Transcript Document

ISE 370 Industrial Automation
Instructor: Thomas Koon
Introduction To Robotics
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Introduction
• The main purpose of this discussion is to
provide a very basic understanding of
“Robotics”, and how to apply that
knowledge to our lab using the ADEPT
“Robot” in Lab B-9
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Topics of Discussion
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Overview of Robotics
Classification and application of robotics
Robot components and subsystems
Kinematics and inverse transformation
Control of actuators in robotics systems
Robot sensory devices
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What is a Robot?
"A reprogrammable, multifunctional
manipulator designed to move material, parts,
tools, or specialized devices through various
programmed motions for the performance of a
variety of tasks"
Robot Institute of America, 1979
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Robots: Hollywood Fiction
vs. Real-World Fact
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Why Use Robots?
•To save money?
•To save people?
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Robot Concepts
• Notion derives from 2 strands of thought:
– Humanoids -- human-like
– Automata -- self-moving things
• “Robot” -- derives from Czech word robota
– “Robota” : forced work or compulsory service
• Term coined by Czech playwright Karel Capek
– 1921 play “R.U.R” (Rossum’s Universal Robots”)
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Robot Concepts
• Current notion of a Robot:
– Programmable
– Mechanically capable
– Flexible
• One working definition of robot: physical agent
that generates “intelligent” connection between
perception and action
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Advantages of Machines
• Do not tire or grumble
• Higher quality.
• Repeatable performance
• Stronger, faster, more accurate
• More productive.
• Work 24 hours each day
• Immune to dangerous environment.
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Advantages of People:
• Adaptable to problems and environments.
• Wide range of sensory inputs, with pattern
recognition.
• Make decisions, set priorities and define
goals.
• Investigate new techniques.
• Easy to program.
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Some Current State-of-theArt Robots
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Robot Applications
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ROBOT KINEMATICS
* Kinematics: is the science of motion.
Kinematics is important in robots, used to model:
• Mechanisms
• Actuators
• Sensors
from Greek kinema = movement
Forward kinematics is the transformation from joint space
to Cartesian space
Inverse kinematics solves for the joint angles given the
desired position and orientation in Cartesian space
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Forward & Reverse Kinematics
Forward Kinematics: For a
given set of joint
displacements, the endeffector position and
orientation can be
calculated.
Inverse Kinematics: For
a given set of end-effector
position and orientation,
joint displacements are
computed.
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Rotational Transforms
Rotation about a single axis:
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Joints & Links
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Link Frame Assignments
Denavit-Hartenberg notation
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Joints in Zero Position
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Tool Frame to Base
Multiplication
of these
matrices leads
to the
complete
transformation
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Possible Robot Classifications
• Power Source?
• Classification by Level of
Technology
• Arm Configuration?
• Classification by Controller
• Application?
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Robotic Power Sources
• Electric - Stepper motors (for economy) or
servo motors (for precision)
• Hydraulic – For Power
• Pneumatic - For Speed
• Vacuum – For pick and place operations
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Level of Technology
3 current levels of technology now used by
robots:
1. Low technology robots are nonservocontrolled.
2.
Medium technology robots use point to point
controllers.
3.
High technology robots use continuous-path
controllers.
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Robotic Arm Configuration
Five recognized arm configurations:
1. Rectangular (or Cartesian) Coordinates
2. Cylindrical Coordinates
3. SCARA
4. Polar Coordinates
5. Jointed Arm (or revolute-coordinates,
articulate, or anthropomorphic).
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Cartesian Configuration (TTT)
3 Linear Axis
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Cylindrical Configuration
(TTR, RTR, RRT)
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SCARA Configuration (RRT)
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SCARA
Selective Compliant Assembly Robot Arm
In general, traditional SCARA’s are 4-axis robot arms, i.e., they
can move to any X-Y-Z coordinate within their work envelope.
There is a fourth axis of motion which is the wrist rotate (ThetaZ).
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Polar Configuration (RRT)
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Jointed arm/ Revolute
Configuration (RRR)
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Classification by Controller
Three basic types of robot controllers:
1. Limited Sequence
2. Point to Point
3. Continuous Path.
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Comparisons
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Robotics Applications
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Industrial Automation and
Robots
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While industrial robots and automated
machines are usually treated as two
separate topics, most industrial robots
work in cooperation with other
automated machines.
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Robot Communications
LAN - is short for "local area network
MAP - stands for "manufacturing automation
protocol"; it is a communications
standard developed for General Motors.
TOP - is an acronym for "technical and office
protocol," was developed for use in office
automation by Boeing Computer Services
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Automated Machines
Automated machines classes: hard
automation and flexible automation machines.
Hard automation deals with specialized machines
designed for a specific operation or a narrow
range of operations.
Flexible automation deals with relatively generalpurpose machines, such as the industrial robot.
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An Early Use
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An early automated programmable industrial
machine was the automatic loom, invented by
Joseph Marie Jacauard in 1801.
Jacquard showed
how powerful it
was by using
10,000 punched
cards to weave a
portrait of
himself in black
and white silk
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Terms
1. Computer-aided design (CAD) and
computer-aided engineering (CAE)
2. Computer-Aided Manufacturing
(CAM)
3. Computer-Aided Robotics (CAR)
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Robot Components
Robots use arms, end
effectors (grippers),
drive mechanisms,
sensors, controllers,
gears and motors to
perform the
human-like
functions necessary
to perform their
jobs
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Robot Components
Arms:
Robot arms come in all
shapes and sizes. The arm
is the part of the robot that
positions the end-effector
and sensors to do their preprogrammed business.
•Many (but not all) resemble human arms, and have shoulders,
elbows, wrists, even fingers. This gives the robot a lot of ways to
position itself in its environment. Each joint is said to give the
robot 1 degree of freedom.
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Robot Components
Degrees of freedom:
So, a simple robot arm with 3
degrees of freedom could
move in 3 ways: up and
down, left and right, forward
and backward. Most working
robots today have 6 degrees
of freedom.
Humans have many more degrees of freedom. Most jointedarm robots in use today have 6 degrees of freedom
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Degrees of Freedom
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Links
Robot links are considered to be rigid and
inflexible. It is the link geometry which is used to
determine the relative position of the kinematic
coordinate frames.
The position of a robots end-effector can be
described in two ways, in Cartesian coordinates
relative to its base frame and in joint coordinates.
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2 Most Common Joints:
Prismatic (linear)
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Revolute (Rotary)
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Types of Joint
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Robot Components
AXIS OF ROTATION:
X, Y, & Z,
Are 3 of the degrees of
freedom that robots
perform. Most arms
move according to
Cartesian coordinates
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Robot Components
End-effector
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The end-effector is the "hand"
connected to the robot's arm. It is
often different from a human hand it could be a tool such as a gripper,
a vacuum pump, tweezers, scalpel,
blowtorch - just about anything that
helps it do its job. Some robots can
change end-effectors, and be
reprogrammed for a different set of
tasks.
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Robot DC Motors
Parts of a 2-Pole DC Motor:
An armature or rotor
A commutator
Brushes
An axle
A field magnet
A DC power supply of
some sort

