Rapporten avhandlar en konceptstudie för omvandling av termisk energi till elektrisk samt mekanisk energi, i den autonoma undervattensfarkosten SAPPHIRES. Inledningsvis utreds vilka förväntningar och krav som finns på konceptet för energiomvandling samt om där finns någon publicerad litteratur som redan gjort ansträngningar för att lösa det aktuella problemet. Allmän teori kring värmemotorer och en bred, systematisk litteratursökning inkluderas även i det arbetet. Energiomvandlingen antas kunna ske enligt två fall kallade ”hög-prestanda” och ”låg/medel-prestanda”, vilka innebär att mekanisk samt elektrisk effekt, respektive endast elektrisk effekt ska kunna levereras av konceptet. De mekaniska samt elektriska effekterna ska, vidare, kunna levereras om maximalt 600, respektive 6 kW, och konceptet ska åtminstone kunna uppfylla ett av energiomvandlingsfallen. Den faktiska konceptstudien utgörs av två iterationer av konceptgenereringar, -utvärderingar och -val och de visar att ett koncept kallat ”Öppet system inspirerat av nukleär värmeframdrivning” förefaller vara det bästa sättet att omvandla termisk energi i SAPPHIRES. Därtill indikerar en mer detaljerad analys, bestående av bland annat matematisk modellering och konceptuell konstruktion, att konceptet möjligen skulle kunna uppfylla så kallad ”hög-prestanda” och sedermera leverera både mekanisk och elektrisk effekt om 600, respektive 6 kW. Mer specifikt visar en matematisk analys, med hjälp av vissa antaganden rörande konceptets funktion, att ett ”Öppet system inspirerat av nukleär värmeframdrivning” skulle kunna leverera en mekanisk effekt om 1025 kW samt en elektrisk effekt om 141 kW. En grov, konceptuell konstruktion bekräftar också att konceptets vitala, ingående komponenter faktiskt kan rymmas inom de specificerade dimensionskraven (en cylinderformad volym med en längd och diameter om 1,7, respektive 0,5 m.). Det står dock klart att de möjliga koncepten för energiomvandling kraftigt begränsas av deras möjligheter att leverera tillräcklig mekanisk effekt, för att uppnå ”hög-prestanda”. Om endast ”låg/medel-prestanda” ska uppfyllas tillåts fler av de möjliga koncepten och i ett sådant fall skulle faktorer som underhåll, miljöpåverkan och SAPPHIRES signatur kunna prioriteras i högre utsträckning. / The report discusses a concept study regarding the conversion of thermal energy into electrical and mechanical energy, in the autonomous underwater vehicle SAPPHIRES. First, the requirements and expectations regarding the concept of energy conversion are investigated and efforts are made to identify any published literature, which has already made attempts of solving the issue. General theory regarding heat engines and an extensive literature study are also included in this work. The energy conversion is assumed to perform according to two cases called "high-performance" and "low/medium-performance", meaning mechanical and electrical energy or electrical power should be delivered by the concept, respectively. More specifically, the mechanical and electrical powers should be delivered of a maximum of 600 and 6 kW, respectively and the concept should at least fulfill one of the performance settings. The actual concept study comprises of two iterations of concept generations, evaluations and selections and shows that a concept called "Open system inspired by nuclear thermal propulsion" seems to be the best way of converting thermal energy on-board SAPPHIRES. Moreover, a more detailed analysis, comprising of, inter alia, mathematical modelling and conceptual design, indicates that the concept possibly can meet the so-called "high-performance" and thus, deliver both mechanical and electrical powers of 600 and 6 kW, respectively. More specifically, a mathematical analysis, based on some assumptions regarding the concept's functionality, shows that an "Open system inspired by nuclear thermal propulsion" could deliver a mechanical power of 1025 kW and an electrical power of 141 kW. Rough conceptual design also shows that the vital parts of the concept could fit within the specified maximal dimensions (a cylinder-shaped volume with a length and diameter of 1.7 and 0.5 m, respectively). However, it is clear the possible concepts of energy conversion are severely limited by their capacities of delivering enough mechanical energy, to meet the "high-performance" demands. Assuming only the "low/medium-performance" has to be met, more possible concepts becomes available and in that case, factors such as maintenance, environmental impact and signature of SAPPHIRES could be considered to a greater extent.

