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Zhao, Yang. "Path-following Control of Container Ships." Cleveland State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=csu1563275115222067.
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Palm, William, and Fredrik Fischer. "PATH CONTROL OF AN AUTOMATED HAULER." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-35913.
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The vision of self driving cars has existed for a long time and the field of autonomous vehicles has been of great interest to researchers and companies. Volvo construction equipment presented their Electrical Site project in September 2016, with predictions of reducing carbon emission up to 95% and total cost of ownership by 25%. In the project, multiple autonomous haulers are intended to work in a fleet, loading, unloading and charging in a cyclic behavior. This masterthesis focus on the lateral control system of the automated hauler platform HX. The platform is modeled in an comprehensive simulation environment and three different control algorithms have been implemented and tested; An adaptive Proportional, Integral and Derivative (PID) controller, Stanley and the Proportional Integral + Proportional controller. The PID controller is tuned using the Nyquist stability criterion and the other two algorithms are tuned using a Genetic Algorithm. Results indicate that, to reach the optimal performance of the tested algorithms, manual tuning from experimental testing is required.
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Ito, Hiroyuki, Hiroshi Hasegawa, and Ken-ichi Sato. "Impact of path granularity and operation interval on dynamic path network control." IEEE, 2009. http://hdl.handle.net/2237/14018.
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Barbosa, Filipe Marques. "Robust recursive path-following control for autonomous heavy-duty vehicles." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/18/18153/tde-14032019-082753/.
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Path following and lateral stability are crucial issues for autonomous vehicles. Moreover, these problems increase in complexity when handling heavy-duty vehicles due to their poor manoeuvrability, large sizes and mass variation. In addition, uncertainties on mass may have the potential to significantly decrease the performance of the system, even to the point of destabilising it. These parametric variations must be taken into account during the design of the controller. However, robust control techniques usually require offline adjustment of auxiliary tuning parameters, which is not practical and leads to sub-optimal operation. Hence, this work presents an approach to path-following and lateral control for autonomous heavy-duty vehicles subject to parametric uncertainties by using a robust recursive regulator. The main advantage of the proposed controller is that it does not depend on the offline adjustment of tuning parameters. Parametric uncertainties were assumed to be on the payload, and an H∞ controller was used for performance comparison in simulations. The performance of both controllers is evaluated in a double lane-change manoeuvre. Simulation results showed that the proposed method had better performance in terms of robustness, lateral stability, driving smoothness and safety, which demonstrates that it is a very promising control technique for practical applications. Ultimately, experiment tests in a rigid heavy-duty truck validate what was found in simulation results.<br>O seguimento de caminho e a estabilidade lateral são questões cruciais para veículos autônomos. Além disso, devido à baixa capacidade de manobra, tamanho e grande variação de massa, estes problemas se tornam mais complexos quando se trata de veículos pesados. Adicionalmente, as incertezas na massa têm o potencial de diminuir significativamente o desempenho do sistema, chegando ao ponto de desestabilizá-lo, assim, essas variações paramétricas devem ser consideradas durante o projeto do controlador. No entanto, as técnicas de controle robusto geralmente exigem o ajuste off-line de parâmetros auxiliares do controlador, o que não é prático e lava a uma operação sub-ótima. Assim, este trabalho apresenta uma abordagem de controle de seguimento de caminho e controle lateral para veículos pesados autônomos sujeitos a incertezas paramétricas usando um regulador robusto recursivo. A principal vantagem deste controlador é que ele não depende do ajuste off-line de parâmetros. Assumiu-se que as incertezas paramétricas estavam na carga do veículo, e um controlador H∞ foi usado para comparar o desempenho em simulação. O desempenho de ambos os controladores é avaliado em uma manobra de mudança de faixa. Os resultados de simulação mostraram que o método proposto apresentou melhor desempenho em termos de robustez, estabilidade lateral, suavidade na condução e segurança, o que o demonstra como uma técnica de controle bastante promissora para aplicações práticas. Por fim, testes experimentais em um caminhão rígido reforçam os resultados obtidos em simulação.
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Schäfer, Frank René. "Generalized feedback control and application to vehicle path following control." [S.l.] : [s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=972295356.
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Smith, Winston. "Local path planning using optimal control techniques." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/23065.
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Chen, Yiyang. "Iterative learning control for spatial path tracking." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/415865/.
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Iterative learning control (ILC) is a high performance method for systems operating in a repetitive manner, which aims to improve tracking performance by learning from previous trial information. In recent years research interest has focused on generalizing the task description in order to achieve greater performance and flexibility. In particular, researchers have addressed the ease of tracking only at a single, or a collection of time instants. However, there still remain substantial open problems, such as the choice of the time instants, the need for system constraint handling, and the ability to release explicit dependence on time. A number of ILC methods have tackled the latter problem, loosely termed spatial ILC, but are all application specific and limited in scope. The aim of this thesis is to unlock this potential, and the specific contributions are as follows: first a mechanism to optimize the time instants at the critical tracking positions within point-to-point tracking is developed. This is achieved by embedding an additional cost function and deriving a ‘Two Stage’ design framework to yield an iterative algorithm which minimizes control effort as well as guaranteeing high performance tracking. This approach is based on norm optimal ILC and gradient minimization. Then the task description is further generalized by expanding the formulation to embed via-point constraint and linear planar constraints. This embeds the incorporation of various design objectives including spatial path tracking in a general class of systems, and a mixed form of system constraints are added into this framework. An algorithmic ILC solution is derived using the successive projection method to achieve high performance tracking of the design objectives. Finally, the Two Stage design framework and the generalized ILC framework are combined together to yield the first spatial ILC algorithm capable of optimizing an additional cost function whilst completing the spatial path tracking objective for a general class of systems. All proposed algorithms are verified experimentally on a gantry robot platform, whose experimental results demonstrate their practical efficacy and ability to substantially widen the scope of the current ILC framework.
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Furci, Michele <1988>. "Mobile Robots Control and Path Planning Strategies." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7511/1/furci_michele_tesi.pdf.
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Mobile robots gained lots of attention in the last decades. Because of its flexibility and increased capabilities of automation, mobile robots are used in many applications: from domotic, to search and rescue missions, to agriculture, environment protection and many more.
The main capability of mobile robots to accomplish a mission is the mobility in the work environment. To move in a certain environment the robots should achieve: guidance, navigation and control.
This thesis focuses on guidance and control of mobile robots, with application to certain classes of robots: Vertical Take Off and Landing Unmanned Aerial Vehicles (VTOL UAV) and Differential Wheel robots (DWR).
The contribution of this thesis is on modeling and control of the two classes of robots, and on novel strategies of combined control and motion planning for kinodynamic systems.
A new approach to model a class of multi-propeller VTOL is proposed, with the aim of generating a general model for a system as a composition of elementary modules such as actuators and payloads.
Two control law for VTOL vehicles and DWR are proposed. The goal of the first is to generate a simple yet powerful control to globally asymptotically stabilize a VTOL for acrobatic maneuvers. The second is a simple saturated input control law for trajectory tracking of a DWR model in 2D.
About planning, a novel approach to generate non-feasible trajectories for robots that still guarantees a correct path for kinodynamic planning is proposed. The goal is to reduce the runtime of planners to be used in real-time and realistic scenario. Moreover an innovative framework for mobile robots motion planning with the use of Discrete Event Systems theory is introduced.
The two proposed approaches allow to build a global, robust, real-time, quasi-optimal, kinodynamic planner suitable for replanning.
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Furci, Michele <1988>. "Mobile Robots Control and Path Planning Strategies." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7511/.
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Mobile robots gained lots of attention in the last decades. Because of its flexibility and increased capabilities of automation, mobile robots are used in many applications: from domotic, to search and rescue missions, to agriculture, environment protection and many more.
