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Festival International des Sciences e Technologies - Championat du Monde de Robotique Mobile

This event, organised by the French private company Découverte et Communication, has been running annually since 1994 in France, plus two extra editions in Portugal in 1997 and 1998 (the former also co-organised by Instituto Superior Técnico and Universidade de Aveiro), as well as two other editions in Moscow, in 1998 and 1999. This is an international event involving several countries world-wide.

The competition has several categories, with new ones appearing almost every edition. The most participated so far have been the monotype and open categories whose purposes are nevertheless much alike (with small complexity variations for the open category). The main difference is that, whereas in the open class the designers only have limited (geometric) restrictions to build their robots, the monotype robots are subject to common constraints, such as the base platform, number and capacity of batteries, motors and wheels. These restrictions are nonetheless not a deception; it is very interesting to see, despite these impositions, how the teams reach rather different but competitive solutions. It then becomes easier to compare approaches and that is a major compensation for the developers of every robot.

The main idea for the open and monotype categories is to present a robot that is supposed to execute a path drawn on the floor with a line alternating in a black and white chessboard-like background (see figure). Furthermore, the robot must collect and sort billiard balls spread throughout the path. Parameters to evaluate the classification of robots have modified over the various editions, but robot path execution time, handling track interruptions and ball picking performance are the most significant items considered. On the technological side, perception (including vision) and path following control, along with electro-mechanical solutions to handle the billiard balls, are the most relevant matters to deal with. Obviously, integrated control of the system is also a relevant concern.


Moliceiro

The University of Aveiro started to participate in the FIST – Championnat du Monde de Robotique Mobile in 1996, the event's 3rd edition. The first two participations were in the open category although, later, the team moved on to the monotype category. The technical specifications for both cases are based mainly on floor painted line tracking. The initial idea was twofold: to motivate electronics engineering students to exercise their technical knowledge in an integrated and informal way, and also to promote interest in the field of mobile robotics which, at the time, was not a subject of active research and teaching in that university.

The initial technical solutions used were chosen so that the robot could be built as an extra-curricular activity in roughly 3 months. The 96 team was formed by the students José Vieira, Tiago Oliveira, António Carvalho, Maria João Magalhães and Rosa Pasadas and coached by Luís Almeida. The option was for simplicity, either in the mechanical structure as well as in the control system. The result, called Moliceiro (the name of a typical boat of Aveiro) was the smallest and lightest robot among all the competitors in the open category. It used active infrared light analog detection either for line tracking as well as for reflector tracking (during line breaks).

The billiard balls were captured passively by running over them and then sorted out by means of visible red light reflection. The motors used were hacked radiocontrol servos, which would allow for a top speed of 0.3 m/s (however, the effective speed under contest conditions was never above 0,23 m/s). Total weight without canopy was 1.8Kg and 2.3Kg with canopy. The supply was a single 12V 2Ah NiCd battery.

The control algorithm, executed on a 68HC11 processor, was based on fuzzy logic but using only the actual error (aprox. proportional control). The motors' speed was not controlled in closed loop. The control loop was closed by the tracking error with respect to the line, only. The main problem was related to control stability under increasing load caused by the incoming billiard balls. These would represent an increase of about 50% in the robot's total weight along with an even larger variation in the moment of inertia. The robot would typically lose the track after gathering the 2nd ball when running with the canopy on or the 4th ball when not using the canopy. Nevertheless, it ranked 8th among 14 teams competing in that category.

R2D2-v2

The problem caused by the large variation of the moment of inertia caused by the incoming billiard balls was tackled by the 97 team, formed by students Ricardo Pereira and Ana Cristina Almeida, coached by Luís Almeida and Pedro Fonseca and with special participation of ex-students Joaquim Ferreira and Tiago Oliveira. The main idea was to maintain the same simple approach (similar motors, electronics and supply) but to reduce the total moment of inertia in order to facilitate the robot's control. A MATLAB simulator built for this sort of robots allowed to observe a considerable gain in control stability by keeping the moment of inertia as low as possible. Therefore, the robot named R2D2-v2 used a lift, built just on top of the robot's centre of mass, to store the billiard balls vertically with a minimum increase in the total moment of inertia. Although this solution was innovative and appealing, its implementation revealed low mechanical reliability, raising problems that were difficult to deal with. The total robot weight increased to about 2.5Kg. The control algorithm was a PID type which, together with the reduction in the moment of inertia, allowed for an improved control performance. The result was, nevertheless, a 5th place among 12 competitors. Furthermore, this was probably the best result that could be achieved with those very low power motors. The remaining robots used motors 10 times more powerful allowing for much higher speeds.

