What is a Robot

1
What is a Robot?

• Definition of Robot
• Webster
• An automatic apparatus or device that performs
  functions ordinarily ascribed to human beings or
  operates with what appears to be almost human
  intelligence
• 2. Robot Institute of America
• A robot is a re-programmable, multifunctional
  manipulator designed to move material, parts,
  tools or specialized devices through variable
  programmed motions for the performance of variety
  of tasks

2
Technologies that go to make up a robot

• Mechanical Engineering
• Design of the mechanism.Understanding of the
  kinematics and
• dynamics of the system.
• Electronic Engineering
• Design of the actuator and sensor systems.
• Systems Engineering
• Analysis and integration of the overall system.
  Signal conditioning and Control.
• Computer Science
• Design of the logic, intelligence or
  adaptability, networking and
• interface.

3
Robot Characteristics

• The following definition are used to
  characterized robot specification
• Payload
• Reach
• Precession
• Repeatability

4
Robot Characteristics (cont)
Payload

• Payload is the weight a robot can carry and still
  remain within its other specifications
• E.g. A robot maximum load capacity may be much
  larger than its specified payload, but at maximum
  level it may become less accurate, may not follow
  its intended path accurately, or may have
  excessive deflections

5
Robot Characteristics (cont)
Reach

• Maximum distance a robot can reach within its
  work envelope

Precision (validity)

• Defined as how accurately a specified point can
  be reached.
• Most industrial robot can have precision of 0.001
  inch or better

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Robot Characteristics (cont)
Repeatability (variability)

• Repeatability is how accurate the same position
  can be reached of the motion repeated many times.
• Repeatability is more important than precision
• If a robot is not precise, it will generally show
  a consistent error, which can be predicted and
  thus corrected using programming.
• If the error is random, it cannot be predicted
  and thus cannot be eliminated.
• Most industrial robots have repeatability in the
  0.001 inch range

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Advantages Disadvantages of Robots
Advantages

• Robotics and automation can, in many situations
  increase productivity, safety,efficiency, quality
  and consistency of product
• Robot can work in hazardous environments without
  the need of life support, comfort or concern
  about safety
• Robot needs no environmental comfort, such as
  lightning, air conditioning, ventilation and
  noise protection
• Robots work continuously without experiencing
  fatigue or boredom, do not get mad, do not have
  hangovers and need medical insurance or vacation

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Advantages Disadvantages of Robots (cont)
Advantages

• Robots have repeatable precision at all times,
  unless something happens to them or unless wear
  out
• Robots can be much more accurate than human. E.g.
  New wafer handling robots have micro inch
  accuracies
• Accessories and sensor can have capabilities
  beyond humans
• Can process multiple stimuli or tasks
  simultaneously.

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Advantages Disadvantages of Robots (cont)
Disadvantages

• Robots replace human workers creating economic
  problems. E.g. lost salaries, social problems
  (dissatisfaction and resentment among workers)
• Robots lack capability to respond in emergencies,
  unless the situation is predicted and the
  response is included in the system. Safety
  measures are needed to ensure that they do not
  injured operators and machine working with them

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Advantages Disadvantages of Robots (cont)
Disadvantages

• This includes
• Inappropriate or wring responses
• A lack of decision making power
• A loss of power
• Damage to the robot and other devices
• Human injuries

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Advantages Disadvantages of Robots (cont)
Disadvantages

• Robots have limited capabilities in
• Degree of freedom
• Dexterity
• Sensors
• Vision systems
• Real time response

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Advantages Disadvantages of Robots (cont)
Disadvantages

• Robots are costly due to
• Initial cost of equipment
• Installation cost
• Need of peripherals
• Need for training
• Need for programming

13
Robot Components

• A Robot as a system consists of the following
  elements which are integrated together to form a
  whole
• Manipulator (or rover)
• End effectors
• Actuators
• Sensors
• Controller
• Processor
• Software

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Robot Components (cont)
Manipulator

• Is the main body of the robot and consists of
  links, the joints and other structural elements

End Effectors

• The part that is connected to the last joint
  (hand) of a manipulator.
• In most cases the action of the end effector is
  either controlled by the robots controller or
  the controller communicates with the end
  effectors controlling device such as (e.g. PLC)

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Robot Components (cont)
Actuators

• Are the muscles of the manipulator that move or
  create mechanical action
• Common types
• Servomotors power driven mechanism that help
  main controller operates using low force
• Stepper motors a rotating motor in a small step
  and not continuous
• Pneumatic cylinders relating to air or other
  gases
• Hydraulic cylinders moved by, or operated by a
  fluid, especially water, under pressure.

