Robotics

Lecturer: Dr. Saeed Shiry GhidaryEmail: autrobotics@yahoo.Com

Outline of Course

We will study fundamental algorithms for robotics with:Introduction to industrial robots andParticular emphasis on research in and applications of autonomous mobile robots

Method

The course consists of Lectures with discussions, Homework assignments, Reading assignments,One of these assignments might involve a (group) project.

Course Requirements

Each student will:Explore and present a topic in depth,Carry out a small-scale research project, such as a software simulation or a mathematical model.Pass exams and tests.

Grading Scheme

The grade will break down as follows: Classroom presence and participation: 5% Paper presentation 25%Assignments: 10% Research project: 35% Exams 25%An extra bonus for creative students

Text Book

The following are suggested readings:Introduction to robotics mechanics and control, second edition. By JOHN J. CRAIG, Addison Wesley, 1989.Modeling and control of robotmanuplators. By Lorenzo Sciavicco & Bruno Siciliano. McGraw Hill, 1996.

Content of the CourseLectures:

IntroductionKinematicsInverse kinematicsDynamicsTrajectory generationRobot programming languages

Content of the CoursePresentations:

Mobile robot kinematicsPerceptionMobile robot localizationObstacle avoidance Planning and navigationSensor fusion Humanoid and legged robots

What Is Robotics?

Robotics is the intelligent connection of perception to action.Or simply the science of dealing with robots.

What Is Robot?

ISO, the international standard organization, have formulated the following definition with respect to robots and manipulators

Manipulating industrial robot is an automatically controlled, re-programmable, multi-purpose, manipulative machine with several degrees of freedom, which may be either fixed in place or mobile for use in industrial automation applications

What Is a Robot?By general agreement a robot is:

A programmable machine that imitates the actions or appearance of an intelligent creature–usually a human.

What Is a Robot?To qualify as a robot, a machine must have the ability for:

Sensing and perception: get information from its surroundings.Carry out different tasks: locomotion or manipulation, do something physical–such as move or manipulate objects.Re-programmable: can do different things.Function autonomously and/or interact with human beings.

Robotics As an Interdisciplinary Science

Arts,Politics,Economics,Mathematics,Physics,Control-theory,Cybernetics,Computer science,

Artificial Intelligence,Biology,Psychology,Sociology,Social-Psychology,Philosophy,Artificial life,Sports

Historical Overview

Leonardo da Vinci created many robot-like sketches and designs in the 1500’s.In 1920, the word robot was first used in a play byKarel Capek entitled “Rossum’s universal robots”performed in Paris. In this play small artificial creatures strictly obeyed their master’s orders. In Czech and Russian they were called Robotnic, from “Robota” meaning hard work and drudgery.

Historical Overview

In 1950, Isaac Asimovintroduced the idea of good robots (androids) in his stories and popularized the word “robotics”.The first robots were thought to be evil human-looking machines.

First Industrial RobotsRobot manipulators were first realized in 1945with the onset of nuclear age.In 1961 George C. Devol obtains the first U.S. Robot patent, no. 2,998,237.Joe Engelberger formed Unimation and was the first to market robots. In fact Joseph Englebergerand George Devol were the fathers of industrial robots.1978 the first PUMA (programmable universal machine for assembly) robot is developed byUnimation for general motors.

ImpactRobotics offers benefits such as high reliability, accuracy, and speed of operation.

Advantages of industrial robots.Flexibility in production.High productivity.Improve quality of products.Improve quality of human life (safety of personnel) by performing the undesirable jobs.

Asimov’s Laws of RoboticsAsimov invented the three laws of robotics:

Robotics offers benefits such as high reliability, accuracy, and speed of operation.A robot may not injure a human being or, through inaction, allow a human being to come to harm. A robot must obey the orders given it by human beings except where such orders conflict with the first law.A robot must protect its own existence as long as such protection does not conflict with the first or second law.

Why Use Robots?

