INDUSTRIAL ROBOTICS AND EXPERT SYSTEMS

robot: (noun)

What is a robot?

Jacques de Vaucanson(1709-1782)Master toy maker who won the heart of Europe.Flair for inventing the mechanical revealed itself early in life. He was impressed by the uniform motion of the pendulum of the clock in his parents hall.Soon he was making his own clock movements.

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The Origins of Robots

Mechanical horse

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Pre-History of Real-World Robots:The earliest remote control vehicles were built by Nikola Tesla in the 1890's.

Tesla is best known as the inventor of AC power, induction motors, Tesla coils, and other electrical devices.

Robots of the media

History of Robotics?RURMetropolis(1927) Forbidden planet(1956) 2001 A Space Odyssey(1968) Logans Run(1976) Aliens(1986) Popular culture influenced by these ideas

The U.S. military contracted the "walking truck" to be built by the General Electric Company for the U.S. Army in 1969.

Walking robots

Unmanned Ground VehiclesThree categories:MobileHumanoid/animalMotes

Famous examplesDARPA Grand ChallengeNASA MERRoombaHonda P3, Sony AsimoSony Aibo

Unmanned Aerial VehiclesThree categories:Fixed wingVTOLMicro aerial vehicle (MAV), which can be either fixed wing or VTOLFamous examplesGlobal HawkPredatorUCAV

Autonomous Underwater VehiclesCategoriesRemotely operated vehicles (ROVs), which are tetheredAutonomous underwater vehicles, which are free swimming

ExamplesPersephoneJason (Titanic)Hugin

Discussion of Ethics and Philosophy in Robotics

Can robots become conscious?Is there a problem with using robots in military

applications?How can we ensure that robots do not harm

people?Isaac Asimovs Three Laws of Robotics

Isaac Asimov and Joe EnglebergerTwo fathers of roboticsEngleberger built first robotic arms

Asimovs Laws of Robotics

First law (Human safety):A robot may not injure a human being, or, through inaction, allowa human being to come to harm.

Second law (Robots are slaves):A robot must obey orders given it by human beings, except wheresuch orders would conflict with the First Law.

Third law (Robot survival):A robot must protect its own existence as long as such protectiondoes not conflict with the First or Second Law.

These laws are simple and straightforward, and they embrace the essential guiding principles of a good many of the worlds ethical systems.

But: They are extremely difficult to implement

The Advent of Industrial Robots - Robot ArmsThere is a lot of motivation to use robots to perform task which would otherwise be performed by humans:SafetyEfficiencyReliabilityWorker RedeploymentCheaper

Industrial Robot DefinedA general-purpose, programmable machine possessing certain anthropomorphic characteristicsHazardous work environmentsRepetitive work cycleConsistency and accuracyDifficult handling task for humansMultishift operationsReprogrammable, flexibleInterfaced to other computer systems

What are robots made of?

Effectors: Manipulation

Degrees of Freedom

*Degrees of freedom descrribes the number of ways that a robot can move. In order to reach any possible point in space within its work envelope, a robot needs a total of 6 degrees of freedom. The human arm has 6 degrees of freedom, in total a human has about 111.

Robot AnatomyManipulator consists of joints and linksJoints provide relative motionLinks are rigid members between jointsVarious joint types: linear and rotaryEach joint provides a degree-of-freedomMost robots possess five or six degrees-of-freedomRobot manipulator consists of two sections:Body-and-arm for positioning of objects in the robot's work volumeWrist assembly for orientation of objects

Manipulator JointsTranslational motionLinear joint (type L)Orthogonal joint (type O)

Rotary motionRotational joint (type R) Twisting joint (type T)Revolving joint (type V)

Polar Coordinate Body-and-Arm Assembly

Notation TRL:

Consists of a sliding arm (L joint) actuated relative to the body, which can rotate about both a vertical axis (T joint) and horizontal axis (R joint)

Cylindrical Body-and-Arm AssemblyNotation TLO:

Consists of a vertical column, relative to which an arm assembly is moved up or downThe arm can be moved in or out relative to the column

