J.M. de la Cruz

Evolutionary Trajectory Planner for Multiple UAVs in Realistic Scenarios

This paper presents a path planner for multiple unmanned aerial vehicles (UAVs) based on evolutionary algorithms (EAs) for realistic scenarios. The paths returned by the algorithm fulfill and optimize multiple criteria that 1) are calculated based on the properties of real UAVs, terrains, radars, and missiles and 2) are structured in different levels of priority according to the selected mission. The paths of all the UAVs are obtained with the multiple coordinated agents coevolution EA (MCACEA), which is a general framework that uses an EA per agent (i.e., UAV) that share their optimal solutions to coordinate the evolutions of the EAs populations using cooperation objectives. This planner works offline and online by means of recalculating parts of the original path to avoid unexpected risks while the UAV is flying. Its search space and computation time have been reduced using some special operators in the EAs. The successful results of the paths obtained in multiple scenarios, which are statistically analyzed in the paper, and tested against a simulator that incorporates complex models of the UAVs, radars, and missiles, make us believe that this planner could be used for real-flight missions.

A mathematical model for planning transportation of multiple petroleum products in a multi-pipeline system

A multiproduct pipeline provides an economic way to transport large volumes of refined petroleum products over long distances. In such a pipeline, different products are pumped back-to-back without any separation device between them. Sometimes, multiproduct pipelines can be connected together, resulting in a more complex system commonly named multi-pipeline system. This paper proposes a new discrete mathematical approach to solve short-term operational planning of multi-pipeline systems for refined products. This model is based on a discrete approach that divides both the planning horizon into time intervals of equal duration and the individual polyducts into packages of equal volume each containing a single product. Numerical examples are solved in order to show the performance of the proposed model. All the instances are implemented with the OPL modeling language running CPLEX as solver.

Fast Ferry Vertical Accelerations Reduction with Active Flaps and T-Foil

Abstract The research deals with the design and use of actuators to improve the seakeeping performances of a fast ferry. The interest of the research is now restricted to heaving and pitching motions, with heading sea. The ship has active control surfaces (flaps and T-foil). The paper presents a control-oriented model of these actuators, in SIMULINK. This model can be easily coupled with a SIMULINK model of the ship, furnishing a simulation environment for control studies. Using this facility, a study of control alternatives (moving the actuators) has been started. We include in the paper first results with conventional PID control, which are useful as reference for comparison purposes.

A new Expert System for greenness identification in agricultural images

Highlights? We design an Expert System for plant discrimination in agricultural fields. ? A decision making module determines the image quality. ? A greenness identification module extracts green plants. ? The Expert System is valid under adverse conditions and different devices. ? Plants segmentation is required for weeds specific treatments. It is well-known that one important issue emerging strongly in agriculture is related with the automation of tasks, where camera-based sensors play an important role. They provide images that must be conveniently processed. The most relevant image processing procedures require the identification of green plants, in our experiments they comes from barley and maize fields including weeds, so that some type of action can be carried out, including site-specific treatments with chemical products or mechanical manipulations.The images come from outdoor environments, which are affected for a high variability of illumination conditions because of sunny or cloudy days or both with high rate of changes.Several indices have been proposed in the literature for greenness identification, but under adverse environmental conditions most of them fail or do not work properly. This is true even for camera devices with auto-image white balance.This paper proposes a new automatic and robust Expert System for greenness identification. It consists of two main modules: (1) decision making, based on image histogram analysis and (2) greenness identification, where two different strategies are proposed, the first based on classical greenness identification methods and the second inspired on the Fuzzy Clustering approach. The Expert System design as a whole makes a contribution, but the Fuzzy Clustering strategy makes the main finding of this paper. The system is tested for different images captured with several camera devices.