The main capability of mobile robots to accomplish a mission is the mobility in the work environment. To move in a certain environment the robots should achieve: guidance, navigation and control.
This thesis focuses on guidance and control of mobile robots, with application to certain classes of robots: Vertical Take Off and Landing Unmanned Aerial Vehicles (VTOL UAV) and Differential Wheel robots (DWR).
The contribution of this thesis is on modeling and control of the two classes of robots, and on novel strategies of combined control and motion planning for kinodynamic systems.
A new approach to model a class of multi-propeller VTOL is proposed, with the aim of generating a general model for a system as a composition of elementary modules such as actuators and payloads.
Two control law for VTOL vehicles and DWR are proposed. The goal of the first is to generate a simple yet powerful control to globally asymptotically stabilize a VTOL for acrobatic maneuvers. The second is a simple saturated input control law for trajectory tracking of a DWR model in 2D.
About planning, a novel approach to generate non-feasible trajectories for robots that still guarantees a correct path for kinodynamic planning is proposed. The goal is to reduce the runtime of planners to be used in real-time and realistic scenario. Moreover an innovative framework for mobile robots motion planning with the use of Discrete Event Systems theory is introduced.
The two proposed approaches allow to build a global, robust, real-time, quasi-optimal, kinodynamic planner suitable for replanning.
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Knappskog, Håvard. "Nonlinear control of Tethered Airfoils : Path-following control of Tethered Airfoils." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for teknisk kybernetikk, 2011. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-13458.
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This master thesis contains modeling, analysis and control design for atethered airfoil. A path-following controller has been developed and provenlocally asymptotically stable. The guidance law is general, and applicableto other path-following systems. The closed loop system is demonstratedin simulations, where a certain level of robustness is concluded.
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Okura, Yuki. "Trajectory Design Based on Robust Optimal Control and Path Following Control." Kyoto University, 2019. http://hdl.handle.net/2433/242499.
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付記する学位プログラム名: デザイン学大学院連携プログラム<br>Kyoto University (京都大学)<br>0048<br>新制・課程博士<br>博士(工学)<br>甲第21761号<br>工博第4578号<br>新制||工||1713(附属図書館)<br>京都大学大学院工学研究科航空宇宙工学専攻<br>(主査)教授 藤本 健治, 教授 泉田 啓, 教授 太田 快人<br>学位規則第4条第1項該当
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Oral, Zeki Okan. "Hopf bifurcations in path control of marine vehicles." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA268818.
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Jayaraman, Anand. "Concurrent Multi-Path Real-Time Transmission Control Protocol." Scholarly Repository, 2007. http://scholarlyrepository.miami.edu/oa_theses/85.
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In this thesis, a new transport protocol, the Concurrent Multi-Path Real-time Transmission Control Protocol (cmpRTCP) is proposed. The proposed protocol has been designed to handle real-time streams (video and audio) over IP-networks. One of the key strengths of this protocol lies in its ability to intelligently exploit the availability of multiple paths between multi-homed hosts for concurrent transmission of unicast real-time streams. This work describes the architecture and operation of cmpRTCP in detail. In addition, the limitations of currently used transport protocols in handling real-time streams are also discussed. These limitations of other protocols have played a vital role in the design process of the proposed protocol. Experiments to evaluate the performance of cmpRTCP against other protocols and the results obtained therein are also documented in this work. Results show that cmpRTCP is a best effort protocol that tries to maximize the amount of data that is successfully delivered to the destination in a timely manner under varying drop and delay conditions of the network.
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Youns, Mohammednur, Derick Nduge, and Augustine Chika. "Improving Network Performance byImplementing the Path Control Tools." Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-24554.
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Designing an IP network requires a deep knowledge of both infrastructures, and theperformance of the devices that are used. At the same time how packets are handled bythe devices. In networking infrastructure where there are multiple branches with lots ofredistribution points, performance is very important thing that a network designershould consider. A company can have different brunches, where those brunches usedifferent routing protocols. Branches of the same company should communicate witheach other. The existence of multiple routing protocols in different branches willrequire redistributing those protocols so that, routes from one routing protocol can beadvertised in to another routing protocol.The main issues, which can affect the performance of a network, are the results ofimproper redistribution. These issues, which affect the network performance, areexcessive routing updates, suboptimal routing and routing loop, which can lead tonetwork downtime.This thesis discusses the issues of network performance. It explains how to overcomethese issues using different path control tools. The authors of this thesis decided topresent some of the network performance issues and also give a solution to the issuesdiscussed earlier.
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Gustavsson, Viktor. "Path Control for Autonomous Four-Wheel Steered Haulers." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232186.
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Path following control is a fundamental part of vehicle autonomy and over the lastdecades extensive research has been conducted towards the development of moreadvanced algorithms for path control of autonomous vehicles. The primary interestin improving path following control for autonomous vehicles is to be able to reducethe tracking error relative to the vehicle's reference path while also increasing thespeed at which trajectory tracking is possible. In this thesis, path following controlwas considered for an autonomous electric four-wheel steered hauler. For thispurpose, two dierent control paradigms were tested. Non-linear feedback controland model predictive control. Both controllers were designed to stabilize the lateraloset of the hauler in the curvilinear coordinate system constituting its referencepath. The controllers were synthesized with regards to a kinematic model of afour-wheel steered vehicle in a curvilinear coordinate system, and tuned extensivelyversus a multi-body simulation of the hauler. The MPC was also implemented inexisting ROS code for a prototype of the real hauler and its real-time schedulabilitywas tested on the machine control hardware in the hauler prototype. It was foundthat both controllers met the required tracking precision, while the model predictivepath controller performed better but at a signicantly higher cost in terms ofcomputational complexity and coding overhead.<br>Banfoljningsreglering ar en fundamental del av fordonsautonomi och under de senasteartioendena har mycket forskning fokuserat pa utveckling av mer avancerade regleralgoritmerfor banfoljning i autonoma fordon. Det huvudsakliga intresset i attforbattra banfoljningsreglering i sjalvkorande fordon ligger i att kunna reducerabanfoljningsfelet och samtidigt mojliggora en okning av hastigheten for vilken trajektoriefoljning ar mojligt. I detta examensarbete utforskas banfoljningsregleringfor en autonom elektrisk fyrhjulstyrd dumper. I detta avseende provades tva olikareglerparadigmer, ickelinjar aterkoppling och modelprediktiv reglering. Bada regulatorernadesignades for att stabilisera fordonets laterala rorelse i det kurvlinjarakoordinatsystemet som utgor dess referensbana. Regulatorerna syntetiserades medavseende pa en kinematisk modell av ett fyrhjulsstyrt fordon i ett kurvlinjart koordinatsystemoch justerades genom testkorningar pa en simulerad erkroppsmodellav den fyrhjulsstyrda dumpern. Den modellprediktiva regulatorn implementeradesaven i existerande ROS-kod for en prototyp av den riktiga dumpern varpa implementationensschemalaggningsmojlighet testades pa prototypens regulatorhardvara.Simulatortesterna visade att bada regulatorerna uppfyllde kraven pa banfoljningsprecision,medan modelprediktiv reglering presterade battre till priset av avsevarthogre berakningskomplexitet och kodunderhall.
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Mellodge, Patricia. "Feedback Control for a Path Following Robotic Car." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/32100.
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This thesis describes the current state of development of the Flexible Low-cost Automated Scaled Highway (FLASH) laboratory at the Virginia Tech Transportation Institute (VTTI). The FLASH lab and the scale model cars contained therein provide a testbed for the small scale development stage of intelligent transportation systems (ITS). In addition, the FLASH lab serves as a home to the prototype display being developed for an educational museum exhibit.