Cartesian Coordinate Body-and-Arm Assembly

Notation LOO:

Consists of three sliding joints, two of which are orthogonalOther names include rectilinear robot and x-y-z robot

Jointed-Arm Robot

Notation TRR:

SCARA RobotNotation VROSCARA stands for Selectively Compliant Assembly Robot ArmSimilar to jointed-arm robot except that vertical axes are used for shoulder and elbow joints to be compliant in horizontal direction for vertical insertion tasks

Wrist ConfigurationsWrist assembly is attached to end-of-armEnd effector is attached to wrist assembly Function of wrist assembly is to orient end effector Body-and-arm determines global position of end effectorTwo or three degrees of freedom:Roll PitchYawNotation :RRT

An Introduction to Robot KinematicsRenata Melamud

Kinematics studies the motion of bodies

An Example - The PUMA 560The PUMA 560 has SIX revolute jointsA revolute joint has ONE degree of freedom ( 1 DOF) that is defined by its angle1234There are two more joints on the end effector (the gripper)

Other basic jointsSpherical Joint3 DOF ( Variables - 1, 2, 3)Revolute Joint1 DOF ( Variable - )Prismatic Joint1 DOF (linear) (Variables - d)

We are interested in two kinematics topics

Forward Kinematics (angles to position)What you are given: The length of each link The angle of each joint What you can find: The position of any point (i.e. its (x, y, z) coordinates

Inverse Kinematics (position to angles)What you are given:The length of each linkThe position of some point on the robot

What you can find:The angles of each joint needed to obtain that position

Quick Math ReviewDot Product: Geometric Representation:

Unit VectorVector in the direction of a chosen vector but whose magnitude is 1. Matrix Representation:

Quick Matrix Review

Matrix Multiplication:

An (m x n) matrix A and an (n x p) matrix B, can be multiplied since the number of columns of A is equal to the number of rows of B.

Non-Commutative MultiplicationAB is NOT equal to BAMatrix Addition:

Basic TransformationsMoving Between Coordinate Frames

Translation Along the X-AxisNOXYVNOVXYPxVNVOPx = distance between the XY and NO coordinate planesP(VN,VO)Notation:

NXVNOVXYPVNVOYO

Writing in terms of

XVXYPXYNVNOVNVOOYTranslation along the X-Axis and Y-Axis

Unit vector along the N-Axis Unit vector along the N-Axis Magnitude of the VNO vector Using Basis VectorsBasis vectors are unit vectors that point along a coordinate axisNVNOVNVOO

Rotation (around the Z-Axis) = Angle of rotation between the XY and NO coordinate axis

XYNVNVOOVVXVY

Unit vector along X-Axis Can be considered with respect to the XY coordinates or NO coordinates(Substituting for VNO using the N and O components of the vector)

Similarly.So.Written in Matrix FormRotation Matrix about the z-axis

X1Y1NO

VXYX0Y0VNOP(VN,VO)In other words, knowing the coordinates of a point (VN,VO) in some coordinate frame (NO) you can find the position of that point relative to your original coordinate frame (X0Y0). (Note : Px, Py are relative to the original coordinate frame. Translation followed by rotation is different than rotation followed by translation.) Translation along P followed by rotation by

HOMOGENEOUS REPRESENTATIONPutting it all into a MatrixWhat we found by doing a translation and a rotationPadding with 0s and 1sSimplifying into a matrix formHomogenous Matrix for a Translation in XY plane, followed by a Rotation around the z-axis

Rotation Matrices in 3D OK,lets return from homogenous repnRotation around the Z-AxisRotation around the Y-AxisRotation around the X-Axis

Homogeneous Matrices in 3DH is a 4x4 matrix that can describe a translation, rotation, or both in one matrixTranslation without rotationYXZONAONARotation without translationRotation part: Could be rotation around z-axis, x-axis, y-axis or a combination of the three.

Homogeneous Continued.The (n,o,a) position of a point relative to the current coordinate frame you are in.The rotation and translation part can be combined into a single homogeneous matrix IF and ONLY IF both are relative to the same coordinate frame.

