Mário Lima

Mechatronics education at the University of Minho: a summary of the present; perspectives for the future

The paper describes the topics on Mechatronics related subjects currently taught at the School of Engineering of Minho University and refers to the respective courses. The aims and syllabuses of undergraduate and postgraduate subjects, laboratory facilities and project topics are presented and discussed, together with a sequence of laboratory coursework aimed at improving the theoretical understanding of subjects and the development of practical skills. A general structure is proposed for a postgraduate course in Mechatronics to be taught in three blocks: the first two giving access to a diploma, the third being a laboratory project and dissertation leading to an M.Sc. degree.

Mechatronic approach to the feeding system of an overlock sewing machine

Abstract This paper describes the initial study of the research program being carried out on the feeding system of an industrial overlock sewing machine. The results obtained from the displacement and compression force, together with the graphic kinematic analysis, which includes the velocity and acceleration taken from the displacement–time curves of the presser foot bar, led to further understanding of the feeding system dynamics. This study is expected to provide the basis for the development of a redesigned and optimised fabric feeding system, in which the role of an actuator integrated in the presser foot bar will also be discussed as a major contribution to achieving a desired dynamic behaviour at high sewing speeds.

Study, Design, Development and Construction of a Linear Tribometer for Testing Human Skin

The study of the tribological properties of the skin is a very important research field for medical investigation, development of dermatological products and the analysis of the interactions between textile products and the skin. To obtain these properties it is necessary to perform tests using tribological equipments which can simulate the conditions to obtain reliable values that will allow the measurement of skin wrinkling. The skin aggressions are usually analyzed using special equipments, known as tribometers, that enable the performance of the tribological characterization of a pair of materials, in order to obtain parameters such as friction coefficient and wear; for this purpose, the control of test variables, such as normal applied load, displacement speed, environmental conditions and other relevant circumstances which influence the interaction of surfaces in contact is required. The most important objective is the evaluation of a concept commonly known as touch, difficult to define and measure (which is related to the quantification of the level of comfort provided by the contact with the skin), with the requirement of studying soft materials, namely the skin. For that purpose it became necessary to design and manufacture a tribological equipment capable of responding to the demands of the required tests.

Machine and Mechanism Design at UMinho: Research-Teaching Interaction

The Multiweave project involved the design of a prototype machine with several mechanisms, namely gear trains and various conjugate cams with oscillating roller followers. For this design phase the research team integrated postgraduate student work. In order to evaluate the quality of the manufactured cam profiles as well as the accuracy of the follower’s displacement, an experimental work has been designed. This study, which was carried out within a final year Mechanical Engineering student’s group project, was of great importance in the development of the prototype machine to produce multidirectional woven fabrics, which was the main objective of the Multiweave project. The whole set-up is presented with the experimental details and the results are analysed and discussed. This measurement system is based on a laser triangulation sensor Micro-Epsilon ILD 1302-50 to measure with no contact and high resolution. The obtained results were compared with the expected theoretical values and it could be concluded that, in general, the experimental results adjust very well to the theoretical ones. However it was possible to conclude about the existence of some differences due to clearances in joints, geometric differences in the kinematic chain and manufacturing defects on the follower in terms of irregularities and surface roughness as well as some manufacturing imperfections of the cam surface.

Application of the TRIZ Methodology in the Innovation of the FRICTORQ Test Equipment

The TRIZ – ‘Teoria Rechenia Izobretatelskih Zadatchi’ (Russian acronym for ‘Theory of Inventive Problem Solving’ - TIPS) is a methodology applied for problem solving that aims to create a systematic and algorithmic way to find new design solutions and to enhance individual creativity. This methodology was created and developed by Genrikh Altshuller in the 40’s of the twentieth century in the former Soviet Union. Throughout the study of thousands of patents Altshuller discovered that independently of its field, all technologies follow the same defined principles, and that these principles could be used for solving new problems.This paper is intended to demonstrate how the TRIZ methodology can be used in the innovation of a testing device (named FRICTORQ) designed and developed at the Department of Mechanical Engineering at the University of Minho to measure the friction coefficient in flexible materials. Throughout the study of the patterns of technical evolution described in this methodology, the authors will search for new possible evolution phases for this device, which will stimulate new ideas and the design of innovative solutions.© 2014 ASME

A new electromagnetic actuation system on an industrial sewing machine with on-line efficiency monitoring

This paper briefly reviews the study to evaluate the standard presser foot performance and a new actuation set-up to avoid the bouncing and the lack of fabric control. The compression force and displacement waveforms are also presented and widely discussed, as well as the seams quality analysis. A spectral (Fast Fourier Transform and Harmonic Distortion) analysis on the obtained waveforms, as well as an Admissible Displacement Limits (ADL) analysis are also described as important techniques to be used to supervise the presser foot force and to monitor the feeding efficiency. ADL have proved to be a better method. Further research should be undertaken in this area, in order to achieve, in a near future, a closed loop control of the presser foot .