48 research outputs found

    Controlling a CyberOctopus Soft Arm with Muscle-like Actuation

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    This paper presents an application of the energy shaping methodology to control a flexible, elastic Cosserat rod model of a single octopus arm. The novel contributions of this work are two-fold: (i) a control-oriented modeling of the anatomically realistic internal muscular architecture of an octopus arm; and (ii) the integration of these muscle models into the energy shaping control methodology. The control-oriented modeling takes inspiration in equal parts from theories of nonlinear elasticity and energy shaping control. By introducing a stored energy function for muscles, the difficulties associated with explicitly solving the matching conditions of the energy shaping methodology are avoided. The overall control design problem is posed as a bilevel optimization problem. Its solution is obtained through iterative algorithms. The methodology is numerically implemented and demonstrated in a full-scale dynamic simulation environment Elastica. Two bio-inspired numerical experiments involving the control of octopus arms are reported

    Energy Shaping Control of a CyberOctopus Soft Arm

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    This paper entails application of the energy shaping methodology to control a flexible, elastic Cosserat rod model. Recent interest in such continuum models stems from applications in soft robotics, and from the growing recognition of the role of mechanics and embodiment in biological control strategies: octopuses are often regarded as iconic examples of this interplay. Here, the dynamics of the Cosserat rod, modeling a single octopus arm, are treated as a Hamiltonian system and the internal muscle actuators are modeled as distributed forces and couples. The proposed energy shaping control design procedure involves two steps: (1) a potential energy is designed such that its minimizer is the desired equilibrium configuration; (2) an energy shaping control law is implemented to reach the desired equilibrium. By interpreting the controlled Hamiltonian as a Lyapunov function, asymptotic stability of the equilibrium configuration is deduced. The energy shaping control law is shown to require only the deformations of the equilibrium configuration. A forward-backward algorithm is proposed to compute these deformations in an online iterative manner. The overall control design methodology is implemented and demonstrated in a dynamic simulation environment. Results of several bio-inspired numerical experiments involving the control of octopus arms are reported

    Trajectory optimization of advanced launch system

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    Trajectory optimization of an advanced launch vehicle is addressed. The optimal control problem is converted into a parameter optimization problem. Then, simulated annealing based single and multiobjective optimization algorithms are used. The single objective optimization problem is formulated to minimize the total flight time, while the multiobjective formulation tries to maximize payload mass and orbit insertion velocity. The problem is also solved using our novel multiple cooling multiobjective simulated annealing algorithm. It is shown that the algorithm is capable of finding the Pareto front of such nonlinear, multimodal problems

    Netherton's syndrome and neonatal hypernatremia - A case report

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    Netherton's syndrome is characterized by ichthyosiform desquamation, bamboo hair and often atopic diathesis. It is transmitted as an autosomal-recessive trait. In this paper we report a baby with Netherton's syndrome who developed hypernatremia during the neonatal period. This complication should be remembered in erythrodermic infants as a preventable cause of neonatal morbidity

    Netherton's syndrome and neonatal hypernatremia - A case report

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    Netherton's syndrome is characterized by ichthyosiform desquamation, bamboo hair and often atopic diathesis. It is transmitted as an autosomal-recessive trait. In this paper we report a baby with Netherton's syndrome who developed hypernatremia during the neonatal period. This complication should be remembered in erythrodermic infants as a preventable cause of neonatal morbidity

    Modeling and Finite Element Analysis of Drill Bit Vibrations

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    Netherton's syndrome and neonatal hypernatremia: A case report

    No full text
    Netherton's syndrome is characterized by ichthyosiform desquamation, bamboo hair and often atopic diathesis. It is transmitted as an autosomal-recessive trait. In this paper we report a baby with Netherton's syndrome who developed hypernatremia during the neonatal period. This complication should be remembered in erythrodermic infants as a preventable cause of neonatal morbidity
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