DESIGN, MODELLING AND CONTROL OF AN AUTONOMOUS UNDERWATER VEHICLE Louis .
DESIGN, MODELLING AND CONTROLOF ANAUTONOMOUS UNDERWATER VEHICLELouis Andrew GonzalezBachelor of Engineering Honours Thesis 2004Mobile Robotics Laboratory,Centre for Intelligent Information Processing Systems,School of Electrical, Electronic and Computer Engineering,The University of Western Australia.SupervisorAssociate Professor Thomas Bräunl
Letter of TransmittalLouis Gonzalez12 St John RdWattle Grove WA 610731st October 2004The DeanFaculty of Engineering, Computing and MathematicsUniversity of Western AustraliaCrawley WA 6009Dear Professor Mark Bush,It is with great pride and honour that I submit this thesis entitled Design, Modelling andControl of an Autonomous Underwater Vehicle to the University of Western Australia aspartial fulfilment of the requirements for a degree of Bachelor of Engineering with Honours.Yours Faithfully,Louis Gonzalez
For CIIPS and the Mobile Robot LabThomas, I hope that the founding of Project Mako will begin a long running tradition forthe Mobile Robotics Lab with many students eager to participate in this exciting and rewarding ongoing underwater project every year.It has been a sheer pleasure in establishing and participating in UWA’s first ever AUVproject and developing one of the largest and most distinctive robotic vehicles to havecome out of the laboratory.
AbstractAutonomous underwater vehicles are currently being utilised for scientific, commercialand military underwater applications. These vehicles require autonomous guidance andcontrol systems in order to perform underwater tasks. Modelling, system identificationand control of these vehicles are still major active areas of research and development.This thesis is concerned with the design and development of an AUV specifically intended for entry into international underwater vehicle competitions. The thesis consists oftwo phases; the first involves the design and construction of the vehicle while the secondphase is concerned with the modelling and system identification of the vehicle, as well asthe simulation of a control system.The design and development of the vehicle consisted of implementing a mechanicaland electrical system, as well as the integration of subsystems. The development of thesesystems has resulted in a low-speed, bottom-heavy, open-frame underwater vehicle namedthe Mako that exhibits high symmetry, modularity and stability.The modelling of the Mako was then performed which involved the application of thedynamic model of an underwater vehicle and the consequent identification of the relevantparameters. The system identification of the vehicle parameters consisted of using onboardsensors to perform static and dynamic experiments. Least squares estimation was used toestimate the parameters from the experimental data obtained.For the control system of the Mako, a PID tracking controller based on computedtorque control was adopted. The controller was applied to the vehicle’s dynamics andsimulated using the parameters found in the system identification process. The resultsof the simulations demonstrate that this type of controller could indeed be successfullyimplemented on the vehicle.The undertakings in this thesis have resulted in a functioning autonomous underwatervehicle that has undergone modelling, system identification and preliminary control analysis. The groundwork has indeed been laid for the Mako’s entry into future underwatercompetitions.i
AcknowledgementsThere are a number of people that deserve mention and gratitude for their help, guidanceand support during the course of this thesis project.Firstly, I would like to give thanks to my fellow submariners, Minh Nguyen, DanielLim and Evan Broadway whom undertook the sonar, vision and communications projectsrespectively. Despite the odds and sheer size of the project, we held our heads up highand our uncompromising perseverance, determination and teamwork brought about thesuccess and realisation of the Mako AUV.I would like to give many thanks to my supervisor, Associate Professor Thomas Bräunl.His expertise, knowledge and his confidence in not only myself, but the whole project,despite its enormity and many setbacks, was vital and greatly aided in the project’s success.Thankyou also for putting up with the ‘renovations’ in your lab. Thanks must also go tomy co-supervisor by default, Chris Croft, for helping me acquire access to the water tanksin the hydraulics lab for testing the vehicle.Many thanks go to the gentlemen in the mechanical and electronic workshops, particularly to Mark Henderson and Ivan Neubronner whom I collaborated closely with and whomhelped me in realising the mechanical and electrical requirements of my AUV design usingtheir expertise and first-rate skills. I also thank them for putting up with my persistentscrutinising of their work and my frequent adjustments and modifications. Without theirdedication and commitment to detail, the AUV would not be as great as it is. I learntmany things from these gentlemen, namely that the gap between theory and practice ismuch larger than I had so naively believed it to be.Thanks also go to my fellow colleagues, particularly Noah Ong and Christian Schmitz,whom were great sources of help and of support.Thankyou also to my parents for their unconditional love, support and understandingthroughout the year. Thanks for especially understanding my stress and neurosis, aswell as putting up with my arriving home late (or early depending on your perspective)on numerous occasions. Thanks as well to my brother Christian and his wife Kathy forallowing me to use their pool for testing purposes.iii
