Graduation Year

2008

Document Type

Dissertation

Degree

Ph.D.

Degree Granting Department

Computer Science and Engineering

Major Professor

Rafael Perez, Ph.D.

Co-Major Professor

Kimon Valavanis, Ph.D.

Keywords

Function Generation, Formula Generation, VTOL Control, Automated Helicopter Control, GPS Independent Pilot

Abstract

This dissertation investigates the application of Genetic Algorithms (GA) and Simulated Annealing (SA) based search techniques to the problem of deriving an auto-pilot that can emulate a human operator or other controller flying a Small unmanned Helicopter (SH). A Helicopter is a type of Vertical Take Off and Landing Vehicle (VTOL). The maneuvers are none aggressive, mild maneuvers, that include u-turns, ascending spirals and other none extreme flight paths. The pilot of the helicopter is a Fuzzy logic Controller (FC) pilot; it is assumed that the pilot executes the maneuvers with skill and precision. The FC pilot is given set- points (points in space) that represent a path/flight maneuver and is expected to follow them as closely as possible. Input/Output data is then collected from the FC pilot executing maneuvers in real time.

The collected data include control signals from the FC pilot to the SH and the resulting output signals from the SH that include time, x, y, z coordinates and yaw (the angle of the SH relative to the x, y axis). The Genetic Algorithm/Simulated Annealing based search algorithm attempts to generate a set of mathematical formulas that best map the collected data. The search algorithm presented in this dissertation was implemented in Java and has a JSP (Java Server Pages) graphical user interface. The results obtained show that the search technique developed; termed Genetic Algorithm / Simulated Annealing controller or (GA/SA) controller allows for the derivation of accurate SH control equations. The results include performance quantification of the algorithm in the derivation phase and the testing phase. Graphs are included; they demonstrate the accuracy and path data of the GA/SA controller as compared to the FC pilot and other controllers.

The final results showing the formulas found are also included. A technique was also developed during this dissertation to encode the genetic strings that represent the candidate formulas during the search. This technique allowed the combination of strings to yield new formulas that are valid. The results can be used by other investigators to expand the complexity of the formulas generated during the search. The technique has advantages such as the ability to operate in open-loop conditions and is able to fly the SH without the need for set-point data and without the need for GPS or some other location determination technology. The technique may be used as a backup controller that can take over control of a helicopter in case the main controller is unable to function due to a GPS malfunction or another situation where accurate positioning data cannot be obtained.

Share

COinS