Automated Assembly and AGVs

1. DR3310 – MANUFACTURING TECHNOLOGY
1.0 Automated Assembly and Automated Guided Vehicles (AGV)
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2. Historical Review and Definition
• An assembly line is a
production process
that breaks the
manufacture of a good
into steps that are
completed in a pre-
defined sequence.
• Assembly lines are the
most commonly used
method in the mass
production of products.
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3. Historical Review and Definition
• The work comes to the worker
rather than the worker having
to leave the workstation.
• They reduce labor costs
because unskilled workers are
trained to perform specific
tasks.
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4. Ford and the Model T
The assembly line developed by Ford Motor Company
between 1908 and 1915 made assembly lines famous in
the following decade through the concept of mass
production.
Economy of Scale caused the price of an automobile to fall
drastically, and they weren’t only for the rich anymore.
• Cut in half ($825) in 1908 and down even more ($575) in 1912
• Henry Ford was able to improve other aspects of industry
by reducing labor hours required to produce a single
vehicle, and increased production numbers and parts.
• 12.5 hours versus > 6 hours using assembly line
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5. Ford and the Model T
• The assembly line compartmentalized
tasks.
• People did the same basic tasks over and over.
• Efforts were made to ensure worker
safety.
• Workdays were reduced to 8 hours
(versus 9 h)
• Wages were increased from $2.83 /day
to $5.00 /day!
• That’s 62.5 cents/hour versus 31.4 cents/hour.
Nearly a 100% wage increase without a union!
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6. Ford and the Model T
People soon realized that some of these
simple, repetitive tasks could be done by
machines….
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7. Automated Assembly
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• Automated Assembly refers to a manner of producing goods
by use of automated machinery or assembly robots.
• It is a systematic approach to assembling products that
operates at least partly independent from human control.
• In most cases, automated machinery is used to produce
products using standardized parts added in a specific series
of motions or activities along the assembly line.
• In many technology firms, medical research facilities and
clinical factories, automated assembly is an important part of
the process.
• Less error, better cleanliness, faster, less cost, etc.

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9. Automated Assembly
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• In many factories today, automated assembly is
used to create parts and then assemble a wide
variety of consumer products, from foods to
electronics.
• Workers are on hand to oversee the process and
make sure that the flow of the assembly line is
maintained for long periods of time to maximize the
production of thousands of quality products in the
shortest period of time.
• Much of the machinery used requires careful
calibration and adjustments but does not require
any other human interaction.

10. Automated Assembly
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• Large-scale manufacturing companies use
larger automated assembly processes including
the use of heavy robotic equipment to put
together large products, such as automobiles.
• Assembly systems in these environments are
operated by a central control center by just a
few workers, but otherwise assemble vehicles
independently during this process.

11. Automated Assembly
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• While this form of manufacturing may seem like
it replaces human workers, it has improved
assembly and reduced human injury and failure
rates in many industries, while making vehicles
more affordable for consumers.

12. Automated Assembly Line
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13. Current Status
• Industries served by automated assembly equipment
include aerospace, aeronautics, agriculture,
automotive, computer, electrical, electronics, fiber
optics, food and beverage, furnace and heat treat,
general industry, medical, plumbing, microelectronics
or semiconductor, and telecommunications.
• In 1987, International Standards Organization (ISO)
9000 standards were developed.
• Common certifications for automated assembly
equipment include ISO 9001 and ISO 9002.
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14. Advantages / Disadvantages
• Advantages:
• Assembly using relatively less skilled labor
• Much lower cost in mass production
• Simple repair with interchangeable parts
• Consistent, high quality
• Relieves workers of repetition / monotony
• Higher production rates
• Efficient use of materials
• Efficient handling of parts
• Improved safety
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15. Advantages / Disadvantages
• Disadvantages:
• Large capital requirement, fixed costs
• Initial set up and troubleshooting
• Not suited to custom parts or frequent design changes
(lack of flexibility)
• Not suited to a short product cycle
• Single failure shuts down entire assembly line
• Systems are complex
• If one machine goes offline, entire production may halt
• Benefit of employee input on making improvements is
lost
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16. Classification
Assembly lines can be classified according to:
1. The number of models assembled on the line.
• Distinguishes between a line that assembles a single model (Single-model
Line) and a line which assembles several models simultaneously (Mixed-model
Line).
2. The line pace.
• On the basis of whether they are paced or unpaced.
• In paced lines, a mechanical material handling mechanism links the stations in a rigid
nature and ensures that the product spends a fixed and identical amount of time at
each station.
• In unpaced lines the products spend the time needed to complete the work at the
station and are then moved downstream.
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17. Principal Components
• Assembly systems are usually subdivided into
several logical or physical components to
alleviate complexity.
• The design team usually includes members from
several departments
• Each responsible for one or more components.
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18. Principal Components
One possible break down is given as follows:
• Process design
• Line balance
• Test strategy
• Yield management
• Material Handling
• Maintenance policy
• Work in progress management
• Parts Procurement
• Human Resource
• Line Size
• Line Layout
• Information System
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19. Machine Vision
• Defined as a process of applying computer vision to industrial
application.
• Engineering discipline mainly concerned with industrial problems.
• Machine vision uses digital input/output devices and computer
networks to control other manufacturing equipment such as robotic
arms and equipment to eject defective products.
• One of the most common applications of Machine Vision is the
inspection of manufactured goods such as semiconductor chips
(counting objects), automobiles (searching for surface defects).
• Also applications such as control of Automated Guided Vehicles
(AGVs).
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20. Imaging and Machine Vision Systems
Imaging and Machine Vision Systems can be described as the integration of image acquisition
devices, computers, and imaging software.
The automated manufacturing also requires application-specific material handling, Motion Controllers,
Part-tracking Controllers and sensors, and control software.
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22. • Today's high-speed, complex manufacturing systems require a
machine vision system that can efficiently:
• collect data
• use historical information to provide context
• use the process data for automatic characterization and control of
product quality and the manufacturing process
• By “knowing” what the normal operational parameters are, the control
system can automatically take steps to correct malfunctions detected
(sensed) by the machine vision system.
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Control of Automated Systems

