To eliminate the problem of the structural damage of traditional manipulators caused by deep water pressure, a novel piezoelectric actuated underwater robotic finger is proposed in this study. The robotic finger, adopting an open configuration, is composed of three phalanges and two joints. A novel bonded-type piezoelectric transducer employed as the actuator in each phalanx pushes the joints by friction. The geometrical parameters of the bonded-type piezoelectric transducer are determined by the finite element method, and a prototype of the proposed robotic finger is manufactured and tested. Experiment investigation is conducted to confirm the calculation results and evaluate output performances of the robotic finger prototype. Experimental results indicate that water has little effect on the driving frequency of the piezoelectric transducer. The maximum average velocities of the phalanges A and C driven by the phalanx B and the phalanx C driven by itself in water are 638 deg s−1, 676 deg s−1, and 689 deg s−1, respectively, under the excitation voltage of 500 Vpp. The maximum output torque of the phalanges A and C driven by the phalanx B and the phalanx C driven by itself in water are 10.98 mN m, 13.18 mN m, and 11.38 mN m, respectively, under the excitation voltage of 450 Vpp. The proposed robotic finger exhibits potential to be employed as underwater manipulators.
Abstract-Recent innovations in Network Virtualization and Elastic Optical Networks (EONs) enable flexible deployment of optical networks as a service. However, one open challenge is how to embed Virtual Optical Network (VON) requests onto the physical substrate network to maximize the sharing of physical resources, which is the so called Virtual Network Embedding (VNE) problem. EONs are prone to the fragmentation of spectral resources during the process of routing and spectrum allocation. The fragmentation of spectral resources in the substrate fiber links may lead to the blocking of incoming virtual network requests. This degrades the utilization of the physical resources of the Infrastructure Providers and also, decreases the revenue of the Service Providers. In this paper, we propose a novel virtual network embedding algorithm called Alignment and Consecutiveness-aware Virtual Network Embedding (ACT-VNE), which takes into account the spectrum alignment and relative loss in spectrum consecutiveness when mapping virtual nodes/links onto the physical substrate nodes/links. We also propose a minmax reconfiguration scheme called Relative Consecutiveness Lossaware and Misalignment-aware Virtual Network Reconfiguration (RCLM-VNR) that minimizes relative consecutiveness loss and maximizes alignment with adjacent links when reconfiguring the virtual network. Simulation results show that ACT-VNE and RCLM-VNR yield a lower blocking probability and a higher link utilization ratio, which leads to better utilization of the physical resources and increased revenue.
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