Fast Dynamics of an Eel-Like Robot—Comparisons With Navier–Stokes Simulations

Inst. de Rech. en Commun. et Cybernetique de Nantes, Ecole des Mines de Nantes, Nantes
IEEE Transactions on Robotics (Impact Factor: 2.43). 01/2009; 24(6):1274 - 1288. DOI: 10.1109/TRO.2008.2006249
Source: IEEE Xplore


This paper proposes a dynamic model of the swim of elongated fish suited to the online control of biomimetic eel-like robots. The approach can be considered as an extension of the original reactive ldquolarge elongated body theoryrdquo of Lighthill to the 3-D self-propulsion to which a resistive empirical model has been added. While all the mathematical fundamentals have been detailed by Boyer . (, 2007), this paper essentially focuses on the numerical validation and calibration of the model and the study of swimming gaits. The proposed model is coupled to an algorithm allowing us to compute the motion of the fish head and the field of internal control torque from the knowledge of the imposed internal strain fields. Based on the Newton-Euler formalism of robot dynamics, this algorithm works faster than real time. As far as precision is concerned, many tests obtained with several planar and 3-D gaits are reported and compared (in the planar case) with a Navier-Stokes solver, which, until today have been devoted to the planar swim. The comparisons obtained are very encouraging since in all the cases we tested, the differences between our simplified and reference simulations do not exceed 10%.

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    • "As a result, the drag forces are modeled with an empirical model due to Morison et al. [36]. The complete model was validated through extensive Navier–Stokes simulation in the case of the self-propelled swimming of an elongated fish in [37]. "
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    ABSTRACT: The new and promising field of soft robotics has many open areas of research such as the development of an exhaustive theoretical and methodological approach to dynamic modeling. To help contribute to this area of research, this paper develops a dynamic model of a continuum soft robot arm driven by cables and based upon a rigorous geometrically exact approach. The model fully investigates both dynamic interaction with a dense medium and the coupled tendon condition. The model was experimentally validated with satisfactory results, using a soft robot arm working prototype inspired by the octopus arm and capable of multibending. Experimental validation was performed for the octopus most characteristic movements: bending, reaching, and fetching. The present model can be used in the design phase as a dynamic simulation platform and to design the control strategy of a continuum robot arm moving in a dense medium.
    IEEE Transactions on Robotics 10/2014; PP:1-14. DOI:10.1109/TRO.2014.2325992 · 2.43 Impact Factor
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    • "The first kinematics correspond to the so called Kirchhoff model of shells while the second correspond to the Reissner model [23]. Geometrically exact beam theories have been recently applied to continuous (hyper-redundant) and soft robotics in the context of underwater and terrrestrial locomotion of fish [24] and snakes [25] and for manipulation of octopus like arms [26]. In this new article, we use the geometrically exact shell model to address the issue of cephalopod jet propelling. "
    Bioinspired Robotics, Frascati, Italy; 06/2014
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    • "Here, an empirical 'resistive' force model is therefore added following [36] and [33]: f v = −1/2C d u n |u n |n, (6) where C D is the empirical drag coefficient, and C D = 1 is used in the following for circular cross-sections [see 29, for a discussion of the impact of this coefficient on the flapping dynamics]. [37] tuned the drag coefficients to show good agreement with direct numerical simulations. Thus the fluid force, f , in Eq. (1) is modelled as the sum of the reactive (f i ) and resistive (f v ) components. "
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    ABSTRACT: The problem of energy harvesting from flutter instabilities in flexible slender structures in axial flows is considered. In a recent study, we used a reduced order theoretical model of such a system to demonstrate the feasibility for harvesting energy from these structures. Following this preliminary study, we now consider a continuous fluid-structure system. Energy harvesting is modelled as strain-based damping and the slender structure under investigation lies in a moderate fluid loading range, for which {the flexible structure} may be destabilised by damping. The key goal of this work is to {analyse the effect of damping distribution and intensity on the amount of energy harvested by the system}. The numerical results {indeed} suggest that non-uniform damping distributions may significantly improve the power harvesting capacity of the system. For low damping levels, clustered dampers at the position of peak curvature are shown to be optimal. Conversely for higher damping, harvesters distributed over the whole structure are more effective.
    Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences 07/2012; 468(2147). DOI:10.1098/rspa.2012.0145 · 2.19 Impact Factor
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