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Hardware and software development of the Anglescan tracking system


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Dirita, Vito 1994 , 'Hardware and software development of the Anglescan tracking system', Research Master thesis, University of Tasmania.

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In this thesis, the author describes all the developmental work of an automated surveying
tracking theodolite referred to as The Anglescan Tracking System. This system consists
of an optical system, an electronic system (with detailed schematics and printed circuit
artwork, included) the software system which is approximately 100 pages of C source
code, system identification and controller simulation, modelling and design, and finally
instrument calibration and testing effort over a 2 year period.
The project is a collaboration between the Department of Electrical and Electronic
Engineering and the School of Surveying at the University of Tasmania. It is supported
by an ARC university research fund granted to the School of Surveying over a two year
The initial investigation into the feasibility of the project was carried out by Dr. A. Sprent,
then at the North East London Polytechnic (Sprent, 1.12). During this time the optical
system of the instrument was developed. Following this investigation, it was decided to
further undertake the continuation of the project as a Master's Degree in order to develop
the electronics, measurement, tracking and control software.
The Anglescan system is similar to a standard surveying theodolite mounted on a tripod
and capable of determining the position of a retro-reflective mirror based within the
instrument's field of view with respect with its optical centre of field (in both azimuth and
elevation planes). This involves a new and different technique for target location than the
currently existing electronic theodolites (see sections 1.5, 1.6).
One of the main advantages of this method is the improved target locating accuracy, it has
been field tested with an accuracy of +1-1 second of arc, and simplicity in optical design.
The disadvantages however include increased complexity of both the hardware
(electronics), software, and calibration involved.
The instrument deviates from a standard theodolite in that it has been fitted with precision
DC servomotor drives on the azimuth and elevation axes for target tracking. The
servomotors also include optical rotary encoders for measurement..
While tracking, the system operates by continuously locating the target mirror with
respect to its centre of field of view, then applying a feedback control signal to the
azimuth and elevation motors in order to re-centre the instrument directly onto the target,
this is updated at a rate of 30 samples/second. Part of the objectives of this work is to design the necessary hardware and software to
achieve this task, this includes the design of a return (laser) analog signal processor card,
the design of a target position measurement card, and azimuth/elevation servo motors
interface cards (azimuth card and elevation card).
Furthermore, the project also requires the design of an appropriate target acquisition and
control loop strategy to allow smooth and accurate tracking of a moving target. A number
of control system designs have been investigated, including proportional control, pole
placement design and linear quadratic control. We have also used system identification
techniques to obtain an accurate model of the plant which is necessary for controller
design and simulation.
To achieve the high precision required in measurement, it is necessary to calibrate the
instrument. The calibration method is a complex procedure which uses least squares
techniques to produce the required calibration accuracy (this is discussed in detail in
section 5).
The instrument finds applications in areas such as monitoring earth movements, motion of
large structures such as building and bridges, locating earth working machinery such as
tractors, bulldozers, graders, concrete and asphalt paving machines where an accurate
level surface is required.
Another application of particular interest is in surface contour mapping where we require
to map a 3 dimensional surface (obtain the surface contour or topography), this
application is a slightly more complex problem requiring the use of two instruments, this
then becomes a multivariable control problem. As a result of this research work, one paper was presented at the IREECON -91
conference in Sydney and is published in the proceedings [Dirita 1.13]. Another paper
was presented at the CONTROL-92 conference held in Perth in November 1992 and is
published in the proceedings [Dirita 4.4].

Item Type: Thesis - Research Master
Authors/Creators:Dirita, Vito
Keywords: Theodolites
Copyright Holders: The Author
Copyright Information:

Copyright 1994 the Author - The University is continuing to endeavour to trace the copyright
owner(s) and in the meantime this item has been reproduced here in good faith. We
would be pleased to hear from the copyright owner(s).

Additional Information:

Thesis (M.Eng.Sc.)--University of Tasmania, 1995. Includes bibliographical references

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