Power Hardware In Loop (PHIL) simulation is a test method where equipment intended for field application can be debugged and tested in the factory by connecting to a virtual power system model simulated on a real-time simulator. Hence the PHIL simulation may be very effective in developing, debugging and commissioning power equipment. However, due to imperfections (e.g., time delay, noise injection, phase lag, limited bandwidth) in the power interface, simulations in this method show errors or even instable results. This thesis presents means to improve the simulation accuracy of the PHIL simulation. In order to achieve this, a simulation model is constructed for the PHIL simulation process itself. Using simulation, the sensitivity of the simulation to parameters in the interface equipment as well as interface software is thoroughly investigated. One interesting result is that the simulation is significantly affected by phase delay. Based on the analysis, an improved algorithm that uses additional interface filters (implemented in hardware and/or software) is proposed. The thesis shows that more stable and accurate results can be obtained by using the new algorithm. The validity of the proposed methods is verified through a simulation based study and hardware based studies.

Power Hardware In Loop (PHIL) simulation is a test method where equipment intended for field application can be debugged and tested in the factory by connecting to a virtual power system model simulated on a real-time simulator. Hence the PHIL simulation may be very effective in developing, debugging and commissioning power equipment. However, due to imperfections (e.g., time delay, noise injection, phase lag, limited bandwidth) in the power interface, simulations in this method show errors or even instable results. This thesis presents means to improve the simulation accuracy of the PHIL simulation. In order to achieve this, a simulation model is constructed for the PHIL simulation process itself. Using simulation, the sensitivity of the simulation to parameters in the interface equipment as well as interface software is thoroughly investigated. One interesting result is that the simulation is significantly affected by phase delay. Based on the analysis, an improved algorithm that uses additional interface filters (implemented in hardware and/or software) is proposed. The thesis shows that more stable and accurate results can be obtained by using the new algorithm. The validity of the proposed methods is verified through a simulation based study and hardware based studies.

This thesis presents a new way of combining non-linear optimization algorithms and electromagnetic transient (EMT) simulation. In this new combination, a non-linear optimization algorithm utilizes a real-time EMT simulation environment as objective function evaluator. However, as more applications of the off-line EMT simulation software implementation were made, the combination between non-linear optimization algorithms and off-line EMT simulation software revealed new need, which this research work attempts to address. The first need arose from the speed of simulation of the off-line EMT simulation software. With a certain breed of non-linear optimization algorithms, heuristics bases algorithms in particular, a large number of objective function evaluations are required before the termination or convergence criterion in the selected algorithms is satisfied. Sometimes, the number of evaluations as well as the complexity of the simulation case where the objective function is based upon translates into a very long simulation time, which goes beyond the boundary of given resources. This research work attempts to address this simulation timing issue by capitalizing on the real timeness of the simulation environment as well as utilizing the multiple instances of the simulation environment in parallel. The second need arose from the modeling requirement of the off-line EMT simulation software. In order to properly design the necessary objective function evaluator, which is largely a simulation case, a large amount of information needs to be embedded into the case. Under certain circumstances, the necessary information would not be available. Therefore, the simulation case needs to include approximations which may cause compromise in the end result. This limitation becomes more obvious when a real world device such as a commercial controller becomes involved. On the contrary, this limitation can be addressed by the real-time simulation environment because this environment can be directly interfaced with the real world device. In this way, the need for detailed information regarding the device is eliminated. This elimination would enlarge the application of the combination, between the non-linear optimization algorithm and EMT type simulation environment. The effectiveness of the proposed approach is demonstrated by various examples throughout this thesis.

This thesis presents a new way of combining non-linear optimization algorithms and electromagnetic transient (EMT) simulation. In this new combination, a non-linear optimization algorithm utilizes a real-time EMT simulation environment as objective function evaluator. However, as more applications of the off-line EMT simulation software implementation were made, the combination between non-linear optimization algorithms and off-line EMT simulation software revealed new need, which this research work attempts to address. The first need arose from the speed of simulation of the off-line EMT simulation software. With a certain breed of non-linear optimization algorithms, heuristics bases algorithms in particular, a large number of objective function evaluations are required before the termination or convergence criterion in the selected algorithms is satisfied. Sometimes, the number of evaluations as well as the complexity of the simulation case where the objective function is based upon translates into a very long simulation time, which goes beyond the boundary of given resources. This research work attempts to address this simulation timing issue by capitalizing on the real timeness of the simulation environment as well as utilizing the multiple instances of the simulation environment in parallel. The second need arose from the modeling requirement of the off-line EMT simulation software. In order to properly design the necessary objective function evaluator, which is largely a simulation case, a large amount of information needs to be embedded into the case. Under certain circumstances, the necessary information would not be available. Therefore, the simulation case needs to include approximations which may cause compromise in the end result. This limitation becomes more obvious when a real world device such as a commercial controller becomes involved. On the contrary, this limitation can be addressed by the real-time simulation environment because this environment can be directly interfaced with the real world device. In this way, the need for detailed information regarding the device is eliminated. This elimination would enlarge the application of the combination, between the non-linear optimization algorithm and EMT type simulation environment. The effectiveness of the proposed approach is demonstrated by various examples throughout this thesis.