This thesis also gives details of the path following lateral controller implemented on the FLASH car. The controller was developed using the kinematic model for a wheeled robot. The global model is converted into the path coordinate model so that only local variables are needed. then the path coordinate model is converted into chained form and a controller is given to perform path following.
The path coordinate model introduces a new parameter to the system: the curvature of the path. Thus, it is necessary to provide the path's curvature value to the controller. Because of the environment in which the car is operating, the curvature values are known a priori. Several online methods for determining the curvature are developed.
A MATLAB simulation environment was created with which to test the above algorithms. The simulation uses the kinematic model to show the car's behavior and implements the sensors and controller as closely as possible to the actual system.
The implementation of the lateral controller in hardware is discussed. The vehicle platform is described and the harware and software architecture detailed. The car described is capable of operating manually and autonomously. In autonomous mode, several sensors are utilized including: infrared, magnetic, ultrasound, and image based technology. The operation of each sensor type is described and the information received by the processor from each is discussed.<br>Master of Science
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Idman, Tobias. "Path planning and trajectory generation - model predictive control." Thesis, KTH, Fordonsdynamik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-265621.
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Autonomous vehicle technology is a rapidly expanding field that will play an important role in society in the future. The ambition of autonomous technology is to improve safety for drivers, passengers and pedestrians, reduce traffic congestion and lower fuel consumption. To reach these goals advanced driver-assistance systems and autonomous driving aid the driver or takes full control over the vehicle. With the help of computers, a more optimal driving style is implemented. This thesis focuses on implementing lateral and longitudinal control for an autonomous vehicle with the help of model predictive control using artificial potential fields. The model predictive controller foresees the future for a finite time horizon using a mathematical model of the vehicle. Here a linearized and discretized kinematic bicycle model is used as the internal vehicle model in the controller. The model predictive controller avoids obstacles with artificial potential fields that are quadratically approximated using Taylor series with the help of Bézier curves. The control inputs are the vehicle’s side slip angle and the longitudinal acceleration. The simulations take place on roads in the United Kingdom with left-hand traffic in urban environments. The simulated use-cases are limited to roadside parking scenarios with and without traffic. The goal is to follow the lane center while navigating around obstacles in a predictable way, respecting traffic laws and avoiding collisions or hazardous situations. A simplistic decision-making module is used to determine the vehicle’s next course of action. After the subsequent maneuver is decided a velocity profile and a lane center reference are created for the ego vehicle to follow. The model predictive controller solves the optimization problem as a quadratic programming problem that minimizes a cost function while satisfying a set of constraints. The cost function minimizes the error for the velocity, the lateral lane position, the control inputs, the control input’s rate of change and the yaw angle. The artificial potential fields are also included in the cost function to guide the ego vehicle away from high cost regions. The algorithms were built and simulated using MATLAB. The quadratic programming problem was solved using MATLAB’s quadprog routine in the optimization toolbox, with a sample time of 0.1 seconds. The MPC developed good results with quick calculation times. The highest average calculation time was 0.0159 s with a maximum calculation time of 0.0549 s. The vehicle could perform overtaking maneuvers of two parked cars at 6 m/s in 8.4 s and in 17.2 s when overtaking from a standstill.<br>Autonoma fordonssytem är ett snabbt växande område som kommer att spela en stor roll i vårt samhälle i framtiden. Ambitionen för autonoma fordonssytem är att förbättra säkerheten för förare och passagerare, reducera trafik samt sänka bränsleförbrukningen. För att nå dessa mål kan aktiva hjälpsystem och autonoma fordonssystem ta delvis eller full kontroll över fordonet. Datorer kan sedan beräkna en optimal kontrollstrategi som kan bidra till en bättre och säkrare körning. Detta examensarbete fokuserar på att implementera lateral och longitudinell kontroll för ett autonomt fordon med hjälp av modell-prediktiv reglering (model predictive control) och artificiella potentiella fält. Där modell-prediktiv reglering förutspår framtiden för en finit tidshorisont med hjälp av en matematisk fordonsmodell. En linjäriserad och diskretiserad kinematisk cykelmodell används som den interna fordonsmodellen i regulatorn. Modell-prediktiv reglering undviker hinder genom artificiella potentiella fält som är kvadratiskt approximerade med Taylor approximering med hjälp av Bézier kurvor. Regulatorns styrsignaler är fordonets avdriftsvinkel och acceleration. Simuleringarna är baserade på vägar i Storbritannien med vänstertrafik i stadsmiljö. De simulerade scenariona är begränsade till väggrensparkering med och utan trafik. Där målet är att följa filens mittlinje samt att navigera runt hinder på ett tydligt sätt, respektera trafiklagarna samt undvika kollisioner och farliga situationer. En enkel besluts-modul används för att bestämma fordonets nästa manöver. Efter manövern är bestämd skapas en hastighetsprofil samt en mittfilsreferens för fordonet att följa. Regulatorn löser optimeringsproblemet med hjälp av kvadratisk programmering som minimerar en kostnadsfunktion och samtidigt håller sig inom definierade gränsvärden. Kostnadsfunktionen minimerar differensen för hastigheten, laterala positionen, styrsignalerna, styrsignals ändringen samt girvinkeln. Även de artificiella potentiella fälten är inkluderade i kostnadsfunktionen för att leda fordonet från högkostnadsregioner. Det kvadratiska programmeringsproblemet beräknades i MATLAB’s quadprog rutin från optimerings verktyget med en samplingstid på 0,1 sekunder. Regulatorn visade goda resultat med snabba beräkningar. Det högsta medelvärdet på beräkningstiden var 0,0159 s med ett maximum på 0,0549 s. Fordonet kunde göra omkörningsmanövrar runt två på raken parkerade bilar med en hastighet på 6 m/s på 8,4 s och på 17,2 s när omkörningen gjordes från ett stillastående tillstånd.
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Boström-Rost, Per. "On Informative Path Planning for Tracking and Surveillance." Licentiate thesis, Linköpings universitet, Reglerteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-157026.
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This thesis studies a class of sensor management problems called informative path planning (IPP). Sensor management refers to the problem of optimizing control inputs for sensor systems in dynamic environments in order to achieve operational objectives. The problems are commonly formulated as stochastic optimal control problems, where to objective is to maximize the information gained from future measurements. In IPP, the control inputs affect the movement of the sensor platforms, and the goal is to compute trajectories from where the sensors can obtain measurements that maximize the estimation performance. The core challenge lies in making decisions based on the predicted utility of future measurements. In linear Gaussian settings, the estimation performance is independent of the actual measurements. This means that IPP becomes a deterministic optimal control problem, for which standard numerical optimization techniques can be applied. This is exploited in the first part of this thesis. A surveillance application is considered, where a mobile sensor is gathering information about features of interest while avoiding being tracked by an adversarial observer. The problem is formulated as an optimization problem that allows for a trade-off between informativeness and stealth. We formulate a theorem that makes it possible to reformulate a class of nonconvex optimization problems with matrix-valued variables as convex optimization problems. This theorem is then used to prove that the seemingly intractable IPP problem can be solved to global optimality using off-the-shelf optimization tools. The second part of this thesis considers tracking of a maneuvering target using a mobile sensor with limited field of view. The problem is formulated as an IPP problem, where the goal is to generate a sensor trajectory that maximizes the expected tracking performance, captured by a measure of the covariance matrix of the target state estimate. When the measurements are nonlinear functions of the target state, the tracking performance depends on the actual measurements, which depend on the target’s trajectory. Since these are unavailable in the planning stage, the problem becomes a stochastic optimal control problem. An approximation of the problem based on deterministic sampling of the distribution of the predicted target trajectory is proposed. It is demonstrated in a simulation study that the proposed method significantly increases the tracking performance compared to a conventional approach that neglects the uncertainty in the future target trajectory.<br>WASP
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Techy, Laszlo. "Flight Vehicle Control and Aerobiological Sampling Applications." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/29680.
