Introduction to Robotics Analysis, systems, Applications

What is a robot? Joseph Engelberger, a pioneer in industrial robotics: "I can't define a robot, but I know one when I see one." Joseph Engelberger, a pioneer in industrial robotics: "I can't define a robot, but I know one when I see one."

Arkin (1998) Arkin (1998) “An intelligent robot is a machine able to extract information from its environment and use knowledge about its world to move safely in a meaningful and purposive manner”

What is Robotics? Robotics is the art, knowledge base, and the know-how of designing, applying, and using robots in human endeavors. Robotics is the art, knowledge base, and the know-how of designing, applying, and using robots in human endeavors. Robotics is an interdisciplinary subject that benefits from mechanical engineering, electrical and electronic engineering, computer science, biology, and many other disciplines. Robotics is an interdisciplinary subject that benefits from mechanical engineering, electrical and electronic engineering, computer science, biology, and many other disciplines.

What is a Robot ? Random House Dictionary A machine that resembles a human being and does mechanical routine tasks on command. Random House Dictionary A machine that resembles a human being and does mechanical routine tasks on command. Robotics Association of America An industrial robot is a re-programmable, multifunctional manipulator designed to move materials, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks. Robotics Association of America An industrial robot is a re-programmable, multifunctional manipulator designed to move materials, parts, tools, or specialized devices through variable programmed motions for the performance of a variety of tasks.

What is a Robot ? A manipulator (or an industrial robot) is composed of a series of links connected to each other via joints. Each joint usually has an actuator (a motor for eg.) connected to it. A manipulator (or an industrial robot) is composed of a series of links connected to each other via joints. Each joint usually has an actuator (a motor for eg.) connected to it. These actuators are used to cause relative motion between successive links. One end of the manipulator is usually connected to a stable base and the other end is used to deploy a tool. These actuators are used to cause relative motion between successive links. One end of the manipulator is usually connected to a stable base and the other end is used to deploy a tool.

Classification of Robots - JIRA (Japanese Industrial Robot Association) Class1: Manual-Handling Device Class2: Fixed Sequence Robot Class3: Variable Sequence Robot Class4: Playback Robot Class5: Numerical Control Robot Class6: Intelligent Robot

Classification of Robots - RIA (Robotics Institute of America) Variable Sequence Robot(Class3) Playback Robot(Class4) Numerical Control Robot(Class5) Intelligent Robot(Class6)

Classification of Robots AFR (Association FranÇaise de Robotique) Type A: Manual Handling Devices/ telerobotics Type B: Automatic Handling Devices/ predetermined cycles Type C: Programmable, Servo controlled robot, continuous point-to-point trajectories Type D: Same type with C, but it can acquire information.

What are the parts of a robot? Manipulator Pedestal Controller End Effectors Power Source

Manipulator Base Appendages -Shoulder -Arm -Grippers

Robot Anatomy Manipulator consists of joints and links Manipulator consists of joints and links Joints provide relative motion Joints provide relative motion Links are rigid members between joints Links are rigid members between joints Each joint provides a “degree-of-freedom” Each joint provides a “degree-of-freedom” Base Link0 Joint1 Link2 Link3 Joint3 End of Arm Link1 Joint2

Robot Anatomy Robot manipulator consists of two sections: Robot manipulator consists of two sections: Body-and-arm – for positioning of objects in the robot's work volume Body-and-arm – for positioning of objects in the robot's work volume Wrist assembly – for orientation of objects Wrist assembly – for orientation of objects Base Link0 Joint1 Link2 Link3 Joint3 End of Arm Link1 Joint2

Manipulator Joints Translational motion Translational motion Linear joint (type L) Linear joint (type L) Orthogonal joint (type O) Orthogonal joint (type O) Rotary motion Rotary motion Rotational joint (type R) Rotational joint (type R) Twisting joint (type T) Twisting joint (type T) Revolving joint (type V) Revolving joint (type V)

