On the reachability and observability of path and cycle graphs

In this paper we investigate the reachability and observability properties of a network system, running a Laplacian based average consensus algorithm, when the communication graph is a path or a cycle. More in detail, we provide necessary and sufficient conditions, based on simple algebraic rules from number theory, to characterize all and only the nodes from which the network system is reachable (respectively observable). Interesting immediate corollaries of our results are: (i) a path graph is reachable (observable) from any single node if and only if the number of nodes of the graph is a power of two, $n=2^i, i\in \natural$, and (ii) a cycle is reachable (observable) from any pair of nodes if and only if $n$ is a prime number. For any set of control (observation) nodes, we provide a closed form expression for the (unreachable) unobservable eigenvalues and for the eigenvectors of the (unreachable) unobservable subsystem

Centrifugally Stiffened Rotor: Eternal Flight as the Solution for 'X': NIAC Phase I Final Report

Flight has always captured man's imagination. This is evidenced by the great variety of aerial vehicles that exist today. Everything from fixed-wing to rotorcraft; satellites to spaceships;mono-wing to quadrotor. However, despite the wide variety of flying vehicles, not one of them has attained eternal flight. Accomplishing this feat is one of the great challenges still facing the aviation community. Motivation Achieving eternal flight opens the doors to atmospheric satellites. Existing satellites have a great number of capabilities that enrich our lives; however,their distance from the surface of the earth precludes certain types of transmission capabilities. Once eternal flight is achieved, that vehicle can serve the same role as ordinary satellites, but its close proximity will allow for real time two way communications,like wireless broadband internet. And with active controls, atmospheric satellites would not be constrained to geosynchronous orbits, like our existing satellite technology. Many projects are under way to achieve this goal;however, most of these research efforts follow the same design methodology, and have exhausted the limits of this particular design. This concept introduces a completely new aerial vehicle structure,which uses the best features of fixed-wing and rotorcraft designs. Combining the best features of different classes of aircraft, expands the capabilities beyond what either one can achieve on its own

Modeling, Control, and Hardware Development of a Thrust-Vector Coaxial UAV

This thesis introduces a unique thrust vector coaxial unmanned aerial vehicle (UAV) configuration and presents a comprehensive investigation encompassing dynamics modeling, hardware design, and controller development. Using the Newton-Euler method, a dynamic model for the UAV is derived to gain in-depth insights into its fundamental flight characteristics. A simple thrust model is formulated and modified by comparing it with data obtained from vehicle testing. The feasibility of manufacturing such a vehicle is assessed through the development of a hardware prototype. Finally, a linear state feedback controller is designed and evaluated using the non-linear dynamics model. The results demonstrate successful validation of the hardware through flight tests. The initial thrust model is enhanced by two methods, incorporating correction factors derived from a regression line, and employing the system identification method based on the test stand data. Implementation of the linear state feedback controller effectively maintains attitude authority over a non-linear simulation of the vehicle. The limits of the controller are explored, and simulation highlights that the controller\u27s authority fails if the operating states deviate from the linearized region of attraction. Beyond the specific thrust vector coaxial UAV configuration, this research holds implications for enhancing UAV dynamics modeling, analysis, and control in broader applications

Dexterous Hexrotor UAV Platform

Mobile manipulation is a hot area of study in robotics as it unites the two classes of robots: locomotors and manipulators. An emerging niche in the field of mobile manipulation is aerial mobile manipulation. Although there has been a fair amount of study of free-flying satellites with graspers, the more recent trend has been to outfit UAVs with graspers to assist various manipulation tasks. While this recent work has yielded impressive results, it is hampered by a lack of appropriate testbeds for aerial mobile manipulation, similar to the state of ground-based mobile manipulation a decade ago. Typical helicopters or quadrotors cannot instantaneously resist or apply an arbitrary force in the plane perpendicular to the rotor axis, which makes them inadequate for complex mobile manipulation tasks. Based on the concept of force closure (a term from the dexterous manipulation community), this thesis introduces the new type of dexterous, 6-DoF UAV which provides the unique capability of being able to resist any applied wrench, or generalized force-torque. In this thesis, we describe the importance of force closure for mobile manipulation, explain why it is lacking in current UAV platforms, and describe how our hexrotor provides this important capability as well as exhibiting holonomic behavior

