João Sepúlveda

Parallel Association of Shunt Active Power Filters

This paper describes different types of parallel association of Shunt Active Power Filters, presents computer simulation models developed in PSCAD®/EMTDC¿, and shows simulated results for each case. The control system used in the active filters is based on the Instantaneous Reactive Power Theory (p-q Theory). The active filters use periodic sampling as switching technique. Two types of parallel associations are presented: two active filters in different parallel feeders; and both active filters connected in parallel at the same point of the electric installation. The paper also proposes a control strategy to solve an inherent operation problem that occurs in the second type of parallel association.

Instrumented insole system for ambulatory and robotic walking assistance: First advances

Current research highlights the emergent need for the development of wearable, calibrated, and accurate sensory systems for ambulatory human gait analysis. The purpose of this work is to develop a lightweight and calibrated instrumented insole system for the real-time monitoring of gait events in healthy, pathological and robotic-assisted gait. We designed the insole with four force sensing resistors (FSRs) to detect four gait events. We also implemented an electronic interface for the data acquisition and processing and the wireless transmission with the motherboard and the user interface. The validation involved 3 healthy female subjects, which reported that this prototype is flexible, lightweight and comfortable for daily usage. Results showed a maximal error of 6.02±3.02% in the detection of foot flat due to the small sensing area of FSRs placed on the first and fifth metatarsus. Future challenges comprise aesthetic and functional improvements and a more comprehensive validation.

A New Energetically Optimized Power Supply System for a Mobile Robot Platform, using Ultracapacitors and Batteries to Ensure Both Ultra-fast Charging and Autonomy

The smallest charging times required by fully discharged conventional batteries are some tens of minutes. This is an important limitation for mobile robot platforms. A previous paper already validated the possibility of integrating ultracapacitors and batteries in the same system. However, it has some significant limitations: 1) It works with an ultracapacitors module or a battery, but it does not work with both devices at the same time; 2) It requires an external dedicated charging station; 3) It is not possible to take profit from a part - which is non-negligible - of the energy previously stored in the ultracapacitors. This paper presents a new power supply system for mobile robot platforms that has been developed in order to overcome these limitations. Its main goals are evaluating the feasibility of: 1) Fully integrating batteries and ultracapacitors, working simultaneously as energy-storing devices, with the aim of enabling a mobile robot platform to achieve a reasonable autonomy after a very reduced charging time and considerable autonomy when there are no charging time constraints; 2) Installing all the system in the mobile robot platform, avoiding the use of an external dedicated charging station; 3) Extracting almost all the energy previously stored in the ultracapacitors. Both simulation results and experimental results are presented.

Learning Electronics Project Inside a Control Inspired Conceptual Map

This paper describes two laboratory and project semester modules in the Electronics Engineering programme of Universidade do Minho. Along time, the learning objectives of these modules evolved from integrating conventional laboratory work across disciplines to include first time experience in project of electronics with collaboration of industry. The design of the modules joins elements of conventional laboratory work, project based learning and cooperation with industry. Cooperation with industry has a crucial role in framing the project work and ultimately the laboratory work. Control is, beyond one of the topics to be learned, a main source of inspiration for the design of the modules at large, as the feedback loop concept is used to unify laboratory work from several disciplines with project into a coherent learning experiment.

Using ultracapacitors as energy-storing devices on a mobile robot platform power system for ultra-fast charging

The large charging times required by conventional batteries constitute an important limitation in many applications. The use of ultracapacitors as energy storage elements allows substantially faster charging. This paper presents a power supply system developed in order to validate the possibility of providing a mobile robot platform with an electrical energy storage system based on ultracapacitors and batteries, ensuring both the autonomy and the charging time required by this vehicle. Both simulations results and experimental results - also presented in this paper - validate this possibility. Using exclusively one ultracapacitors module as energy-storing device of the new power supply system, the mobile platform achieved an autonomy of 22 minutes after a charging time of 1 minute and 57 seconds. The charging time is less than 10% of the autonomy time. The system also proved its ability to properly charge lead-acid batteries or nickel-metal hydride batteries, which may be used as energy-storing devices, allowing the mobile platform to achieve greater autonomy than the one obtained with ultracapacitors (at the cost of larger charging times).

Developing an automated system for shoe sole halogenation

This paper describes a project developed in the Department of Industrial Electronics for a shoe wear manufacturer to study and automation of a human operated position of a shoe production line. A trade of investment and operational costs, technical feasibility and environmental benefits pointed to the selection of the shoes sole halogenation position. This operation, manually performed, is done before glue application. Its purpose is the preparation of the shoe sole to receive, in good conditions, the glue. The chemical material used is toxic and harmful to operators. The developed system integrates a manipulator and an artificial vision system. The results that emerged from the experimental tests demonstrated that the proposed automated system works as desired. The system exhibits the additional advantage of performing the halogenation procedure in almost half of the time required by a human operator. The image processing algorithms included in the system software are fast enough to enable image acquisition and processing as well as the transmission of the path to the robot controller, on line.