Contents1 Introduction1.11Autonomous Underwater Vehicles . . . . . . . . . . . . . . . . . . . . . . . .11.1.1Commercial and Research AUVs . . . . . . . . . . . . . . . . . . . .21.1.2Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21.2AUV Systems and Components . . . . . . . . . . . . . . . . . . . . . . . . .31.3Modelling and System Identification . . . . . . . . . . . . . . . . . . . . . .31.4Control Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41.5Underwater Vehicle Competitions . . . . . . . . . . . . . . . . . . . . . . . .41.5.1AUVSI. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41.5.2Australasian Competition . . . . . . . . . . . . . . . . . . . . . . . .41.6Project Motivations and Objectives . . . . . . . . . . . . . . . . . . . . . . .51.7Outline of Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 Design Essentials and Concepts72.1AUV Coordinate System . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72.2Factors Affecting an Underwater Vehicle . . . . . . . . . . . . . . . . . . . .82.2.1Buoyancy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82.2.2Hydrodynamic Damping . . . . . . . . . . . . . . . . . . . . . . . . .92.2.3Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92.2.4Coriolis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.2.5Added Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.2.6Environmental Forces . . . . . . . . . . . . . . . . . . . . . . . . . . 112.2.7Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.32.4General Design of an AUV . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.3.1Hull Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112.3.2Propulsion2.3.3Submerging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.3.4Electric Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11IAUVC Vehicle Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132.4.1Massachusetts Institute of Technology . . . . . . . . . . . . . . . . . 132.4.2University of West Florida . . . . . . . . . . . . . . . . . . . . . . . . 142.4.3Cornell University . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14v
2.52.4.4University of Florida . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.4.5Remark on Vehicle Designs . . . . . . . . . . . . . . . . . . . . . . . 15Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Mechanical and Electrical Design173.1Choosing the Final Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173.2Mechanical System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.3Electrical System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183.4Mechanical and Electrical Systems Outline. . . . . . . . . . . . . . . . . . 203.4.1Propulsion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.4.2Range of Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213.4.3Upper Hull - Electronics . . . . . . . . . . . . . . . . . . . . . . . . . 223.4.4Lower Hull - Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . 223.4.5Skeletal Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223.4.6Through-hull Connections . . . . . . . . . . . . . . . . . . . . . . . . 233.4.7Power System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.4.8Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 243.4.9Motor Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.4.10 Depth Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.4.11 Digital Magnetic Compass . . . . . . . . . . . . . . . . . . . . . . . . 263.4.12 Velocity Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.4.13 Leak Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263.4.14 Power Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.53.6Integration of Subsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.5.1Vision System. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273.5.2Sonar System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 283.5.3Communications System . . . . . . . . . . . . . . . . . . . . . . . . . 28Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 Modelling and Control of AUVs314.1Control Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.2Control Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314.3State Vector Representation . . . . . . . . . . . . . . . . . . . . . . . . . . . 324.44.3.1Reference Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 334.3.2Notation of Transformations4.3.3Attitude and Euler Angles . . . . . . . . . . . . . . . . . . . . . . . . 334.3.4State Space Representation . . . . . . . . . . . . . . . . . . . . . . . 354.3.5Position State Vector Transformation . . . . . . . . . . . . . . . . . 364.3.6Velocity State Vector Transformation . . . . . . . . . . . . . . . . . 37. . . . . . . . . . . . . . . . . . . . . . 33AUV Dynamic Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 394.4.1Mass and Inertia Matrix . . . . . . . . . . . . . . . . . . . . . . . . . 39vi
