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Embedded command and control infrastructures for intelligent autonomous systemsFraser, Robert James C. January 1994 (has links)
The issue of Command and Control (C2) is generally associated with the management infrastructure of large scale systems for warfare, public utilities and public transportation, and is concerned with ensuring that the distributed human elements of command and control can be fully integrated into a coherent, total system. Intelligent Autonomous Systems (IASs) are a class of complex systems that perform tasks autonomously in uncertain, dynamic environments, the management of which can be viewed from the perspective of embedded command and control systems. This thesis establishes a vision for the modular construction of intelligent autonomous embedded C2 systems, which defines a complex integration problem characterised by distributed intelligence, world knowledge and control, concurrent processing on heterogeneous platforms, and real-time performance requirements. It concludes that by adopting an appropriate systems infrastructure model, based on Object Technology, it is possible to view the construction of embedded C2 systems as the integration of a temporally assembled collection of reusable components. To support this metaphor it is necessary to construct a common reference model, or standards framework, for the representation and specification of modular C2 systems. This framework must support the coherent long term development and evolution in system capability, ensuring that systems are extensible, robust and perform correctly. In this research, which draws together the themes of other published research in object oriented systems and robotics, classical AI models for intelligent systems architectures are used to specify the overall system structure, with open systems technologies supporting the interoperation of elements within the architecture. All elements of this system are modelled in terms of objects, with well defined, implementation independent interfaces. This approach enables the system to be specified in terms of an object model, and the development process to be framed in terms of object technology, defining a new approach to IAS development. The implementation of an On-board Command and Control System for an Autonomous Underwater Vehicle is used to validate these concepts. The further application of emergent industrial standards in distributed object oriented systems means that this kind of component-based integration is scaleable, providing a near-term solution to generic command and control problems, including Computer Integrated Manufacturing and large scale autonomous systems, where individual autonomous systems, such as robots, form elements of a complete, total intelligent system, for application to areas such as fully automated factories and cooperating intelligent autonomous vehicles for construction sites.
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AN AUTOMATED ANCHORING SYSTEM FOR AN UNMANNED SURFACE VEHICLEUnknown Date (has links)
The goal of this thesis is to simulate, design and build an automated device that allows unmanned vessels to anchor themselves in specified locations while being United States Coast Guard Navigation Rules compliant. This is a part of a larger project funded by the U.S. Department of Energy for Florida Atlantic University to build an unmanned platform with an Undershot Water Wheel on it. By simulating the environment of the South Florida Intercoastal Water Ways, forces acting on the line, anchor and the vessel are analyzed. These forces are used as the guide for the design and build of a line locking mechanism that takes the tension off the winch and a sensor package to monitor the environment the platform is in as well as control of the system. Based off experimental testing, the system was successful in handling all emulated environments with loads exceeding 150lbs of tension. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection
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AUTOMATED VEHICLES AT SIGNALIZED INTERSECTIONS – IMPACT OF COMMERCIAL ADAPTIVE CRUISE CONTROL (ACC)Unknown Date (has links)
The first generation of autonomous vehicles are equipped with Adaptive Cruise Control
(ACC), which automatically adjusts the vehicle speed to maintain a safe following distance and gap selected by the driver. Today’s ACC can also operate at low speeds and signalized intersections on arterial streets. However, the latency of the on-board sensors can significantly increase the start-up lost time and reduce capacity and increase delay on arterials with signalized intersections. This study investigates the fundamental characteristics of traffic flow under ACC vehicles and mixed driving scenarios. Field tests demonstrated that the design of ACC vehicles can lead to delayed response and gradual acceleration when operating on arterials with speed fluctuations due to disturbances. This study also examines the effect of increasing adoption of ACC vehicles at signalized intersections. Field validated simulations suggest that 100% market penetration of ACC vehicles could decrease the capacity by up to 10%. Furthermore, fuel consumption and emissions (CO2, NOx, CO, HC) can increase by up to 33%. / Includes bibliography. / Thesis (MS)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection
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TRAJECTORY PLANNING WITH DYNAMICS-AWARE PARABOLIC BLENDSUnknown Date (has links)
This thesis presents the concept of dynamics-aware parabolic blends for an unmanned surface vehicle. Typically, trajectory generation techniques consider only kinematic constraints on a vehicle. By transforming the equations of motion for a surface vehicle to the body fixed frame, the dynamical constraints on the system are more intuitively integrated into the trajectory generator, when compared to working in the Earth fixed frame. Additionally, the accelerations, velocities, and positions generated by the parabolic blend algorithm are incorporated into the dynamic equations of motion for the vehicle to provide the feedforward control input of a two degree of freedom control law. The feedback control input of the two degree of freedom scheme is an integral sliding mode control law, which tracks the error between the vehicle state and the desired states generated by the novel parabolic blend technique. The approach is numerically validated through simulation, where the described control law demonstrates a 71.93% reduction in error when compared to a standard proportional-derivative control law subjected to the same desired trajectory. Furthermore, on water experiments were performed using both a proportional-derivative control law and an integral sliding mode control law. Both showed the ability to track the proposed parabolic blend approach. / Includes bibliography. / Dissertation (PhD)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection
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Multi Sensor Multi Object Tracking in Autonomous VehiclesKollazhi Manghat, Surya 12 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Self driving cars becoming more popular nowadays, which transport with it's own intelligence and take appropriate actions at adequate time. Safety is the key factor in driving environment. A simple fail of action can cause many fatalities. Computer Vision has major part in achieving this, it help the autonomous vehicle to perceive the surroundings. Detection is a very popular technique in helping to capture the surrounding for an autonomous car. At the same time tracking also has important role in this by providing dynamic of detected objects. Autonomous cars combine a variety of sensors such as RADAR, LiDAR, sonar, GPS, odometry and inertial measurement units to perceive their surroundings. Driver-assistive technologies like Adaptive Cruise Control, Forward Collision Warning system (FCW) and Collision Mitigation by Breaking (CMbB) ensure safety while driving.