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Aerobiological sampling using unmanned aerial vehicles (UAVs) is an exciting research field blending various scientific and engineering disciplines. The biological data collected using UAVs helps to better understand the atmospheric transport of microorganisms. Autopilot-equipped UAVs can accurately sample along pre-defined flight plans and precisely regulated altitudes. They can provide even greater utility when they are networked together in coordinated sampling missions: such measurements can yield further information about the aerial transport process.
In this work flight vehicle path planning, control and coordination strategies are considered for unmanned autonomous aerial vehicles. A time-optimal path planning algorithm, that is simple enough to be solved in real time, is derived based on geometric concepts. The method yields closed-form solution for an important subset of candidate extremal paths; the rest of the paths are found using a simple numerical root-finding algorithm. A multi-UAV coordination framework is applied to a specific control-volume sampling problem that supports aerobiological data-collection efforts conducted in the lower atmosphere.
The work is part of a larger effort that focuses on the validation of atmospheric dispersion models developed to predict the spread of plant diseases in the lower atmosphere. The developed concepts and methods are demonstrated by field experiments focusing on the spread of the plant pathogen <i>Phytophthora infestans</i>.<br>Ph. D.
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Yang, Zhijia. "Optimal air and fuel-path control of a diesel engine." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/16318.
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The work reported in this thesis explores innovative control structures and controller design for a heavy duty Caterpillar C6.6 diesel engine. The aim of the work is not only to demonstrate the optimisation of engine performance in terms of fuel consumption, NOx and soot emissions, but also to explore ways to reduce lengthy calibration time and its associated high costs. The test engine is equipped with high pressure exhaust gas recirculation (EGR) and a variable geometry turbocharger (VGT). Consequently, there are two principal inputs in the air-path: EGR valve position and VGT vane position. The fuel injection system is common rail, with injectors electrically actuated and includes a multi-pulse injection mode. With two-pulse injection mode, there are as many as five control variables in the fuel-path needing to be adjusted for different engine operating conditions.
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Nayl, Thaker. "Modeling, control and path planning for an articulated vehicle." Licentiate thesis, Luleå tekniska universitet, Signaler och system, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25708.
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This licentiate thesis is focusing on the modeling, control and path planning problems for an articulated vehicle. Based on a novel error dynamics modeling approach, the nonlinear kinematic model of the vehicle has been transformed in a linear switching model representation, which is also able to take under consideration the effect of slip angles, a factor that significantly deteriorates the overall system approach.According to the proposed switching modeling, a switching model predictive control scheme has been established. Each of the controllers has been fine tuned for dealing with a specific model representation, translational speed, magnitude of slip angles and physical / mechanical constraints. In the proposed control scheme the varying slip angle and speed have been considered as the switching signal for selecting the active controller.The final contribution is related to the path planning problem where an on line path planning algorithm, being able to consider the full kinematic model of the vehicle, have been proposed.The presented algorithm is a variation of the well known Bug-like path planning scheme.The efficiencies of the presented approaches have been evaluated by multiple simulation results.<br>Godkänd; 2013; 20130517 (thanay); Tillkännagivande licentiatseminarium 2013-05-23 Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Thaker Nayl Ämne: Reglerteknik/Automatic Control Uppsats: Modeling, Control and Path Planning for an Articulated Vehicle Examinator: Professor Thomas Gustafsson, Institutionen för system- och rymdteknik, Luleå tekniska universitet Diskutant: Professor Kalevi Hyyppä, Institutionen för system- och rymdteknik, Luleå tekniska universitet Tid: Måndag den 17 juni 2013 kl 10.00 Plats: A109, Luleå tekniska universitet
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Haugen, Joakim. "Guidance Algorithms for Planar Path-based Motion Control Scenarios." Thesis, Norwegian University of Science and Technology, Department of Engineering Cybernetics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-10036.
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<p>The problem of performing accurate path maneuvering tasks in planar space is investigated in thesis. The purpose is to utilize limited knowledge about the vehicle's maneuverability constraints to output feasible reference signals. Acceleration limitations of the vehicle have been used in an algorithm that determines forward speeds in such way that a predefined path can be followed at high speeds. The algorithm ensures that the speed is reduced before acute turns. Furthermore, an existing steering law has been modified to dynamically take the limitations of the vehicle into consideration when determining the desired course. This modified steering law exhibits desirable convergence characteristics toward the desired path. A complete guidance system, which combines the path convergence algorithm with the path speed algorithm, has been proposed. This system is able to rapidly converge to the desired path and follow this path, even for paths where the curvature is large. The modified steering law has been combined with a path-tracking speed controller. The path-tracking speed controller makes sure the vehicle can track a target on a predefined path. The resulting path-tracking system is able to follow a leader vehicle's path by creating accurate paths online from periodically sampled positions. A method for creating feasible U-turns in a lawn-mower pattern has been proposed. For a given vehicle speed, the resulting path obeys angular speed and angular acceleration constraints. Finally, the proposed algorithms are tested in simulations to illustrate their behavior and usefulness.</p>
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Taniguchi, Mitsuru, and Kenji Fujimoto. "Time-varying path following control for port-Hamiltonian systems." IEEE, 2009. http://hdl.handle.net/2237/13952.
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Peng, Xiaozhe, and 彭晓哲. "Visual path information on the active control of heading." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B41633817.
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balakrishnan, mohanakrishnan. "COVERAGE PATH PLANNING AND CONTROL FOR AUTONOMOUS MOBILE ROBOTS." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2769.
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Coverage control has many applications such as security patrolling, land mine detectors, and automatic vacuum cleaners. This Thesis presents an analytical approach for generation of control inputs for a non-holonomic mobile robot in coverage control. Neural Network approach is used for complete coverage of a given area in the presence of stationary and dynamic obstacles. A complete coverage algorithm is used to determine the sequence of points. Once the sequences of points are determined a smooth trajectory characterized by fifth order polynomial having second order continuity is generated. And the slope of the curve at each point is calculated from which the control inputs are generated analytically. Optimal trajectory is generated using a method given in research literature and a qualitative analysis of the smooth trajectory is done. Cooperative sweeping of multirobots is achieved by dividing the area to be covered into smaller areas depending on the number of robots. Once the area is divided into sub areas, each robot is assigned a sub area for cooperative sweeping.<br>M.S.<br>Department of Electrical and Computer Engineering<br>Engineering and Computer Science<br>Electrical Engineering
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Midha, Raj Chander 1977. "Path following control system for a small autonomous vehicle." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/89321.
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Jhunjhunwala, Manish. "Multiphase flow and control of fluid path in microsystems." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/37456.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, February 2005.<br>Includes bibliographical references.<br>Miniaturized chemical-systems are expected to have advantages of handling, portability, cost, speed, reproducibility and safety. Control of fluid path in small channels between processes in a chemical/biological network is crucial for connecting process elements. We show complete separation of individual phases (phase routing) from two-phase gas-liquid and liquid-liquid (aqueous-organic) mixtures on microscale. To provide for robust interfacing of operations in a network, we demonstrate this ability over a wide range of two-phase flow conditions, including transient ones. Enabled by the technique for complete separation of individual phases from two-phase mixtures, we show mixing of liquids by introduction of a passive gas-phase and demonstrate integration of mixing, reaction and phase separation on a single platform. Additionally, we use the principles developed for phase routing to design microfluidic valves that do not rely on elastic deformation of material. Such valves can be used in a variety of chemical environments, where polymer-based deformable materials would fail.<br>(cont.) We show a concept for realization of logic-gates on microscale using appropriate connections for these valves, paving the way for design of automation and computational control directly into microfluidic analysis without use of electronics. Further, we use the phase separation concept for sampling liquid from gas-liquid and liquid-liquid mixtures. Such sampling ability, when coupled with a suitable analysis system, can be used for retrieving process information (example mass-transfer coefficients, chemical kinetics) from multiphase-processes. We provide evidence of this through estimation of mass-transfer coefficients in a model oxygen-water system and show at least an order-of-magnitude improvement over macroscale systems. Controlled definition of fluid path enabled by laminar flow on microscale is used in a large number of applications. We examine the role of gravity in determining flow path of fluids in a microchannel. We demonstrate density-gradient-driven flows leading to complete reorientation of fluids in the gravitational field.<br>(cont.) We provide estimates of the time and velocity scales for different parameter ranges through two-dimensional and three-dimensional finite-element models, in agreement with experimental observations. We believe this thesis addresses a number of both: system and fundamental issues, advancing applications and understanding of microfluidic networks.<br>by Manish Jhunjhunwala.<br>Ph.D.
