eVentos 2 - Autonomous sailboat control

Dissertação para obtenção do Grau de Mestre em Engenharia Electrotécnica e de ComputadoresSailboat navigation started as a way to explore the world. Even though performance is significantly lower than that of a motorboat, in terms of resources, these vessels still are the best low-cost solutions. On the past, navigation depended greatly on estimates or on the stars. Nowadays it depends on precise data provided by a variety of electronic devices, independent from the user’s location. Autonomous sailboats are vessels that use only the wind for propulsion and have the capacity to control its sails and rudders without human intervention. These particularities give them almost unlimited autonomy and a very valuable ability to fulfill long term missions on the sea, such as collecting oceanographic data, search and rescue or surveillance. This dissertation presents a fuzzy logic controller for autonomous sailboats based on a proposed set of sensors, namely a GPS receiver, a weather meter and an electronic compass. Following a basic navigation approach, the proposed set of sensorswas studied in order to obtain an effective group of variables for the controller’s fuzzy sets, and rules for its rule base. In the end, four fuzzy logic controllers were designed, one for the sail(to maximize speed) and three for the rudder (in order to comply with all navigation situations). The result is a sailboat control system capable of operation in a low cost platform such as an Arduino prototyping board. Simulated results obtained from a data set of approximately 100 tests to each controller back up the theory presented for the controller’s operation, since physical experimentation was not possible

Segmentation Of Retinal Blood Vessels Using A Novel Fuzzy Logic Algorithm

In this work, a rule-based method is presented for blood vessel segmentation in digital retinal images. This method can be used in computer analyses of retinal images, e.g., in automated screening for diabetic retinopathy. Diabetic retinopathy is the most common diabetic eye disease and a leading cause of blindness. Diagnosis of diabetic retinopathy at an early stage can be done through the segmentation of the blood vessels of retina. Many studies have been carried out in the last decade in order to obtain accurate blood vessel segmentation in retinal images including supervised and rule-based methods. This method uses eight feature vectors for each pixel. These features are means and medians of intensity values of pixel itself, first and second nearest neighbor at four directions. Features are used in fuzzy logic algorithm as crisp input. The final segmentation is obtained using a thresholding method. The method was tested on the publicly available database DRIVE and its results are compared with distinguished published methods. Our method achieved an average accuracy of 93.82% and an area under the receiver operating characteristic curve of 94.19% for DRIVE database. Our results demonstrated an average sensitivity of 72.28% and a specificity of 97.04%. The calculated sensitivity and specificity values for DRIVE database also state that the proposed segmentation method is effective and robust

Fuzzy Controlled Hydraulic Excavator with Model Parameter Uncertainty

The hydraulic actuated excavator, being a non-linear mobile machine, encounters many uncertainties. There are uncertainties in the hydraulic system in addition to the uncertain nature of the load. The simulation results obtained in this study show that there is a need for intelligent control of such machines and in particular interval type-2 fuzzy controller is most suitable for minimizing the position error of a typical excavator’s bucket under load variations. We consider the model parameter uncertainties such as hydraulic fluid leakage and friction. These are uncertainties which also depend up on the temperature and alter bulk modulus and viscosity of the hydraulic fluid. Such uncertainties together with the load variations cause chattering of the bucket position. The interval type-2 fuzzy controller effectively eliminates the chattering and manages to control the end-effecter (bucket) position with positional error in the order of few millimeters

Fuzzy Logic in Decision Support: Methods, Applications and Future Trends

During the last decades, the art and science of fuzzy logic have witnessed significant developments and have found applications in many active areas, such as pattern recognition, classification, control systems, etc. A lot of research has demonstrated the ability of fuzzy logic in dealing with vague and uncertain linguistic information. For the purpose of representing human perception, fuzzy logic has been employed as an effective tool in intelligent decision making. Due to the emergence of various studies on fuzzy logic-based decision-making methods, it is necessary to make a comprehensive overview of published papers in this field and their applications. This paper covers a wide range of both theoretical and practical applications of fuzzy logic in decision making. It has been grouped into five parts: to explain the role of fuzzy logic in decision making, we first present some basic ideas underlying different types of fuzzy logic and the structure of the fuzzy logic system. Then, we make a review of evaluation methods, prediction methods, decision support algorithms, group decision-making methods based on fuzzy logic. Applications of these methods are further reviewed. Finally, some challenges and future trends are given from different perspectives. This paper illustrates that the combination of fuzzy logic and decision making method has an extensive research prospect. It can help researchers to identify the frontiers of fuzzy logic in the field of decision making