Perceiving the information from environment include setting up sensors on the car. These sensors will collect the data it sees and this will be further processed for taking actions. The sensor system can be a single sensor or multiple sensor. Different sensors have different strengths and weaknesses which makes the combination of them important for technologies like Autonomous Driving. Each sensor will have a limit of accuracy on it's readings, so multi sensor system can help to overcome this defects. This thesis is an attempt to develop a multi sensor multi object tracking method to perceive the surrounding of the ego vehicle. When the Object detection gives information about the presence of objects in a frame, Object Tracking goes beyond simple observation to more useful action of monitoring objects. The experimental results conducted on KITTI dataset indicate that our proposed state estimation system for Multi Object Tracking works well in various challenging environments.
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Studying the Electrostatic Effects on the Dynamics of Charged Lunar Dust via Discrete Element MethodWang, Hao 01 January 2022 (has links) (PDF)
Dust problems raise significant concerns in planetary surface exploration. The unusual behavior of the dust particles that surround the vehicle after engine cutoff has the potential to have more of an influence on surface systems than the high velocity lunar rocket plume ejecta in the landing process. A prevailing hypothesis attributes the levitation and transport of dust particles on the surface of airless bodies to the electrostatic effects and electric field. However, there is no accurate model considering the inter-particle electrostatic interactions, especially when the particles are charged by plume. This dissertation aims to understand the behavior of charged lunar regolith with a discrete element method (DEM) approach focusing on the inter-particle interactions and contact charge transfer. To accomplish this, the grain dynamics is coupled with mechanical and electrical particle interactions, and both short-range and long-range interactions between particles are incorporated. A tribo-charging model based on instantaneous collisions is adopted and validated by simulation and experimental data. Sensitivity analysis is conducted to quantify the effects of initial charge, tribo-charging, and E-field on transport of lunar dust. DEM simulations are then performed for a near realistic lunar environment that show the differences of position and velocity distributions between charged particles and uncharged particles. The results indicate that the charged dust particles have higher dispersion and wider distribution of velocity due to the electrostatic effects. This provides a possible explanation for the phenomena of the approximately 30 s dust lofting following Apollo Lunar Module landing. It is shown that tribo-charging has a more considerable effect on the dynamics of charged particles with a large amount of charge, while the change of E-field does not significantly affect the results. Furthermore, superquadrics and multi-sphere approximations are introduced as two approaches to aspherical geometry to accomplish high-fidelity simulation of lunar dust in the future.
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Viscoelastic Analysis of High Strain Composites for Deployable Structures in Space ApplicationsGomez-Delrio, Andrew 01 January 2020 (has links) (PDF)
Thin-ply composite laminates capable of enduring high strains are currently under investigation for compliant deployable spacecraft structures. Deployable structures such as booms fabricated from these materials can be flattened and coiled to high curvatures, achieving a compact configuration for stowage. Once in orbit, they are released with minimal actuation for deployment, allowing the operational geometry to be recovered. Previous studies have shown that the viscoelastic properties of the composite epoxy matrix can negatively impact final shape accuracy due to stress relaxation during stowage. In addition, since the strain energy stored is relied upon for deployment, considerable relaxation can potentially result in deployment stall. Stress relaxation in composites and the aforementioned effects it can have on deployment have not been analyzed sufficiently for space applications. The objective of this thesis is to investigate the moment relaxation and curvature recovery behavior of thin-ply composite laminates through a combination of analytical, numerical, and experimental approaches. The viscoelastic Kirchhoff plate model that serves as the theoretical basis of the analyses is first presented. An analytical solution for the recovery of a composite plate after stowage is derived. The numerical integration of the viscoelastic plate constitutive equations and its implementation as a user-defined subroutine in finite element programs is then described. The subroutine allows relaxation of 3D thin-shell structures to be modeled, and is applied to simulate stowage and recovery of a thin-ply composite currently of interest for solar sailing applications. The subroutine is then compared with results obtained from experiments for a thin-ply composite for bending relaxation and curvature creep recovery after being unloaded.