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Okoloko, Innocent. "Multi-path planning and multi-body constrained attitude control." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/71905.
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Thesis (PhD)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: This research focuses on the development of new efficient algorithms for multi-path planning
and multi-rigid body constrained attitude control. The work is motivated by current
and future applications of these algorithms in: intelligent control of multiple autonomous
aircraft and spacecraft systems; control of multiple mobile and industrial robot systems;
control of intelligent highway vehicles and traffic; and air and sea traffic control.
We shall collectively refer to the class of mobile autonomous systems as “agents”. One
of the challenges in developing and applying such algorithms is that of complexity resulting
from the nontrivial agent dynamics as agents interact with other agents, and their environment.
In this work, some of the current approaches are studied with the intent of exposing
the complexity issues associated them, and new algorithms with reduced computational
complexity are developed, which can cope with interaction constraints and yet maintain
stability and efficiency.
To this end, this thesis contributes the following new developments to the field of multipath
planning and multi-body constrained attitude control:
• The introduction of a new LMI-based approach to collision avoidance in 2D and 3D
spaces.
• The introduction of a consensus theory of quaternions by applying quaternions directly
with the consensus protocol for the first time.
• A consensus and optimization based path planning algorithm for multiple autonomous
vehicle systems navigating in 2D and 3D spaces.
• A proof of the consensus protocol as a dynamic system with a stochastic plant matrix.
• A consensus and optimization based algorithm for constrained attitude synchronization
of multiple rigid bodies.
• A consensus and optimization based algorithm for collective motion on a sphere.<br>AFRIKAANSE OPSOMMING: Hierdie navorsing fokus op die ontwikkeling van nuwe koste-effektiewe algoritmes, vir
multipad-beplanning en veelvuldige starre-liggaam beperkte standbeheer. Die werk is gemotiveer
deur huidige en toekomstige toepassing van hierdie algoritmes in: intelligente beheer
van veelvuldige outonome vliegtuig- en ruimtevaartuigstelsels; beheer van veelvuldige mobiele
en industrile robotstelsels; beheer van intelligente hoofwegvoertuie en verkeer; en in
lug- en see-verkeersbeheer.
Ons sal hier “agente” gebruik om gesamentlik te verwys na die klas van mobiele outonome
stelsels. Een van die uitdagings in die ontwikkeling en toepassing van sulke algoritmes
is die kompleksiteit wat spruit uit die nie-triviale agentdinamika as gevolg van
die interaksie tussen agente onderling, en tussen agente en hul omgewing. In hierdie werk
word sommige huidige benaderings bestudeer met die doel om die kompleksiteitskwessies
wat met hulle geassosieer word, bloot te l^e. Verder word nuwe algoritmes met verminderde
berekeningskompleksiteit ontwikkel. Hierdie algoritmes kan interaksie-beperkings hanteer,
en tog stabiliteit en doeltreffendheid behou.
Vir hierdie doel dra die proefskrif die volgende nuwe ontwikkelings by tot die gebied
van multipad-beplanning van multi-liggaam beperkte standbeheer:
• Die voorstel van ’n nuwe LMI-gebasseerde benadering tot botsingsvermyding in 2D
en 3D ruimtes.
• Die voorstel van ’n konsensus-teorie van “quaternions” deur “quaternions” vir die
eerste keer met die konsensusprotokol toe te pas.
• ’n Konsensus- en optimeringsgebaseerde padbeplanningsalgoritme vir veelvoudige
outonome voertuigstelsels wat in 2D en 3D ruimtes navigeer.
• Die bewys van ’n konsensusprotokol as ’n dinamiese stelsel met ’n stochastiese aanlegmatriks.
• ’n Konsensus- en optimeringsgebaseerde algoritme vir beperkte stand sinchronisasie
van veelvoudige starre liggame. • ’n Konsensus- en optimeringsgebaseerde algoritme vir kollektiewe beweging op ’n sfeer.
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Marcondes, Cesar Augusto Cavalheiro. "Inline path estimators to improve congestion control and applications." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1580937011&sid=1&Fmt=2&clientId=1564&RQT=309&VName=PQD.
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Peng, Xiaozhe. "Visual path information on the active control of heading." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/B41633817.
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Lechliter, Matthew C. "Decentralized control for UAV path planning and task allocation." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3314.
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Thesis (M.S.)--West Virginia University, 2004.<br>Title from document title page. Document formatted into pages; contains x, 198 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 134-138).
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Tanakitkorn, Kantapon. "Guidance, control and path planning for autonomous underwater vehicles." Thesis, University of Southampton, 2017. https://eprints.soton.ac.uk/412635/.
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Over-actuated, hover-capable autonomous underwater vehicles (AUVs) are hybrid vehicles designed to serve a wide range of operations, from detailed survey tasks in a hover style to long-range exploration tasks in a flight style. Due to the over-actuated design and the different operating styles, it is challenging to operate these types of AUVs. This research developed a navigation system for over-actuated, hover-capable AUVs, with a primary focus on interconnections between guidance, control and path planning systems. A detailed 6-degrees of freedom mathematical model was developed to represent dynamics of these hybrid AUVs. The model was validated with horizontal plane manoeuvring trials carried out on the over-actuated, hover-capable Delphin2 AUV. The results showed that the model can satisfactorily predict the AUV's response over a range of operating conditions. Using this dynamics model, the guidance and control systems were designed to effectively and efficiently operate over a range of forward speeds with a seamless transition between hover-style and flight-style operation. A path planning system was tested, seeking for the collision-free path between two locations that requires the least energy for an AUV to navigate along. The proposed navigation system has been verified on the Delphin2 AUV through experiments. The comprehensive results have shown that the system can maintain excellent performance regardless of a range of forward speeds. By applying the proposed navigation system, it is also possible to launch a long-endurance AUV from a shore. The vehicle would be able to automatically navigate along an energy efficient path to perform, for instance, a seabed survey mission at a remote part of the ocean, then come back to the recovery point. This concept eliminates a ship from the AUV launching process, hence, making the operation more cost-effective.
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Haghshenas, Hamed. "Time-Optimal Cooperative Path Tracking for Multi-Robot Systems." Licentiate thesis, Linköpings universitet, Reglerteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-179217.
