Browsing by Subject "cooperative control"
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Item A Bio-Inspired Multi-Agent System Framework for Real-Time Load Management in All-Electric Ship Power Systems(2012-07-16) Feng, XianyongAll-electric ship power systems have limited generation capacity and finite rotating inertia compared with large power systems. Moreover, all-electric ship power systems include large portions of nonlinear loads and dynamic loads relative to the total power capacity, which may significantly reduce the stability margin. Pulse loads and other high-energy weapon loads in the system draw a large amount of power intermittently, which may cause significant frequency and voltage oscillations in the system. Thus, an effective real-time load management technique is needed to dynamically balance the load and generation to operate the system normally. Multi-agent systems, inspired by biological phenomena, aim to cooperatively achieve system objectives that are difficult to reach by a single agent or centralized controller. Since power systems include various electrical components with different dynamical systems, conventional homogeneous multi-agent system cooperative controllers have difficulties solving the real-time load management problem with heterogeneous agents. In this dissertation, a novel heterogeneous multi-agent system cooperative control methodology is presented based on artificial potential functions and reduced-order agent models to cooperatively achieve real-time load management for all-electric ship power systems. The technique integrates high-order system dynamics and various kinds of operational constraints into the multi-agent system, which improves the accuracy of the cooperative controller. The multi-agent system includes a MVAC multiagent system and a DC zone multi-agent, which are coordinated by an AC-DC communication agent. The developed multi-agent system framework and the notional all-electric ship power system model were simulated in PSCAD software. Case studies and performance analysis of the MVAC multi-agent system and the DC zone multi-agent system were performed. The simulation results indicated that propulsion loads and pulse loads can be successfully coordinated to reduce the impact of pulse loads on the power quality of all-electric ship power systems. Further, the switch status or power set-point of loads in DC zones can be optimally determined to dynamically balance the generation and load while satisfying the operational constraints of the system and considering load priorities. The method has great potential to be extended to other isolated power systems, such as microgrids.Item Cooperative control of autonomous underwater vehicles.(Texas A&M University, 2004-09-30) Savage, ElizabethThe proposed project is the simulation of a system to search for air vehicles which have splashed-down in the ocean. The system comprises a group of 10+ autonomous underwater vehicles, which cooperate in order to locate the aircraft. The search algorithm used in this system is based on a quadratic Newton method and was developed at Sandia National Laboratories. The method has already been successfully applied to several two dimensional problems at Sandia. The original 2D algorithm was converted to 3D and tested for robustness in the presence of sensor error, position error and navigational error. Treating the robots as point masses, the system was found to be robust for all such errors. Several real-life adaptations were necessary. A round-robin communication strategy was implemented on the system to properly simulate the dissemination of information throughout the group. Time to convergence is delayed but the system still functioned adequately. Once simulations for the point masses had been exhausted, the dynamics of the robots were included. The robot equations of motion were described using Kane's equations. Path-planning was investigated using optimal control methods. The Variational Calculus approach was attempted using a line search tool "fsolve" found in Matlab and a Genetic Algorithm. A dynamic programming technique was also investigated using a method recently developed by Sandia National Laboratories. The Dynamic Programming with Interior Points (DPIP) method was a very effcient method for path planning and performed well in the presence of system constraints. Finally all components of the system were integrated. The motion of the robot exactly matched the motion of the particles, even when subjected to the same robustness tests carried out on the point masses. This thesis provides exciting developments for all types of cooperative projects.Item Dynamical formulations and control of an automatic retargeting system(Texas A&M University, 2007-04-25) Sovinsky, Michael CharlesThe Poincare equations, also known as Lagrange's equations in quasi coordinates, are revisited with special attention focused on a diagonal form. The diagonal form stems from a special choice of quasi velocities that were first introduced by Georg Hamel nearly a century ago. The form has been largely ignored because the quasi velocities create so-called Hamel coefficients that appear in the governing equations and are based on the partial derivative of the mass matrix factorization. Consequently, closed-form expressions for the Hamel coefficients can be difficult to obtain and relying on finite-dimensional, numerical methods are unattractive. In this thesis we use a newly developed operator overloading technique to automatically generate the Hamel coefficients through exact partial differentiation together with numerical evaluation. The equations can then be numerically integrated for system simulation. These special Poincare equations are called the Hamel Form and their usefulness in dynamic modeling and control is investigated. Coordinated control algorithms for an automatic retargeting system are developed in an attempt to protect an area against direct assaults. The scenario is for a few weapon systems to suddenly be faced with many hostile targets appearing together. The weapon systems must decide which weapon system will attack which target and in whatever order deemed sufficient to defend the protected area. This must be performed in a real-time environment, where every second is crucial. Four different control methods in this thesis are developed. They are tested against each other in computer simulations to determine the survivability and thought process of the control algorithms. An auction based control algorithm finding targets of opportunity achieved the best results.