4.54.4.2Coriolis and Centripetal Matrix . . . . . . . . . . . . . . . . . . . . . 404.4.3Hydrodynamic Damping Matrix . . . . . . . . . . . . . . . . . . . . 414.4.4Gravitational and Buoyancy Vector . . . . . . . . . . . . . . . . . . . 424.4.5Forces and Torque Vector . . . . . . . . . . . . . . . . . . . . . . . . 42Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 435 Modelling the Mako5.15.25.35.445Assertions on Dynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 455.1.1Low Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465.1.2Roll and Pitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465.1.3Symmetry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465.1.4Posture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 465.1.5Environmental Disturbances . . . . . . . . . . . . . . . . . . . . . . . 465.1.6Sway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475.1.7Decoupling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Simplifying the Dynamic Model Matrices . . . . . . . . . . . . . . . . . . . 475.2.1Mass and Inertia Matrix . . . . . . . . . . . . . . . . . . . . . . . . . 485.2.2Hydrodynamic Damping Matrix . . . . . . . . . . . . . . . . . . . . 495.2.3Gravitational and Buoyancy Vector . . . . . . . . . . . . . . . . . . . 495.2.4Forces and Torque Vector . . . . . . . . . . . . . . . . . . . . . . . . 50System Identification Approach . . . . . . . . . . . . . . . . . . . . . . . . . 515.3.1Model for Each Degree of Freedom . . . . . . . . . . . . . . . . . . . 515.3.2Least Squares Estimation . . . . . . . . . . . . . . . . . . . . . . . . 525.3.3Static Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525.3.4Dynamic Experiment. . . . . . . . . . . . . . . . . . . . . . . . . . 53Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 546 System Identification6.16.26.355Thrust Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556.1.1Thrust Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556.1.2Remark on Thrust Outputs . . . . . . . . . . . . . . . . . . . . . . . 56Testing and Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 566.2.1Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596.2.2Remotely Controlling the Mako . . . . . . . . . . . . . . . . . . . . . 596.2.3Sensor Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 606.2.3.1Magnetic Compass . . . . . . . . . . . . . . . . . . . . . . . 606.2.3.2Velocity Sensor . . . . . . . . . . . . . . . . . . . . . . . . . 616.2.3.3Depth Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . 61System Identification Results . . . . . . . . . . . . . . . . . . . . . . . . . . 616.3.1Static Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . . 616.3.1.1Surge Static Experiment . . . . . . . . . . . . . . . . . . . 62vii
6.3.26.3.1.2Heave Static Experiment . . . . . . . . . . . . . . . . . . . 636.3.1.3Yaw Static Experiment . . . . . . . . . . . . . . . . . . . . 65Dynamic Experiments . . . . . . . . . . . . . . . . . . . . . . . . . . 666.3.2.1Surge and Heave Inertial Parameters. . . . . . . . . . . . 666.3.2.2Yaw Inertial Parameters . . . . . . . . . . . . . . . . . . . . 686.4Mako Dynamic Model Parameters . . . . . . . . . . . . . . . . . . . . . . . 686.5Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 697 Controller Simulation717.1Computed Torque Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 717.2Applying Computed Torque Control to the Mako . . . . . . . . . . . . . . . 727.2.1PD Tracking Controller . . . . . . . . . . . . . . . . . . . . . . . . . 727.2.2PID Tracking Controller . . . . . . . . . . . . . . . . . . . . . . . . . 737.3Trajectory Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 747.4Controller Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 757.4.17.4.27.57.6Simulator Implementation Issues . . . . . . . . . . . . . . . . . . . . 757.4.1.1Simulating Feedback . . . . . . . . . . . . . . . . . . . . . . 757.4.1.2Degrees of Freedom . . . . . . . . . . . . . . . . . . . . . . 757.4.1.3Model Parameters . . . . . . . . . . . . . . . . . . . . . . . 767.4.1.4Realism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 767.4.1.5Trajectory Generation . . . . . . . . . . . . . . . . . . . . . 76Simulation Study . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76Analysis of Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777.5.1Overshoot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 777.5.2Thrust Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 827.5.3Final Remark . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Limitations of Simulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 827.6.1Thrust Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 837.6.2Heading Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 837.6.3Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 837.7Controller Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 837.8Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 858 Conclusion878.1Contributions of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 878.2Discussion on Outcomes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888.2.1Mechanical System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888.2.2Electrical System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 888.2.3Subsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 898.2.4Simplification of the Dynamic Model . . . . . . . . . . . . . . . . . . 898.2.5Thrust Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . 89viii