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Robotic systems are nowadays the key technology in a wide variety of applications. The increasing demand for performance of robotic systems is often met by employing a team of cooperating robots for a specific task.When the task carried out by the robots involves manipulation of an object, the multi-robot system is said to perform a cooperative manipulation task.Cooperative manipulation is an important capability for extending the domain of robotic applications.This thesis studies the time-optimal path tracking problem for a cooperative manipulation scenario where an object is rigidly grasped by multiple manipulators. The goal is to move the object along a predefined geometric path in minimum time while satisfying the imposed constraints on the motion. First, it is shown that the time-optimal path tracking problem for cooperative manipulators can be cast as a convex optimization problem. A fundamental property of convex optimization problems is that any locally optimal solution is also a globally optimal one. Furthermore, by recognizing and formulating a problem as a convex optimization problem, it can be solved very reliably and efficiently using interior-point or other methods for convex optimization.These results are presented in two separate studies. In the first one which is a preliminary study, the manipulation setup is a particular setup comprised of two planar manipulators and a bar. Furthermore, the load distribution among the manipulators is considered to be equal. The second study extends the results in the preliminary study to a general scenario with $N$ generic manipulators and an object with a desired orientation during the motion. Here, the load distribution among the manipulators is determined via a generic pseudo-inverse of the grasp matrix that can be chosen by the user.The freedom in the choice of the pseudo-inverse allows to consider different load distributions which can be exploited to account for the potential differences in the capabilities of the manipulators.The second part of this thesis is devoted to finding load distributions that are free of internal forces. A drawback of using multiple manipulators in a cooperative manipulation task is that internal forces can be introduced.Internal forces are forces exerted by the end-effectors at the grasping points that do not contribute to the motion of the manipulated object. While a certain amount of such forces can be useful in some cases, in general they must be avoided to prevent object damage and unnecessary effort of the manipulators.This thesis proposes a new approach to obtain internal force-free load distributions.The proposed approach results in a new pseudo-inverse of the grasp matrix parameterized by coefficients that have the meaning of the inertial parameters of some parts of the object. The freedom in the choice of the parameters of the pseudo-inverse allows to assign different loads to the manipulators. This can be exploited to account for the differences in the power capabilities of the manipulators.The results are further explored for scenarios where the object is three-dimensional and convex and has uniform mass density. Finally, the proposed pseudo-inverse is combined with the results in the first part of the thesis to solve the problem of time-optimal cooperative path tracking subject to zero internal forces during the motion.
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Lindell, Tobias. "Model-based Air and Fuel Path Control of a VCR Engine." Thesis, Linköping University, Department of Electrical Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-52468.
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<p>The objective of the work was to develop a basic control system for an advancedexperimental engine from scratch. The engine this work revolves around is a Saabvariable compression engine.A new control system is developed based on the naked engine, stripped of theoriginal control system. Experiments form the basis that the control system isbuilt upon. Controllers for throttles, intake manifold pressure for pressures lessthan ambient pressure and exhaust gas oxygen ratio are developed and validated.They were found to be satisfactory. The lambda controller is tested with severalparameter sets, and the best set is picked to be implemented in the engine. Modelsnecessary for the development and validation of the controllers are developed.These models include models for the volumetric efficiency, the pressure dynamicsof the intake manifold, the fuel injectors and wall wetting.</p>
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Kong, Jiantao. "Trusted data path protecting shared data in virtualized distributed systems." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33820.
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When sharing data across multiple sites, service applications should not be trusted automatically. Services that are suspected of faulty, erroneous, or malicious behaviors, or that run on systems that may be compromised, should not be able to gain access to protected data or entrusted with the same data access rights as others. This thesis proposes a context flow model that controls the information flow in a distributed system. Each service application along with its surrounding context in a distributed system is treated as a controllable principal. This thesis defines a trust-based access control model that controls the information exchange between these principals. An online monitoring framework is used to evaluate the trustworthiness of the service applications and the underlining systems. An external communication interception runtime framework enforces trust-based access control transparently for the entire system.
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Lundberg, Marcus. "Path planning for autonomous vehicles using clothoid based smoothing of A* generated paths and optimal control." Thesis, KTH, Numerisk analys, NA, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-216388.
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Autonomous vehicles is a rapidly expanding field and the need for robust and efficient path planners is high. We approach the global path- planning problem for an autonomous load carrier for quarry environments, developed at Volvo Construction Equipment, using two methods: a two- step path planning and path smoothing approach, and a method based on an optimal control formulation of the path planning problem. The two-step method is based on smoothing an initial path found by A*, an efficient grid search algorithm, by fitting a curve consisting of as few clothoid segments as possible to the A* path. The smoothing is done by rewriting the non-linear optimization problem to a convex form by a linearization of the deviation constraints around the curvature of the A* path. An iterative method is then used to relax the l0-norm, which measures the number of non-zero elements in a vector, with a weighted l1-norm which, in turn, is then solved efficiently using CVX in Matlab. The optimal control based path planning method solves the nonlinear optimization problem using IPOPT. It was found that the completeness of the A* algorithm, coupled with the guaranteed solution of a convex problem, resulted in a very robust method that was able to find paths through mazes and difficult situations. The optimal control approach produced better paths, but had a tendency to sometimes show inconsistent behavior.<br>Autonoma fordon är ett snabbt växande forskningsområde och behovet av robusta och effektiva lösningar för vägplanering är stort. Vi undersöker ett globalt vägplaneringsproblem för en autonom dumper som utvecklas på Volvo Construction Equipment och som är byggd för att användas i bergtäkter. Två metoder undersöks: en tvåstegsmetod med grafbaserad vägplanering följt av en utslätning av vägen, och en metod som bygger på optimal styrteori. Tvåstegsmetoden går ut på att först hitta en väg fri från hinder med hjälp av A*, en effektiv grafbaserad sökalgoritm, och sedan släta ut denna väg genom att anpassa ett så lågt antal klotoid-kurvor som möjligt till vägen. Denna utslätning genomförs genom att skriva om det icke-linjära problemet på konvex form med hjälp av en linjärisering kring referensvägens kurvatur. En iterativ metod beskrivs för att relaxera l0 - normen, som mäter antalet nollskilda element i en vektor, med en viktad l1-norm. Sedan löses problemet med CVX i Matlab. I metoden baserad på optimal styrteori löser vi det icke-linjära problemet direkt med IPOPT. Det visade sig att robustheten hos A* tillsammans med ett lättlöst konvext problem gjorde att tvåstegsmetoden blev mycket robust och pålitlig och kunde hitta tillåtna vägar genom labyrinter och svåra situationer. Vägar planerade med hjälp av optimal styrteori var kortare och hade bättre egenskaper, men algoritmen hade en tendens att få svårigheter med konvergens.
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Prasad, P. Saravana. "Tool path plotting using Plot10." Thesis, Kansas State University, 1985. http://hdl.handle.net/2097/9873.
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Behere, Sagar. "A Generic Framework for Robot Motion Planning and Control." Thesis, KTH, Centrum för Autonoma System, CAS, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-104806.
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This thesis deals with the general problem of robot motion planning and control. It proposes the hypothesis that it should bepossible to create a generic software framework capable of dealing with all robot motion planning and control problems, independent of the robot being used, the task being solved, the workspace obstacles or the algorithms employed. The thesis work then consisted of identifying the requirements and creating a design and implementation of such a framework. This report motivates and documents the entire process. The framework developed was tested on two different robot arms under varying conditions. The testing method and results are also presented.The thesis concludes that the proposed hypothesis is indeed valid.
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Kim, Joonyoung. "Path-invariant and time-optimal motion control for industrial robots." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61295.