Application in 4D environmentsDangerousDirtyDullDifficult

Application 4A tasksAutomationAugmentationAssistanceAutonomous

Applications of Robotics

Service robotsAutomatic cleaning of (large) areasClient supportAgriculturalHazard environmentsConstruction and

demolishing

SpaceMilitaryForestsMaterial HandlingSafetyCivil TransportationElderly and HandicappedEntertainment

Elements of a Robot SystemThe mechanical structure comprises the links of a manipulator or the body and wheels of a mobile robot.The actuators cause the robot to move.Sensors measure robot motion and sense a robot’s environment. A computer controller

reads sensors, sends control signals to actuators, interacts with command.

Types of Robots

• Mobile Manipulators

Robot Manipulators

Trends in Robotics

Reactive Paradigm (mid-80’s)• no models• relies heavily on good sensing

Probabilistic Robotics (since mid-90’s)• integration of models and sensing• inaccurate models, inaccurate sensors

Hybrids (since 90’s)• model-based at higher levels• reactive at lower levels

Classical Robotics (mid-70’s)• exact models• no sensing necessary

Industrial Robot

Manipulator is a machine, the mechanism of which usually consists of a series of segments jointed or sliding relative to one another, for the purpose of grasping and/or moving objects (pieces or tools) usually in several degrees of freedom .

Industrial Robot

Robot Parts

BaseShoulderElbowWristTool-plateEnd-effecter (not

shown)

How are they used

Industrial robots70% welding and painting20% pick and place10% others

Research focus onManipulator controlEnd-effectors design

Compliance deviceRobot hand

Visual and force feedbackFlexible automation

Installed Industrial Robots

Japan take the lead, why? Shortage of labor, high labor cost

Common Robot DesignsCartesian.

Robots which have three linear (P, as opposed to rotational R joints) axes of movement (X, Y, Z). Used for pick and place tasks and to move heavy loads. They can trace out rectangular volumes in 3D space.

Cartesian: PPP

Common robot designs

CylindricalThe positions of these robots are controlled by a radius, a height and an angle (that is, two P joints and one R joint). These robots are commonly used in assembly tasks and can trace out concentric cylinders in 3D space.

Cylindrical: RPP

Common robot designs

SphericalSpherical robots have two rotational R axes and one transnational P (radius) axis. The robots’ end-effectors can trace out concentric spheres in 3D space.

Spherical: RRP

Common Robot DesignsArticulated.

The positions of articulated robots are controlled by three angles, via R joints. These robots resemble the human arm (anthropomorphic). They are the most versatile robots,but also the most difficult to program.

Articulated: RRR

Common Robot DesignsSCARA (selective compliance articulated robot arm).

SCARA robots are a blend of the articulated and cylindrical robots. The robot arm unit can move up and down, and at an angle around the axis of the cylinder, but the arm itself is jointed like a revolute coordinate robot to allow precise and rapid positioning. It consists of three R and one P joints.

SCARA: RRP

Master/slave Manipulators

Parallel Robots

Parallel robots have many “legs” with active and passive joints and links, supporting the load in parallel.Can handle higher loads with greater accuracy, higher speeds, and lighter robot weight;

Parallel Robots

Workspace of parallel robots is severely restricted compared to equivalent serial robots.

Are used in expensive flight simulators, as machining tools, and can be used for high-accuracy, high-repeatability, high-precision robotic surgery

Technical Terms in Robotics

Speed.The amount of distance per unit time at which the

robot can move. M/s.Load bearing capacity (pay load).

The maximum weight-carrying capacity of the robot.Accuracy.

The ability of a robot to position itself to the desired location with the minimal error (example: 0.001inch).

Technical Terms in RoboticsRepeatability.

The ability of a robot to repeatedly position itself when asked to perform a task multiple times.Work envelope.

The maximum reach, or volume within which a robot can operate.

Robot Power Sources/actuatorsElectric motors (DC servomotors).