8.38.48.2.6Remote Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 908.2.7System Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . 908.2.8Control System Simulation . . . . . . . . . . . . . . . . . . . . . . . 90Recommendations and Future Work . . . . . . . . . . . . . . . . . . . . . . 908.3.1Mechanical System . . . . . . . . . . . . . . . . . . . . . . . . . . . . 918.3.2Electrical System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 918.3.3Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 918.3.4System Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . 918.3.5Communications System . . . . . . . . . . . . . . . . . . . . . . . . . 928.3.6Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92Final Word . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92A IAUVC Rules and Mission 200493A.1 Mission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93A.1.1 Breakdown of Mission . . . . . . . . . . . . . . . . . . . . . . . . . . 93A.1.2 Size and Weight Constraints. . . . . . . . . . . . . . . . . . . . . . 94A.1.3 Other Restrictions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94A.2 Placement of Elements in the Arena . . . . . . . . . . . . . . . . . . . . . . 95A.2.1 Validation Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95A.2.2 Target . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95A.2.3 Markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96A.2.4 Pinger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96A.2.5 Recovery Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96B Electronic Components97B.1 Thrusters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97B.2 Batteries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97B.3 Computer/Microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98B.4 Digital Magnetic Compass . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99B.5 Echo Sounder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99B.6 Velocity Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99C Design Concepts101C.1 Torpedo Shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101C.2 One Hull, Four Thrusters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102C.3 Two Hulls, Four Thrusters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102C.4 Two Hulls, Two Rotating Thrusters . . . . . . . . . . . . . . . . . . . . . . 103C.5 Comparison of Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104D Mechanical System Design105D.1 Mechanical Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105D.2 Mechanical Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106ix
D.2.1 Overview of Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106D.2.2 Material Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107D.2.2.1Hulls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108D.2.2.2Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108D.2.3 Motor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108D.2.4 Hull Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108D.2.5 Mass and Volume Relationship . . . . . . . . . . . . . . . . . . . . . 108D.2.5.1Total Expected Mass . . . . . . . . . . . . . . . . . . . . . 109D.2.5.2Total Expected Volume . . . . . . . . . . . . . . . . . . . . 110D.3 Comments on Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110E Electrical System Design113E.1 Motion Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113E.2 Sonar and Vision Processing . . . . . . . . . . . . . . . . . . . . . . . . . . . 114E.3 Measuring Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114E.4 Attitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115E.5 Velocity Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115E.6 Hull Breaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115E.7 Power Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116E.8 Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117E.9 Through-hull connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117F Construction Process119F.1 Construction of Components . . . . . . . . . . . . . . . . . . . . . . . . . . 119F.1.1 Hulls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119F.1.2 Through-hull Connections . . . . . . . . . . . . . . . . . . . . . . . . 120F.1.3 Motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120F.1.4 Frame . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121F.1.5 Motor Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122F.1.6 Power Board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123F.1.7 Regulators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123F.2 Uniting the Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123F.3 Summary of Design and Construction . . . . . . . . . . . . . . . . . . . . . 125G CDROM Listing129References131x