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This thesis presents practical methods for planning and control to improve the motion performance of industrial robots. Particular attention is given to the commercial six degrees-of-freedom articulated robot with a low-cost generic controller. A comparative study of motion control methods demonstrated that both smooth trajectory planning and filtering techniques, when combined with a traditional Proportional-Derivative control, are limited in achievable performance due to reduced accelerations (smooth trajectory) or large path-distortions (filtering technique). Instead, faster and more accurate motion is achieved with a low-order trajectory, namely, trapezoidal velocity profile, with feedforward control design based on an elastic model. The key component that makes the latter approach more appealing is the delay-free dynamic input shaper embedded in the feedforward control. Following the results from the comparative study, two innovations are proposed to satisfy the path-invariant and time-optimal motion. First, an online time-optimal trapezoidal velocity profile planned along multiple path segments is presented. The trajectory can be planned for arbitrary boundary conditions and path curvatures with only four system-dynamics computations per path segment. Next, a novel control method based on the flexible joint dynamic model is proposed to achieve high tracking performance for the proposed trajectory. The proposed nonlinear multivariable control can place the closed-loop poles arbitrarily with only position and velocity feedback. Real-world experiments with commercial industrial robots are carried out to validate the presented methods.<br>Applied Science, Faculty of<br>Mechanical Engineering, Department of<br>Graduate
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Daily, Robert L. Bevly David M. "Stream function path planning and control for unmanned ground vehicles." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Mechanical_Engineering/Dissertation/Daily_Robert_45.pdf.
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Ma, Ka-yiu Eric, and 馬家耀. "Effect of scene information on path perception and steering control." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50434469.
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Human observers can perceive self-motion from optic flow for both circular paths and straight paths. However, when view does not rotate during travel on a circular path, observers often show significant bias in path judgments from optic flow. A proposed explanation is that human observers use the velocity field of optic flow for perception of self-motion and assume that path curvature is accompanied by body rotation.
Use of a scene-based strategy, as opposed to optic flow, could potentially reduce the bias in judgments of circular path with no view rotation. It has been shown that human observers can judge heading direction from a sequence of static pictures of a scene, suggesting that observers can perceive self-motion from change in observer position relative to a scene. Another previous study found that showing the same configuration of landmarks repeatedly improved performance in a steering task, suggesting that familiarity of a scene may further improve perception of self-motion and steering control.
In this thesis, I explored the effect of scene information on judgments of circular path and steering control. Experiments 1 and 2 tested path judgments for simulated travel along a circular path. Observers viewed 1 s presentations of optic flow and adjusted a response pole to lie on their future path, i.e. where they would intercept the pole if they keep travelling on the current path. Precision and accuracy of judgments were compared across conditions that varied in the presence and consistency of landmarks. I found no effect of landmarks on precision and accuracy, and curvature underestimation remained present in all conditions.
Experiment 3 tested whether familiarity with a scene can improve steering control. I used the same steering task by Andersen and Enriquez (2006). During a trial, heading direction was perturbed horizontally in a smooth, pseudo-random manner, as if unexpectedly wind perturbed a car and caused it to slide to the left and right while driving straight ahead. Observers were instructed to counteract these perturbations and steer to maintain a straight path of travel. Contrary to previous findings, I found no effect of scene familiarity on steering control.
I found no benefit from landmarks in any of the conditions tested in this thesis. These results suggest that scene information has a limited role for path judgments and steering control.<br>published_or_final_version<br>Psychology<br>Master<br>Master of Philosophy
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Cheng, Li. "Transient modelling of a diesel engine and air-path control." Thesis, University of Sussex, 2015. http://sro.sussex.ac.uk/id/eprint/55340/.
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Due to the inherent nonlinearity of the diesel engine, real-time control of the variable geometry turbocharger (VGT) and exhaust gas recirculation (EGR) valve still remains a challenging task. A controller has to be capable of coping with the transient operating condition of the engine, the interactions between the VGT and EGR, and also the trade-off effect in this control problem. In this work, novel real-time fuzzy logic controllers (RFLC) were developed and tested. Firstly, the proposed controllers were calibrated and validated in a transient diesel engine model which was developed and validated against the Caterpillar 3126B engine test bed located at the University of Sussex. The controllers were then further tested on the engine test bed. Compared to conventional controllers, the proposed controllers can effectively reduce engine emissions as well as fuel consumption. Experimental results show that compared to the baseline engine running on the Nonroad Transient Cycle (NRTC), mean values of the exhaust gas opacity and the nitrogen oxides (NOx) emission production were reduced by 36.8% and 33%, respectively. Instant specific fuel consumption of the RFLC engine was also reduced by up to 50% compared to the baseline engine during the test. Moreover, the proposed fuzzy logic controllers can also reduce development time and cost by avoiding extensive engine mapping of inlet air pressure and flow. When on-line emission measurements were not available, on-board emission predictors were developed and tested to supply the proposed fuzzy logic controller with predictions of soot and NOx production. Alternatively, adaptive neuro fuzzy inference system (ANFIS) controllers, which can learn from fuzzy logic controllers, were developed and tested. In the end, the proposed fuzzy logic controllers were compared with PI controllers using the transient engine model.
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Yan, Yutong. "Simulation, Control and Path Planning for Articulated Unmanned Ground Vehicles." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-126394.
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The purpose of this project is to implement obstacle avoidance algorithms to drive the articulated vehicle autonomously in an unknown environment, which is simulated by AgX Dynamics™ simulation software and controlled by Matlab® programming software. Three driving modes are developed for driving the vehicle (Manual, Semi-autonomous and Autonomous) in this project. Path tracking algorithms and obstacle avoidance algorithms are implemented to navigate the vehicle. A GUI was built and used for the manual driving mode in this project. The semi-autonomous mode checked different cases: change lanes, U-turn, following a line, following a path and figure 8 course. The autonomous mode is implemented to drive the articulated vehicle in an unknown environment with moving to a pose path tracking algorithm and VFH+ obstacle avoidance algorithm. Thus, the simulation model and VFH+ obstacle avoidance algorithm seems to be working fine and still can be improved for the autonomous vehicle. The result of this project showed a good performance of the simulation model. Moreover, this simulation software helps to minimize the cost of the articulated vehicle since all tests are in the simulation rather than in the reality.
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Eddy, Wesley M. "Improving Transport Control Protocol Performance With Path Error Rate Information." Ohio University / OhioLINK, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1087844627.
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Eng, Pillar C. S. "Path planning, guidance and control for a UAV forced landing." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/43898/1/Pillar_Eng_Thesis.pdf.