Approved for public release, distribution is unlimited / In order to plug-in current open sourced, open standard Java programming technology into the building blocks of the US Navy's ForceNet, first, stove-piped systems need to be made extensible to other pertinent applications and then a new paradigm of adopting extensible and cross-platform open technologies will begin to bridge gaps with old and new weapons systems. The battle-space picture in real time and with as much detail, or as little detail needed is now a current vital requirement. Access to this information via wireless laptop technology is here now. Transmission of data to increase the resolution of that battle-space snapshot will invariably be through noisy links. Noisy links such as found in the shallow water littoral regions of interest will be where Autonomous Underwater and Unmanned Underwater Vehicles (AUVs/UUVs) are gathering intelligence for the sea warrior in need of that intelligence. The battle-space picture built from data transmitted within these noisy and unpredictable acoustic regions demands efficiency and reliability features abstract to the user. To realize this efficiency Extensible Markup Language (XML) Schema-based Binary Compression (XSBC), in combination with Vandermode-based Forward Error Correction (FEC) erasure codes, offer the qualities of efficient streaming of plain text XML documents in a highly compressed form, and a data self-healing capability should there be loss of data during transmission in unpredictable transmission mediums. Both the XSBC and FEC libraries detailed in this thesis are open sourced Java Application Program Interfaces (APIs) that can be readily adapted for extensible, cross-platform applications that will be enhanced by these desired features to add functional capability to ForceNet for the sea warrior to access on demand, at sea and in real-time. These features will be presented in the Autonomous Underwater Vehicle (AUV) Workbench (AUVW) Java-based application that will become a valuable tool for warriors involved with Undersea Warfare (UW). / Lieutenant, United States Navy

This master thesis project is focused on the development of an LQR controller and its comparison with other controllers (PID and MPC), in order to successfully control an Autonomous Underwater Vehicle manipulation system. The modelling of the manipulator was performed first in Matlab and later on in Simulink-Simscape. Once the manipulator was integrated with the AUV model, the LQR controller was also developed initially in Matlab and then in Simulink. The controller was then extracted from Simulink as a C-code and verified in Stonefish. After confirming that the LQR code was working in Stonefish, its results from Simulink were compared with PID and MPC results for two different trajectories. The data for comparison and statistical analysis were divided into the two trajectory scenarios (horizontal and vertical) since the weight matrices of both controllers were different. Looking at the system’s overall behavior the Model Predictive Control (MPC) and LQR had similar results, regarding the rise time, overshoot, steady-state error and robustness to disturbances. An anticipated fact for the MPC was that it takes the longest run time for both scenarios. Lastly, as expected the PID had the worst response of all three controllers, in both scenarios. Implementing a PID on a nonlinear system, produced many oscillations without being able to stabilize at the reference value, thus giving a large steady-state error. In addition, it could not counteract the noise disturbances in the signal. / Detta examensarbete är inriktat på utvecklingen av en LQR-styrenhet och dess jämförelse med andra kontroller (PID och MPC), för att framgångsrikt styra ett autonomt undervattensfordon-manipulationssystem. Modelleringen av manipulatorn utfördes först i Matlab och senare i Simulink-Simscape. När manipulatorn väl hade integrerats med AUV modellen, utvecklades LQR styrenheten också inledningsvis i Matlab och sedan i Simulink. Kontrollenheten extraherades sedan från Simulink som en C-kod och verifierades i Stonefish. Efter att ha bekräftat att LQR koden fungerade i Stonefish, jämfördes resultaten från Simulink med PID och MPC resultat för två olika banor. Data för jämförelse och statistisk analys delades in i de två bana-scenarierna (horisontella och vertikala), eftersom viktmatriserna för båda kontrollerna var olika. När man tittar på systemets övergripande beteende hade Model Predictive Controller (MPC) och LQR liknande resultat när det gäller stigningstid, överskott, steady-state fel och robusthet mot störningar. Ett förväntat faktum för MPC var att det tar den längsta körtiden för båda scenarierna. Slutligen, som väntat, hade PID det sämsta svaret av alla tre kontrollerna, i båda scenarierna. Implementering av ett PID på ett olinjärt system gav många oscillationer utan att kunna stabilisera sig vid referensvärdet, vilket gav ett stort steady-state fel. Dessutom kunde den inte motverka bullerstörningarna i signalen.