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Maintenance of offshore wind turbines is a complex and costly undertaking which acts as a barrier to the development of this source of energy. Factors such as the size of the turbines, the size of the wind farms, their distance from the coast, meteorological conditions, etc. make it difficult for the stakeholders to select the optimal maintenance strategy. With the objective of reducing costs and duration of such operations it is important that new maintenance techniques are investigated. In this paper we propose a hybrid model of maintenance that is based on multi-agent systems, which allows for the modelling of systems with dynamic interactions between multiple parts. A multi-criteria decision algorithm has been developed to allow analysis and selection of different maintenance strategies. A cost model that includes maintenance action cost, energy loss and installation of monitoring system cost has been presented. For the purposes of this research we have developed a simulator using NetLogo software and have provided experimental results. The results show that employing the proposed hybrid maintenance strategy could increase wind farm productivity and reduce maintenance cost.

Our aim is to implement a force feedback joystick on a powered wheelchair provided with a set of range sensors. This system is intended to people with disability for whom a traditional joystick control (or any other adapted sensor control) is difficult or impossible because of too severe motor disabilities. The force feedback is calculated according to the proximity of the obstacles and helps the user, without forcing him, to move towards the free direction. Adopted methodology aims at circumventing certain obstacles which slow down the diffusion and thus the current use of smart wheelchairs: problems of safety, of reliability and of acceptability in particular. The results presented aim at identifying the driving situations for which an assisted control can really improve the piloting performances compared to a traditional manual control.

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