This thesis discusses a practical approach to the concurrent analysis and synthesis of reconfigurable robot manipulators based on the alternative design methodology of Linguistic Mechatronics (LM) as well as the utilization of a modular Robotic Hardware-In-the-Loop Simulation (RHILS) platform. Linguistic Mechatronics is a systematic design methodology for mechatronic systems, which formalizes subjective notions and simplifies the optimization process, in the hope that numerous naturally different design variables can be considered concurrently. The methodology redefines the ultimate goal of design based on the qualitative notions of wish and must satisfactions. The underlying concepts of LM are investigated through a simulation case study. In addition, the RHILS platform involving physical joint modules and a control unit, which takes into account various physical phenomena and reduces the simulation complexities, is employed to the design architecture. Ultimately, the new approach is applied to redesigning kinematic, dynamic and control parameters of an industrial manipulator.

This thesis discusses a practical approach to the concurrent analysis and synthesis of reconfigurable robot manipulators based on the alternative design methodology of Linguistic Mechatronics (LM) as well as the utilization of a modular Robotic Hardware-In-the-Loop Simulation (RHILS) platform. Linguistic Mechatronics is a systematic design methodology for mechatronic systems, which formalizes subjective notions and simplifies the optimization process, in the hope that numerous naturally different design variables can be considered concurrently. The methodology redefines the ultimate goal of design based on the qualitative notions of wish and must satisfactions. The underlying concepts of LM are investigated through a simulation case study. In addition, the RHILS platform involving physical joint modules and a control unit, which takes into account various physical phenomena and reduces the simulation complexities, is employed to the design architecture. Ultimately, the new approach is applied to redesigning kinematic, dynamic and control parameters of an industrial manipulator.

Thesis--Auburn University, 2009. / Abstract. Vita. Includes bibliographical references (p. 49).

Ingeniero Civil Eléctrico / El estándar de nanosatélites Cubesat fue pensado para facilitar el desarrollo de pequeños proyectos espaciales con fines científicos y educacionales, a un bajo costo y en cortos periodos de tiempo. Siguiendo esta línea, la Facultad de Ciencias Físicas y Matemáticas de la Uni- versidad de Chile ha impulsado el proyecto SUCHAI, que consiste en implementar, poner en órbita y operar el primer satélite desarrollado por una universidad del país. El computador a bordo de la aeronave, que consiste un sistema embebido de limitada capacidad de cómputo, escasa memoria y bajo consumo de energía, debe ejecutar el software de vuelo que controlará sus operaciones una vez en órbita. El objetivo de este trabajo es el diseño e implementación de este software para el satélite SUCHAI, como una solución confiable, flexible y extensible que sea la base para futuras misiones aeroespaciales. El diseño del software consiste en una estructura de tres capas, que consigue dividir el problema convenientemente. La de más bajo nivel considera los controladores de hardware, la capa intermedia alberga al sistema operativo, y la de nivel superior, contiene los detalles de la aplicación requerida específicamente para este sistema. Para la arquitectura de la capa de aplicación, se estudia y aplica el concepto de patrón de diseño, en específico, se realiza una adaptación de command pattern. De esta manera, el satélite se concibe como un ejecutor de comandos genéricos y se obtiene una solución mantenible, modificable y extensible en el tiempo, mediante la programación de los comandos concretos que sean requeridos. La implementación se realiza sobre un PIC24F y considera controladores para los periféricos I2C, RS232 y SPI, así como para los subsistemas de radiocomunicaciones y energía. Se decide utilizar el sistema operativo FreeRTOS, como capa intermedia, lo que permite contar con el procesamiento concurrente de tareas, herramientas de temporización y sincronización. Se ha puesto especial énfasis en la implementación de la arquitectura planteada para la capa de aplicación, consiguiendo un software capaz de ejecutar una serie de comandos, programados para cumplir los requerimientos operacionales del proyecto, lo cual representa el método principal para extender sus funcionalidades y adecuarse a futuras misiones. Para probar y verificar el sistema desarrollado, se ha utilizado la técnica denominada hardware on the loop simulation. Se han obteniendo datos de funcionamiento, bajo condiciones de operación hipotéticas, a través del registro generado por la consola serial. Con esto se verifican los requerimientos operacionales de la misión, con resultados exitosos, obteniendo el sistema base y funcional del satélite. Como trabajo futuro, se utilizará este software para integrar el resto de los sistemas del satélite SUCHAI, demostrando su capacidad de adaptación y extensión, en un paso previo a la prueba final: funcionar adecuadamente en el espacio exterior.

