SUMMARY: This paper proposes a method for task based design of modular serial robotic arms using evolutionary algorithms (EA). We introduce a 3D kinematics and a global optimization for both topology and configuration from task specifications. The search features revolute as well as prismatic joints and any number of DOF to build up a solution without using any design knowledge. A study of the evolution dynamics gives some keys to set evolution parameters that enable artificial evolution. An adapted algorithm dealing with the topology/configuration search tradeoff is proposed, descibed, and discussed. Illustrations of the algorithms results are given and conclusions are drawn from their analysis. Perspectives of this work are given, extending its reach to control and complex system design.

This paper presents the concept and design of a new reconfigurable magnetic-coupling thruster (RMCT). Mechanical models, as well as digital and real-world experiments, are proposed to understand the fundamental aspects of such technology. The principle of RMCT is to reorient the propeller, and therefore the thrust vector, to the desired direction without adding or moving any motors. The focus of this study is to propose a new design to solve the problems raised in a previous work on RMCT and to understand how the transmitted coupling torque behaves with regard to the new kinematics of the propeller shaft. After introducing the models underlying this thruster design, we build a numerical simulation and validate it through experimental results. The performance of this design is then discussed based on open-loop trials and its potential integration and control. The conclusion proposes guidelines for developing an underwater prototype that will be designed and tested on real autonomous underwater vehicles.

Reconfigurable Magnetic Coupling Thruster (RMCT) is an enabling technology for achieving vectorial thrust on AUVs. This allows us to dispose of dynamic, compliant, and secure propulsion to enhance their agility for demanding locomotion tasks. RMCT can generate and control a thrust vector by redirecting its propeller through the compliance of the magnetic coupling and therefore achieve thrust vectoring for AUVs. In this paper, a new design of RMCT is presented. This new prototype uses a flat geometry magnetic coupling for a better AUV full integrability. The new design provides some additional advantages with regard to its predecessor (spherical RMCT); namely, construction simplicity and better torque transmission. The first characteristic is derived from its flat shapes, which makes it easier to manufacture (cubic magnets) and to isolate (planar air gap between rotors). The second characteristic is due to the fact that now both parts of the magnetic coupling can store magnets (increasing the maximal transmitted torque). This paper proposes a thruster dynamics model, a magnetic coupling model, and shows the use of a dynamic parameter identification method based on algorithms used for robotic manipulators. The validity of the dynamic model and identified parameters is then analyzed by means of experimental tests.

Hydrogen is an excellent energy source for long-term storage and free of greenhouse gases. However, its high production cost remains an obstacle to its advancement. The two main parameters contributing to the high cost include the cost of electricity and the cost of initial financial investment. It is possible to reduce the latter by the optimization of system design and operation conditions, allowing the reduction of the cell voltage. Because the CAPEX (initial cost divided by total hydrogen production of the electrolyzer) decreases according to current density but the OPEX (operating cost depending on the cell voltage) increases depending on the current density, there exists an optimal current density. In this paper, a genetic algorithm has been developed to find the optimal evolution parameters and to determine an optimum electrolyzer design. The optimal current density has been increased by 10% and the hydrogen cost has been decreased by 1%.

Manoeuvrability is one of the essential keys in the development of improved autonomous underwater vehicles for challenging missions. In the last years, more researches were dedicated to the development of new hulls shapes and thrusters to assure more manoeuvrability. The present review explores various enabling technologies used to implement the vectorial thrusters (VT), based on water-jet or propellers. The proposals are analysed in terms of added degrees of freedom, mechanisms, number of necessary actuators, water-tightness, electromagnetomechanical complexity, feasibility, etc. The usage of magnetic coupling thrusters (conventional or reconfigurable) is analysed in details since they can assure the development of competitive full waterproof reconfigurable thrusters, which is a frictionless, flexible, safe, and low-maintenance solution. The current limitations (as for instance the use of non conductive hull) are discussed and ideas are proposed for the improvement of this new generation of underwater thrusters, as extending the magnetic coupling usage to obtain a fully contactless vector thrust transmission.