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Final Year Projects Academic Year 2011/2012

A VERY FAST, LINE-FOLLOWING WHEELED MACHINE ADAPTED TO IMITATE AIRCRAFT LANDING SYSTEMS

Student: Matthew Borg
Supervisor: Prof. Carmel Pulé

2012_A1

Introduction
In bad weather such as in  heavy fog pilots have to rely on instruments to land an aircraft since their visibility is greatly impaired. It could be very useful if there would be a  system that follows visible and invisible line contours to help the pilots  especially during landing.

Project Objectives
The aim of this project is  to synthesize a machine which would move horizontally on the floor following a painted curve which would simulate an aircraft closing in to the centreline of  the runway. In this project only the localizer which provides lateral guidance  to the aircraft was simulated.

Project Methodologies
The project was tackled as  follows:
• First a literature review on Instrument Landing Systems  was done along with researching ways in which this wheeled machine could be  built electrically and mechanically for best performance.
• Designing the electronic circuitry required and simulating  how it would perform when built. In a nutshell, the circuit consists of a sensor comprising of 8 LDRs which indicate the position of the line. Using the  sensor’s output the distance from the centreline could be calculated. This is  then fed to a controller which determines the best way how to drive the motors  in order to improve the response and reduce oscillations as far as possible.  Then the motors are driven using Pulse Width Modulation (PWM) which increases the efficiency of the system by up to 30%. The system is powered by four 3.7V  3000mAh Lithium-ion batteries which have a larger energy density compared to  other batteries and are also much lighter.
• Then the circuit was built on a prototype board and  tested. After successfully testing the circuits, a PCB was designed to make the circuits permanent.
• Finally the controller was tuned to give the best  performance possible.
 
Results and Achievements
A stable and reliable system was obtained in  which the machine followed the line painted on the floor accurately and at a reasonable speed. The machine may show some difficulty in tackling sharp  corners because of its speed however it follows straight lines and moderate  curves very well.

   
   

DESIGN OF AN EMBEDDED SYSTEM FOR GPS & IMU DATA FUSION

Student: Andrew Terry Buttigieg
Supervisor: Paul Zammit

2012_B

Introduction
Multiple Sensors  often can measure the same or similar parameters, each with its own accuracy,  limitations and error characteristics. What if accuracy can be improved, if  these sensors could be merged [1]. In this case two distinct navigation  sensors GPS (Global Positioning System) FV-M8 and IMU (Inertial Measurement  Unit) ADIS16350 are combined exactly for that purpose. The aim of the project is  to develop a platform capable of fusing data from both navigation sensors to  achieve better estimates of Position, Velocity and Acceleration, than possible  with each individual sensor alone.
   
Project Objectives
The main objective was that of building an  embedded system for IMU and GPS data fusion, this main objective is subdivided  in the following parts:
    • Design of  electronic circuitry capable of interfacing GPS and IMU to a central processor.
    • Prototyping of the system, on a printed circuit board – design, manufacture and assembly.
    • Development of Firm-ware to operate system, and communicate to a host system such as a personal computer.
    • Testing and  Utilizing the system to obtain data sets for the Data fusion process.  
   
Project Methodologies
The primary step  of the project involved researching and understanding the sensors utilized, and  of reaching to a conceptual model of how these can be combined. (See figure 2)  The secondary step was the actual electronic design of the system with rigorous printed circuit board specifications and tolerances in mind. Thirdly the  manufacture of the printed circuit board was carried out via an international  company called PCB-Pool®. (See Figure 1).
Soldering of  components on the PCB (Printed Circuit Board) was then carried out.  Lastly firm-ware was developed, programmed  and debugged. The system was made operational ready to be tested out with data  fusion algorithms[2].  

Results and Achievements
The whole design  was completed, the printed circuit board manufactured and preliminary tests  carried out. Difficulties were encountered in the actual soldering of  components, due to the small dimensions and these being done by hand. The  voltage supplies of circuit where stabilized and the next stage was to test out  the MCU (micro-controller unit), Firmware programming of the MCU and then connection  of the platform to the PC (personal computer) over serial link.
   