M14 (R2D2-v3)

This robot was an improved version of the R2D2-v2. The improvement was focused on the mechanical construction of the billiard balls lift system. Although it presented a better reliability, the overall performance was still unstable. The competition was a reduced version of the french contest with promotional purposes. Our robot was awarded the prize for Integration by the contest jury.

RUA-v3

The year of 1998 marked a new era for the UA participations. The open category was exchanged by the monotype one. In this case, the chassis, motors, wheels and battery supply were the same for all teams. The motors were hacked windscreen wiper DC motors, which are considerably powerful (aprox. 60W) and allow to drive the heavier robot (aprox. 18Kg) to speeds of up to 1m/s using 12V supply. Furthermore, the team resulted from a co-operation between the Mechanical and Electronics Engineering Departments, which allowed to improve the robot structure and its mechanical subsystems. Team students were Emanuel Oliveira, Paulo Dias and Rui Lisboa, coached by Luis Almeida and Vitor Santos. The robot was named RUA-v3. The electronic systems were built around an 80C188 processor and the line tracking subsystem was also exchanged by an array of 16 digital IR sensors. The billiard balls capturing subsystem was also redesigned using an active approach based on a rolling sponge to effectively catch the balls. However, the overall mechanical configuration had, again, a large moment of inertia that was thought not to be so restrictive due to the more powerful motors. This belief was wrong. Once again, the robot control, which used a PD type algorithm, was relatively unstable, requiring a very precise tuning of the control gains. Moreover, the tight schedule for building the robot did not allow using closed loop control of the motors' speeds, as planned. For these reasons, the robot's average speed had to be severely reduced to about 0.35m/s. Nevertheless, the result was a 5th place among 12 competitors.

ZQiub

In 1999, the team formed by students Nuno Neto, Carlos Loureiro, Mário Martinho and Pedro Monteiro and coached by José Luís Azevedo, Pedro Fonseca, Luís Almeida and Vítor Santos, was determined to solve the previous problems. Therefore, the same robot was redesigned, mainly by exchanging the placement of several subsystems in order to reduce the total moment RA installed. The result, named Zqiub, behaved as expected, tracking the line smoothly with speeds near to 1m/s. It was ranked 3rd on its class, very close to the 2nd robot. The robot that won used stacked batteries, applying 24V to the motors which, this way, could drive the robot beyond 1.5m/s. This will probably be one of the features of our next line-tracking robot, too. Moreover, Zqiub's modular design together with its stable and regular behaviour were rewarded with the Special Jury Award for the monotype category.

CRAB

CAN-based Robot with Astonishing Behaviour...

O robot com que a Universidade de Aveiro participou no Campeonato do Mundo de Robótica Móvel, baptizado CRAB, nome inglês para caranguejo, possui um particular e eficiente mecanismo de recolha das bolas de bilhar, que usa uma pinça colocada na traseira do robot. Pode atingir até 2.5 m/s de velocidade e o respectivo mecanismo de seguimento de linha está suportado por uma estrutura basculante que lhe permite ultrapassar as rampas com facilidade, mantendo os sensores de linha a uma distância ao solo aproximandamente constante.

Em termos de construção, o robot utiliza um chassis de madeira de contraplacado marítimo, é traccionado por motores eléctricos de limpa-párabrisas de automóvel e os sensores utilizados quer para o seguimento da linha quer para a detecção das bolas de bilhar são do tipo infra-vermelhos. Uma das características que distinguem este robot é a utilização de um sistema de controlo distribuído, i.e. usa 2 processadores interligados por uma rede de comunicação CAN (Controller Area Network). Enquanto um dos processadores está dedicado exclusivamente ao controlo dos motores, o outro esta' encarregue da leitura e tratamento dos sensores de linha, do sistema de detecção e recolha das bolas de bilhar e ainda do controlo global dos modos de funcionamento do robot.

De referir que a maioria dos sistemas electrónicos e de controlo foi projectada e construída pela própria equipa, bem como a colocação e adaptação das partes mecânicas.