Control Driven Scaling Effects of Motor and Rotors for Urban Air Mobility Design

Through this thesis research the problem of controllability and propulsion associated with scaling-up consumer drones to vehicles that may carry significantly larger payloads, including passenger will be analyzed and tested. Controllability is mainly compromised due to the increasing response time of a larger rpm controlled rotor. This requires a more powerful motor, which translates into heavier and larger devices compromising the thrust-to-weight ratio. Collective pitch control at constant rpm is proposed as a first approach to mitigate the controllability problem, and it is tested in a MATLAB Simulink environment. This solution, linked to a Non-linear Dynamic Inversion controller, is simulated as part of the Personal Aerial Vehicle Embry-Riddle aircraft, which serves as test bed. The simulation includes the electric motor, rotor and aircraft mathematical models, which are developed in this research. Included in this thesis are motor sizing and weigh analysis as well as a thrust-to-weight ratio study, which allows to identify the scaling-up effects in consumer drones\u27 propulsion plant. This portion of the thesis is closely linked to the behavior displayed in the simulation, which leads to conclude that collective pitch control at constant rpm can mitigate controllability drawbacks. However, due to the size and weight of electric motors increasing very rapidly, it is demonstrated that, while it is possible to obtain an optimal solution where controllability and thrust-to-weight ratio are in balance, scaling-up consumer drones is a highly complex and limited task

Robust Operation and Control Synthesis of Autonomous Mobile Rack Vehicle in the Smart Warehouse

Nowadays, with the development of science and technology, to manage the inventory in the warehouse more efficiency, so the warehouse must have the stability and good operation chain such as receive and transfer the product to customer, storage the inventory, manage the location, making the barcode...in that operation chain, storage the inventory in the warehouse is most important thing that we must consider. In addition, to reduce costs for larger warehouse or expand the floor space of the small warehouse, it is impossible to implement this with a traditional warehouse. The warehouse is called the traditional warehouse when it uses the fixed rack. To build this type of warehouse, the space for storage must be very large. However, the cost for renting or buying the large warehouse is too expensive, so to reduce cost and build the flexible warehouse which can store the huge quantity of product within limited area, then the smart warehouse is necessary to consider. The smart warehouse system with autonomous mobile rack vehicles (MRV) increases the space utilization by providing only a few open aisles at a time for accessing the racks with minimal intervention. It is always necessary to take into account the mobile-rack vehicles (or autonomous logistics vehicles). This thesis deals with designing the robust controller for maintaining safe spacing with collision avoidance and lateral movement synchronization in the fully automated warehouse. The compact MRV dynamics are presented for the interconnected string of MRV with communication delay. Next, the string stability with safe working space of the MRV has been described for guaranteeing complete autonomous logistics in the extremely cold environment without rail rack. In addition, the controller order has been significantly reduced to the low-order system without serious performance degradation. Finally, this control method addresses the control robustness as well as the performances of MRV against unavoidable uncertainties, disturbances, and noises for warehouse automation.Contents List of Tables vii List of Figures viii Chapter 1. Introduction 1 1.1 Mobile rack vehicle 2 1.2 Leader and following vehicle 5 1.2.1 Cruise control 5 1.2.2 Adaptive cruise control 6 1.2.3 String stability of longitudinal vehicle platoon 10 1.2.4 String stability of lateral vehicle platoon 15 1.3 Problem definition 20 1.4 Purpose and aim 21 1.5 Contribution 22 Chapter 2. Robust control synthesis 23 2.1 Introduction 23 2.2 Uncertainty modeling 23 2.2.1 Unstructured uncertainties 24 2.2.2 Parametric uncertainties 25 2.2.3 Structured uncertainties 26 2.2.4 Linear fractional transformation 26 2.2.5 Coprime factor uncertainty 27 2.3 Stability criterion 31 2.3.1 Small gain theorem 31 2.3.2 Structured singular value synthesis brief definition 33 2.4 Robustness analysis and controller design 34 2.4.1 Forming generalized plant and structure 34 2.4.2 Robustness analysis 37 2.5 Robust controller using loop shaping design 39 2.5.1 Stability robustness for a coprime factor plant description 41 2.6 Reduced controller 44 2.6.1 Truncation 45 2.6.2 Residualization 46 2.6.3 Balanced realization 47 2.6.4 Optimal Hankel norm approximation 48 Chapter 3. Dynamical model of mobile rack vehicle. 53 3.1 Dynamical model of longitudinal mobile rack vehicle 53 3.2 Dynamical model of lateral mobile rack vehicle 56 3.1.1 Kinematics and dynamics of mobile rack vehicles 56 3.1.2 Lateral vehicle model with nominal value 62 Chapter 4. Controller design for mobile rack vehicle 65 4.1 Robust controller synthesis for longitudinal of mobile rack vehicles 65 4.2 Robust controller synthesis for lateral of mobile rack vehicles 73 4.2.1 Lateral vehicle model with uncertainty description 74 4.2.2 Controller design 78 4.2.3 Robust performance problem 82 4.3 String stability of connected mobile rack vehicle 85 4.4 Lower order control synthesis 87 Chapter 5. Numerical simulation and discussion 92 5.1 Mobile rack longitudinal control simulation and discussion 92 5.2 Mobile rack lateral control simulation and discussion 99 Chapter 6. Conclusion 110 Reference 112Docto

