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Authors
Abstract(s)
A navegação à vela entre dois pontos não pode em geral ser realizada adoptando a correspondente derrota direta. As caraterísticas do veleiro e a direção do
vento obrigam a adotar trajetórias constituídas por diferentes pernadas realizadas
a rumos distintos do rumo direto. A escolha das pernadas influência diretamente
o tempo de trajeto. A escolha do trajeto que minimize o tempo de percurso é um
problema de otimização complexo de difícil abordagem analítica.
A disponibilização duma ferramenta computacional que resolva este problema é, sem dúvida alguma, uma mais-valia para os utilizadores de veleiros de
qualquer dimensão. No contexto da vela autónoma a disponibilização desta ferramenta, mais do que ser uma mais-valia, é um fator essencial na utilização deste tipo
de meios.
Nesta dissertação, usando técnicas de otimização inspiradas na simulação
do recozimento, desenvolveremos uma ferramenta destinada a calcular trajetórias
que minimizam o tempo de percurso dum veleiro entre dois pontos, utilizando um
número de pernadas fixado inicialmente (duas ou mais pernadas). Não consideraremos, para simplificar, os efeitos das correntes e assumir-se-á que o campo de
velocidades do vento é uniforme e estacionário. A ferramenta computacional desenvolvida é parametrizável com recurso ao diagrama polar de velocidades de qualquer
veleiro. Simulações numéricas usando veleiros com diferentes caraterísticas, diferentes trajetos e diferentes configurações do campo de velocidade do vento serão
apresentadas e discutidas.
O recurso a um modelo fenomenológico, parametrizável, de penalização temporal das mudanças de rumo, destinadas a descrever as pernadas geradas, conduz à
geração de soluções geometricamente mais simples e com menos pernadas
In general, sailing between two points can’t be carried out by adopting a corresponding direct course. The characteristics of sail boats and the wind direction compel it to adopt trajectories with different courses to steer, each of them with a distinctive bearing, when compared to the direct course. The choice of courses to steer has a direct influence over the journey time. The choice of a path that minimizes the travel time is a complex optimization problem, encompassing a difficult analytical approach. The availability of a computational tool to solve this problem is undoubtedly an added value asset for users of sailboats of any size. In the scope of autonomous sailing, the availability of this tool, more than being an added value asset, is an essential factor in the use of this type of means. In this work, using optimization techniques based on the simulation of annealing, we will develop a tool to calculate trajectories allowing the minimization of a sailboat travel time between two points, using a predetermined number of courses to steer (two or more). In order to simplify the problem, we will not consider the effects of the currents, and it will be assumed that the range of wind speeds is uniform and stationary. The computational tool developed is configurable using the polar diagram of any sailboat. We will present and discuss numerical simulations using sailboats with different characteristics, different paths and different configurations of the wind speed range. The use of a phenomenological and parameterizable model, with temporal penalization of course changes, designed to describe the generated courses to steer, produces solutions which are geometrically simpler and with a lower number of courses to steer.
In general, sailing between two points can’t be carried out by adopting a corresponding direct course. The characteristics of sail boats and the wind direction compel it to adopt trajectories with different courses to steer, each of them with a distinctive bearing, when compared to the direct course. The choice of courses to steer has a direct influence over the journey time. The choice of a path that minimizes the travel time is a complex optimization problem, encompassing a difficult analytical approach. The availability of a computational tool to solve this problem is undoubtedly an added value asset for users of sailboats of any size. In the scope of autonomous sailing, the availability of this tool, more than being an added value asset, is an essential factor in the use of this type of means. In this work, using optimization techniques based on the simulation of annealing, we will develop a tool to calculate trajectories allowing the minimization of a sailboat travel time between two points, using a predetermined number of courses to steer (two or more). In order to simplify the problem, we will not consider the effects of the currents, and it will be assumed that the range of wind speeds is uniform and stationary. The computational tool developed is configurable using the polar diagram of any sailboat. We will present and discuss numerical simulations using sailboats with different characteristics, different paths and different configurations of the wind speed range. The use of a phenomenological and parameterizable model, with temporal penalization of course changes, designed to describe the generated courses to steer, produces solutions which are geometrically simpler and with a lower number of courses to steer.
Description
Keywords
Velejar Otimização Vela Robótica Simulação do Recozimento Matlab Python