Identification of the Vertical Plane Motion Model of a High Speed Craft by Model Testing in Irregular Waves

Abstract Experiments in towing tanks are concerned with the determination of the motion transfer functions, which are obtained by testing in irregular waves. For this purpose a model of pitch and heave motions has been developed, and the identified models of the vertical plane motions of a high-speed craft are showed. Linear models are obtained for different sea states and ship speeds. A general low order model is obtained by pole-zero cancellation. So, a full model may be considered for simulation and verification, and a low order model for design. From the lowest order models, a state space model is obtained.

Improving the comfort of a fast ferry

A study was conducted to determine the effectiveness of using controlled flaps and a T-foil to smoothen a ships vertical motion while navigating in head seas. The study comprised two steps: to develop a tool for control design in the form of a computer-based simulation and to use this tool to develop satisfactory controllers. The simulation was based on mathematical models of the ship, the actuators, the waves and the seasickness effect. Since the actuators have limited action, there is a limited margin for improvement based on more sophisticated control strategies. Possible improvements of motion sickness incidence (MSI) are linked to a control strategy that exploits better synchronization with incident waves.

On combining support vector machines and simulated annealing in stereovision matching

This paper outlines a method for solving the stereovision matching problem using edge segments as the primitives. In stereovision matching, the following constraints are commonly used: epipolar, similarity, smoothness, ordering, and uniqueness. We propose a new strategy in which such constraints are sequentially combined. The goal is to achieve high performance in terms of correct matches by combining several strategies. The contributions of this paper are reflected in the development of a similarity measure through a support vector machines classification approach; the transformation of the smoothness, ordering and epipolar constraints into the form of an energy function, through an optimization simulated annealing approach, whose minimum value corresponds to a good matching solution and by introducing specific conditions to overcome the violation of the smoothness and ordering constraints. The performance of the proposed method is illustrated by comparative analysis against some recent global matching methods.

Modelling of a High Speed Craft by a Non-Linear Least Squares Method with Constraints

Abstract A non linear least squares method with constraints have been tried. However, the extra complexity associated with non-linear systems, with constrains and no initial information of model structure, means that exhaustive search is not always feasible. In these cases genetic identification strategy can be used to obtain initial values. On the other hand, a trend in the area of system identification is to try to model the system uncertainties to fit the available analysis and design tools of robust control. The method described is applied to obtain the interval model of the vertical dynamic of a high speed craft for different speed, and comparative results obtained with the mathematical model and with a scaled model in a towing tank are showed.

Multisensor Out of Sequence Data Fusion for Estimating the State of Discrete Control Systems

The fusion center of a complex control system estimates its state with the information provided by different sensors. Physically distributed sensors, communication networks, pre-processing algorithms, multitasking, etc, introduce non-systematic delays in the arrival of information to the fusion center, making the information available out-of-sequence (OOS). For real-time control systems, the state has to be efficiently estimated with all the information received so far. So, several solutions of the OOS problem for dynamic multiple-input multiple-output (MIMO) discrete control systems traditionally solved by the Kalman filter (KF) have been proposed recently. This paper presents two new streamlined algorithms for the linear and non-linear case. IFAsyn, the linear algorithm, is equivalent to other optimal solutions but more general, efficient and easy to implement. EIFAsyn, the nonlinear one, is a new solution of the OOS problem in the extended KF (EKF) framework.

Between fuzzy-PID and PID-conventional controllers: a good choice

The main problem in the synthesis of a control system is its parameter adjustment. Fuzzy logic controllers (FLC) have been proved to be very efficient in controlling complex and difficult-to-model processes. One of the main problems of these fuzzy controllers is that there is no systematic procedure for tuning. So, the necessity of methods for guiding the initial selection of the fuzzy controller parameters is clear. We propose an indirect method of tuning. It consists of describing the FLC like a classical controller from the external point of view. This allows the plant operator to feel comfortable with this regulator because he knows the direct influence between the variation of the FLC tuning parameters and the system response. It also facilitates the selection of some initial values that assure a reasonable behavior for the FLC, that could be improved by the qualitative tuning of these parameters.