Unmanned Vehicles (UVs) currently perform a variety of tasks critical to a military mission. In future, they are envisioned to have the ability to accomplish a mission co-operatively and effectively with limited fuel onboard. In particular, they must search for targets, classify the potential targets detected, attack the classified targets and perform an assessment of the damage done to the targets. In some cases, UVs are themselves munitions. The targets considered in this thesis are stationary. The problem considered in this thesis, referred to as the UV problem, is the allotment of tasks to each UV along with the sequence in which they must be performed so that a maximum number of tasks are accomplished collectively. The maneuverability constraints on the UV are accounted for by treating them as Dubin's vehicles. Since the UVs considered are disposable with life spans governed by their fuel capacity, it is imperative to use their life as efficiently as possible. Thus, we need to develop a fuel-optimal (equivalently, distance optimal) motion plan for the collection of UVs. As the number of tasks to be performed and the number of vehicles performing these tasks grow, the number of ways in which the set of tasks can be distributed among the UVs increases combinatorially. The tasks a UV is required to perform are also subject to timing constraints. A UV cannot perform certain tasks before completing others. We consider a simplified version of the UV problem and do not take into account the timing constraints on the tasks to be performed on targets. We use linear programming and graph theory to find a solution to this simplified UV problem; in the graph theory approach, we develop an algorithm which is a generalization of the solution procedures available to solve the Traveling Salesman Problem (TSP). We provide an example UV problem illustrating the solution procedure developed in this thesis.

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

An autonomous system has been widely applied for various civil/military research because of its versatile capability of understanding high-level intent and direction of a surrounding environment and targets of interest. However, as autonomous systems can be out of control to cause serious loss, injury, or death in the worst case, the verification of their functionalities has got increasing attention. For that reason, this study is focused on the verification of a heterogeneous multi-agent autonomous system. The thesis first presents an overview of formal methods, especially focuses on model checking for autonomous systems verification. Then, six case studies are presented to verify the decision making behaviours of multi-agent system using two basic scenarios: surveillance and convoy. The initial system considered in the surveillance mission consists of a ground control system and a micro aerial vehicle. Their decision-making behaviours are represented by means of Kripke model and computational tree logic is used to specify the properties of this system. For automatic verification, MCMAS (Model Checker for Multi-Agent Systems) is adopted due to its novel capability to accommodate the multi-agent system. After that, the initial system is extended to include a substitute micro aerial vehicle. These initial case studies are then further extended based on SEAS DTC exemplar 2 dealing with behaviours of convoy protection. This case study includes now a ground control system, an unmanned aerial vehicle, and an unmanned ground vehicle. The MCMAS successfully verifies the targeting behaviours of the team-level unmanned systems. Reversely, these verification results help retrospectively improve the design of decision-making algorithms by considering additional agents and behaviours during four steps of scenario modification. Consequently, the last scenario deals with the system composed of a ground control system, two unmanned aerial vehicles, and four unmanned ground vehicles with fault-tolerant and communications relay capabilities. In conclusion, this study demonstrates the feasibility of model checking algorithms as a verification tool of a multi-agent system in an initial design stage. Moreover, this research can be an important first step of the certification of multi-agent autonomous systems for the domains of robotics, aerospace and aeronautics.

To satisfy the requirements of small satellites with attitude control requirements, a guidance, navigation, and control module was designed at the Texas Spacecraft Laboratory. However, these small satellites tend to have attitude constraints in the form of keep-in and keep-out cones. Two methods for autonomous constrained attitude guidance are presented. The first satisfies the problem of guiding a single axis through keep-out constraints while satisfying a second keep-in constraint through an adjoined optimization routine. The method leverages methods for discretizing the attitude shell combined with the graph pathfinding algorithm A*. The second approach generalizes the problem to any number of attitude constraints in the body and inertial frame by discretizing the quaternion space using a series of concentric discretized shells. An approach for discretized attitude optimization is created to allow the vehicle to identify which attitude mode to operate under while simultaneously optimizing the solar power input. The discretized constrained attitude guidance and attitude optimization techniques are tied together in the flight software architecture and tested in a hardware-in-the-loop simulation environment. / text