Polar Coordinate Body-and-Arm Assembly Notation TRL: 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) 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 Assembly Notation TLO: Notation TLO: Consists of a vertical column, relative to which an arm assembly is moved up or down Consists of a vertical column, relative to which an arm assembly is moved up or down The arm can be moved in or out relative to the column The arm can be moved in or out relative to the column

Cartesian Coordinate Body-and-Arm Assembly Notation LOO: Notation LOO: Consists of three sliding joints, two of which are orthogonal Consists of three sliding joints, two of which are orthogonal Other names include rectilinear robot and x-y-z robot Other names include rectilinear robot and x-y-z robot

Jointed-Arm Robot Notation TRR: Notation TRR:

SCARA Robot Notation VRO Notation VRO Similar 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 Similar 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 Configurations End effector is attached to wrist assembly End effector is attached to wrist assembly Function of wrist assembly is to orient end effector Function of wrist assembly is to orient end effector Body-and-arm determines global position of end effector Body-and-arm determines global position of end effector Two or three degrees of freedom: Two or three degrees of freedom: Roll Roll Pitch Pitch Yaw Yaw Notation :RRT Notation :RRT

Example Sketch following manipulator configurations Sketch following manipulator configurations (a) TRT:R, (b) TVR:TR, (c) RR:T. (a) TRT:R, (b) TVR:TR, (c) RR:T. Solution:

Robots degrees of freedom Degrees of Freedom: Number of independent position variables which would has to be specified to locate all parts of a mechanism. Degrees of Freedom: Number of independent position variables which would has to be specified to locate all parts of a mechanism. In most manipulators this is usually the number of joints. In most manipulators this is usually the number of joints.

DOF of a Rigid Body In a plane In space

Degrees of Freedom As DOF 3 position 3 orientation 3D Space = 6 DOF In robotics: DOF = number of independently driven joints computational complexity cost flexibility power transmission is more difficult positioning accuracy

The Six Possible Lower Pair Joints

Degree of freedom - one joint one degree of freedom Degree of freedom - one joint one degree of freedom Simple robots - 3 degrees of freedom in X,Y,Z axis Simple robots - 3 degrees of freedom in X,Y,Z axis Modern robot arms have up to 7 degrees of freedom Modern robot arms have up to 7 degrees of freedom XYZ, Roll, Pitch and Yaw XYZ, Roll, Pitch and Yaw The human arm can be used to demonstrate the degrees The human arm can be used to demonstrate the degrees of freedom. of freedom. Crust Crawler- 5 degrees of freedom Crust Crawler- 5 degrees of freedom Degrees of Freedom

Cartesian Robot Applications Applying adhesive to a pane of glass Transferring ICs from a pallet to a holding location Transferring & Stacking Camera monitoring of products

The Humanoid Robot Previously developed for recreational and Previously developed for recreational and entertainment value. entertainment value. Research into use for household chores, Research into use for household chores, aid for elderly aid aid for elderly aid

Fig. 1.3 A Fanuc P-15 robot. Reprinted with permission from Fanuc Robotics, North America, Inc. Consider what is the degree of Fig. 3 1 D.O.F. 2 D.O.F.3 D.O.F. Robots degrees of freedom

Robot Joints Prismatic Joint: Linear, No rotation involved. (Hydraulic or pneumatic cylinder) Revolute Joint: Rotary, (electrically driven with stepper motor, servo motor)

Robot Coordinates  Cartesian/rectangular/gantry (3P) : 3 cylinders joint  Cylindrical (R2P) : 2 Prismatic joint and 1 revolute joint Fig. 1.4  Spherical (2RP) : 1 Prismatic joint and 2 revolute joint  Articulated/anthropomorphic (3R) : All revolute(Human arm)  Selective Compliance Assembly Robot Arm (SCARA): 2 paralleled revolute joint and 1 additional prismatic joint

Robot Reference Frames Fig. 1.6 A robot ’ s World, Joint, and Tool reference frames. Most robots may be programmed to move relative to either of these reference frames.

