The potential benefits of autonomous satellite formation flying in such areas as high- resolution remote sensing, and sparse aperture radar, has stimulated interest in modeling the satellite environment for feasibility and simulation studies to help explore and define the technical challenges that must be solved in order to achieve successful autonomous satellite formations. The purpose of this paper is to develop and describe a numerical simulation of the orbital environment including central force field perturbations and atmospheric drag effects which will be a useful analytical tool for investigating issues relating to maintaining satellite formations in low-earth-orbit. Many of the studies done in this area confine their research to circular orbits, with and without perturbation effects. This study will investigate apply orbital dynamic equations to the problem of maintaining satellite formations in both circular and elliptical orbits, with and without the presence of J2 gravity perturbation effects and atmospheric drag. This effort is primarily focused on modeling the orbital mechanics of one and two satellites in the presence of J2 and drag perturbations This effort is being performed as part of a multi-disciplined University of Central Florida KnightSat project, sponsored by the Air Force, to develop a two-satellite formation in the nanosatellite class, for investigating issues related to using formation satellites for remote earth sensing, to develop three-dimensional mapping.

This document describes the design, analysis of Orbit Maneuvers and Attitude Control for NanoSat class satellites, which uses an electro-magnetic force controller which was proposed by the Florida Space Institute (FSI). Orbit Maneuvering and the Attitude Control System (ACS) play a very important role for the success of this mission, as that can allow making the satellite go to the desired orbit as well do the sun pointing of the solar arrays with su¢ cient accuracy to achieve desired power levels. The primary mission would be to attain attitude stabilization using the torque from the coils. This is also used for pointing at the direction of the sun, for achieving desired power levels. The secondary mission would be to use the force of the magnetic field and utilize that for orbit maneuvering, and attain the desired trajectory. This thesis gives a presentation of this detailed analysis with a simulation using Matlab/Simulink. Mathematical model of the actuators and sensors used for this satellite are designed, so that the simulation gives us results very near to the actual ones.Health Monitoring is also one of the main issues addressed in this work. This simulation helps us in understanding the mission as well as the requirements very well, and helps us know all the shortcomings. The FUNSAT satellite is modeled as an example in Simulink together with a Kalman filter for attitude estimation based on all sensor measurements. The theory behind this, and extending the Kalman filter, is also presented.

The feasibility of neural networks to control dynamic systems is examined. Control of a one-dimensional problem is initially investigated to develop an understanding of the structure and simulation of the neural networks. A nondimensional problem is also explored to apply a single neural network design to controlling a class of systems with a wide variety of modeling parameters. Finally, these techniques are applied to control a space vehicle to transfer, intercept, and rendezvous with another orbiting vehicle using the Clohessy-Wiltshire equations of relative motion in two dimensions. A combination of open-loop and closed-loop neural network controllers is shown to work effectively for this problem. Noise is added to the neural network inputs to demonstrate the robustness of these networks. / Ph. D.

It is generally assumed that the implementation of adaptive control requires a precise identification of plant parameters. In the case of a system with varying parameters, the identification problem gets very involved, as speed of identification and accuracy are contradictory requirements. In this thesis it has been shown that using a feedback policy, the optimal controller is relatively· insensitive to changes in plant parameters as long as these lie within some specified ranges. It is, therefore, concluded that, with such an arrangement, adaptive control can be implemented if one has only the knowledge of the ranges within which the parameters of the plant lie. Thus identification can be carried on more rapidly, as stringent accuracy is no longer necessary. / Thesis / Master of Engineering (ME)