An autonomous system has been widely applied for various civil/military research because of its versatile capability of understanding high-level intent and direction of a surrounding environment and targets of interest. However, as autonomous systems can be out of control to cause serious loss, injury, or death in the worst case, the verification of their functionalities has got increasing attention. For that reason, this study is focused on the verification of a heterogeneous multi-agent autonomous system. The thesis first presents an overview of formal methods, especially focuses on model checking for autonomous systems verification. Then, six case studies are presented to verify the decision making behaviours of multi-agent system using two basic scenarios: surveillance and convoy. The initial system considered in the surveillance mission consists of a ground control system and a micro aerial vehicle. Their decision-making behaviours are represented by means of Kripke model and computational tree logic is used to specify the properties of this system. For automatic verification, MCMAS (Model Checker for Multi-Agent Systems) is adopted due to its novel capability to accommodate the multi-agent system. After that, the initial system is extended to include a substitute micro aerial vehicle. These initial case studies are then further extended based on SEAS DTC exemplar 2 dealing with behaviours of convoy protection. This case study includes now a ground control system, an unmanned aerial vehicle, and an unmanned ground vehicle. The MCMAS successfully verifies the targeting behaviours of the team-level unmanned systems. Reversely, these verification results help retrospectively improve the design of decision-making algorithms by considering additional agents and behaviours during four steps of scenario modification. Consequently, the last scenario deals with the system composed of a ground control system, two unmanned aerial vehicles, and four unmanned ground vehicles with fault-tolerant and communications relay capabilities. In conclusion, this study demonstrates the feasibility of model checking algorithms as a verification tool of a multi-agent system in an initial design stage. Moreover, this research can be an important first step of the certification of multi-agent autonomous systems for the domains of robotics, aerospace and aeronautics.

This dissertation addresses model form uncertainty quantification, non-deterministic simulations, and sensitivity analysis of the results of these simulations, with a focus on application to analysis of unmanned aircraft systems. The model form uncertainty quantification utilizes equation error to estimate the error between an identified model and flight test results. The errors are then related to aircraft states, and prediction intervals are calculated. This method for model form uncertainty quantification results in uncertainty bounds that vary with the aircraft state, narrower where consistent information has been collected and wider where data are not available. Non-deterministic simulations can then be performed to provide uncertainty quantified estimates of the system performance. The model form uncertainties could be time varying, so multiple sampling methods were considered. The two methods utilized were a fixed uncertainty level and a rate bounded variation in the uncertainty level. For analysis using fixed uncertainty level, the corner points of the model form uncertainty were sampled, providing reduced computational time. The second model better represents the uncertainty but requires significantly more simulations to sample the uncertainty. The uncertainty quantified performance estimates are compared to estimates based on flight tests to check the accuracy of the results. Sensitivity analysis is performed on the uncertainty quantified performance estimates to provide information on which of the model form uncertainties contribute most to the uncertainty in the performance estimates. The proposed method uses the results from the fixed uncertainty level analysis that utilizes the corner points of the model form uncertainties. The sensitivity of each parameter is estimated based on corner values of all the other uncertain parameters. This results in a range of possible sensitivities for each parameter dependent on the true value of the other parameters. / Ph. D.

