Current Issue : January - March Volume : 2014 Issue Number : 1 Articles : 5 Articles
We consider a path planning problem where a\r\nteam of Unmanned Vehicles (UVs) is required to visit a\r\ngiven set of targets. The UVs are assumed to carry\r\ndifferent sensors, and as a result, there are vehicle-target\r\nconstraints that require each UV to visit a distinct subset\r\nof targets. The objective of the path planning problem is\r\nto find a path for each UV such that each target is visited\r\nat least once by some vehicle, the vehicle-target\r\nconstraints are satisfied and the total distance travelled by\r\nthe vehicles is a minimum. This path planning problem is\r\na generalization of the Hamiltonian path problem and is\r\nNP-Hard. We develop a primal-dual heuristic and\r\nincorporate the heuristic in a Lagrangian relaxation\r\nprocedure to find good, feasible solutions and lower\r\nbounds for the path planning problem. Computational\r\nresults show that solutions whose costs are on an average\r\nwithin 14% of the optimum can be obtained relatively\r\nquickly for the path planning problem involving five UVs\r\nand 40 targets....
The rehabilitation of patients should not only be limited to the first phases during intense hospital care but also support and therapy\r\nshould be guaranteed in later stages, especially during daily life activities if the patient�s state requires this.However, aid should only\r\nbe given to the patient if needed and asmuch as it is required. To allow this, automatic self-initiatedmovement support and patientcooperative\r\ncontrol strategies have to be developed and integrated into assistive systems. In this work, we first give an overview\r\nof different kinds of neuromuscular diseases, review different forms of therapy, and explain possible fields of rehabilitation and\r\nbenefits of robotic aided rehabilitation. Next, the mechanical design and control scheme of an upper limb orthosis for rehabilitation\r\nare presented. Two control models for the orthosis are explained which compute the triggering function and the level of assistance\r\nprovided by the device. As input to themodel fused sensor data from the orthosis and physiology data in terms of electromyography\r\n(EMG) signals are used....
Energyefficiencyisveryimportantforwireless\r\nsensor networks (WSNs) since sensor nodes have a\r\nlimited energy supply from a battery. So far, a lot\r\nresearch has focused on this issue, while less emphasis\r\nhasbeenplacedontheadaptivesleeptimeforeachnode\r\nwith a consideration for the application constraints. In\r\nthis paper, we propose a hierarchically coordinated\r\npower management (HCPM) approach, which both\r\naddresses the energy conservation problem and reduces\r\nthe packet forwarding delay for target tracking WSNs\r\nbased on a virtualgridbased network structure. We\r\nextend the network lifetime by adopting an adaptive\r\nsleep scheduling scheme that combines the local power\r\nmanagement (PM) and the adaptive coordinate PM\r\nstrategiestoscheduletheactivitiesofthesensornodesat\r\nthe surveillance stage. Furthermore, we propose a\r\nhierarchicalstructureforthetrackingstage.Experimental\r\nresults show that the proposed approach has a greater\r\ncapability of extending the network lifetime while\r\nmaintaining a short transmission delay when compared\r\nwiththeprotocolwhichdoesnotconsidertheapplication\r\nconstraintsintargettrackingsensornetworks....
Finger prostheses are devices developed to\r\nemulate the functionality of natural human fingers. On\r\ntop of their aesthetic appearance in terms of shape, size\r\nand colour, such biomimetic devices require a high level\r\nof dexterity. They must be capable of gripping an object,\r\nand even manipulating it in the hand. This paper presents\r\na biomimetic robotic finger actuated by a hybrid\r\nmechanism and integrated with a tactile sensor. The\r\nhybrid actuation mechanism comprises a DC micromotor\r\nand a Shape Memory Alloy (SMA) wire. A customized\r\ntest rig has been developed to measure the force and\r\nstroke produced by the SMA wire. In parallel with the\r\nactuator development, experimental investigations have\r\nbeen conducted on Quantum Tunnelling Composite\r\n(QTC) and Pressure Conductive Rubber (PCR) towards\r\nthe development of a tactile sensor for the finger. The\r\nviability of using these materials for tactile sensing has\r\nbeen determined. Such a hybrid actuation approach aided\r\nwith tactile sensing capability enables a finger design as\r\nan integral part of a prosthetic hand for applications up to\r\nthe transradial amputation level....
In this study, analytical techniques and fuzzy\r\nlogic methods are applied to the dynamic modelling and\r\nefficient swimming control of a biomimetic robotic fish,\r\nwhich is actuated by an ionic polymer-metal composite\r\n(IPMC). A physical-based model for the biomimetic\r\nrobotic fish is proposed. The model incorporates both the\r\nhydrodynamics of the IPMC tail and the actuation\r\ndynamics of the IPMC. The comparison of the results of\r\nthe simulations and experiments shows the feasibility of\r\nthe dynamic model. By using this model, we found that\r\nthe harmonic control of the actuation frequency and\r\nvoltage amplitude of the IPMC is a principal mechanism\r\nthrough which the robotic fish can obtain high thrust\r\nefficiency while swimming. The fuzzy control method,\r\nwhich is based on the knowledge of the IPMC fish�s\r\ndynamic behaviour, successfully utilized this principal\r\nmechanism. By comparing the thrust performance of the\r\nrobotic fish with other control methods via simulation,\r\nwe established that the fuzzy controller was able to\r\nachieve faster acceleration compared with what could be\r\nachieved with a conventional PID controller. The thrust\r\nefficiency during a steady state was superior to that with\r\nconventional control methods. We also found that when\r\nusing the fuzzy control method the robotic fish can\r\nalways swim near a higher actuation frequency, which\r\ncould obtain both the desired speed and high thrust\r\nefficiency....
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