Robot Workspace Fig. 1.7 Typical workspaces for common robot configurations

Actuators Motors- control the movement of a robot. Identified as Actuators there are three common types DC Motor DC Motor Stepper Motor Stepper Motor Servo motor Servo motor Stepper motor

Joint Drive Systems Electric Electric Uses electric motors to actuate individual joints Uses electric motors to actuate individual joints Preferred drive system in today's robots Preferred drive system in today's robots Hydraulic Hydraulic Uses hydraulic pistons and rotary vane actuators Uses hydraulic pistons and rotary vane actuators Pneumatic Pneumatic Typically limited to smaller robots and simple material transfer applications Typically limited to smaller robots and simple material transfer applications

DC Motors Most common and cheapest Most common and cheapest Powered with two wires from source Powered with two wires from source Draws large amounts of current Draws large amounts of current Cannot be wired straight from a PIC Cannot be wired straight from a PIC Does not offer accuracy or speed control Does not offer accuracy or speed control

Stepper Motors Stepper has many electromagnets Stepper has many electromagnets Stepper controlled by sequential turning on and off of Stepper controlled by sequential turning on and off of magnets magnets Each pulse moves another step, providing a step angle Each pulse moves another step, providing a step angle Example shows a step angle of 90° Example shows a step angle of 90° Poor control with a large angle Poor control with a large angle Better step angle achieved with the toothed disc Better step angle achieved with the toothed disc

Stepper motor operation Step1

Step 2 Stepper motor operation

Step 3

Stepper motor operation Step 4

Servo motors Servo offers smoothest control Servo offers smoothest control Rotate to a specific point Rotate to a specific point Offer good torque and control Offer good torque and control Ideal for powering robot arms etc. Ideal for powering robot arms etc.However: Degree of revolution is limited Degree of revolution is limited Not suitable for applications which require Not suitable for applications which require continuous rotation continuous rotation

Servo motors Contain motor, gearbox, driver controller and potentiometer Contain motor, gearbox, driver controller and potentiometer Three wires - 0v, 5v and PIC signal Three wires - 0v, 5v and PIC signal Potentiometer connected to gearbox - monitors movement Potentiometer connected to gearbox - monitors movement Provides feedback Provides feedback If position is distorted - automatic correction If position is distorted - automatic correction + 5V

Servo motors Operation Pulse Width Modulation (0.75ms to 2.25ms) Pulse Width Modulation (0.75ms to 2.25ms) Pulse Width takes servo from 0° to 150° rotation Pulse Width takes servo from 0° to 150° rotation Continuous stream every 20ms Continuous stream every 20ms On programming block, pulse width and output pin must be set. On programming block, pulse width and output pin must be set. Pulse width can also be expressed as a variable Pulse width can also be expressed as a variable

Controller (The brain) Issues instructions to the robot. Controls peripheral devices. Interfaces with robot. Interfaces with humans.

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

Robot Control System Joint 1 Joint 2 Joint 3 Joint 4 Joint 5 Joint 6 Controller & Program Controller & Program Cell Supervisor Cell Supervisor Sensors Level 0 Level 1 Level 2

End Effectors (The hand) Spray paint attachments Welding attachments Vacuum heads Hands Grippers

End Effectors Tools: Tools are used where a specific operation needs to be carried out such as welding, painting drilling to be carried out such as welding, painting drilling etc. - the tool is attached to the mounting plate. etc. - the tool is attached to the mounting plate. Grippers: mechanical, magnetic and pneumatic. Mechanical: Two fingered most common, also multi-fingered available Two fingered most common, also multi-fingered available Applies force that causes enough friction between object to Applies force that causes enough friction between object to allow for it to be lifted allow for it to be lifted Not suitable for some objects which may be delicate / brittle Not suitable for some objects which may be delicate / brittle

End Effectors Magnetic: Ferrous materials required Ferrous materials required Electro and permanent magnets used Electro and permanent magnets usedPneumatic: Suction cups from plastic or rubber Suction cups from plastic or rubber Smooth even surface required Smooth even surface required Weight & size of object determines size and number of cups Weight & size of object determines size and number of cups

