Title: Chapter 7 Automated MaterialHandling and Storage Systems
1Chapter 7Automated Material-Handling and Storage
Systems
2Agenda
- Material Handling System
- Automated Guided Vehicle Systems
- Automated Storage and Retrieval Systems
- Distributed Computer Control Architecture for
AGVSs and AS/RSs - Conveyors
3Material Handling System
- Definition an integrated system involving such
activities as handling, storing, and controlling
of materials - Objectivematerial in the right amount is safely
delivered to the desired destination at the right
time and at minimum cost - Principles of Material Handling 20 guidelines
for designing and operating material-handling
systems (reading). E.g. unit load principle,
space utilization principle, etc. - Material-handling equipments industrial trucks,
conveyors, AGVSs, AS/RSs, and others (monorails,
cranes, hoists, etc.)
4Automated Guided Vehicle Systems
- Definition an AGVS is a battery-powered
driverless vehicle with programming capabilities
for destination, path selection, and positioning - Materials loading locations ? unloading
locations - Collision avoidance capability
- Communication wire in the floor, radio
- Components
- The vehicle
- The guide path
- The control unit
- The computer interface
5Types of AGVs
6Automated Guided Vehicle Systems
- Management of AGVSs
- AGVS guidance systems low cost change, flexible.
Selection need, application, environment
constraints - Wire-guided guidance system energized wire, the
antenna - Optical guidance system colorless flourescent
particles, photosensors, clean operating
environment - Inertial guidance system a microprocessor, a
sonar system, a gyroscope - Infrared guidance system infrared light
transmitters, reflectors, radar-like detectors,
computer - Laser guidance system a laser beam, bar-coded
detectors - Teaching-type guidance system use neural
network concepts to learn the path
7Automated Guided Vehicle Systems
- Management of AGVSs (cont.)
- AGVS steering control control the turn and
maneuvering. - Differential-speed steer control balancing the
amplitudes of the left and right signals, less
tracking tolerance - Steered-wheel steer control detect the positive
or negative phase of the sensor signal received
from the guided path wire, high tolerance - AGVS routing to take the shortest path
- Frequency select method
- Path-switch select method
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9Automated Guided Vehicle Systems
- Management of AGVSs (cont.)
- AGVS control systems
- Computer-controlled system most efficient,
expensive and complex. - Remote dispatch control system operator uses a
remote control station to send instructions
directly to the vehicle. Automatic load/unload - Manual control system operator load/unload and
enters instructions on the vehicle - Interface with other subsystems
- Subsystems AS/RS, FMS, CNC machines, process
control equipment, shop floor control system - Methods Distributed data processing network,
host computer - AGVS load transfer loading and unloading
operations - Manual load transfer coupling and uncoupling
towed trailers, by folk lift truck, by roller,
manual loading/unloading - Automatic load transfer automatic
couple/uncouple powered roller, belt, chain
powered lift and lower device powered push or
pull device
10Automated Guided Vehicle Systems
- AGVS design features common features to
material-handling and special features must be
considered in the design of AGVSs - Stopping accuracy depend on the applications,
e.g. 0.001 inch for machine tool interfaces - Facilities automatic door-opening devices,
elevators, environmental compatibility - Safety emergency contact bumpers and stop
buttons, automatic warning signals, etc. - Maintenance service manual, Preventive
maintenance (intervals replacement,
condition-based checking)
11Automated Guided Vehicle Systems
- System design of AGVSs
- Attributes for selection of guidance and AGVS
- Methods MCDM, ranking approaches
- Groups of attributes (reading) the vehicle,
vendor support and services - Steps choose a feasible set of AGV models based
on attribute values ? rank - Flow path design often use simulation, determine
- The type of guidepath layout application
- The type of flow path within the layout
controls, economic - The number and location of load transfer points