23. Control of Automated Systems
• The System may consist of:
• Image Acquisition Devices - Lighting to illuminate the object,
Optics/Lens to couple the image to a camera sensor, a Camera to
convert optical image to an analog signal, and for automated
manufacturing a Trigger Sensor to initiate the image acquisition.
• Computer – Typically a PC with a CPU (decision-making and
control), an Operator Console (the operator interface), and Imaging
Hardware (typically an analog to digital converter and image
processing). The automated manufacturing also requires an
addition of I/O Interface, Material Handling and communications to
customer process information and control system.
• Software – Operating System Software and Imaging Software (the
user interface, image acquisition and processing, image analysis
and decision-making, historical data collection and analysis).
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24. Artificial Intelligence [AI]
• Traditionally, most industrial assembly is follows an unchanging
program to describe and modify the machine moves.
• This method cannot perform the most complex tasks.
•
• There is an increasing need for integrating sensors feedback into the
automated assembly systems to provide better perception and for
improving the capacity of the machine to reason and make decisions
intelligently in real time.
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25. Automated Guided Vehicles (AGV)
• An automated guided vehicle or automatic guided
vehicle (AGV) is a mobile robot that follows
markers or wires in the floor, or uses vision or
lasers.
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26. • AGVs increase efficiency and reduce costs by helping to
automate a manufacturing facility or warehouse. Allows
transport in areas unsafe for humans.
• The first AGV was brought to market in the 1950s, by Barrett
Electronics of Northbrook, Illinois. It was simply a tow truck that
followed a wire in the floor instead of a rail.
•
• Over the years the technology has become more sophisticated
and today automated vehicles are mainly laser navigated e.g.
LGV (Laser Guided Vehicle).
•
• Programmed to communicate (via an off-board server) with
other robots to ensure product is moved smoothly through the
warehouse, whether it is being stored or shipped.
• Late 1990’s, the port of Rotterdam, in the Netherlands, began
moving ISO shipping containers with AGVs.
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27. AGVs
• https://www.youtube.com/watch?v=XtcLW05wsNo
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28. Classification of AGVs
• AGVS Towing Vehicles, the first
type introduced and remain a very
popular type today. Towing vehicles
can pull a multitude of trailer types
and have capacities ranging from
8,000 pounds to 60,000 pounds.
• AGVS Unit Load Vehicles,
equipped with decks, which permit
unit load transportation and often
automatic load transfer.
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29. Classification of AGVs
• AGVS Pallet Trucks, designed to
transport palletized loads to and
from floor level
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• AGVS Fork Truck, ability to
service loads both at floor
level and on stands or in a
rack.

30. Classification of AGVs
• Light Load AGVS, vehicles
which have capacities in the
neighborhood of 500 pounds
or less and are used to
transport small parts, baskets,
or other light loads though a
light manufacturing
environment. Designed to
operate in areas with limited
space.
• AGVS Assembly Line Vehicles,
an adaptation of the light load
AGVS for applications
involving serial assembly
processes.
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31. Guidance
• AGVs transport an object from Point A to Point B.
• AGVs navigate manufacturing areas by using
sensors.
• There are two main sensor types:
• wired
• wireless
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32. Wired AGVs
• The wired sensor is placed on the bottom of the robot.
• A slot is cut in the ground and a wire is placed approximately 1 inch
below the ground.
• The sensor detects the radio frequency being transmitted from the
wire and follows it.
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33. • Two styles: magnetic or colored.
• The AGV is fitted with the appropriate guide sensor to follow the path
laid out using the tape.
• One major advantage of tape over wired guidance is that it can be
easily removed and relocated if the course needs to change.
• It also does not involve the expense of cutting the factory or
warehouse floor for the entire travel route.
• Colored tape is initially less expensive, but lacks the advantage of
being embedded in high traffic areas where the tape may become
damaged or dirty.
• A flexible magnetic bar can also be embedded in the floor like wire but
works under the same provision as magnetic tape and so remains
unpowered (or passive).
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Guide Tape