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Investigation of Two-Line and Four-Line Chemiluminescence for Equivalence Ratio Mapping of Elevated Pressure CombustionTonarely, Michael 01 January 2022 (has links) (PDF)
Flame stabilization behavior is experimentally investigated at engine relevant conditions using an optical sensor imaging system. Optical imaging systems can provide insight into local engine behavior as opposed to measurements with devices such as flowmeters. Two facilities are utilized to examine premixed flame combustion stabilized by bluff body flame holders at both atmospheric and elevated pressures. C2* and CH* chemiluminescence signals are recorded on a four-band imaging system to calibrate the sensor intensity ratio of C2*/CH* to the flame equivalence ratio. Tracking this ratio across flame position can provide local information concerning flow disturbances and other combustor instabilities. Several fuels (methane, propane, and liquid Jet-A) are tested to examine the change in chemiluminescence ratios that can be found in industrial applications. The calibrations are obtained across a wide range of equivalence ratios (0.6-1.4) and for pressures of 1 and 5 bar. Methane flames showed very low C2* signal value in lean and stoichiometric flames, resulting in non-monotonically increasing calibration curves. Propane flames had a monotonic calibration curve, attributed to greater C2* signal intensity. The Jet-A-air flames also had non-monotonically increasing calibrations at 1 bar, but a monotonic curve at elevated pressure. These calibrations are then applied to the average C2*/CH* intensity ratio images to yield maps of flame equivalence ratio. Downstream variation in the equivalence ratio of the unconfined facility is attributed to air entrainment, while in the weaker signal is thought to be a function of the local flame properties.
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The Effect of Bending and Twisting on a Heaving Flat PlateSoto, Carlos 01 January 2021 (has links) (PDF)
Remotely operated aerial vehicles such as quadcopters and drones have been, and continue to be, used extensively by military personnel, industry, and civilians alike. Current research into unsteady flapping mechanisms has been primarily concerned with the heaving and pitching motion of rigid foils. The purpose of this thesis is to investigate how a dynamically morphing foil affects the fluid-structure interactions of unsteady flapping locomotion as measured by lift, drag, and vorticity. The effects of non-dimensional heaving amplitude and reduced frequency are studied using force sensor and Particle Image Velocimetry (PIV) measurements. Two reduced frequencies are tested: one in the unsteady range, κ=0.105, and one in the highly unsteady range, κ=0.209. Two morphing modes were investigated: spanwise twisting in the direction of upward pitch (Mode A), and spanwise twisting in the direction of downward pitch (Mode B). The effects of changing reduced frequency and nondimensional heaving amplitude were explored for each morphing mode. Force sensor measurements showed that Mode A recovered some of the lift that is usually lost during the upstroke of flapping locomotion. Additionally, Mode A maintained a near-constant lift coefficient during the transition between downstroke and upstroke, suggesting a more stable form of locomotion. PIV results showed that Mode A limits circulation and leading-edge vortex (LEV) growth during the downstroke, keeping Cd ≈ 0 at the cost of reduced lift. By contrast, PIV results showed that Mode B increases the circulation during the downstroke, resulting in large increases in both lift and drag coefficients. Force sensor data showed that this effect on lift is reversed during the upstroke, where Mode B causes negative lift. The effects of each morphing mode is caused by changes in shear layer velocity that occur as a result of spanwise twisting. The twisting performed by Mode A reduces the effective angle of attack, resulting in a reduced shear layer velocity and lower circulation. The twisting performed by Mode B does the exact opposite, increasing the effective angle of attack and consequently increasing the shear layer velocity and circulation.
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Development of Multi-Scale Characterization Techniques for Stress Corrosion Cracking of Aerospace AlloysReed, Nicholas 01 January 2021 (has links) (PDF)
Corrosion presents an inherent challenge in the safe and effective use of metallic aerospace structures for extended periods of time. Progress in the fundamental understanding of corrosion initiation and propagation under stress requires a multi-scale approach that leverages experiments to develop predictive models. Although there exists a large amount of research results tracking the corrosive processes of anodic dissolution and hydrogen embrittlement, the amount of available data and modeling of the micro-scale initiation of corrosion is sparse. This work leverages a suite of characterization techniques to systematically analyze an aerospace grade aluminum alloy AA7075-T6, providing important multi-scale data for correlation with overall corrosion progression. Samples were exposed to 3.5% NaCl solution at various exposure times under loading with a micro-tensile system. Optical microscopy, Raman spectroscopy and Energy Dispersive X-ray Analysis provided spatial maps of the visual and chemical alloy signatures before, during, and after failure, to analyze and track the progression of corrosion. An experimental setup for in-situ Digital Image Correlation (DIC) was developed to provide strain maps to study local concentrations around corrosion pits and quantify the impact on the material tensile performance. The material morphology and composition from these measurements identified localized oxide formations at a high spatial resolution that can be used to quantify the corrosion rates. Meanwhile, in-situ DIC measurements provided results showing stress concentrations formed by the corrosion pits and the reduced mechanical performance with exposure. The results demonstrate that multiple factors affect corrosion susceptibility and material deterioration, and highlight the need to overcome experimental challenges in quantifying these factors distinctly. This work demonstrates the capacity for highly detailed analysis of corrosion initiation and propagation in affected alloys using the processes outlined in the systematic study. The outcomes provide a pathway to address methods for maintaining the integrity of these alloys and extending their lifespan.
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