Thesis (M.S.)--Auburn University, 2007. / Abstract. Includes bibliographic references (ℓ. 94-95)

Spacecraft formation flying (SFF) offers robust observations of multi-scale ionospheric space weather. A number of hardware-in-the-loop (HIL) SFF simulation testbeds based on Global-Navigation-Satellite-Systems (GNSS) have been developed to support GNSS-based SFF mission design, however, none of these testbeds has been directly applied to ionospheric space weather studies. The Virginia Tech Formation Flying Testbed (VTFFTB), a GNSS-based HIL simulation testbed, has been developed in this work to simulate closed-loop real-time low Earth orbit (LEO) SFF scenarios. The final VTFFTB infrastructure consists of three GNSS hardware signal simulators, three multi-constellation multi-band GNSS receivers, three navigation and control systems, an STK visualization system, and an ionospheric remote sensing system. A fleet of LEO satellites, each carrying a spaceborne GNSS receiver for navigation and ionospheric measurements, is simulated in scenarios with ionospheric impacts on the GPS and Galileo constellations. Space-based total electron density (TEC) and GNSS scintillation index S4 are measured by the LEO GNSS receivers in simulated scenarios. Four stages of work were accomplished to (i) build the VTFFTB with a global ionospheric modeling capability, and (ii) apply the VTFFTB to incubate future ionospheric measurement techniques. In stage 1, a differential-TEC method was developed to use space-based TEC measurements from a pair of LEO satellites to determine localized electron density (Ne). In stage 2, the GPS-based VTFFTB was extended to a multi-constellation version by adding the Galileo. Compared to using the GPS constellation only, using both GPS and Galileo constellations can improve ionospheric measurement quality (accuracy, precision, and availability) and relative navigation performance. Sensitivity studies found that Ne retrieval characteristics are correlated with LEO formation orbit, the particular GNSS receivers and constellation being used, as well as GNSS carrier-to-noise density C/N0. In stage 3, the VTFFTB for dual-satellite scenarios was further extended into a 3-satellite version, and then implemented to develop a polar orbit scenario with more fuel-efficient natural motion. In stage 4, a global 4-dimensioanl ionospheric model (TIE-CGM) was incorporated into the VTFFTB to significantly improve the modelling fidelity of multi-scale ionospheric space weather. Equatorial and polar space weather structures (e.g. plasma bubbles, tongues-of-ionization) were successfully simulated in 4-dimensional ionospheric scenarios on the enhanced VTFFTB. The dissertation has demonstrated the VTFFTB is a versatile GNSS-based SFF mission incubator to study ionospheric space weather impacts and develop next-generation multi-scale ionospheric observation missions. / Doctor of Philosophy / Spacecraft formation flying (SFF) is a space mission architecture with a group of spacecraft flying together and working as a team. SFF provides new opportunities for robust, flexible and low-cost observations of various phenomena in the ionized layer of Earth's atmosphere (called the ionosphere). Several hardware SFF simulation platforms based on Global Navigation Satellite Systems (GNSS) have been established to develop GNSS-based SFF missions, however, none of these platforms has ever directly used on-board GNSS receivers to study the impact of space weather on ionospheric density structures. The Virginia Tech Formation Flying Testbed (VTFFTB), a hardware simulation infrastructure using multiple GNSS signals, has been built in this work to emulate realistic SFF scenarios in low altitude orbits. The overall VTFFTB facility comprises three GNSS hardware signal emulators, three GNSS signal receivers, three navigation and control components, a software visualization component, and an ionospheric measurement component. Both Global-Positioning-System (GPS) and Galileo (the European version GNSS) are implemented in the VTFFTB. The objectives of this work are to (i) develop the VTFFTB with a high-fidelity ionospheric modeling capability, and (ii) apply the VTFFTB to incubate future ionospheric measurement techniques with GNSS receivers in space. A fleet of two or three spacecraft, each having a GNSS receiver to navigate and sense the ionosphere is emulated in several space environments. The electron concentration of the ionosphere and the GNSS signal fluctuation are measured by the GNSS receivers from space in simulated scenarios. These measurements are advantageous to study the location, size and structure of irregular ionospheric phenomena nearby the trajectory of spacecraft fleet. The culmination of this study is incorporation of an external global ionospheric model with temporal variations into the VTFFTB infrastructure to model a variety of realistic ionospheric structures and space weather impacts. Equatorial and polar space weather phenomenon were successfully simulated on the VTFFTB to verify a newly developed space-borne electron density measurement technique in the 3-dimensional ionosphere. Overall, it was successfully demonstrated that the VTFFTB is a versatile GNSS-based SFF mission incubator to study multiple kinds of ionospheric space weather impacts and develop next-generation space missions for ionospheric measurements.