References
[1] Hall. L. David Senior Member IEEE and  Llinas James, ‘An Introduction to Multisensor Data Fusion’ Proceedings of the  IEEE, 1997, Vol. 85, No. 1, pp.[6 - 23]
[2] Crowley James L. and Yves Demazeau,  ‘Principles and Techniques for Sensor Data Fusion’ LIFIA (IMAG), 1994, Research  Paper F-38031 Grenoble Cedex, France, pp.[1-39]

 

 

DISPLAYING 3D  TRANSIENTS IN INVERTERS AND NETWORKS 

Student: Gordon Camilleri
Supervisor: Prof. Carmel Pulé

2012_C

Introduction
Inverters are an efficient and  convenient sources of AC power, be it a fixed frequency application or one that  requires variable frequency. Electrical signals in the inverter itself can be  interpreted in a three dimensional from. These three dimensional displays of the output of the inverter, would from a transient set which would have their  limit bounded by two circles of different diameter, whereby the output is  assured to be a smooth sinusoidal waveform.
           
Project Objectives
The final goal of this thesis is  to obtain the circle boundaries as close together as possible to minimize  harmonics. This will be done using different types of switching. While  explaining such types, the use of both theory and software is to follow.
           
Project Methodologies
This  thesis is mainly organized as follows:
First, a study is made on the  types of switching and the effect these have on harmonics and transients. The  output waveforms are to be plotted on an oscilloscope in the X-Y domain and a  circular output is expected. Depending from the shape, distortion and orientation of such an output, one can determine the characteristics of such a  switching type.
An inverter uses switches in  order to produce the output required. It uses a type of modulation in which the  switches are switched on and off in an orderly fashion to produce a sine wave.  If turned on and off only once in each cycle, a square wave waveform results. However, if turned on several times in a cycle, an improved harmonic profile  may be achieved. The types of switching and control in inverters are discussed.
Secondly, BBC BASIC and MATLAB/SIMULINK models are built in the dq-axis  rotor reference frame. The Stator Flux trajectory is discussed and understood.
As a final goal, the proposed direct torque control of the induction  motor method is developed in MATLAB/SIMULINK using the rotor reference frame  with the help of inexpensive hall-effect sensors without using any DC-link  voltage sensing.
           
Results and Achievements
Since this thesis is mostly  theoretical and research based, almost all results are produced by simulation  with software. Various programs were written using two different kinds of  programs: BBC Basic and Matlab/Simulink. Also, a PCB needs to be developed in order to show a mimic of the current trajectory that would be seen at the  current output of a motor. The following chapter is divided into three  sections, each section explaining what program was used and what was simulated.
           
References
[1] Chiu-king Ng. Lissajous Figures. [Online]. http://ngsir.netfirms.com/englishhtm/Lissajous.htm.
[2] D.Casadei, G.Serra G.Buja, "Direct Stator Flux and  Torque Control of an Induction Motor: Theoretical Analysis and experimentation  results," Proceedings of the IECON '98, pp. T50-T64, 1998.
[3] D. Wang K. Zhou, "Relationship Between  Space-Vector Modulation and Three-Phase Carrier-Based PWM: A Comprehensive  Analysis," IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, vol. 49,  no. 1, February 2002.
[4] Microchip, "Sensorless Field Oriented Control of  PMSM Motors," AN1078, 2008.
   

         

LOW POWER PIEZOELECTRICITY ENERGY HARVESTING

Student: Jason Caruana Camenzuli
Supervisor: Prof. Ing. D. Zammit Mangion
Co-Supervisor: Ing. Evan Dimech

2012_D
            
Introduction
Harvesting small amount of energies from environmental  sources to power portable or remote electronic devices which work in the mW range has been the incentive for carrying out this thesis.  Even though the main materials  available that are capable of energy coupling have been around for decades,  their harvesting capabilities haven’t been examined until recent years.  Only recently have electronic devices  evolved in a way so that their power requirements have gone down and the gap  between energy scavenging from environmental sources and power requirements has  narrowed.

Project Objectives
Analyzing and  investigating present energy harvesting solutions.  
Designing and  developing methods to enhance the power output of a piezoelectric energy  harvesting device to power an autonomously/partially powered automotive  electronic sensor.  