A framework for culture-aware robots based on fuzzy logic

Cultural adaptation, i.e., the matching of a robot's behaviours to the cultural norms and preferences of its user, is a well known key requirement for the success of any assistive application. However, culture-dependent robot behaviours are often implicitly set by designers, thus not allowing for an easy and automatic adaptation to different cultures. This paper presents a method for the design of culture-aware robots, that can automatically adapt their behaviour to conform to a given culture. We propose a mapping from cultural factors to related parameters of robot behaviours which relies on linguistic variables to encode heterogeneous cultural factors in a uniform formalism, and on fuzzy rules to encode qualitative relations among multiple variables. We illustrate the approach in two practical case studies

Prosody in text-to-speech synthesis using fuzzy logic

For over a thousand years, inventors, scientists and researchers have tried to reproduce human speech. Today, the quality of synthesized speech is not equivalent to the quality of real speech. Most research on speech synthesis focuses on improving the quality of the speech produced by Text-to-Speech (TTS) systems. The best TTS systems use unit selection-based concatenation to synthesize speech. However, this method is very timely and the speech database is very large. Diphone concatenated synthesized speech requires less memory, but sounds robotic. This thesis explores the use of fuzzy logic to make diphone concatenated speech sound more natural. A TTS is built using both neural networks and fuzzy logic. Text is converted into phonemes using neural networks. Fuzzy logic is used to control the fundamental frequency for three types of sentences. In conclusion, the fuzzy system produces f0 contours that make the diphone concatenated speech sound more natural

A new fuzzy logic based career guidance system: WEB-CGS

Izbor zanimanja na mnogo načina uvelike utječe na društveni život pojedinaca. Ipak, izbor odgovarajuće karijere postaje sve teži kad se uzme u obzir postojanje sve većeg broja zanimanja i mogućnosti usmjeravanja. Shodno tome, sve je veća važnost profesionalnog usmjeravanja. U ovom se radu razvija sustav pomoću kojega se automatski može ponuditi profesionalno usmjeravanje. To je WEB-CGS (web-based carrier guidance system) koji funkcionira kao web usluga koja se zasniva na neizrazitoj (fuzzy) logici. Cilj je olakšati pojedincu izbor odgovarajućeg zanimanja. U tom sustavu integrirani su prethodni uspjesi u obrazovanju učenika i mišljenja nastavnika te je omogućeno prepoznavanje profesionalnih interesa i mogućnosti učenika. Sustav predviđa interes učenika za usmjeravanje u području informacijske tehnologije, elektrike-elektronike, računovodstva i industrije automobila. Postignuti su obećavajući rezultati usmjeravanja za 300 neopredijeljenih studenata 9. razreda u strukovnoj srednjoj školi.Choosing a career affects individuals’ social life deeply in terms of many dimensions. However, choosing the right career is becoming increasingly difficult given the existence of an increasing number of professions and training opportunities. Consequently, the importance of career orientation increases. In this study, a system that can automatically offer vocational guidance has been developed. This new system is referred to as WEB-CGS (web-based carrier guidance system) and works as a fuzzy logic based web service. The aim is that it will make it easier for an individual to choose the right profession. In this system, students’ prior educational successes and teachers’ views were integrated in a manner which made it possible to identify the students’ professional interests and capacities. The system forecasts vocational school students’ interest with regard to Information Technology, Electrics-Electronics, Accounting, and Automotive. Promising results were obtained with regard to 300 unbiased 9th grade students in terms of orienting them towards an appropriate profession

From n-grams to n-sets: A Fuzzy-Logic-Based Approach to Shakespearian Authorship Attribution.

