A dissertation submitted to the Faculty of Engineering, University of the
Witwatersrand, in fulfilment of the requirements for the degree of Master of
Science in Engineering. / The requirement of the project was to design an automatic storage and retrieval
system (AS/RS) to be incorporated into a flexible manufacturing cell (FMC) at the
University of the Witwatersrand. This flexible manufacturing cell currently being
developed in the Industrial engineering department consists of a CNC milling
machine and a CNC turning centre supported by an automated materials handling
system, and an integrated computer control system. The automated materials
handling system consists of a loop conveyor, parts transfer device, tool changing
robot and the AS/RS. All the devices of the materials handling system have been
constructed from low cost items readily available or alternatively have been
manufactured at the University. The research philosophy adopted was to produce a
low cost FMC, using local technology and expertise, to produce a system that is both
economically feasible and relatively simple to implement.
The AS/IRS is computer controlled consisting of three axis, driven by direct current
motors. The AS/RS has a storage matrix of sixteen pallets (four by four) and is able
to operate autonomously. The controlling software was written in turbo Pascal and
designed to allow interface with the other material handling devices. The software
allows for future incorporation of scheduling rules such as first in first out, shortest
operating time or a schedule desired by the user. The AS/RS also allows the system
to generate managerial reports on the status of the system as well as feedback to
the FMC supervisory computer.
The design was carried out with the same philosophy used In the FMC i.e, to use
low cost items to provide an economically feasible design that is both flexible yet
simple to incorporate within a FMC.
In conclusion the AS/RS performs the required pick and place function with sufficient
accuracy to ensure that parts are correctly positioned. The controlling program of the
AS/RS functions correctly in terms of controlling the AS/RS. The AS/RS is fully
autonomous in all operations.
The AS/RS has the following specifications :
Value Units
Accuracy 3.67 mm
Repeatability 7.2 mm
Resolution 0.00977 mm
Average pick & place time 41.6 s
X Axis travel 1000 mm
Y Axis travel 640 mm
Z Axis travel 420 mm
Lifting capacity 20 N
Gripping force 10 N
Degrees of freedom 3
The design can be further improved by using stepper motors instead of direct
current motors to provide a finer control in terms of velocity and position accuracy.
A!though the stepper motors need to have the same price for performance characteristics. / AC 2018
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:wits/oai:wiredspace.wits.ac.za:10539/24279 |
| Date | January 1997 |
| Creators | Corsaro, Livio Fabio |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | application/pdf |
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