(P/D station) - Load transfer station storage space
- Number of AGVs required
- Total time/delivery/vehicle
- Number of deliveries/vehicle/h
- Number of AGVs Ndr/Nd
- Where Dd(De) total av. loaded (empty) travel
distance Ndr no. of deliveries required/hr Th
loading and unloading time Tf traficfactor
(0.85 - 1) v vehicle speed
12Example 1
13Automated Guided Vehicle Systems
- Advantages of AGVSs
- Flexibility
- Higher reliability
- Higher operating savings and lower investment
- Unobstructed movements
- Easy interfacing with other systems
- Applications of AGVSs
- Raw material storage
- Finished goods storage
- Assembly operations
- FMSs
- Manufacturing operations
14Applications
15Automated Storage and Retrieval Systems (AS/RSs)
- Definition an AR/RS system is a combination of
equipment and controls which handles, stores and
retrieves materials with precision, accuracy and
speed under a defined degree of automation - Functions An RS/RS attempts to achieve
automatically the storage functions in
cost-effective and efficient manner - Operations
- Automatic removal of an item from a storage
location - Transportation of this item to a specific
processing or interface point - Automatic storage of an item in a predetermined
location, having received an item from a
processing or interface point
16AS/RS Components
- A series of storage aisles having storage racks
- S/R machines
- One or more pickup and delivery stations
17Why an AS/RS?
- Highly space efficient
- Increased storage capacity to meet long-term plan
- Improved inventory management and control
- Quick response time to locate, store, and
retrieve items - Reduced shortages of inventory items due to
real-time information and control - Reduced labor costs
- Improved stock rotation
- Improved security and reduced pilferage
- Flexibility in design to accommodate a wide
variety of loads - Flexibility in interfacing with other systems
- Reduced scrap and rework
- Reduced operating expenses for light power, heat
- Helps implement JIT concepts.
18Types of AS/RS
- Unit load AS/RS standard-size containers, loadgt
500lb/unit, computer controlled, automatic S/R
machines guided by rails - Mini-load AS/RS small loads, small investment
- Person-on-board AS/RS operator rides on a
platform with S/R to pick up items - Deep-lane AS/RS variation of unit load,
multi-deep storage, flow-through rack. Load S/R
machines ? rack-entry vehicle ( a platform)
?storage rack - Automated item retrieval system flow-through,
storerear, retrieve-front
19Design of an AS/RS
- Determining load sizes dimensions of the unit
load (h,l,w) with appropriate clearance
(c1,c2,c3) - Determining the dimensions of an individual
storage space - Height of a storage space h c1
- Length of a storage space l c2
- Width of a storage space u(wc3),
- Normally, the storage space depth (width) u 3
unit loads - Example2 Determine the size of a single storage
space. Dimension of a unit load are 48(w)
x52(l)x52(h). The clearances are
c110in.c28in.,c3 6in., and u 3 - Solution high 52 10 62 in.
- length 52 8 60 in.
- width 3(48 6) 162 in.
20Design of an AS/RS
- Determining the number of storage spaces
- Dedicated storage (fixed-slot storage) policy
each product ? set of slots. Number of slots
?maximum inventory levels for all the products - Randomized storage policy (floating-slot)
probability of S/R are the same for very slot/
product unit. Number of slots max aggregate
inventory level of all products
21Example 3
22Design of an AS/RS
- Determining the system throughput and the number
of S/R machines - The system throughput the number of loads to be
stored and number of loads to be retrieved/hour - Speed of S/R machine
- Mix of single- and dual- cycle transaction
- percent utilization of storage racks
- Arrangement of stored items
- AS/RS control system speed
- Speed and efficiency of the material-handling
equipment used to move loads to the input and
remove loads from the output - Number of S/R machines (system throughput)/
(S/R machine capacity in cycles/h) - Example 4 suppose the single command cycle
system for the S/R machine is recommended. The
average cycle time per operation is 1min. The
desired system throughput is 360 operations/h. An
operation refers to either storage or retrieval
and both take approximately the same time.