Software memory compression has been a common practice among operating systems. Since then, prior works have explored hardware memory compression to reduce the load on the CPU by offloading memory compression to hardware. However, prior works on hardware memory compression cannot provide critical isolation in multi-tenant systems like cloud servers. Our evaluation of prior work (TMCC) shows that a tenant can be slowed down by more than 12x due to the lack of isolation. This work, Compressed Memory Management Unit (CMMU), prototypes hardware compression for multi-tenant systems. CMMU provides critical isolation for multi-tenant systems.First, CMMU allows OS to control individual tenants' usage of physical memory. Second, CMMU compresses a tenant's memory to an OS-specified physical usage target. Finally, CMMU notifies the OS to start swapping the memory to the storage if it fails to compress the memory to the target. We prototype CMMU with a real compression module on an FPGA board. CMMU runs with a Linux kernel modified to support CMMU. The prototype virtually expands the memory capacity to 4X. CMMU stably supports the modified Linux kernel with multiple tenants and applications. While achieving this, CMMU only requires several extra cycles of overhead besides the essential data structure accesses. ASIC synthesis results show CMMU fits within 0.00931mm2 of silicon and operates at 3GHz while consuming 36.90mW of power. It is a negligible cost to modern server systems. / Master of Science / Memory is a critical resource in computer systems. Memory compression is a common technique to save memory resources. Memory compression consumes the computing resource, traditionally supplied by the CPU. In other words, memory compression traditionally competes with applications for CPU computing power. The prior work, TMCC, provides a design to perform memory compression in ASIC hardware, therefore no longer competing for CPU computing power. However, TMCC provides no isolation in a multitenant system like a modern cloud server. This thesis prototypes a new design, Compressed Memory Management Unit (CMMU), providing isolation in hardware memory compression. This prototype can speed up applications by 12x compared to without the isolation, with a 4x expansion in virtual memory capacity. CMMU supports a modified Linux OS running stably. CMMU also runs at high clock speed and offers little overhead in latency, silicon chip area, and power

Many types of devices based on power converters have been proposed and studied for utility applications. In recent years most of the control systems for these converters have been digital. Unfortunately, such digital controllers, which are often based on a digital signal processor (DSP), are difficult to model in simulation. Thus, hardware prototypes are usually required. This thesis presents a tool for fast prototyping that helps overcome these difficulties. Namely, a hardware-in-the-loop simulation is provided for the digital controller in order to evaluate control algorithms without the voltage source converter and power system. The controller in the loop design methodology is described and the division between the real-time power system model and the hardware controller with an interface is shown. Also, the modulation type, integration time step selection and synchronization between the controller and the real-time system simulation are discussed. The hardware configuration for the real-time simulator and the software implementation of the simulator is discussed. In this thesis an example application of a shunt active compensator following this formal procedure is presented. The active compensator prototyping was first developed in MATLAB/Simulink. Then, following a formal design procedure, the power system was modeled in a digital simulator and the controller was implemented in a digital controller board. Finally, a hardware-in-the-loop test was carried out to validate the performance of the hardware controller for the active compensator. Although the tools and methods presented here are aimed at shunt connected current controller application, they may be generalized for use in the development of any digitally controlled power electronic converter.

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A hard chromium electroplating process is normally used for preventing mechanical and electrical parts such as roller, piston and mold from the harmful environments and giving the good physical properties on the surface such as increased wear resistance, increased hardness, low frictional coefficient as well as good aesthetic look on the surface of workpieces. The problem that often found in this process is the deflected workpieces after plating process due to the low plating performance during a plating period. These deflected workpieces are needed to replating it again. However, the replating method causes a large amount of resource consumptions and increases the production time. To handle this problem, the plating solution temperature is needed to maintain the plating solution temperature at a set point about 50 °C in order to improve the plating performance during the plating period and decrease the occurrence of the deflected workpieces. In this work, the mathematical models are developed to explain the dynamic behavior of the plating solution temperature during the plating time and validated with the real data from a plant. The conventional (PID) controller is applied to this process for the purpose of keeping the plating solution temperature at the set point throughout the plating time. The result demonstrates that the developed mathematical models can be used to explain the dynamic behavior of the plating solution temperature because it gives the good simulation of the plating solution temperature with a slightly different from the real data. Furthermore, the PID controller shows the high control performance for maintaining the plating solution temperature at the set point throughout the plating period with small overshoot at the beginning of every batch.