CRAMROMLCDPDPIDADCPWMAhAutonomous Underwater VehicleRemotely Operated VehicleUniversity of Western AustraliaMassachusetts Institute of TechnologyAssociation for Unmanned Vehicle Systems InternationalInternational Autonomous Underwater Vehicle Competitionn Degrees of FreedomPolyvinylchloridePersonal ComputerRandom Access MemoryRead Only MemoryLiquid Crystal DisplayProportional DerivativeProportional Integral DerivativeAnalog-to-Digital ConverterPulse Width ModulationAmp-hourNautical Front side of vehicleBack side of vehicleRight side of vehicleLeft side of vehicleMotion in the longitudinal or x directionMotion in the lateral or y directionMotion in the vertical or z directionxi
Variable TableSymbolWBgRMNameweightbuoyant forcegravitational accelerationrighting momentmρVcDmassdensityvolumedrag coefficientsAspeedarea{B}body frame{W }world frameRrotation matrixPBposition state vectorxBposition vectorΘBattitude vectorxyzφθψx positiony positionz positionroll Euler anglepitch Euler angleyaw Euler angleDescriptionMagnitude of the weight of vehicleMagnitude of the weight of water displaced byvehicleAcceleration due to gravityThe magnitude of the moment created by a distance existing between a body’s centre of massand centre of buoyancyMass of vehicleDensity of seawaterVolume of vehicleThe coefficient of drag due to movement of abody underwater at constant speedSpeed of vehicle in an arbitrary directionThe surface area of an arbitrary face of the vehicleThe Cartesian reference frame positioned on thevehicleThe Cartesian reference frame positioned on thesurface of the worldMatrix for converting from body to world coordinates. The inverse is used to convert fromworld to body coordinates.The position state vector corresponding to thevehicleVector defining the position of the vehicle inCartesian coordinatesVector defining the attitude in Euler angles ofthe vehiclePosition along the x axisPosition along the y axisPosition along the z axisAngle of rotation about the x axisAngle of rotation about the y axisAngle of rotation about the z axisxii
SymbolVBNamevelocity state vectorυBlinear velocity vectorωBangular velocity vectoruvwpqrTBFBsurgeswayheavevehicle roll ratevehicle pitch ratevehicle yaw rateforce/torque state vectorforce vectorWBtorque vectorXYZKMNφ̇θ̇ψ̇Wroll ratepitch rateyaw rateMmass and inertia matrixMRBrigid body mass matrixMAadded mass matrixDescriptionThe velocity state vector corresponding to thevehicleVector defining the linear velocities of the vehicle along the Cartesian axesVector defining the angular velocities of the vehicle about the Cartesian axesThe vehicle’s linear velocity along the x axisThe vehicle’s linear velocity along the y axisThe vehicle’s linear velocity along the z axisThe vehicle’s angular velocity about the x axisThe vehicle’s angular velocity about the y axisThe vehicle’s angular velocity about the z axisThe force and torque state vector correspondingto the vehicleVector defining the forces applied to the vehiclealong the Cartesian axesVector defining the torques or moments appliedto the vehicle about the Cartesian axesForce applied to vehicle along the x axisForce applied to vehicle along the y axisForce applied to vehicle along the z axisTorque applied to vehicle along the x axisTorque applied to vehicle along the y axisTorque applied to vehicle along the z axisAngular velocity about the world frame’s x axisAngular velocity about the world frame’s y axisAngular velocity about the world frame’s z axisMatrix for converting body angular velocities toworld angular velocities. The inverse is used toconvert from world to body angular velocities.Matrix that defines the mass and inertia of thevehicleMatrix defining the mass and inertia of the vehicle when viewed as a rigid bodyMatrix used to account for the added mass likeeffect that occurs during acceleration underwaterxiii
SymbolIxNameIyIzC (V)CRB (V)CA (V)D (V)GfBfGrBrGCoriolis and centripetalmatrixrigid body Coriolis andcentripetal matrixCoriolis-like matrixhydrodynamic dampingmatrixgravitational and buoyancy vectorbuoyant force vectorgravitational force vectorcentre of buoyancy vectorcentre of gravity vectorxByBzBLthrust mapping matrixUthrust vectormξmRB,ξmA,ξDescriptionMass moment of inertia coefficient about the xaxisMass moment of inertia coefficient about the yaxisMass moment of inertia coefficient about the zaxisMatrix that defines the Coriolis and centripetaleffects affecting the vehicle underwaterMatrix that defines the rigid body Coriolis andcentripetal effects induced by MRBMatrix that defines the Coriolis effects inducedby MAMatrix that defines the damping effects due tounderwater dragVector matrix that defines the gravitational andbuoyant forces acting on the vehicleVector matrix denoting the buoyant forces acting on the vehicleVector matrix denoting the gravitational forcesacting on the vehicleVector matrix defining the position of the vehicle’s centre of buoyancyVector matrix defining the position of the vehicle’s centre of gravityDistance along x axis from origin of vehicle’sreference frame to centre of buoyancyDistance along y axis from origin of vehicle’sreference frame to centre of buoyancyDistance along z axis from origin of vehicle’sreference frame to centre of buoyancyMatrix that maps the thrusts produced by thevehicle’s thrusters to external forces and torqueson the vehicle along and about the CartesianaxesVector matrix that defines the thrusts producedby each of the vehicle’s thrustersInertial parameter for a particular degree of freedomRigid body inertial parameter for a particulardegree of freedomAdded mass parameter for a particular degreeof freedomxiv
