On using Multiple Quality Link Metrics with Destination Sequenced Distance Vector Protocol for Wireless Multi-Hop Networks

In this paper, we compare and analyze performance of five quality link metrics forWireless Multi-hop Networks (WMhNs). The metrics are based on loss probability measurements; ETX, ETT, InvETX, ML and MD, in a distance vector routing protocol; DSDV. Among these selected metrics, we have implemented ML, MD, InvETX and ETT in DSDV which are previously implemented with different protocols; ML, MD, InvETX are implemented with OLSR, while ETT is implemented in MR-LQSR. For our comparison, we have selected Throughput, Normalized Routing Load (NRL) and End-to-End Delay (E2ED) as performance parameters. Finally, we deduce that InvETX due to low computational burden and link asymmetry measurement outperforms among all metrics

A Survey on Energy Efficient Network Coding for Multi-hop Routing in Wireless Sensor Networks

AbstractNetwork coding consists of intelligently aggregating data packets by means of binary or linear combinations. Recently, network coding has been proposed as a complementary solution for energy efficient multi-hop routing in Wireless Sensor Networks (WSNs). This is because network coding, through the aggregation of packets, considerably reduces the number of transmissions throughout the network. Although numerous network coding techniques for energy efficient routing have been developed in the literature, not much is known about a single survey article reporting on such energy efficient network coding within multi-hop WSNs. As a result, this paper addresses this gap by first classifying and discussing the recent developed energy efficient network coding techniques. The paper then identifies and explains open research opportunities based on analysis of merits of such techniques. This survey aims at providing the reader with a brief and concise idea on the current state-of-art research on network coding mainly focusing on its applications for energy efficient WSNs

Evaluating Impact of Mobility on Wireless Routing Protocols

In this paper, we evaluate, analyze, and compare the impact of mobility on the behavior of three reactive protocols (AODV, DSR, DYMO) and three proactive protocols (DSDV, FSR, OLSR) in multi-hop wireless networks. We take into account throughput, end-to-end delay, and normalized routing load as performance parameters. Based upon the extensive simulation results in NS-2, we rank all of six protocols according to the performance parameters. Besides providing the interesting facts regarding the response of each protocol on varying mobilities and speeds, we also study the trade-offs, the routing protocols have to make. Such as, to achieve throughput, a protocol has to pay some cost in the form of increased end-to-end delay or routing overhead

A Driving Behaviour Model of Electrical Wheelchair Users

In spite of the presence of powered wheelchairs, some of the users still experience steering challenges and manoeuvring difficulties that limit their capacity of navigating effectively. For such users, steering support and assistive systems may be very necessary. To appreciate the assistance, there is need that the assistive control is adaptable to the user’s steering behaviour. This paper contributes to wheelchair steering improvement by modelling the steering behaviour of powered wheelchair users, for integration into the control system. More precisely, the modelling is based on the improved Directed Potential Field (DPF) method for trajectory planning. The method has facilitated the formulation of a simple behaviour model that is also linear in parameters. To obtain the steering data for parameter identification, seven individuals participated in driving the wheelchair in different virtual worlds on the augmented platform. The obtained data facilitated the estimation of user parameters, using the ordinary least square method, with satisfactory regression analysis results

Non-singular terminal sliding mode controller: Application to an actuated exoskeleton

International audienceThis paper presents a robust controller of an active orthosis used for rehabilitation purposes. The system is composed of the orthosis worn by the shank and has a complex dynamical model. No prior knowledge is considered on the dynamical model and the flexion/extension movements considered are of sinusoidal form and are generally defined by the doctor. The used non-singular terminal sliding mode technique permits to have a finite time convergence. The experimental results have been conducted online on an appropriate dummy and then on three healthy subjects. A comparison of performances obtained by the proposed approach with those obtained by a conventional controller has also been realized. Several situations have been considered to test the robustness and it has been concluded with the effectiveness of the developed controller

Modular-Controller-Design-Based Fast Terminal Sliding Mode for Articulated Exoskeleton Systems

International audienceThis brief deals with a modular controller using a fast terminal sliding mode approach for articulated systems represented by exoskeletons to perform flexion/extension movements. The proposed controller supposes that all model functions are unknown except classical properties related to the boundedness of some parameters. On the other hand, the disturbances are assumed to be bounded. It permits finite-time convergence to the desired trajectories in both position and velocity. The system is divided into several subsystems and a particular unit controls each subsystem. A supervisor using the Lyapunov approach ensures the closed-loop stability of the overall system. The proposed robust controller has been applied in a real-time application to drive an upper limb exoskeleton having 3 DOF. The used device worn by a healthy subject performs flexion/extension movements often practiced for rehabilitation purposes. A strict security protocol, which is generally used by therapists, has been respected. The obtained results are satisfactory and prove the effectiveness and the robustness of the proposed controller

Adaptive controller based on uncertainty parametric estimation using backstepping and sliding mode techniques: Application to an active orthosis

International audienceIn this paper we propose an adaptive controller based on sliding mode and backstepping approaches. The system to be controlled is an exoskeleton used for the rehabilitation of the knee joint. The person wearing the exoskeleton is healthy, sitting and performs movements of flexion/extension. This kind of movement is usually applied by the doctor. The parameters of the dynamic model of the overall system (knee & exoskeleton) are considered unknown. The proposed controller is stable and robust against bounded external disturbances. The experimental results show the effectiveness of the proposed approach. The tests have also been validated when the wearer applies a resistive/assistive torque

Finite-time Control of an Actuated Orthosis Using Fast Terminal Sliding Mode

International audienceThis paper deals with the controller of an active orthosis for rehabilitation reasons of the knee joint. The dynamical model of the system, constituted of the shank and the orthosis is complex and is considered as unknown in the conception of the proposed controller. The full security protocol has been carefully applied and we have selected a healthy person for our experiments. The flexion/extension movements used for our experiments are of sinusoidal form and are generally applied by therapeutic doctors. The fast terminal sliding mode technique used in the proposed controller permits a finite time convergence towards zero of the tracking errors both in position and in velocity. The experimental results are satisfactory and prove clearly the effectiveness of the proposed approach. As the wearer used can develop a muscular effort, we have tested the two cases: resistive and assistive effort and we have obtained a good performance in both cases as has been proven in the stability analysis by the the Lyapunov approach

Velocity and Orientation Control in an Electrical Wheelchair on an inclined and slippery surface

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