Finding the Homogeneous MatrixEX.YXZJIKNOATPPoint relative to theN-O-A framePoint relative to theX-Y-Z framePoint relative to theI-J-K frame

Substituting for

Product of the two matricesNotice that H can also be written as:H = (Translation relative to the XYZ frame) * (Rotation relative to the XYZ frame) * (Translation relative to the IJK frame) * (Rotation relative to the IJK frame)

The Homogeneous Matrix is a concatenation of numerous translations and rotationsYXZNOATPOne more variation on finding H: H = (Rotate so that the X-axis is aligned with T)* ( Translate along the new t-axis by || T || (magnitude of T))* ( Rotate so that the t-axis is aligned with P)* ( Translate along the p-axis by || P || )* ( Rotate so that the p-axis is aligned with the O-axis) This method might seem a bit confusing, but its actually an easier way to solve our problem given the information we have. Here is an example

F o r w a r d K i n e m a t i c s

The Situation:You have a robotic arm that starts out aligned with the xo-axis.You tell the first link to move by 1 and the second link to move by 2.

The Quest:What is the position of the end of the robotic arm? Solution:1. Geometric ApproachThis might be the easiest solution for the simple situation. However, notice that the angles are measured relative to the direction of the previous link. (The first link is the exception. The angle is measured relative to its initial position.) For robots with more links and whose arm extends into 3 dimensions the geometry gets much more tedious.

2. Algebraic Approach Involves coordinate transformations.

X2X3Y2Y3

123123Example Problem: You are have a three link arm that starts out aligned in the x-axis. Each link has lengths l1, l2, l3, respectively. You tell the first one to move by 1 , and so on as the diagram suggests. Find the Homogeneous matrix to get the position of the yellow dot in the X0Y0 frame.

H = Rz(1 ) * Tx1(l1) * Rz(2 ) * Tx2(l2) * Rz(3 ) i.e. Rotating by 1 will put you in the X1Y1 frame. Translate in the along the X1 axis by l1. Rotating by 2 will put you in the X2Y2 frame. and so on until you are in the X3Y3 frame.

The position of the yellow dot relative to the X3Y3 frame is(l1, 0). Multiplying H by that position vector will give you the coordinates of the yellow point relative the the X0Y0 frame.

X1Y1X0Y0

Slight variation on the last solution:Make the yellow dot the origin of a new coordinate X4Y4 frame

X2X3Y2Y3

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X1Y1X0Y0X4Y4H = Rz(1 ) * Tx1(l1) * Rz(2 ) * Tx2(l2) * Rz(3 ) * Tx3(l3)

This takes you from the X0Y0 frame to the X4Y4 frame.

The position of the yellow dot relative to the X4Y4 frame is (0,0). Notice that multiplying by the (0,0,0,1) vector will equal the last column of the H matrix.

More on Forward KinematicsDenavit - Hartenberg Parameters

Denavit-Hartenberg NotationZ(i - 1)X(i -1)Y(i -1)( i - 1)a(i - 1 )Z i Y i X i a i d i i IDEA: Each joint is assigned a coordinate frame. Using the Denavit-Hartenberg notation, you need 4 parameters to describe how a frame (i) relates to a previous frame ( i -1 ). THE PARAMETERS/VARIABLES: , a , d,

The ParametersZ(i - 1)X(i -1)Y(i -1)( i - 1)a(i - 1 )Z i Y i X i a i d i i You can align the two axis just using the 4 parameters1) a(i-1) Technical Definition: a(i-1) is the length of the perpendicular between the joint axes. The joint axes is the axes around which revolution takes place which are the Z(i-1) and Z(i) axes. These two axes can be viewed as lines in space. The common perpendicular is the shortest line between the two axis-lines and is perpendicular to both axis-lines.

a(i-1) cont...Visual Approach - A way to visualize the link parameter a(i-1) is to imagine an expanding cylinder whose axis is the Z(i-1) axis - when the cylinder just touches the joint axis i the radius of the cylinder is equal to a(i-1). (Manipulator Kinematics)

Its Usually on the Diagram Approach - If the diagram already specifies the various coordinate frames, then the common perpendicular is usually the X(i-1) axis. So a(i-1) is just the displacement along the X(i-1) to move from the (i-1) frame to the i frame.