Project Methodologies
The thesis starts with an  investigation of present power harvesting technologies available for harvesting  from the different types of energy source, including solar, thermal and the  various types of mechanisms to harvest from vibrations detailing power output  levels found from literature.
Following this, reasons for  focusing on piezoelectric conversion of vibration energy were outlined and an  overview of the piezoelectric concept and materials was introduced. A view of the technological contexts with  approaches to power enhancement of piezoelectric generators was given.
The thesis then progressed to  studying methods of enhancing the power output of a piezoelectric energy  harvesting device. Through initial  investigation, the power output of a prototype device using a simple test setup  was observed.  A computer-based optimization  algorithm was developed with Matlab to predict outputs and optimize the device.
The second part concerned the  harvesting circuitry. Initial investigations were performed using the prototype  harvesting device and a bridge rectifier circuit. The operation was also analysed via circuit  simulation.  The mechanisms that limit  power from being transferred from the harvesting device to the load were  observed and analyzed from the simulation.   Following this, a new harvesting circuit concept was proposed. The new  concept comprises: a Synchronised Switch Harvesting on Inductor (SSHI) functional block, which boosts the output voltage of the piezoelectric  generator; a ‘storage’ functional block, and a ‘DC-DC converter’ block which  can provide regulated DC power to an end application system. In figure A, the block diagram shows the  relevant blocks and connections.
A prototype circuit that can  implement the concept was designed and built, using a mixture of discrete and  integrated components, and the performance of the concept was assessed through  an experimental and simulation approach.

Results and Achievements
Both the  analytical model simulation and new harvesting circuit concepts provided  methods of enhanced power output.  The  model helped in designing for the optimized parameters of the material.  The new circuit concept provided an approximate  of 80% more energy harvested into storage over the commonly used bridge  rectifier.  At the time of writing the  circuit is now being compared to other techniques found in literature to verify  its efficiency.

   


AN ASYMMETRIC DATA TRANSCEIVER SYSTEM FOR A U.A.V.    

Student: André Cilia
Supervisor: Ing. Marc Anthony Azzopardi

2012_E

Introduction
Long distance communication has been a  challenge for humanity for millennia. Radio technology can provide long  distance transmission and reception of data. However, it is difficult to give a  direction to radio signals, and a lot of power is required to achieve  successful reception at long distances. Free space optical communications solve  this problem by using lasers. Their narrow beam contains all the power required  for long distance transmission and the signal to be transmitted.

Project Objectives
The aim was create a highly directional  network between two data terminals (a U.A.V and a ground station), through  which data and commands can be transmitted and received as shown in Figure 1.
The directionality of the network ensures  that the power used to transmit the required data is used as efficiently as  possible by directing it only where this is required [1].
This directionality also has the added  advantage of making the system practically tap-proof. In fact for an  eavesdropper to successfully gather any information, he must be located across  the beam. Also, such activity is easily detected, since the transmission of  data is interrupted or severely hampered.
     
Project Methodologies
The whole project was subdivided into the  following categories:
      • Conducting a Literature  review of other similar works was conducted so as to find the best way to  implement this system. Hence a list of sub-divisions required for successful  transmission and reception was created as can be seen in Figure 2.
      • Creating a test  to ensure that Ethernet works on a directional cable pair.
      • Designing and  simulating the required circuitry for the different sub-sections.
      • Designing and  etching the boards implementing the designed circuitry.
      • Testing the  individual subsections to ensure correct operation at the required frequencies.
      • Connecting a  network between two computers or a computer and a network webcam.
     
Results and Achievements
Signals ranging from 3MHz up to 25MHz have  been successfully transmitted and received. The signals transmitted and  received are square-wave signals (hence confirming operation at least up to  75MHz, three times 25MHz). Hence 10Base-T frequencies and 100Base-T frequencies  are covered. 100Base-T need a minimum of 31.25MHz [2]
     
References
[1] Lakhra S., Sharma D. P., Singh J., “Study of Laser Based Transmission/Reception  Parameters Under Fading Conditions”, Instrument Society of India,  Hyderabad, India, 2003.
[2] IEEE Computer  Society, “IEEE Standard for  Information technology — Telecommunications and information exchange between systems — Local and metropolitan area networks — Specific requirements Part 3:  Carrier sense multiple access with Collision Detection (CSMA/CD) Access Method  and Physical Layer Specifications”, IEEE, New York, USA, 2008.