The testing of unmanned vehicles presents a need for an independent device capable of accurately collecting position and orientation data. While commercial-off-the-shelf components could be pieced together to sense and record this information, this is an expensive, large, and heavy solution, not suitable for small or aerial vehicles. The micro wireless instrumented payload, or μWIP, was designed precisely for this purpose. The μWIP includes a GPS receiver, 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer which are used to measure an unmanned vehicle's position and orientation. The device also uses a secure digital card for data storage, and an 802.11b module to provide wireless connectivity. Additionally, the μWIP contains a on-board battery and the circuitry required to charge it. Firmware for the ARM7 processor was written to allow sensor calibration and data transmission, and a user interface was designed to run on a personal computer. The finished design is a tiny 3''x5''x1'', and weighs a mere 0.8 pounds including battery and antennas. It is capable of continuously streaming accurate GPS and inertial data over an 802.11b wireless network for over 5 hours. Having a bill of materials cost just over $600, the μWIP is also more cost effective than any alternative solutions. This thesis details the hardware and software design of the μWIP, as well as the initial testing, calibration, and evaluation of the device. / Master of Science

As the use of unmanned vehicles continues to grow, so does the need for systems to safely test and operate these vehicles. While there are safety systems designed for this purpose, they are often developed for a specific vehicle platform. The Multi-Level Emergency Stop (MLES) system provides three user-defined emergency response contingencies that can be adapted to a wide variety of unmanned vehicles. The Multi-Level Emergency Stop system is designed to be an ad-on safety system that can be integrated into ground, air, or surface unmanned vehicles. A complete MLES system consists of a hand held transmitter and a vehicle mounted receiver. The three levels of contingencies are controlled by three switches on the transmitter. These switches engage and disengage contacts located in the receiver via a wireless link. The function of these contacts is determined by the user for each unique application. Presented in this thesis is the detailed hardware design and software layout of the Multi-Level Emergency Stop system. Also included are the performance results and operational tests. / Master of Science

We present real-time autonomous implementations of a practical distributed formation control scheme for a multi-quadrotor system for two different cases: parameters of linearized dynamics are exactly known, and uncertain system parameters. For first case, we design a hierarchical, decentralized controller based on the leader-follower formation approach to control a multi-quadrotor swarm in rigid formation motion. The proposed control approach has a two-level structure: high-level and low-level. At the high level, a distributed control scheme is designed with respect to the relative and global position information of the quadrotor vehicles. In the low-level, we analyze each single quadrotor control design in three parts. The first is a linear quadratic controller for the pitch and roll dynamics of quadrotors. The second is proportional controller for the yaw motion. The third is proportional-integral-derivative controller in altitude model. For the second case, where inertial uncertainties in the pitch and roll dynamics of quadrotors are considered, we design an on-line parameter estimation with the least squares approach, keeping the yaw, altitude and the high-level controllers the same as the first case. An adaptive linear quadratic controller is then designed to be used with lookup table based on the estimation of uncertain parameters. Additionally, we study on enhancement of self and inter-agent relative localization of the quadrotor agents using a single-view distance-estimation based localization methodology as a practical and inexpensive tool to be used in indoor environments for future works. Throughout the formation control implementations, the controllers successfully satisfy the objective of formation maintenance for non-adaptive and adaptive cases. Simulations and experimental results are presented considering various scenarios, and positive results obtained for the effectiveness of our algorithm.

Includes supplementary material. / Published as received: "volume 1" only. / Distributing naval combat power into many small ships and unmanned air vehicles that capitalize on emerging technology offers a transformational way to think about naval combat in the littorals in the 2020 time frame. Project CROSSBOW is an engineered systems of systems that proposes to use such distributed forces to provide forward presence to gain and maiantain access, to provide sea control, and to project combat power in the littoral regions of the world. Project CROSSBOW is the result of a yearlong, campus-wide, integrated research systems engineering effort involving 40 student researchers and 15 supervising faculty members. This report (Volume I) summarizes the CROSSBOW project. It catalogs the major features of each of the components, and includes by reference a separate volume for each of the major systems (ships, aircraft, and logistics). It also prresents the results of the mission and campaign analysis that informed the trade-offs between these components. It describes certain functions of CROSSBOW in detail through specialized supporting studies. The student work presented here is technologically feasible, integrated and imaginative. The student project cannot by itself provide definitive designs or analyses covering such a broad topic. It does strongly suggest that the underlying concepts have merit and deserve further serious study by the Navy as it transforms itself.