34. • Laser Target
Navigation
• The wireless navigation is
achieved by mounting retro-
reflective tape on walls,
poles or machines.
• The AGV carries a laser
transmitter and receiver on
a rotating turret.
• The AGV has the reflector
map stored in memory and
can correct its position
based on errors between
the expected and received
measurements.
• It can then navigate to a
destination target using the
constantly updated position.
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35. • AGV guidance via Inertial Navigation (gyroscope).
• A computer control system directs and assigns tasks to the vehicles.
• Transponders are embedded in the floor of the work place in locations
“known” to the robot.
• The AGV uses these transponders to verify that the vehicle is on
course.
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Gyroscopic Navigation

36. Gyroscopic Navigation
• A gyroscope is able to detect the slightest change in the direction of
the vehicle and corrects it in order to keep the AGV on its path.
• The gyroscope detects the inertial effects of turning.
• The margin of error for the inertial method is ±1 inch.
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37. System Management
• Factories and warehouses using AGVs need to have some sort of
control over them.
• There are three main ways to control and/or monitor the AGVs:
1. locator panel
2. graphics display
3. central logging and report
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38. System Management
• A Locator Panel is a simple panel used to see which
area the AGV is in. If the AGV is in one area for too
long, it could mean it is stuck or broken down.
• Graphics Display shows real time location. It also
gives the status of the AGV. [Ex., its battery voltage,
unique identifier, and can show blocked spots.]
• Central Logging is used to keep track of the history of
all the AGVs in the system. Central logging stores all
the data (history) from these vehicles, which can be
printed out for technical support or logged to check
for “up” time (time functioning without input).
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39. Vehicle Dispatch and System Monitoring
• Systems containing more than one AGV will require it to have traffic
control so the AGVs will not run into one another.
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Methods include
zone control,
forward sensing
control, and
combination control,
each with its
advantages and
disadvantages.

40. Zone Control
• Zone control is most common because it is simple to install and easy to
expand.
• Zone control uses a wireless transmitter to transmit a signal in a fixed
area.
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41. Zone Control
• Each AGV contains a sensing device to receive this signal
and transmit back to the transmitter.
• If the area is clear the signal is set at “clear” allowing any
AGV to enter and pass through the area.
• When an AGV is in the area, the “STOP” signal is sent
and all AGVs attempting to enter the area will stop and
wait for their turn.
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42. Zone Control
The carts can move between stations in this layout without programming and without a central
control system. They direct themselves around the layout by interrogation of floor mounted
route tags and trolley mounted data tags. Destination stations are uniquely identified with a
zone and station number which the cart uses to select the correct path to follow after reading
direction information from the floor at junctions; just like road signs on a highway. They even
know when to give way to other carts so they won’t collide with one another or cause traffic
jams.
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43. • Forward-sensing control uses collision avoidance sensors to avoid
collisions with other AGVs in the area.
• These sensors include: sonic, which work like radar; optical, which
uses an infrared sensor; and bumper, physical contact sensor.
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Forward-sensing Control

44. • Combination control sensing uses collision avoidance sensors
as well as the zone control sensors.
• This setup is better at monitoring and controlling the movements
of AGVs making it more dependable and safer.
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Combination Control

45. AGV Control
• AGVs can be very large and, when in motion, can present
serious dangers to people and equipment.
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46. Safety Issues
• AGV travel paths should be kept clear of materials / objects.
• Employees should be trained not to ride the AGVs.
• Instruct personnel to stay clear of an approaching AGV.
• Weighed cones or other portable obstacles can be placed where workers
may be working on or near an AGV travel path.
• The training program should also include contractors that may come into
a plant or warehouse to perform work.
• AGV travels paths should be clearly marked, including turning areas.
• "Virtual" bumper systems can increase productivity and system flexibility,
and, improve plant safety with regard to object detection/avoidance.
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47. Latest Trends
• This technology has been moving forward.
• There have been advances in navigation systems. (laser guided
systems)
• Obstacle detection systems (Virtual bumper)
• Increased Speed and payload.
• E-Stop [Emergency Stop] - immediately stop if any contact is made
with the bumper, and then wait for the obstruction to move before it
resumes its route.
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