   

THE USE OF A  ROTATING VANE CAPACITOR TO DETECT A TARGET POSITION    

Student: Christopher Cusens
Supervisor: Prof Carmel Pule’

2012_F

Introduction
Even with the development of new technologies, such as the Global Positioning  System, sonar remains one of the primary uses for detecting objects located  underwater. The increase in terrorist attacks has given rise to the need for  enhanced protection. A subsurface attack can have devastating results, thus the  detection of any threat is of utmost importance. The use of a module that can  detect the position of an enemy vessel during surveillance operations could  come as a great advantage.
   
Project Objectives
There are three main aims to this project.  The first aim is to investigate and study the various types of capacitors and  oscillators available in order to identify the most suitable setup. Following  this, the development and construction of a device capable of detecting the  angular position of a threat/target is to be implemented. Finally, the  appropriate circuitry shall be designed and tested in order to display a  positional result in a digital format to the user.
     
Project Methodologies
The methodology  implemented in the project is essentially divided into the below stages:    
      • Literature Review – This was carried out to  in order to obtain a better understanding of the task at hand. The literature  survey provided a better understanding of the different types of transducers  available. Each component to be used in the final design was thoroughly researched in order to gain optimum performance.
      • Design of the Capacitor – Equations  that relate Position to Capacitance and Frequency led to the appropriate shape of the capacitor to be used. A prototype was built to simulate and gather  results.
      • Oscillator Design – Different RC and LC oscillators were studied. The LC oscillator was chosen to produce the frequency required from the variable capacitance.
      • Converter and Microcontroller Implementation – A suitable converter was chosen to change the varying frequency to a varying voltage. The voltage was then fed to a microcontroller input and with the use of an appropriate algorithm, an output that shows the angular position of the capacitor plates was given. This output is presented on a digital display.
     
Results and Achievements
Once the construction of the capacitor was  complete, the capacitance was measured for varying angular positions. The capacitor was connected to the oscillator, which in turn produced a varying  frequency. Figure [2] shows how frequency varied in a linear fashion along a  large portion of the 360° revolution.
Non-linearity was displayed towards the extremities  due to stray capacitances. This was the main limitation of the project. However, this could be overcome by manipulating the microcontroller’s  algorithm. As a result, a wider range of the 360°  intervals could be digitally displayed.

     
   

ACQUISITION AND TRACKING FOR UAV COMMUNICATIONS      

Student: Andre Micallef
Supervisor: Ing. Marc Anthony Azzopardi

2012_G

Introduction
Nowadays UAV’s  have gained a lot of importance due to their efficiency and flexibility. Most  of these vehicles are equipped with Radio Frequency links which are rather  inefficient and slow when it comes to signal transmission. A free space optical  link would be ideal for such use. However due to its high directionality this  requires a system to automatically point and track the laser beam to ensure  data connectivity between two points.
     
Project Objectives
The main  targets are to gain knowledge on free space optical communication systems  whilst also designing and implementing a simple hardware solution capable of  maintaining an optical link between two points.
   
Project Methodologies
In the initial  stages a literature review was done to search and explore any previous work  done in this field. This was followed by a thorough research and analysis to  determine which configuration is best based on resources available. It was decided to opt for a 2 DOF gimbal while tracking was to be based on beam directionality. Moreover a project plan was drawn for the  following stages of work, leading up to a finished product.
The final set-up consists of 4 main thematic areas, with each being further divided into market and feasibility search, development, and finally implementation and testing.
The first  component is the sensor, which is responsible of detecting the direction of the  incoming beam. This sensor ideally has to be used with an optical set-up  capable of projecting the beam onto an image plane as a spot.  
The second block is the processing part. Here is where the data is being processed for both  tracking and acquisition in high speed so that the motors are actuated accordingly. Last on the loop are the drivers. These must be responsible for the current modulation required by the stepper motor, including any safety features required.
Another  important part is the mechanical and optical section. An extensive research was  done in regards to optical engineering, and specifically Gaussian laser optics.  An in depth review of the theory involved was done together with utilization of  optical simulation software for design purposes.