Optimal steering for kinematic vehicles with applications to spatially distributed agents

The recent technological advances in the field of autonomous vehicles have resulted in a growing impetus for researchers to improve the current framework of mission planning and execution within both the military and civilian contexts. Many recent efforts towards this direction emphasize the importance of replacing the so-called monolithic paradigm, where a mission is planned, monitored, and controlled by a unique global decision maker, with a network centric paradigm, where the same mission related tasks are performed by networks of interacting decision makers (autonomous vehicles). The interest in applications involving teams of autonomous vehicles is expected to significantly grow in the near future as new paradigms for their use are constantly being proposed for a diverse spectrum of real world applications. One promising approach to extend available techniques for addressing problems involving a single autonomous vehicle to those involving teams of autonomous vehicles is to use the concept of Voronoi diagram as a means for reducing the complexity of the multi-vehicle problem. In particular, the Voronoi diagram provides a spatial partition of the environment the team of vehicles operate in, where each element of this partition is associated with a unique vehicle from the team. The partition induces, in turn, a graph abstraction of the operating space that is in a one-to-one correspondence with the network abstraction of the team of autonomous vehicles; a fact that can provide both conceptual and analytical advantages during mission planning and execution. In this dissertation, we propose the use of a new class of Voronoi-like partitioning schemes with respect to state-dependent proximity (pseudo-) metrics rather than the Euclidean distance or other generalized distance functions, which are typically used in the literature. An important nuance here is that, in contrast to the Euclidean distance, state-dependent metrics can succinctly capture system theoretic features of each vehicle from the team (e.g., vehicle kinematics), as well as the environment-vehicle interactions, which are induced, for example, by local winds/currents. We subsequently illustrate how the proposed concept of state-dependent Voronoi-like partition can induce local control schemes for problems involving networks of spatially distributed autonomous vehicles by examining different application scenarios.PhDCommittee Chair: Tsiotras Panagiotis; Committee Member: Egerstedt Magnus; Committee Member: Feron Eric; Committee Member: Haddad Wassim; Committee Member: Shamma Jef

Operationally Efficient Propulsion System Study (OEPSS) data book. Volume 4: OEPSS design concepts

This study was initiated to identify operations problems and cost drivers for current propulsion systems and to identify technology and design approaches to increase the operational efficiency and reduce operations costs for future propulsion systems. To provide readily usable data for the Advanced Launch System (ALS) program, the results of the OEPSS study have been organized into a series of OEPSS Data Books. This volume describes three propulsion concepts that will simplify the propulsion system design and significantly reduce operational requirements. The concepts include: (1) a fully integrated, booster propulsion module concept for the ALS that avoids the complex system created by using autonomous engines with numerous artificial interfaces; (2) an LOX tank aft concept which avoids potentially dangerous geysering in long LOX propellant lines; and (3) an air augmented, rocket engine nozzle afterburning propulsion concept that will significantly reduce LOX propellant requirements, reduce vehicle size and simplify ground operations and ground support equipment and facilities