If the link is prismatic, then a(i-1) is a variable, not a parameter.

2) (i-1)

Technical Definition: Amount of rotation around the common perpendicular so that the joint axes are parallel.

i.e. How much you have to rotate around the X(i-1) axis so that the Z(i-1) is pointing in the same direction as the Zi axis. Positive rotation follows the right hand rule.

3) d(i-1)Technical Definition: The displacement along the Zi axis needed to align the a(i-1) common perpendicular to the ai common perpendicular.

In other words, displacement along the Zi to align the X(i-1) and Xi axes.

4) i Amount of rotation around the Zi axis needed to align the X(i-1) axis with the Xi axis.

The Denavit-Hartenberg MatrixJust like the Homogeneous Matrix, the Denavit-Hartenberg Matrix is a transformation matrix from one coordinate frame to the next. Using a series of D-H Matrix multiplications and the D-H Parameter table, the final result is a transformation matrix from some frame to your initial frame.Put the transformation here

3 Revolute JointsDenavit-Hartenberg Link Parameter TableNotice that the table has two uses:1) To describe the robot with its variables and parameters.2) To describe some state of the robot by having a numerical values for the variables.

i

((i-1)

a(i-1)

di

(i

0

0

0

0

(0

1

0

a0

0

(1

2

-90

a1

d2

(2

Note: T is the D-H matrix with (i-1) = 0 and i = 1.

i

((i-1)

a(i-1)

di

(i

0

0

0

0

(0

1

0

a0

0

(1

2

-90

a1

d2

(2

This is just a rotation around the Z0 axisThis is a translation by a0 followed by a rotation around the Z1 axisThis is a translation by a1 and then d2 followed by a rotation around the X2 and Z2 axis

i

((i-1)

a(i-1)

di

(i

0

0

0

0

(0

1

0

a0

0

(1

2

-90

a1

d2

(2

I n v e r s e K i n e m a t i c sFrom Position to Angles

A Simple Example

1

XY

SRevolute and Prismatic Joints Combined

(x , y)Finding :More Specifically:arctan2() specifies that its in the first quadrantFinding S:

2

1(x , y)l2l1Inverse Kinematics of a Two Link ManipulatorGiven:l1, l2 , x , y

Find: 1, 2

Redundancy:A unique solution to this problem does not exist. Notice, that using the givens two solutions are possible. Sometimes no solution is possible.

(x , y)

l2l1

The Geometric Solutionl1l2

21

(x , y)Using the Law of Cosines:Using the Law of Cosines:Redundant since 2 could be in the first or fourth quadrant.Redundancy caused since 2 has two possible values

The Algebraic Solutionl1l2

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(x , y)Only Unknown

We know what 2 is from the previous slide. We need to solve for 1 . Now we have two equations and two unknowns (sin 1 and cos 1 )Substituting for c1 and simplifying many timesNotice this is the law of cosines and can be replaced by x2+ y2

Joint Drive SystemsElectricUses electric motors to actuate individual jointsPreferred drive system in today's robotsHydraulicUses hydraulic pistons and rotary vane actuatorsNoted for their high power and lift capacityPneumaticTypically limited to smaller robots and simple material transfer applications

Robot Control SystemsLimited sequence control pick-and-place operations using mechanical stops to set positionsPlayback with point-to-point control records work cycle as a sequence of points, then plays back the sequence during program executionPlayback with continuous path control greater memory capacity and/or interpolation capability to execute paths (in addition to points)Intelligent control exhibits behavior that makes it seem intelligent, e.g., responds to sensor inputs, makes decisions, communicates with humans

End EffectorsThe special tooling for a robot that enables it to perform a specific taskTwo types:Grippers to grasp and manipulate objects (e.g., parts) during work cycleTools to perform a process, e.g., spot welding, spray painting