Results and Achievements
Needless to say  each section was implemented in hardware separately after thorough simulation  and testing. A separate module for each component had to be designed,  manufactured, assembled and tested under different conditions to ensure reliability  and thus proof of concept. All different blocks have worked so far and have  shown exceptional results even in extreme conditions. A final product was then  designed and built incorporating every section into one holistic product. At  this time of writing the product is being tested thoroughly.    

  
   

GNSS LOCAL AREA AUGMENTATION SYSTEM

Student: Nathaniel Ebejer
Supervisor: Dr. Ing. Andrew Sammut  

2012_H

Introduction
A Global Navigation Satellite System  (GNSS) is a satellite based technology that provides position, velocity and  timing information of a receiver. The Global Positioning System (GPS) that is  used in this project consists of 24 satellites orbiting the Earth. The navigation solution of a receiver is calculated using the positions of these  satellites and the ranges between them and the user. These measurements are however corrupted by a number of errors such as clock offsets, atmospheric delays and random noise, contributing to an error in the receiver’s GPS derived position. One technique to compensate for these errors is a Local Area Augmentation  System (LAAS). This is a Differential GPS (DGPS) technique that improves the performance of a standalone receiver by factoring out the common-mode error  experienced by a fixed reference station and a roving receiver. This technique is applicable where the range between the reference station and receiver is below 100km and is therefore ideal for the Maltese scenario.  
     
Project Objectives
  • Analysis of the basic GPS principles and Differential GPS  techniques.
  • The selection of two GPS receivers providing the data required to calculate a standalone navigation solution.
  • The implementation of an algorithm that calculates the position for a standalone GPS receiver using Matlab.
  • The setup of an internet link between the base station and rover station.
  • The calculation and transmission of corrections by the base station and the application of these corrections by the rover station.
  • The implementation of a Kalman filter to provide a further  improvement to the differential correction.
 
Project Methodologies
A Ublox GPS receiver was configured in  Matlab and communication was performed using the Instrument Control Toolbox  (ICT). Once a GPS packet is received the satellite positions and ranges are  calculated, hence obtaining a navigation solution. A residence in Attard was  chosen as a fixed reference station whilst an office in Marsa was chosen to act  as a rover station, separated by approximately 6km. An Internet link was setup  between both stations also using the Matlab ICP and the UDP protocol. When the base  station performs the standalone calculation, the satellite range corrections  are calculated using a predetermined set of equations. These corrections are  transmitted to the rover station over the Internet, which once acquired by the  rover are used to obtain a more accurate navigation solution. An adequately tuned Kalman Filter is then used to further improve the estimate of the rover’s position.
     
Results and Achievements
One can  interpret the most significant results of this project as addressing two  position error components which are systematic offsets and random noise. The  differential algorithm reduced the offset and standard deviation whilst the  Kalman filter dealt with the residual random noise. In fact, the standalone  calculation resulted in a standard deviation of 5.96m and an offset of 6.91m. The differential algorithm improved this to a deviation of 1.62m and an offset  of 0.11m. The Kalman filter further improved this solution to a standard deviation of 0.5m as seen in Figure 1.

 

TERRAIN AIDED  NAVIGATION FOR TERCOM UAV/MISSILE GUIDANCE USING FPGA

Student: Barnaby Portelli
Supervisor: Ing. Marc Anthony Azzopardi

2012_I

Introduction
A major part of the navigation problem is obtaining an  accurate position of the aircraft with respect to the surrounding environment. One way to go about this problem is Global Navigation Satellite Systems (GNSS)  such as GPS. The drawback of this technology is that the satellite signals can  be jammed during wartime and in some environments the signal is unavailable. Terrain Aided Navigation (TAN) is a different approach that compares the  terrain with a stored digital elevation map to obtain the position.This system is not dependent on external devices and is very hard to block.

