performance & capability trade-off. 38 1:41 PM
- 39. 3.1: Manipulator Application (before) Benefits in repetitive operation: • Increase volume / capacity • Improve quality and consistency • Untouched by human hand • Reduce wastage • “Up skilling” of work force A Return On Investment (ROI) study would be performed to quantify these factors and justify the investment in a bespoke robotics solution. 39 1:41 PM
- 40. 3.1: Manipulator Application (after) • Pancakes are delicate (use a blown air end effector to grasp) • Require high (variable) volume, fast turn around, minimum waste, • 4 FlexPickers (delta robots) with cameras are used • Stacks ~100 each minute • Increased capacity / reduced costs eliminated the competition 40 1:41 PM
- 41. 3.2 Joints • Different types of joints: 41 Revolute Joint (R) Prismatic Joint (P) 1:41 PM
- 42. Joints • Different types of joints: 42 Cylindrical Joint Spherical Joint Universal Joint 1:41 PM
- 43. 3.3 Manipulators Configuration 43 n Joints n Links End effector 1:41 PM
- 44. 3.4 Manipulators Different types of manipulator: • Cartesian PPP • Cylindrical RPP 44 1:41 PM
- 45. 3.4 Manipulators Different types of manipulator: • Spherical RRP • Articulated RRR 45 1:41 PM
- 46. 3.4 Manipulators Different types of manipulator: • SCARA, RRP 46 1:41 PM
- 47. Manipulator • Links: – n moving link(s) – 1 fixed link • Joints – Revolute (1 DOF) – Prismatic (1 DOF) 47 Base Revolute Joints End effector Link i 1:41 PM
- 48. Position Parameters 48 Position parameters describe the full configuration of the system Generalised coordinates: A set of independent configuration parameters Degree of Freedom: Number of generalised coordinates 1:41 PM
- 49. Position Parameters 49 • We need 6 DOF to have access to 3D space 3 DOF : Position 3 DOF : Orientation Revolute and prismatic joints have 1 DOF How about Cylindrical joint? How about Spherical joint? Revolute Joint Prismatic Joint 1:41 PM
- 50. Generalised coordinates: • A set of independent configuration parameters • Each rigid body needs 6 parameters to be described – 3 positions – 3 orientations • For n rigid body, we need 6n parameters • Constrains must be applied: – Each joint has 1DOF, so 5 constrains will be introduced. n moving links 6n parameters n joints 5n constrains How many DOF? 6n – 5n = n DOF This is for manipulator with fixed base 50 6 parameters 1:41 PM
- 51. End effector configuration 51 End effector is the last rigid-body and it has all the freedom from previous links. A set of parameters describing position and orientation of the end effector: (x1, , x2 , x3 , ...., xm) with respect to {0} On+1 : is operational coordinates (task coordinates) A set of x1, , x2 , x3 , ...., xmo of mo independent configuration parameters mo is number of DOF of the end effector, max 6 DOF {0} On+1 1:41 PM
- 52. End effector, Joint coordinate: 52 Joint space (configuration space) is the space that a manipulator is represented as a point. (x,y) is a vector for position of end effector α defines orientation (angle) of end effector Defines: operational coordinates Operational space θ θ1 θ2 θ3 θ1 θ2 θ3 (x,y) α End effector x y α Robot in configuration space End effector in operational space 1:41 PM
- 53. Redundancy 53 A manipulator is redundant if n m n number of DOF of the manipulator m number of DOF of the end effector (operational space) Degree of redundancy: n - m > 1:41 PM
- 54. General Manipulator Videos • Where it all began (in the 70s) http://www.youtube.com/watch?v=2xNgQhLAPyI • Precise motion control http://www.youtube.com/watch?v=SOESSCXGhFo • 10 application areas for robotics http://www.youtube.com/watch?v=fH4VwTgfyrQ • Programming robots http://www.youtube.com/watch?v=acJ3WDnoDCM • Couple of FlexPicker videos http://www.youtube.com/watch?v=8G59zTXVHHU http://www.youtube.com/watch?v=KC70eDs1D2Y • Robotics for Extreme Environments https://www.bloomberg.com/news/features/2017-02-16/one-job-the-robots-can- have-cleaning-nuclear-waste https://www.youtube.com/watch?v=OLvAQFz5wh8&t=171s 54 1:41 PM
- 55. Summary The aim of this lecture is to understand the brief introductions to robotics, actuators and sensors, and manipulators: • Introduction to Robotics – History of robotics – Application of robotics • Actuators and sensors • Manipulators 55 1:41 PM
Editor's Notes
- #49: Generalised coordinates: has minimum number of parameters involved ,,with much less parameters
- #51: How many constrains the placement of each joint will be introduce?
- #52: With 3 orientation parameters and one position vector, we can describe an end effector Later we will use rotation matrix to transfer the frames We call m0 because it’s independent, before was m >> if we have an end effector in a plane (x,y), how many parameter do we need? 2 for position and one for orientation In space, maximum DOF we can have is 6
- #53: Three revolute joints and this robot moving in plane! This vector shows configuration of the manipulator >> This joint space is very important for motion planning So (x,y, α ) represents fully position and orientation of end effector SO>>> robot is reduced to the point θ in configuration space and its end effector is reduced to a point (x,y,alpha) in operational space
- #54: N=4 M0=3