Current Issue : July - September Volume : 2018 Issue Number : 3 Articles : 5 Articles
Localization of autonomous underwater vehicles (AUVs) is a very important and challenging task for the AUVs applications. In\nlong baseline underwater acoustic localization networks, the accuracy of single-way range measurements is the key factor for the\nprecision of localization of AUVs, whether it is based on the way of time of arrival (TOA), time difference of arrival (TDOA), or\nangle of arrival (AOA). The single-way range measurements do not depend on water quality and can be taken from long distances;\nhowever, there are some limitationswhich exist in thesemeasurements, such as the disturbance of the unknown current velocity and\nthe outliers caused by sensors and errors of algorithm. To deal with these problems, an AUV self-localization algorithm based on\nparticle swarm optimization (PSO) of outliers elimination is proposed, which improves the performance of angle of arrival (AOA)\nlocalization algorithm by taking account of effects of the current on the positioning accuracy and eliminating possible outliers\nduring the localization process. Some simulation experiments are carried out to illustrate the performance of the proposed method\ncompared with another localization algorithm...
State-of-the-art transtibial prostheses provide only ankle joint actuation and thus do not provide the biarticular function of\nthe amputated gastrocnemius muscle. We develop a prosthesis that actuates both knee and ankle joints and then evaluate the\nincremental effects of this prosthesis as compared to ankle actuation alone. The prosthesis employs a quasi-passive clutched-spring\nknee orthosis, approximating the largely isometric behavior of the biological gastrocnemius, and utilizes a commercial powered\nankle-foot prosthesis for ankle joint functionality. Two participants with unilateral transtibial amputation walk with this prosthesis\non an instrumented treadmill, while motion, force, and metabolic data are collected. Data are analyzed to determine differences\nbetween the biarticular condition with the activation of the knee orthosis and the monoarticular condition with the orthosis\nbehaving as a free-joint. As hypothesized, the biarticular system is shown to reduce both affected-side knee and hip moment\nimpulse and positive mechanical work in both participants during the late stance knee flexion phase of walking, compared to\nthe monoarticular condition. The metabolic cost of walking is also reduced for both participants. These very preliminary results\nsuggest that biarticular functionality may provide benefits beyond even those of the most advanced monoarticular prostheses...
This paper proposes a multi-DoF hybrid-powered transradial robotic prosthesis, named HyPro. The HyPro consists of two\nprosthetic units: hand and wrist that can achieve five grasping patterns such as power grasp, tip grasp, lateral grasp, hook grasp, and\nindex point. It is an underactuated device with 15 degrees of freedom. A hybrid powering concept is proposed and implemented on\nhand unit ofHyPro where the key focus is on restoration of grasp functions of biological hand. A novel underactuated mechanism is\nintroduced to achieve the required hand preshaping for a given grasping pattern using electric power in the pregrasp stage and body\npower is used in grasp stage to execute the final grasping action with the selected fingers. Unlike existing hybrid prostheses where\neach of the joints is separately controlled by either electric or body power, the proposed prosthesis is capable of delivering grasping\npower in combination.The wrist unit of HyPro is designed and developed to achieve flexion-extension and supination-pronation\nusing electric power. Experiments were carried out to evaluate the functionality and performance of the proposed hybrid-powered\nrobotic prosthesis.The results verified the potential of HyPro to perform intended grasping patterns effectively and efficiently....
Validating a 3D indoor radio propagation model that simulates the signal strength of a wireless device can be a challenging task\ndue to an incomplete or a faulty environment model. In this paper, we present a novel method to simulate a complete indoor\nenvironment that can be used for evaluating a radio propagation model efficiently. In order to obtain a realistic and robust model\nof the full environment, the OctoMap framework is applied.The system combines the result of a SLAM algorithm and secondly a\nsimple initialmodel of the same environment in a probabilistic way. Due to this approach, sensor noise and accumulated registration\nerrors are minimised. Furthermore, in this article, we evaluate the merging approach with two SLAM algorithms, three vision\nsensors, and four datasets, of which one is publicly available. As a result, we have created a complete volumetric model by merging\nan initial model of the environment with the result of RGB-D SLAM based on real sensor measurements....
The presence of time delays in communication introduces a limitation to the stability of bilateral teleoperation systems. This paper\nconsiders internal model control (IMC) design of linear teleoperation system with time delays, and the stability of the closed-loop\nsystem is analyzed. It is shown that the stability is guaranteed delay-independently. The passivity assumption for external forces\nis removed for the proposed design of teleoperation systems. The behavior of the resulting teleoperation system is illustrated by\nsimulations....
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