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Stepper Motors
Stepping motors can be viewed as
electric motors without
commutators.. All of the
commutation must be handled
externally by the motor controller.
Most stepping motors can be
stepped at audio frequencies,
allowing them to spin quite
quickly, and with an appropriate
controller, they may be started and
stopped "on a dime" at controlled
orientations.
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Robotics Sensors & Controllers
Sensors: collect all the
information a robot needs
to operate and interact
with its environment.
Controllers:
interpret all the input
from the sensors and
decide how to act in
response.
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Robotics Sensors & Controllers
Sensors: control of a manipulator
or industrial robot is based on the
correct interpretation of sensory
information. This information can
be obtained either internally to the
robot (for example, joint positions
and motor torque) or externally
using a wide range of sensors.
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Sensor Types
4 Basic Sensor types:
1. Tactile sensors: respond to contact forces with another object
2. Proximity sensors: indicate when an object is close to another
object (within sensor range)
3. Range sensors: measure the distance from the object to the
sensor
4. Machine vision - views the workspace and interprets what it
sees; used primarily for inspection, part identification
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Sensor Types
Tactile
Range
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Proximity
Machine Vision
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Mobile Sensor Types
Some Basic sensor types:
Light sensors which measure light
intensity.
Heat Sensors which measure
temperature.
Touch sensors which tell the robot
when it bumps into something.
Ultra Sonic Rangers which tell
the robot how far away objects are.
And gyroscopes which tell the
robot which direction is up.

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Rotary Shaft Encoders
Direct (absolute) read out v.s, Pulse
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Robotics Sensors & controllers
Motion control: is the
process of computer
controlled kinetics-- the
foundation of robotics. CNC
(computer numeric control)
is an antiquated term for this
process, recalling an era
when programmers entered
the numeric commands and
coordinates for each machine
move.
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Industrial Robots
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The industrial robot is intended to serve
as a general-purpose unskilled or
semiskilled laborer.
An industrial robot generally has a single
manipulator (arm), a wrist, and a gripper
(hand).
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Industrial Robot Types
Rectangular-coordinates
robots can move up and
down, back and forth,
and in and out.
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Polar-coordinates robots
rotate up and down, rotate
around, and moves in and
out.
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Characteristics of a Robot
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Standards
• Robotics Industries Association (RIA)
• SME/RI
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