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Robot Components (cont)
Actuators (cont)
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Robot Components (cont)
Actuators (cont)
Multiplication factor E.g Left piston 2 inches
in diameter (1-inch radius) Right piston 6
inches in diameter (3-inch radius) Area ?r2
Answer Area of the left piston ?(1)2
3.14 Area of the right piston 28.26. The
piston on the right is 9 times larger than the
piston on the left. What that means is that any
force applied to the left-hand piston will appear
9 times greater on the right-hand piston. So if
you apply a 100-pound downward force to the left
piston, a 900-pound upward force will appear on
the right. The only catch is that you will have
to depress the left piston 9 inches to raise the
right piston 1 inch.
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Robot Components (cont)
Sensors

• Sensors are used to collect information about the
  internal state if the robot to communicate with
  outside environment
• E.g. Vision system, speech, and touch/tactile

Controller

• Similar to cerebellum (controls motions)
• Receive data from computer, control actuators
  motions and coordinates the motions with the
  sensory feedback information
• E.g. Controls angle, velocity, force

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Robot Components (cont)
Processor

• The brain
• Generally a computer but dedicated to a single
  purpose
• E.g. Calculates motions, how much/fast joint must
  move

Software

• Three group of software
• Operating system
• Robotic software calculates necessary motions
  of each joint based on kinematics equations
• Collection of routines and application programs
  to use peripheral devices (e.g. vision routines,
  specific task)

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Types of Robot Function Application
Classification of Robot

• Japanese Industrial Robot Association (JIRA)
• Class 1 Manual Handling Device A device with
  multiple DOF that is actuated by an operator
• Class 2 Fixed-Sequence Robot A device that
  performs the successive stages if a task
  according to predetermined, unchanging method and
  is hard to modify
• Class 3 VariableSequence Robot Same as 2 but
  easy to modify
• Class 4 Playback Robot A human operator
  performs the task manually and records the
  motions for later playback. The robot repeats.

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Types of Robot Function Application
Classification of Robot (cont)

• Japanese Industrial Robot Association (JIRA)
• Class 5 Numerical Control Robot The operator
  supplies the robot with a movement program rather
  than teaching them manually
• Class 6 Intelligent Robot Robot with means to
  understand its environment and the ability to
  successfully complete a task despite changes in
  the surrounding.

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Types of Robot Function Application
Classification of Robot (cont)

• Robotics Institute of America (RIA) only consider
  class 3-6 as robots
• The Association Francaise de Robotique (AFR)
• Type A Handling devices with manual control to
  telerobotics
• Type B Automatic handling devices predetermined
  cycles
• Type C Programmable, servo controlled robot with
  continuous point-to-point trajectories
• Type D Same as type C, but with the capability
  to acquire information from its environment

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Types of Robot Function Application
Robot Application

• 4A tasks
• Automation
• Augmentation
• Assistance
• Autonomous

• 4D Application
• Dangerous
• Dirty
• Dull
• Difficult

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Degree of Freedom (DOF)

• Six degree of freedom is needed to fully place
  the object in space and also oriented it as
  desired (move rotate along x-, y- and z-axes)
• If fewer than six, the robots capabilities are
  limited
• E.g.
• Robot with three DOF can only move along x-, y-
  and z-axes. No orientation can be specified (only
  parallel to axes)
• Robot with five DOF capable of rotating about
  three axes but only moving along x-, y-axes (not
  z-axes)

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Degree of Freedom (DOF) (cont)

• A system with seven degrees of freedom does not
  have unique solution. There are infinite number
  of ways it can position a part and orientate it
  at desired location. There must be additional
  decision making routine (for the controller) that
  allows it to pick the fastest or shortest path to
  the desired destination.
• Due to this which take much computing power and
  time no seven DOF is used in industry
• Human arms have seven DOF. (Shoulder 3 DOF,
  Elbow 1 DOF, wrist - 3 DOF)
• In robot end effectors never consider as on of
  DOF
• ½ DOF - if movement is not fully controlled (e.g
  only can fully extended or retracted, can only at
  0, 30, 60 or 90 degrees)

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Robot Coordinates

• Robot configurations for positioning the hand are
  as follows
• Cartesian/rectangular/gantry (3P)
• Cylindrical (R2P)
• Spherical (2RP)
• Articulated/anthropomorphic (3R)
• Selective Compliance Assembly Robot Arm (SCARA)
•  
• P Prismatic (linear), R Revolute, S
  Spherical

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Robot Coordinates (cont)
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Robot Workspace

• Robot workspace is the ability of a robot to
  reach a collection of points (workspace) which
  depends on the configuration and size of their
  links and wrist joint.
• The workspace may be found mathematically by
  writing equations that define the robots links
  and joints including their limitations, such as
  ranges of motions for each joint
• Alternatively can be found by subtracting all the
  space it can reach with what it cannot reach.

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Robot Workspace (cont)
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Arm Configuration
A Point for a Cartesian-coordinates Robot
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Arm Configuration (cont)
A Point for a Cylindrical-coordinates Robot
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Arm Configuration (cont)
A Point for a Cylindrical-coordinates Robot (cont)
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Arm Configuration (cont)
A Point for a SCARA Robot
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Arm Configuration (cont)
A Point for a SCARA Robot (cont)
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Arm Configuration (cont)
A Point for a Polar-coordinates Robot
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Arm Configuration (cont)
A Point for a Polar-coordinates Robot (cont)
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Arm Configuration (cont)
A Point for a Jointed-arm Robot
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Arm Configuration (cont)
A Point for a Jointed-arm Robot (cont)