1,721,033 research outputs found
Cosserat Geometrically Exact Approach for Modelling Tendon Driven Continuum Soft Robot Arms
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A Cosserat-based formulation for elastic, axisymmetric shells with implications to the pulsed-jetting propulsion of soft-bodied aquatic vehicles
No full textWe take the cue from recent development in geometric-based modelling in order to describe the dynamics of a novel soft-structured aquatic vehicle. The Cosserat-like formulation for an axisymmetric, elastic shell subject to concentrated dynamic loadings lends itself to the case of this new vehicle, recently designed by the authors, which consists of a shell of rubber-like materials undergoing sequential stages of inflation and deflation in order to propel itself in water via pulsed-jetting. The experiments performed on the existing robotic prototypes are used for the validation of the geometric model. This is eventually employed for deriving an accurate measure of the efficiency of propulsion which explicitly accounts for the elastic energy involved during the propulsion routine. The model yields a-priori estimations of swimming efficiency based on vehicle specifications and mode of actuation. These provide invaluable information for both design optimization and control, as well as a means to study the biomechanics of soft-bodied aquatic organisms
Cephalopod-inspired soft robots: design criteria and modelling frameworks
No full textCephalopods (i.e. octopuses and squids) are taken as a source of inspiration for the development of a new kind of underwater soft robot. These cephalopod-inspired, soft-bodied vehicles entail a hollow, elastic shell capable of performing a routine of recursive ingestion and expulsion of discrete slugs of fluids via the actual inflation and deflation of the elastic chamber. This routine allows the vehicle to propel itself in water in a very similar fashion to that of cephalopods. This mode of pulsed jetting enabled by the actual body shape variations can ideally benefit from the positive feedback provided by impulse-rich discontinuous jet formation and added mass recovery. This work is complemented by extensive modelling efforts which are meant to aid in the process of mechanical design optimization as well as providing an advanced tool for biomechanical studies of living cephalopods
A General Mechanical Model for Tendon-Driven Continuum Manipulators
No full textRecently, continuum manipulators have drawn a
lot of interest and effort from the robotic community,
nevertheless control and modeling of such manipulators are
still a challenging task especially because they require a
continuum approach. In this paper, a general mechanical
model with a geometrically exact approach for tendon-driven
continuum manipulators is presented. This model can be
applied to a wide range of manipulators thanks to the
generality of the parameters which can be set. The approach
proposed could as well be a powerful tool for developing the
control strategy. The model is also capable of properly
simulating the coupled tendon drive, because it takes into
account the torsion of the robot arm rather than neglecting it,
as it is common practice in other existing models
Dynamic Model of a Multibending Soft Robot Arm Driven by Cables
No full textThe 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
A 3D Steady State Model of a Tendon-Driven Continuum Soft Manipulator Inspired by Octopus Arm
No full textControl and modelling of continuum robots are challenging tasks for robotic researchers. Most
works on modelling are limited to piecewise constant curvature. In many cases they neglect to
model the actuators or avoid a continuum approach. In particular, in the latter case this leads to
a complex model hardly implemented. In this work, a geometrically exact steady-state model
of a tendon-driven manipulator inspired by the octopus arm is presented. It takes a continuum
approach, fast enough to be implemented in the control law, and includes a model of the
actuation system. The model was experimentally validated and the results are reported. In
conclusion, the model presented can be used as a tool for mechanical design of continuum
tendon-driven manipulators, for planning control strategies or as internal model in an
embedded system
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