Project Objectives
The main objective of the project is to design and simulate alternative ways for the TAN problem. These algorithms are implemented over a  Digital Elevation Map (DEM) of the Maltese islands shown in Figure 1, as they are aimed for future implementation on a UAV that surveys the islands. The algorithms are to be simulated on MATLAB and later implemented on an FPGA in  order to obtain the speed requirement for such system.

Project Methodologies
The project is divided in four stages. The first  stage is research on the current systems with detailed analysis of  disadvantages and advantages. The second state is to analyse alternative  approaches and simulate a 2D model of the system to show its effectiveness. In  this part alternatives to the common iterative trilateration algorithm are  implemented and tested. The algorithm is them converted to 3D space and tested over the Maltese Islands. The final step is to convert the system to VHDL and  using the parallel advantages of this system to obtain a fast system response.
 
Results and Achievements
A system that utilizes system a trilateration and  innovative positioning technique has been successfully implemented. The MATLAB simulation was tested over a DEM of Malta and the continuous increasing  inertial error was corrected. Demanding parts of the algorithm have also been implemented on the COM1500 FPGA development board resulting in an increase time performance.
 
 

AN FPGA BASED INSTRUMENTATION SYSTEM

Student: Stephane Role
Supervisor: Ing. Kenneth Chircop

2012_J

Introduction
Oscilloscopes and signal generators help  resolve the mysteries behind electronics. The most commonly used CRT  oscilloscopes are being replaced with their digital brothers. Digital  oscilloscopes and instrument boast a number of advantages over fully analogue systems. The size of the equipment as well as the functionality of the  instrument has greatly improved. These equipment help engineers daily test, fix  and design complex circuitry. Having both of them combined on a small portable PCB can improve the quality of life for engineers. [1], [2].
 
Project Objectives
The aim of the project is to design and  develop an instrumentation system on an FPGA board. The system should include  an oscilloscope and a signal generator. The board should communicate with a PC  system to display the data on a monitor. The board should also be able to change the frequency and voltage scales as well as the signal generator's type (square  or sine wave).
 
Project Methodologies
The project was divided into six different  phases:
  • Literature review  and research on the components needed to carry out such a system
  • Development of analogue circuitry to interface signals to the analogue to digital converters  and the digital to analogue converters.
  • Devising the FPGA interfaces and input/output modules.
  • Designing a PCB board layout.
  • Research, Design, Development and test the full FPGA system.
  • Development of a C++ program to display the results and provide a user interface.

Figure 1 shows  the simplified PCB diagram. The ADC samples the analogue circuitry and converts  the voltages to digital values. The digital values are selected by the FPGA and  sent to the PC using a Serial (UART) to USB integrated circuit. The PC sends data to the board through the same interface to control the many functions  which are generally found on an oscilloscope such as; the triggering voltage, oscilloscope timescale, the voltage gain, the signal generator frequency, the  type of waveform (sine or square) and the signal generator amplitude.
The board has to display the oscilloscope readings on a screen of  512x1024  pixels. Therefore to populate the screen an  ADC of at least 9-bits (512) is needed. The ADC has to operate at least  twice the frequency of the highest frequency waveform according to the Nyquist theorem.
 
Results and Achievements
The analogue circuitry was simulated and  tested in the lab. Also a number of FPGA modules have been hardware tested on an FPGA development board. Hardware testing involves the writing of physical modules to send the required data to the modules being tested.

References
[1] J.Miguel Dias Pereira, The History and Technology of Oscilloscopes, IEEE, 2006
[2]  http://www.radio-electronics.com/articles/test-measurement/developments-in-oscilloscope-technology-an-36


REAL TIME GROUND VEHICLE NAVIGATION SENSOR

Student: Kevin Theuma
Supervisor: Prof. Ing. David Zammit Mangion

2012_K

Introduction
Most automotive navigation systems such as  the Global Positioning System rely on satellites. Unfortunately these systems  can reach inaccuracies of up to 10m due to sources of errors mainly those from satellite geometry, satellite orbits, multipath effects, atmospheric effects, relativistic effects, clock inaccuracies and rounding errors. Technologies such  as Assisted GPS, Differential GPS, Wide Area Augmentation System and Local Area Augmentation System attempt to reduce these errors. However these systems struggle to provide centimetric accuracy and ones which do are expensive.
 