Determine the number of S/R machines - Solution number of cycles/h/machine 60, number
of machines 6
23Design of an AS/RS
- Determining the size parameters of the S/R system
(length, width, height) - Determining the number of rows and number of bays
in each row if one machine ? one aisle - Number of rows 2 x number of S/R machines
- Number of bays (no. of required storage
spaces)/(no. of rows/machine x no.of machines x
no. of storage spaces/ system height) - Number of storage spaces/system height desired
system height /storage space height desired
system height 30 90ft - Determining bay width, rack length, system
length, bay depth, aisle unit, and system width - Bay width length of a storage space
center-to-center rack support width (l c2)
c4 - Rack length bay width x number of bays
- System lengthrack lengthclearance for S/R
machineclearance for the P/Darea - Bay depth width of individual storage space
bay side support allowance u(w c3) c5 - Aisle unit aisle width (2 x bay depth)
- System width aisle unit x desired number of
aisles
24Example 4
Using the data from examples 2 and 3, determine
the number of rows and the number of bays in each
row in the system
3
2
25Example 5
2,3 and 4
26Design of an AS/RS
- Determining single- and dual-command cycle times
for unit load AS/RS - Single-command cycle either a storage or
retrieval operation is performed, but not both.
Storage/retrieval cycle is assumed to begin with
the S/R machine at the P/D station - Dual-command cycle assume to begin with the S/R
machine at the P/D station - Assumptions
- Randomized storage policy
- Constant horizontal and vertical velocities
- Single-sized rack openings
- P/D station located at the base and at the end of
the aisle - S/R machine travels simultaneously in the aisle
both horizontally and vertically
27Design of an AS/RS
- Determining single- and dual-command cycle times
(cont.) - Time required to travel the full horizontal
length and vertical height of an aisle - th L/Vh n(l c2)/Vh and tv H/Vv m(h
c1)/Vv - Single-command cycle time
- Dual-command cycle time
- Where L, H length, height of an aisle
- n, m number of bays, storage spaces/system
height - Vh, Vv average horizontal, vertical speeds of
S/R machines - T max(th, tv) and Q min(th/T, tv/T)
- Tpd time to perform either a pick up or deposit
28Example 6
Johnson and Johnson has a unit load AS/RS with 6
aisles. Six S/R machines are used, one for each
aisle. From example 5, the aisle length (rack
length) is 275ft and aisle height is 77.5ft. The
horizontal and vertical speeds are 300ft/min and
70ft/min, respectively. A P/D operation of the
S/R machine takes approximately 0.35min.
Determine the single and dual command cycle times
for a unit load AS/RS of JJ company
29Design of an AS/RS
- Determining the utilization of S/R machines
- The number of transactions/(S/R machine)/h
- nt ST /N
- Where
- ST system throughput (no. loads to be stored
and retrieved/h) - N number of S/R machines (one machine, one
aisle) - The workload/(S/R machine) ?ntTsc ?(nt/2)Tdc
(min/h) - Where ? percentage of operations done by sc
cycles - ? percentage of operations done by
dc cycles - number of storages number of
retrievals in long run
30Example 7
Suppose the system throughput is 300 storage and
retrievals per hour. The AS/RS has 10 aisles and
each is served by one S/R machine. Furthermore,
30 of the operations are performed as
single-command and the rest as dual-command
operations. Determine the utilization of the
machine. Other data from example 6 apply to this
problem. Determine the number of transactions at
which the S/R machine is 100 utilized
31Distributed Computer Control Architecture for
AGVSs and AS/RSs
- Central control and distributed control? control
the flow of materials and information - Objective ensure the automated systems keep
running even if a control component fails - Distributed control system for integration of
various components (AGVS, AS/RS, FMS) - Advantages
- Maintenance at level
- No large central computer
- Flexible expansion
32Conveyors
- A conveyor is a convenient and cost-effective
means of moving materials over a fixed path - Types of conveyor2 types according to
- type of product to be handle bulk or unit
- Location of the conveyor overhead or floor
- Conveyors are designed to meet specific
application requirements