End Effectors The special tooling for a robot that enables it to perform a specific task The special tooling for a robot that enables it to perform a specific task Two types: Two types: Grippers – to grasp and manipulate objects (e.g., parts) during work cycle Grippers – to grasp and manipulate objects (e.g., parts) during work cycle Tools – to perform a process, e.g., spot welding, spray painting Tools – to perform a process, e.g., spot welding, spray painting

Grippers and Tools

Working Envelope

Power Source (The food) Electric Pneumatic Hydraulic

Robot Languages Microcomputer Machine Language Level: the most basic and very efficient but difficult to understand to follow. Point-to-Point Level: Funky  Cincinnati Milacron ’ s T3  It lacks branching, sensory information. Primitive Motion Level: VAL by Unimation ™ Interpreter based language. Structured Programming Level: This is a compiler based but more difficult to learn. Task-Oriented Level: Not exist yet and proposed IBM in the 1980s.

Robot Programming Leadthrough programming Leadthrough programming Work cycle is taught to robot by moving the manipulator through the required motion cycle and simultaneously entering the program into controller memory for later playback Work cycle is taught to robot by moving the manipulator through the required motion cycle and simultaneously entering the program into controller memory for later playback Robot programming languages Robot programming languages Textual programming language to enter commands into robot controller Textual programming language to enter commands into robot controller Simulation and off-line programming Simulation and off-line programming Program is prepared at a remote computer terminal and downloaded to robot controller for execution without need for leadthrough methods Program is prepared at a remote computer terminal and downloaded to robot controller for execution without need for leadthrough methods

Robot Programming Textural programming languages Textural programming languages Enhanced sensor capabilities Enhanced sensor capabilities Improved output capabilities to control external equipment Improved output capabilities to control external equipment Program logic Program logic Computations and data processing Computations and data processing Communications with supervisory computers Communications with supervisory computers

Leadthrough Programming 1. Powered leadthrough Common for point- to-point robots Common for point- to-point robots Uses teach pendant Uses teach pendant 2. Manual leadthrough Convenient for continuous path control robots Convenient for continuous path control robots Human programmer physical moves manipulator Human programmer physical moves manipulator

Motion Commands MOVE P1 HERE P1 - used during lead through of manipulator MOVES P1 DMOVE(4, 125) APPROACH P1, 40 MM DEPART 40 MM DEFINE PATH123 = PATH(P1, P2, P3) MOVE PATH123 SPEED 75

Interlock and Sensor Commands Interlock Commands WAIT 20, ON SIGNAL 10, ON SIGNAL 10, 6.0 REACT 25, SAFESTOP Gripper Commands OPENCLOSE CLOSE 25 MM CLOSE 2.0 N

Simulation and Off-Line Programming

Example A robot performs a loading and unloading operation for a machine tool as follows: Robot pick up part from conveyor and loads into machine (Time=5.5 sec) Robot pick up part from conveyor and loads into machine (Time=5.5 sec) Machining cycle (automatic). (Time=33.0 sec) Machining cycle (automatic). (Time=33.0 sec) Robot retrieves part from machine and deposits to outgoing conveyor. (Time=4.8 sec) Robot retrieves part from machine and deposits to outgoing conveyor. (Time=4.8 sec) Robot moves back to pickup position. (Time=1.7 sec) Robot moves back to pickup position. (Time=1.7 sec) Every 30 work parts, the cutting tools in the machine are changed which takes 3.0 minutes. The uptime efficiency of the robot is 97%; and the uptime efficiency of the machine tool is 98% which rarely overlap. Determine the hourly production rate.

Solution T c = = 45 sec/cycle Tool change time T tc = 180 sec/30 pc = 6 sec/pc Robot uptime E R = 0.97, lost time = Machine tool uptime E M = 0.98, lost time = Total time = T c + T tc /30 = = 51 sec = 0.85 min/pc R c = 60/0.85 = pc/hr Accounting for uptime efficiencies, R p = 70.59( ) = pc/hr