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A forced landing is an unscheduled event in flight requiring an emergency landing, and is most commonly attributed to engine failure, failure of avionics or adverse weather. Since the ability to conduct a successful forced landing is the primary indicator for safety in the aviation industry, automating this capability for unmanned aerial vehicles (UAVs) will help facilitate their integration into, and subsequent routine operations over civilian airspace. Currently, there is no commercial system available to perform this task; however, a team at the Australian Research Centre for Aerospace Automation (ARCAA) is working towards developing such an automated forced landing system. This system, codenamed Flight Guardian, will operate onboard the aircraft and use machine vision for site identification, artificial intelligence for data assessment and evaluation, and path planning, guidance and control techniques to actualize the landing. This thesis focuses on research specific to the third category, and presents the design, testing and evaluation of a Trajectory Generation and Guidance System (TGGS) that navigates the aircraft to land at a chosen site, following an engine failure. Firstly, two algorithms are developed that adapts manned aircraft forced landing techniques to suit the UAV planning problem. Algorithm 1 allows the UAV to select a route (from a library) based on a fixed glide range and the ambient wind conditions, while Algorithm 2 uses a series of adjustable waypoints to cater for changing winds. A comparison of both algorithms in over 200 simulated forced landings found that using Algorithm 2, twice as many landings were within the designated area, with an average lateral miss distance of 200 m at the aimpoint. These results present a baseline for further refinements to the planning algorithms. A significant contribution is seen in the design of the 3-D Dubins Curves planning algorithm, which extends the elementary concepts underlying 2-D Dubins paths to account for powerless flight in three dimensions. This has also resulted in the development of new methods in testing for path traversability, in losing excess altitude, and in the actual path formation to ensure aircraft stability. Simulations using this algorithm have demonstrated lateral and vertical miss distances of under 20 m at the approach point, in wind speeds of up to 9 m/s. This is greater than a tenfold improvement on Algorithm 2 and emulates the performance of manned, powered aircraft. The lateral guidance algorithm originally developed by Park, Deyst, and How (2007) is enhanced to include wind information in the guidance logic. A simple assumption is also made that reduces the complexity of the algorithm in following a circular path, yet without sacrificing performance. Finally, a specific method of supplying the correct turning direction is also used. Simulations have shown that this new algorithm, named the Enhanced Nonlinear Guidance (ENG) algorithm, performs much better in changing winds, with cross-track errors at the approach point within 2 m, compared to over 10 m using Park's algorithm. A fourth contribution is made in designing the Flight Path Following Guidance (FPFG) algorithm, which uses path angle calculations and the MacCready theory to determine the optimal speed to fly in winds. This algorithm also uses proportional integral- derivative (PID) gain schedules to finely tune the tracking accuracies, and has demonstrated in simulation vertical miss distances of under 2 m in changing winds. A fifth contribution is made in designing the Modified Proportional Navigation (MPN) algorithm, which uses principles from proportional navigation and the ENG algorithm, as well as methods specifically its own, to calculate the required pitch to fly. This algorithm is robust to wind changes, and is easily adaptable to any aircraft type. Tracking accuracies obtained with this algorithm are also comparable to those obtained using the FPFG algorithm. For all three preceding guidance algorithms, a novel method utilising the geometric and time relationship between aircraft and path is also employed to ensure that the aircraft is still able to track the desired path to completion in strong winds, while remaining stabilised. Finally, a derived contribution is made in modifying the 3-D Dubins Curves algorithm to suit helicopter flight dynamics. This modification allows a helicopter to autonomously track both stationary and moving targets in flight, and is highly advantageous for applications such as traffic surveillance, police pursuit, security or payload delivery. Each of these achievements serves to enhance the on-board autonomy and safety of a UAV, which in turn will help facilitate the integration of UAVs into civilian airspace for a wider appreciation of the good that they can provide. The automated UAV forced landing planning and guidance strategies presented in this thesis will allow the progression of this technology from the design and developmental stages, through to a prototype system that can demonstrate its effectiveness to the UAV research and operations community.
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Capozzi, Brian Joseph. "Evolution-based path planning and management for autonomous vehicles /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/10001.
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Shukla, Poorva Jahnukumar. "Active Flight Path Control for an Induced Spin Flight Termination System." Thesis, Virginia Tech, 2017. http://hdl.handle.net/10919/78881.
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In this thesis, we describe a method for controlling the cycle-averaged velocity direction of a fixed-wing aircraft in an unpowered, helical descent. While the aircraft propulsion system is disabled, either intentionally or due to a failure, the aerodynamic control surfaces (aileron, elevator, and rudder) are assumed to be functional. Our approach involves two steps: (i) establishing a stable, steady, helical motion for which the control surfaces are not fully deflected and (ii) modulating the aircraft control surfaces about their nominal positions to ``slant'' the helical flight path in a desired direction relative to the atmosphere, whether to attain a desired impact location, to counter a steady wind, or both. The effectiveness of the control law was evaluated in numerical simulations of a general transport model (GTM).<br>Master of Science
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Tsui, Kin-shing, and 徐健成. "Tool path generation for protrusion milling." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B36891332.
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Larsen, Oscar. "Autonomous Overtaking Using Model Predictive Control." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-293819.
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For the past couple of years researchers around theworld have tried to develop fully autonomous vehicles. One of theproblems that they have to solve is how to navigate in a dynamicworld with ever-changing variables. This project was initiated tolook into one scenario of the path planning problem; overtakinga human driven vehicle. Model Predictive Control (MPC) hashistorically been used in systems with slower dynamics but withadvancements in computation it can now be used in systems withfaster dynamics. In this project autonomous vehicles controlledby MPC were simulated in Python based on the kinematic bicyclemodel. Constraints were posed on the overtaking vehicle suchthat the two vehicles would not collide. Results show that anovertake, that keeps a proper distance to the other vehicle andfollows common traffic laws, is possible in certain scenarios.<br>Under de senaste åren har forskare världen över försökt utveckla fullt autonoma fordon. Ett av problemen som behöver lösas är hur man navigerar i en dynamisk värld med ständigt förändrande variabler. Detta projekt startades för att titta närmare på en aspekt av att planera en rutt; att köra om ett mänskligt styrt fordon. Model Predictive Control (MPC) har historiskt sett blivit använt i system med långsammare dynamik, men med framsteg inom datorers beräkningskraft kan det nu användas i system med snabbare dynamik. I detta projekt simulerades självkörande fordon, styrda av MPC, i Python. Fordonsmodellen som används var kinematic bicycle model. Begränsningar sattes på det omkörande fordonet så att de två fordonen inte kolliderar. Resultaten visar att en omkörning, som håller avstånd till det andra fordonet samt följer trafikregler, är möjligt i vissa scenarion.<br>Kandidatexjobb i elektroteknik 2020, KTH, Stockholm
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Shen, Tiantian, and 沈添天. "Visual servoing path-planning for generalized cameras and objects." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hub.hku.hk/bib/B50899879.
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Visual servoing (VS) is an automatic control technique which uses vision feedback to control the robot motion. Eye-in-hand VS systems, with the vision sensor mounted directly on the robot end-effector have received significant attention, in particular for the task of steering the vision sensor (usually a camera) from the present position to the desired one identified by image features shown in advance. The servo uses the difference between the present and the desired views (shown a priori) of some objects to develop real-time driving signals. This approach is also known as “teach-by-showing” method. To accomplish such a task, many constraints and limits are required such as camera field of view (FOV), robot joint limits, collision and occlusion avoidance, and etc. Path-planning technologies, as one branch of high-level control strategies, are explored in this thesis to impose these constraints for VS tasks with respect to different types of cameras and objects.
First, a VS path-planning strategy is proposed for a class of cameras that include conventional perspective cameras, fisheye cameras, and catadioptric systems. These cameras are described by adopting a unified mathematical model and the strategy consists of designing image trajectories that allow the camera to reach the desired position while satisfying the camera FOV limit and the end-effector collision avoidance. To this end, the proposed strategy introduces the projection of the available image features onto a virtual plane and the computation of a feasible camera trajectory through polynomial programming. The computed image trajectory is hence tracked by an image-based visual servoing (IBVS) controller. Experimental results with a fisheye camera mounted on a 6-degree-of-freedom (6-DoF) robot arm illustrate the proposed strategy.
Second, this thesis proposes a path-planning strategy for visual servoing with image moments, in the case of which the observed features are not restrained to points. Image moments of some solid objects such as circle, sphere, and etc. are more intuitive features than the dominant feature points in VS applications. The problem consists of planning a trajectory in order to ensure the convergence of the robot end-effector to the desired position while satisfying workspace (Cartesian space) constraints of the robot end-effector and visibility constraints of these solid objects, in particular including collision and occlusion avoidance. A solution based on polynomial parametrization is proposed and validated by some simulation and experiment results.
Third, constrained optimization is combined with robot teach-by-demonstration to address simultaneously visibility constraint, joint limits and whole-arm collisions for robust vision-based control of a robot manipulator. User demonstration data generates safe regions for robot motion with respect to joint limits and potential whole-arm collisions. Constrained optimization uses these safe regions to generate new feasible trajectories under visibility constraint that achieve the desired view of the target (e.g., a pre-grasping location) in new, undemonstrated locations. To fulfill these requirements, camera trajectories that traverse a set of selected control points are modeled and optimized using either quintic Hermite splines or polynomials with C2 continuity. Experiments with a 7-DoF articulated arm validate the proposed method.<br>published_or_final_version<br>Electrical and Electronic Engineering<br>Doctoral<br>Doctor of Philosophy