Project Objectives
The aim of this project was to find a  cheaper solution with which a vehicle can be controlled. An image retrieved  from a CCD camera had to be analysed in real-time by an FPGA in order to  identify the road line and calculate its angle and off track error. This information had to be used to control the vehicle so that it followed the road  line.
 
Project Methodologies
The project was organised in the following  manner. First, research on different algorithms and mathematical procedures  relevant to the project was done. The advantages and disadvantages of these  algorithms and procedures were compared to each other. Most attention was given to the results they produce and their execution time. The best solutions for the project were chosen and they were combined together to construct a prototype on  Matlab. This prototype was tested using different images together with additional effects such as change in contrast, change in brightness and blurring. Figure 1 shows the curve fitting for one of the input images. From the results it was possible to identify the strengths and weaknesses of the program and hence improve it. After applying changes, it was tested once again in order to know its limitations when using it in practice. Once the prototype was fully finished, the Matlab code was ported to the Spartan 3E 1600E development kit which can be  seen in Figure 2. The FPGA design was programmed in VHDL using Xilinx ISE. The project was simulated using the inbuilt simulator. The results of simulation were compared to those of Matlab and it was made sure that they were identical. Then the project was synthesized and tested on the actual hardware using Chipscope in case of any  differences due to timing.
 
Results and Achievements
In this project different algorithms and  mathematical procedures were combined together to produce a real-time system.  These components can be used as low cost solutions for other real-time  applications because they can be integrated into devices like FPGAs and  microcontrollers.


OBSTACLE  AVOIDANCE OF AN UNMANNED VEHICLE

Student: Joseph Vella Wallbank
Supervisor: Dr. Ing. Andrew Sammut

2012_L

Introduction
This work deals with the problem  of autonomous control of a ground vehicle, specifically the issue of path  planning. Solutions have been considered with an emphasis put on the technique  known as Artificial Potential Fields (APF) for navigation of autonomous vehicles. The mathematical formulation of the APF has been explored and an  implementation of a navigation controller has been programmed on a PC. This  work continues with the design of a real world test setup and describes the  issues considered when implementing navigation of unmanned vehicles. The setup  consists of a simple obstacle course to be run by a radio controlled ground vehicle.  An overhead camera allows the  controller to monitor the progress of the vehicle and issue commands over a  wireless link to guide the vehicle around the course.
 
Project Objectives
To test  the viability of APF in a real world scenario the following objectives had to  be achieved:
  • Building a ground vehicle that can be controlled over  wireless link.
  • A program capable of extracting the location of the vehicle,  the end point and any obstacles within an image.
  • Implementing the APF algorithm as a program able to issue  commands to the vehicle so as to complete an obstacle course.
  • Building an obstacle course for the vehicle to traverse with  a camera above the setup providing images for the program.
 
Project Methodologies
Due to  the specifications required it was decided to construct the vehicle using  discrete electronics connected on a PCB.   The PCB was attached to a piece of acrylic plastic and two motors were  mounted underneath, the motors were equipped with encoders so that the speed  could be monitored and adjusted accordingly. A controller program was coded in  C++ which monitored the test setup using an overhead camera. From the camera  the locations of the objects were found, and using an APF algorithm [1] directions  could be passed to the vehicle over the wireless module allowing it to complete  the obstacle course.
 
Results and Achievements
The results  from this project show that the controller program is able to extract objects  from an image, establish the location for each of the objects and pass this  data onto an APF algorithm. The APF indicates in which direction a ground vehicle should travel to reach the destination. Full control over the vehicle  was achieved with the ability of driving each motor at any speed and altering  it on the fly.
 
References
M.A.  Goodrich Potential Fields Tutorial [online  PDF] Available:
http://borg.cc.gatech.edu/ipr/files/goodrich_potential_fields.pdf

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Last Updated: 20 November 2012

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