Georgios P. Kladis

Energy conservation based fuzzy tracking for unmanned aerial vehicle missions under a priori known wind information

The aim of this work is to include the navigation step for the waypoint-based guidance of a UAV system and to illustrate aspects such as tracking of the reference trajectory under wind presence, while conserving total energy requirements. The mission is represented utilising graph theory tools. The mathematical modelling of an aircraft controlled by an actuator surface is presented in terms of simple analytic relationships in order to simulate the actual horizontal motion of the vehicle. Its equivalence with a Tagaki-Sugeno (T-S) fuzzy system is illustrated that can aid the control methodology involved. Additionally, the advantages of utilising such an analysis is also stressed. The model formulated is an error posture model, that depends on current and reference posture. The control law is designed through parallel distributed compensation (PDC) and the gains are computed with the help of linear matrix inequalities (LMIs). Hence stability for the system is also guaranteed provided that the state variables are bounded in a priori known compact space. Moreover the energy requirements are described. This article is contributing towards energy enhancing a UAV mission and generating safely-flyable trajectories to meet mission objectives. The control law used is calculated in the pre-flight planning and can be used in real time for any trajectory to be tracked under any environmental conditions. Provided that angular and linear velocities are bounded, the latter is feasible under the assumption that the magnitude of air speed is small compared to the ground velocity of the aerial vehicle. The methodology offers an improved visualisation to aid an analyst with the representation of a UAV mission through graph theory tools utilising energy requirements for the mission and fast computational schema using matrix analysis. A simulation example of a UAV deployed from a source to reach a destination node under windy conditions is included to illustrate the analysis. The reference trajectory used is a piecewise Bezier-Bernstein curve referred to as the Dubins path.

A node-to-node composite graph and pseudo-Boolean modelling: An unmanned aerial vehicle energy application

Abstract Unmanned aerial vehicles (UAV) have been gaining momentum in recent years because of their vast application areas in the defence and civilian sectors. Their use can result in future missions to be more effective while also be conducted in a safer manner. UAVs, due to their large operational potential may be required to travel over long distances and prespecified way points thus requiring an effective and efficient decision making mechanism which allow the UAV to start and complete its mission. These missions may start and terminate at different or identical topological locations (or nodes). In the current paper a node-to-node graph theory energy costs modelling method is developed and presented. The modelling method requires as a priori the node-to-node energy costs. Furthermore, several propositions were presented to allow for the energy matrix to be perturbable, thus representing possible atmospheric variations which may occur during the UAVs mission. The UAV is modelled using energy graphs which allow a topological optimum to be obtained via suitable optimization algorithms. The energy costs implicitly contain time, propulsion force, and velocity information thus producing realistic results.

Fault diagnosis with matrix analysis for electrically actuated unmanned aerial vehicles

Abstract Because of their large operational potential, unmanned aerial vehicles (UAVs) may be required to perform over long periods of time, which might lead to potential degradation or even failure of their electrical or/and mechanical control surfaces and components. Consequently, the least failure can degrade the performance of the process and might lead to a catastrophic event. Therefore, an efficient mechanism should be capable of making these faults realizable and act accordingly so that a performance index is continuously maintained. However, even when a fault is detected at the monitoring phase, as illustrated in a previous work by Kladis and Economou [

Aerospace energy conservation utilizing optimum methods

In general, the minimum path problem is concerned with finding shortest paths between a start to an end node in the minimum distance sense. There are many interesting algorithms which may be utilized for that purpose, that fall under the category of the Euclidian travelling salesman problem [1] and [2]. Although these methodologies determine the optimum waypoint guidance to be traversed by an aerial vehicle, to reach a destination, there is need for the inclusion of dynamical and functional constraints in order to describe the means to reach the goal. While the resulting path(s) are of minimum-distance sense they do not take into account the energy requirements. Consequently wasting fuel the path may not be feasible or reachable. In the included work the arbitrary energy requirements for the mission are described with a focus on optimum-energy demand for a waypoint based sequence of elementary walks. The later is illustrated through a simulation of an aircraft which needs to reach a goal from a source point passing via intermediate waypoints of interest. In addition wind disturbances are included in the formulation and analysis.

Digraph matrix reliability analysis for fault assessment for A UAV platform application. A fault-tree analysis approach

In this paper potential causes that lead to a failure are investigated through a digraph analysis utilizing graph theory tools and pseudo boolean expressions. A generic scenario of a multi-layered scheme for fault assessment for a UAV application, illustrates the proposed methodology. The resulting solution is obtained by the use of shortest path algorithms due to the means the problem is posed and its similarity to routing problems. In addition mathematical formulation and its relevance is also addressed.

An emergency refuelling problem over a dynamically changing environment in the context of Unmanned Aerial Vehicles

In general routing problems are adapted to the application domain while incorporating constraints and special conditions. Depending on the problem, the classical static shortest path algorithm may be proved unrealized due to insufficient energy reserves. Motivated from the analysis in (Economou et al., 2007) where graph theory tools were utilized in the UAV (unmanned aerial vehicle) context for the static routing problem. The paper presents methods for determining the shortest path while conserving propulsion energy for the overall mission when a dynamically changing environment is concerned. Additional constraints can be incorporated when an adequate refuelling station is also needed in order to reach a goal, thus including real world conditions in the methodology. The later is considered using location theory tools. The overall methodology is illustrated through a simple simulation example where a UAV, with finite fuel reserves, has a task to traverse a dynamically changing environment from a particular starting point towards a goal and passing through an intermediate refuelling point, while minimizing energy requirements.

An Intelligent Rule-Based System For Fault Detection And Diagnosis On A Model-Based Actuator Device

Unmanned aerial vehicles due to their large operational potential may be required to travel over long distances and through various weather conditions, which might lead to potential degradation or even failure of their electrical or/and mechanical actuator parts. Control in trajectory derivations and path following processes is highly dependable on these actuators and sensors. Depending on their efficiency, the outcome will be a near optimum solution to every problem. Consequently, the minor failure can degrade the performance of the process and might drive it to an uncontrollable system. Therefore, an efficient mechanism should be capable of making these faults realizable and act accordingly so that a consistent performance actuator performance qualitative or quantitative index is continuously maintained. In this paper electro-mechanical actuator potential failures are firstly detected and then diagnosed for the application of unmanned aerial vehicles. It includes several scenarios of actuator faults and results which demonstrate the fault conditions and the effectiveness of the detection and diagnosis Kalman based algorithms. It involves the diagnosis strategy to minimizing errors produced due to malfunction in components or inaccuracies in the model. The residuals used are generated using empirical actuator models which are chosen under specific operating regimes.

Optimality and Reachability - Pseudo Boolean Power Flows for multi-sourced Vehicle Topologies

Multi-agents have been gaining momentum in recent years due to their vast application in numerous fields.Due to the limitations of a single vehicle routing problems which are rarely applicable in practical situations, a multi-agent based scenario may accommodate real-world situations more closely. So a collection of parameterized vehicles on a mission can provide an ideal framework for identifying, modelling and analyzing many interesting paradigms, design parameters and solution strategies. While trying to accomplish their mission these agents need to respect the heterogeneous set of constraints on both their physical and communication resources.In this paper a power/energy flow modelling method is presented for multi-sourced vehicles.Graph theory forms the basis for this innovative and powerful methodology.The methodology described is extended to pseudo-Boolean representation of the systems power flow.This work is intended to state contributions while providing an analytical and rigorous method for modelling power flows and obtaining energy paths via reachability matrix properties.Detailed and rigorous analysis and optimality scenarios are also included.