Grippers and Tools

Industrial Robot ApplicationsMaterial handling applicationsMaterial transfer pick-and-place, palletizingMachine loading and/or unloading

Processing operationsWeldingSpray coatingCutting and grinding

Assembly and inspection

Robotic Arc-Welding CellRobot performs flux-cored arc welding (FCAW) operation at one workstation while fitter changes parts at the other workstation

Servo RobotsA more sophisticated level of control can be achieved by adding servomechanisms that can command the position of each joint.The measured positions are compared with commanded positions, and any differences are corrected by signals sent to the appropriate joint actuators.This can be quite complicated

Teach and Play-back Robots

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Robotic Vision system

The most powerful sensor, which can equip a robot with largevariety of sensory information is ROBOTIC VISION. Vision systems are among the most complex sensory system inuse. Robotic vision may be defined as the process of acquiringand extracting information from images of 3-d world. Robotic vision is mainly targeted at manipulation andinterpretation of image and use of this information in robotoperation control. Robotic vision requires two aspects to be addressed1. Provision for visual input2. Processing required to utilize it in a computer basedsystems.

Why UVs Need AISensor interpretationBush or Big Rock?, Symbol-ground problem, Terrain interpretation

Situation awareness/ Big Picture

Human-robot interaction

Open world and multiple fault diagnosis and recovery

Localization in sparse areas when GPS goes out

Handling uncertainty

Manipulators

Learning

Artificial Intelligent RobotsAll Have 5 Common Components Mobility: legs, arms, neck, wristsPlatform, also called effectorsPerception: eyes, ears, nose, smell, touchSensors and sensingControl: central nervous systemInner loop and outer loop; layers of the brainPower: food and digestive systemCommunications: voice, gestures, hearingHow does it communicate (I/O, wireless, expressions)What does it say?

7 Major Areas of AIKnowledge representationhow should the robot represent itself, its task, and the worldUnderstanding natural languageLearningPlanning and problem solvingMission, task, path planningInferenceGenerating an answer when there isnt complete informationSearchFinding answers in a knowledge base, finding objects in the worldVision

Upper brain or cortexReasoning over information about goalsMiddle brainConverting sensor data into informationSpinal Cord and lower brainSkills and responsesIntelligence and the CNS

AI Focuses on AutonomyAutomationExecution of precise, repetitious actions or sequence in controlled or well-understood environmentPre-programmed

AutonomyGeneration and execution of actions to meet a goal or carry out a mission, execution may be confounded by the occurrence of unmodeled events or environments, requiring the system to dynamically adapt and replan.Adaptive

*The words autonomy and automation are often used interchangeably, though they have quite different connotations in robotics. Automation means the execution for precise, repetitious actions or sequence in controlled or well-understood environment. Or, in other words, pre-programmed movements or actions. Autonomy is the generation and execution of actions to meet a goal or carry out a mission, execution may be confounded by the occurrence of unmodelled events, requiring the system to dynamically adapt and replan.

So How Does Autonomy Work?In two layersReactiveDeliberative

3 paradigms which specify what goes in what layerParadigms are based on 3 robot primitives: sense, plan, act

AI Primitives within an AgentSENSEPLANACTLEARN

ReactiveUsers loved it because it workedAI people loved it, but wanted to put PLAN back inControl people hated it because couldnt rigorously prove it worked

Thank you all

*Degrees of freedom descrribes the number of ways that a robot can move. In order to reach any possible point in space within its work envelope, a robot needs a total of 6 degrees of freedom. The human arm has 6 degrees of freedom, in total a human has about 111.*The words autonomy and automation are often used interchangeably, though they have quite different connotations in robotics. Automation means the execution for precise, repetitious actions or sequence in controlled or well-understood environment. Or, in other words, pre-programmed movements or actions. Autonomy is the generation and execution of actions to meet a goal or carry out a mission, execution may be confounded by the occurrence of unmodelled events, requiring the system to dynamically adapt and replan.