Inácio Fonseca

Simulating pursuit with machines. Experiments with robots and artificial vision

This article describes one solution for the problem of pursuit of objects moving on a plane by using a mobile robot and an active vision system. The solution deals with the interaction of different control systems using visual feedback and it is accomplished by the implementation of a visual gaze holding process interacting cooperatively with the control of the trajectory of a mobile robot. These two systems are integrated to follow a moving object at constant distance and orientation with respect to the mobile robot. The orientation and the position of the active vision system running a gaze holding process give the feedback signals to the control used to pursuit the target in real-time. The paper addresses the problems of visual fixation, visual smooth pursuit, navigation using visual feedback and compensation for systems movements. The algorithms for visual processing and control are described in the article. The mechanisms of cooperation between the different control and visual algorithms are also described. The final solution is a system able to operate at approximately human walking rates as the experimental results show in the paper.

On-condition maintenance for wind turbines

This work presents a system to manage wind turbines maintenance through a predictive model. The system is based on specific maintenance software and hardware for data acquisition and also on algorithms for prediction based on time series. The maintenance software is called SMIT — (Terology Integrated Modular System). The acquisition system can be interconnected with professional, industrial and low cost acquisition systems. The communication channel is based on IP networks, using clock synchronization for data sampling. A time series prediction algorithm runs on low cost hardware, working as a monitoring trigger of the central system.

Maintenance planning in wind farms with allocation of teams using genetic algorithms

Renewable energy is essential for global sustainability. Wind power has given a great contribution to this energy paradigm. The paper describes a maintenance management system for inshore and offshore wind farms, as well as a method to schedule maintenance using genetic algorithms. Under this subject there exists a sub-problem that concerns with the determination of the cheapest path between two points. The paper compares the performance of three methods: genetic algorithms, Dijkstras algorithm and ant optimization algorithm to the determination of the cheapest path between different wind parks for maintenance.

The State of the Art of Hidden Markov Models for Predictive Maintenance of Diesel Engines

The maintenance of diesel Engines is usually scheduled according to the maintenance procedures defined by manufacturers. However, the state of the art shows that the condition monitoring maintenance associated with adequate prediction algorithms allows performance improvement both by increasing the intervals between interventions and by helping to maintain reliability levels. There are many types of variables that can be used to measure equipment condition, as is the case of several types of pollutant emissions such as NOx, CO2, HC, PM, and NOISE, among others. This is a typical problem that can be solved through a hidden Markov model, taking into account the specificity of this type of equipment. The paper describes two algorithms that can help to increase the quality of assessment of engine states and the efficiency of maintenance planning. Those are the Viterbi and Baum–Welch algorithms. The importance of how to calculate the performance index of the model by the use of the perplexity algorithm is also emphasized. In this paper, a new paradigm is proposed, designated as ecological predictive maintenance. Copyright

Collaborative projects involving industry and academia to enhance electrical engineering education: The perspective of three Portuguese Higher Education Institutions at the master degree level

In this paper, Electrical Engineering Education at the Master level is presented through three perspectives of collaborative projects involving industry and academia. The presented perspectives originate from three Portuguese Higher Education Institutions representing the University, Military Academy and Polytechnic School viewpoints. Throughout the presented projects, an increasing student motivation was observed, driven by the practical experience provided through the industrial sector approach. This cooperation also generates opportunities to develop new perspectives and ideas for follow-on projects as well as innovative academic publications.

Certification of maintenance providers : a competitive advantage

Purpose – The purpose of this paper is to synthesize some relevant norms, namely European norms (EN), to the maintenance field.Design/methodology/approach – The methodology is based on the conjunction of the most relevant norms to the maintenance field that represent a coherent set of tools to aid maintenance activity and maintenance companies to achieve a new level of competitiveness.Findings – Until now, the companies have not given relevance to specific certifications, such as PAS 55 or NP4492. But, with the increase of competitiveness and the market more and more exigent, it is necessary to introduce this new paradigm to raise the maintenance activity at an upper level.Practical implications – The approach presented in the paper constitutes a base for an upper level of competitiveness among companies, based on common standards that make the maintenance activity more exigent and transparent.Originality/value – The paper presents a conjunction among standards, including the newest ones, that constitutes...

New perspectives on mobile robot navigation with visual and inertial information

Advanced sensor systems, exploring high integrity and multiple sensorial modalities, have been significantly increasing the capabilities of autonomous vehicles and enlarging their application potential. The article describes two relevant sensors for mobile robot navigation-active vision systems and inertial sensors. Vision and inertial sensing are two sensory modalities that can be explored for navigation. The article presents our results on the use and integration of those two modalities. In a first example we present a computational solution for the problem of visual based guidance of a moving observer, by detecting the orientation of the cameras set that maximises the valve of visual information. The algorithm explores the geometric properties of log-polar mapping. The second example, relies on the integration of inertial and visual information to defect the regions in the scene that we can drive a mobile platform: in our case the ground plane. The solution is based on information about the scene that could be obtained during a process of the visual fixation, complemented by the information provided by inertial sensors. The tests were performed with a mobile platform equipped with one active vision system and inertial sensors. The paper presents our results on simulation of visual behaviours for navigation.

Exploring spherical image properties for robot navigation

Addresses the problem of performing navigation with a mobile robot using active vision exploring the image sphere properties in a stereo divergent configuration. The navigational process is supported by the control of the robots steering and forward movements just using visual information as feedback. The steering control solution is based on the difference between signals of visual motion flow computed in images on different positions of a virtual image sphere. The majority of solutions based on motion flow and proposed until now, were usually very unstable because they normally compute other parameters from the motion flow. In our case the control is based directly on the different between motion flow signals on different images. Those multiple images are obtained by small mirrors, that simulate cameras positioned in different positions on the image sphere. The control algorithm described in this work is based on a discrete-event approach to generate a control feedback signal for navigation of an autonomous robot with an active vision system.

Electric Motors Maintenance Planning From Its Operating Variables

Abstract The maintenance planning corresponds to an approach that seeks to maximize the availability of equipment and, consequently, increase the levels of competitiveness of companies by increasing production times. This paper presents a maintenance planning based on operating variables (number of hours worked, duty cycles, number of revolutions) to maximizing the availability of operation of electrical motors. The reading of the operating variables and its sampling is done based on predetermined sampling cycles and subsequently is made the data analysis through time series algorithms aiming to launch work orders before reaching the variables limit values. This approach is supported by tools and technologies such as logical applications that enable a graphical user interface for access to relevant information about their Physical Asset HMI (Human Machine Interface), including the control and supervision by acquisition through SCADA (Supervisory Control And data acquisition) data, also including the communication protocols among different logical applications.

An educational platform for residential and industrial energy monitoring

This paper presents an energy monitoring platform for the home and industrial environments. The solution is based on industrial equipment such as PLCs, power measurement boards and I/O modules for load control. Additionally, the platform includes a Raspberry Pi-based Web component, where the measurement data is stored in a MySQL database and made available through the Web. The platform serves as an educational tool for Electrical Engineering students. Students can learn about hardware and software for energy consumption acquisition and measurement, as well as Web data-base communication, storage and browsing. They can further compare the behavior of different loads, in particular motors, projectors, heaters and lamps.