Symboldξdξ ξ gξτξξΛ̂σ̂Λσ̂ 2ς0TPdVdV̇d NameDescriptionLinear damping coefficient for a particular degree of freedomQuadratic damping coefficient for a particulardegree of freedomGravitational and buoyancy coefficient for a particular degree of freedomInput force/torque for a particular degree offreedomVelocity for a particular degree of freedomEstimate of parameter used in least squares estimationStandard deviation of estimated parameterEstimated Gaussian zero mean measurementnoise varianceError of estimated parameterVariable used in linearising nonlinear system incomputed torque controlDesired position vector for tracking controllerDesired velocity vector for tracking controllerDesired acceleration vector for tracking controllerPosition error vector for tracking controllerVelocity error vector for tracking controllerxv
Chapter 1IntroductionThe robotics world has reached a stage where the remotely operated vehicle (ROV) industry is very well established with thousands upon thousands of ROVs having been createdand deployed since the dawn of this industry. The need for autonomy in robots andvehicles, however, is becoming more and more a prevalent issue in many situations andenvironments worldwide. The ability to communicate between the operator and the vehicle is one of the main factors affecting whether a vehicle is to be designed as an ROVor as an autonomous vehicle. Fo
control systems in order to perform underwater tasks. Modelling, system identification and control of these vehicles are still major active areas of research and development. This thesis is concerned with the design and development of an AUV specifically in-tended for entry into international underwater vehicle competitions. The thesis .
and simplified method to describe masonry vaults in global seismic analyses of buildings. Fig. 1 summarizes three different modelling techniques for ma sonry modelling, respectively, mi cro- , macro- and simplified micro modelling. In the case a micro modelling approach is take n, the challenge is to describe the complex behavior of the
Agile Modelling is a concept invented in 1999 by Scott Ambler as a supplement to Extreme Pro-gramming (XP) [Source: Agile Modelling Values]. Strictly defined, Agile Modelling (AM) is a chaordic, practices-based methodology for effective modelling and documentation [Source: Interview with SA by Clay Shannon].
equately support part modelling, i.e. modelling of product elements that are manufactured in one piece. Modelling is here based on requirements from part-oriented applica-tions, such as a minimal width for a slot in order to be able to manufacture it. Part modelling systems have evolved for some time now, and different modelling concepts have
5. Who can grow the largest crystal from solution? Modelling crystals 15 . 1. Modelling a salt crystal using marshmallows 2. Modelling crystals using cardboard shapes 3. Modelling diamond and graphite 4. Modelling crystal growth using people. More about crystals 21 . 1. Crystalline or plastic? 2. Make a crystal garden. Putting crystals to use .
follow using state-of-the- art modeling tool of BPMN 2.0 and UML. Key words: Computer-aided systems Production logistics Business process modelling BPMN 2.0 UML Modelling techniques INTRODUCTION Business Process Execution Language for web Business Process Modelling (BPM) as the main core Business Process Modelling Notation (BPMN) to
Financial Statements Modelling www.bestpracticemodelling.com Page 5 of 40 Financial Statements Module Location 1.2. Financial Statements Modelling Overview The modelling of the financial statements components of an entity is a unique area of spreadsheet modelling, because it involves the systematic linking in of information from
Keywords: Mechatronics; Physical systems; Design and control; Modelling and simulation; Bond graphs; Energy-based modelling 1. Introduction Mechatronic design deals with the integrated design of a mechanical system and its embedded control system. This definition implies that it is important, as far as possible, that the system be designed as .
mechanical, electrical, hydraulic as well as control systems in mechatronics, particularly within automotive, aerospace and robotics applications). There were many attempts to connect different modelling tools, however the more efficient approach is to use tools which support multi-domain modelling (Van Beck and Roda 2000).