This thesis surveys the principles of Fuzzy Logic as they have been applied in the last three decades in the micro-electronic field and, in the context of resolving problems of authorship verification and attribution shows how these principles can assist with the detection of stylistic similarities or dissimilarities of an anonymous, disputed play to an author’s general or patterns-based known style. The main stylistic markers are the counts of semantic sets of 100 individual words-tokens and an index of counts of these words’ frequencies (a cosine index), as found in the first extract of approximately 10,000 words of each of 27 well attributed Shakespearian plays. Based on these markers, their geometrical representation, fuzzy modelling and on thee ground of Set Theory and Boolean Algebra, in the core part of this thesis three Mamdani (Type-1) genre-based Fuzzy Expert Systems were built for the detection of degrees (measured on a scale from 0 to 1) of Shakespearianness of disputed and, probably, co-authored plays of the early modern English period. Each of these three expert systems is composed of seven input and two output variables that are associated through a set of approximately 30 to 40 rules. There is a detailed description of the properties of the three expert systems’ inference mechanisms and the various experimentation phases. There is also an indicative graphical analysis of the phases of the experimentation and a thorough explanation of terms, such as partial truths membership, approximate reasoning and output centroids on an X-axis of a two-dimensional space. Throughout the thesis there is an extensive demonstration of various Fuzzy Logic techniques, including Sugeno-ANFIS (adaptive neuro-fuzzy inference system), with which the style of Shakespeare can be modelled in order to compare it with well attributed plays of other authors or plays that are not included in the strict Shakespearian canon of the selected 27 well-attributed, sole authored plays. In addition, other relevant issues of stylometric concern are discussed, such as the investigation and classification of known ‘problem’ and disputed plays through holistic classifiers (irrespective of genre). The results of the experimentation advocate the use of this novel, automated and computer simulation-based method of classification in the stylometric field for various purposes. In fact, the three models have succeeded in detecting the low Shakespearianness of non Shakespearian plays and the results they provided for anonymous, disputed plays are in conformance with the general evidence of historical scholarship. Therefore, the original contribution of this thesis is to define fully functional automated fuzzy classifiers of Shakespearianness. The result of this discovery is that we now know that the principles of fuzzy modelling can be applied for the creation of Fuzzy Expert Stylistic Classifiers and the concomitant detection of degrees of similarity of a play under scrutiny with the general or patterns-based known style of a specific author (in our case, Shakespeare). Furthermore, this thesis shows that, given certain premises, counts of words’ frequencies and counts of semantic sets of words can be employed satisfactorily for stylistic discrimination

Practical modelling and control implementation studies on a pH neutralization process pilot plant

In recent years the industrial application of advanced control techniques for the process industries has become more demanding, mainly due to the increasing complexity of the processes themselves as well as to enhanced requirements in terms of product quality and environmental factors. Therefore the process industries require more reliable, accurate, robust, efficient and flexible control systems for the operation of process plant. In order to fulfil the above requirements there is a continuing need for research on improved forms of control. There is also a need, for a variety of purposes including control system design, for improved process models to represent the types of plant commonly used in industry. Advanced technology has had a significant impact on industrial control engineering. The new trend in terms of advanced control technology is increasingly towards the use of a control approach known as an “intelligent” control strategy. Intelligent control can be described as a control approach or solution that tries to imitate important characteristics of the human way of thinking, especially in terms of decision making processes and uncertainty. It is also a term that is commonly used to describe most forms of control systems that are based on artificial neural networks or fuzzy logic. The first aspect of the research described in the thesis concerns the development of a mathematical model of a specific chemical process, a pH neutralization process. It was intended that this model would then provide an opportunity for the development, implementation, testing and evaluation of an advanced form of controller. It was also intended that this controller should be consistent in form with the generally accepted definition of an “intelligent” controller. The research has been based entirely around a specific pH neutralization process pilot plant installed at the University Teknologi Petronas, in Malaysia. The main feature of interest in this pilot plant is that it was built using instrumentation and actuators that are currently used in the process industries. The dynamic model of the pilot plant has been compared in detail with the results of experiments on the plant itself and the model has been assessed in terms of its suitability for the intended control system design application. The second stage of this research concerns the implementation and testing of advanced forms of controller on the pH neutralization pilot plant. The research was also concerned with the feasibility of using a feedback/feedforward control structure for the pH neutralization process application. Thus the study has utilised this control scheme as a backbone of the overall control structure. The main advantage of this structure is that it provides two important control actions, with the feedback control scheme reacting to unmeasured disturbances and the feedforward control scheme reacting immediately to any measured disturbance and set-point changes. A non-model-based form of controller algorithm involving fuzzy logic has been developed within the context of this combined feedforward and feedback control structure. The fuzzy logic controller with the feedback/feedforward control approach was implemented and a wide range of tests and experiments were carried out successfully on the pilot plant with this type of controller installed. Results from this feedback/feedforward control structure are extremely encouraging and the controlled responses of the plant with the fuzzy logic controller show interesting characteristics. Results obtained from tests of these closed-loop system configurations involving the real pilot plant are broadly similar to results found using computer-based simulation. Due to limitations in terms of access to the pilot plant the investigation of the feedback/feedforward control scheme with other type of controllers such as Proportional plus Integral (PI) controller could not be implemented. However, extensive computer-based simulation work was carried out using the same control scheme with PI controller and the control performances are also encouraging. The emphasis on implementation of advanced forms of control with a feedback/feedforward control scheme and the use of the pilot plant in these investigations are important aspects of the work and it is hoped that the favourable outcome of this research activity may contribute in some way to reducing the gap between theory and practice in the process control field