Este robot foi construído pelos alunos Tiago Meireles e Ricardo Abreu no âmbito do projecto de 5º ano da Licenciatura em Engenharia de Electrónica e Telecomunicações da UA. A equipa foi supervisionada pelos docentes José Luís Azevedo, Luís Almeida e Pedro Fonseca.

Participação no 7º Festival Internacional de Ciência e Tecnologia

A sétima edição do Campeonato do Mundo de Robótica Móvel decorreu em Vierzon, França, de 23 a 28 de Maio passado. O referido campeonato realizou-se no âmbito do Festival Internacional de Ciência e Tecnologia de Vierzon, festival este que contou ainda com várias sessões de discussão sobre questões científico-tecnológicas e respectivo impacto na sociedade, e ainda várias palestras e demonstrações relacionadas com a robótica. Várias personalidades de renome internacional participaram no festival entre as quais cientístas dos EUA (NASA), de Inglaterra, França e Rússia.

Nesta edição do referido campeonato o número de equipas participantes foi baixo relativamente às edições anteriores. Segundo os organizadores, esse facto ficou a dever-se essencialmente à mudança de regras que se processou das edições anteriores para esta. De qualquer modo, o campeonato juntou 7 equipas na categoria livre, provenientes de França, Canadá, Rússia, Coreia e Portugal, e ainda 6 equipas na classe monotipo, provenientes de França, Rússia e México. Para além das categorias referidas, havia vários robots em demonstração que provinham de países como Inglaterra, Rússia, França e Estados Unidos da América.

O número de equipas presente bem como as demonstrações realizadas foram, contudo, suficientes para se gerar um ambiente emotivo e de grande interesse científico e tecnológico. Em particular na categoria livre, a competição esteve sempre muito renhida com 4 equipas, entre as quais a da UA, a conseguirem manter níveis de desempenho muito semelhantes.

Nessa categoria os robots eram chamados a seguir uma linha branca sobre fundo preto e vice-versa, a ultrapassar rampas com 20% de inclinação, a imobilizar-se sobre a marca de fim de percurso e a recolher bolas de bilhar colocadas em suportes de 20cm de altura e a cerca de 80cm da linha sem os derrubar. De notar que os robots são completamente autónomos, não tendo qualquer comunicação operacional com o exterior. O campeonato desenrolava-se ao longo de 3 provas, a de velocidade, a de transposição das rampas e a de recolha das bolas. Os tempos obtidos foram os seguintes:

Prova velocidade (comprimento aproximado da pista de 60m)

    1. IUT Velizy (F) - 30s
    2. Univ. Moscovo (RUS) - 37s
    3. EPMontreal (CAN) - 38s
    4. Univ. de Aveiro (P) - 39s
    5. MPEI - Moscovo (RUS) - 1m 25'
    6. IUT Angers (F) - 1m 33'
    7. Univ. Ajou (Coreia) - Nao terminou

Prova de obstaculos (rampas com 20% inclinacao)

    1. IUT Velizy - 39s
    2. Univ. Moscovo - 39s
    3. Univ. de Aveiro - 41s
    4. EPMontreal - 47s
    5. MPEI - Moscovo - 1m 15'
    6. IUT Angers - 1m 49'
    7. Univ. Ajou - Nao terminou

Prova de recolha bolas (nenhuma equipa terminou com bolas recolhidas)

Resultados finais da classe livre.

    1. IUT Velizy
    2. Univ. Moscovo
    3. Univ. de Aveiro
    3. EPMontreal
    5. IUT Angers
    6. MPEI - Moscovo
    7. Univ. Ajou

Como se pode ver, a equipa da UA obteve bons resultados, tendo-se qualificado em 3º lugar na categoria livre, sendo ainda distinguida com o Prémio Especial do Júri para aquela categoria. Este prémio revela-se de particular significado pois pretende premiar o robot mais engenhoso e tecnicamente mais adequado ao cumprimento do conjunto de tarefas imposto pelo regulamento. O Prémio foi entregue pelo Presidente da Câmara de Comércio e Indústria da região do Cher. No momento da entrega, essa individualidade não deixou de salientar o gosto acrescido que sentia por entregar tal prémio a uma equipa de Aveiro, cidade geminada com Bourges, capital daquela região.

A deslocação a França foi apoiada pela Universidade de Aveiro.

Página mantida por: José Luís Azevedo