Uses electric motors to position the robot. These robots can be accurate, but are limited in their load-bearing capacity.Hydraulic cylinders (fluid pressure).

It can carry very heavy objects, but may not be very accurate.Pneumatic cylinders (air pressure).

It is similar to one with a hydraulic drive system; It can carry less weight, but is more compliant (less rigid to disturbing forces).

End Effectors

Grippers.Grippers are the most common end-effectors. They

provide the equivalent of a thumb and an opposing finger, allowing the robot to grasp small parts and manipulate them.Machine tools.

Robot end-effectors can also be machine tools such as drills, grinding wheels, cutting wheels and sanders.

End EffectorsMeasuring Instruments

Allow the robot to precisely measure parts by running the arm lightly over the part using a measuring probe or gauge.Laser & Water Jet Cutters

Use high-intensity laser beams or high-pressure abrasive water jets to cut sheet metal or fiberglass parts to shape.Welding Torches

Allow robots to weld parts together. These end-effectors are widely used in the automotive industry.

Smart Robot Sensors

Vision.Used commonly in electronics assembly to place

expensive circuit chips accurately through holes in the circuit boards.Voice.

Useful in training the robots.Tactile.

Sensors that provide the robot with the ability to touch and feel.

Smart Robot Sensors

Force/PressureHelp the robot auto-correct for misalignments, or to

sense the distribution of loads on irregular geometry. Can be used in conjunction with hapticinterfaces to allow the human operator to feel what the robot is exerting on the environment during tele-operation tasks.Proximity

Allow the robots to detect the presence of objects that are very close to the arm before the arm actually contacts the objects.

Smart Robot SensorsOther sensors

Limit SwitchesEncoder (measures angle)Potentiometer (measures angle or length)LVDT (linear variable displacement transducer, measures length)Strain gauge (measures deflection)Ultrasonic sensor (measures distance)Infrared sensor (measures distance)Light sensor (detects presence)

Autonomous Mobile RobotsMobile robots have wheels, legs, or other means to navigate around the workspace under control.

An autonomous robot is a machine that operates in a partially unknown and unpredictable environment.

Autonomous Mobile RobotsAutonomous robots cannot always be programmed to execute predefined actions.These robots require good sensors to “see”the workspace, avoid collisions,and get the job done.

Mobile RobotFunctional characteristics:

Mobility:Total mobility relative to the environmentA certain level of autonomy:

Perception ability:Sensing and reacting in the environment

The Three Key Questions in Mobile Robotics

Where am I ? Robot localization

Where am I going ?Goal determination

How do I get there ?Motion planning

The Three Key Questions in Mobile Robotics

To answer these questions the robot has to:

Have a model of the environment (given or autonomously built)

Perceive and analyze the environmentFind its position within the environmentPlan and execute the movement

Architecture of Robotic Systems

Mechanical StructureKinematics modelDynamics model

Actuators: Electrical, Hydraulic, Pneumatic, Artificial Muscle Computation and controllersSensorsCommunicationsUser interfacePower conversion unit

Environmentalsensors

Motion planner Controller

MechanicalStructure

Configuration sensor

Humanoid is an autonomous robot with human-like form and abilities.The autonomous humanoid combines advanced manipulation skills with human-like cognitive processes so as to be able to operate in unchanged man-made environments.There is much current research work aimed at creating human-like robots that can walk, talk, think, see, touch, etc.

Humanoid

RoboCupAn international research and education which encourages investigation in the fields of robotics and artificial intelligence using game of soccer.

The dream of the RoboCup:“By the year 2050, develop a team of fully autonomous humanoid robots that can win against the human world soccer champion team.”

It focuses on developing cooperation among autonomous agents in a dynamic multi-agent environment.

Summary

Robotics:interdisciplinary researchMechanical designComputer science and engineeringElectrical engineering

Cognitive psychology, perception and neuroscience

Research open problemsManipulation, LocomotionControl, NavigationHuman-Robot InteractionLearning & Adaptation (AI)

Next Course:

Kinematics