651 research outputs found
Adaptive Wireless Biomedical Capsule Localization and Tracking
Wireless capsule endoscopy systems have been shown as a gold step to develop future
wireless biomedical multitask robotic capsules, which will be utilized in micro surgery, drug
delivery, biopsy and multitasks of the endoscopy. In such wireless capsule endoscopy systems,
one of the most challenging problems is accurate localization and tracking of the capsule inside
the human body. In this thesis, we focus on robotic biomedical capsule localization and
tracking using range measurements via electromagetic wave and magnetic strength based
sensors. First, a literature review of existing localization techniques with their merits and
limitations is presented. Then, a novel geometric environmental coefficient estimation technique
is introduced for time of flight (TOF) and received signal strength (RSS) based range
measurement. Utilizing the proposed environmental coefficient estimation technique, a 3D
wireless biomedical capsule localization and tracking scheme is designed based on a discrete
adaptive recursive least square algorithm with forgetting factor. The comparison between
localization with novel coefficient estimation technique and localization with known coefficient
is provided to demonstrate the proposed technique’s efficiency. Later, as an alternative
to TOF and RSS based sensors, use of magnetic strength based sensors is considered. We
analyze and demonstrate the performance of the proposed techniques and designs in various
scenarios simulated in Matlab/Simulink environment
Least-square based recursive optimization for distance-based source localization
In this paper we study the problem of driving an agent to an unknown source
whose location is estimated in real-time by a recursive optimization algorithm.
The optimization criterion is subject to a least-square cost function
constructed from the distance measurements to the target combined with the
agent's self-odometry. In this work, two important issues concerning real world
application are directly addressed, which is a discrete-time recursive
algorithm for concurrent control and estimation, and consideration for input
saturation. It is proven that with proper choices of the system's parameters,
stability of all system states, including on-board estimator variables and the
agent-target relative position can be achieved. The convergence of the agent's
position to the target is also investigated via numerical simulation
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Wireless capsule gastrointestinal endoscopy: direction of arrival estimation based localization survey
One of the significant challenges in Capsule Endoscopy (CE) is to precisely determine the pathologies location. The localization process is primarily estimated using the received signal strength from sensors in the capsule system through its movement in the gastrointestinal (GI) tract. Consequently, the wireless capsule endoscope (WCE) system requires improvement to handle the lack of the capsule instantaneous localization information and to solve the relatively low transmission data rate challenges. Furthermore, the association between the capsule’s transmitter position, capsule location, signal reduction and the capsule direction should be assessed. These measurements deliver significant information for the instantaneous capsule localization systems based on TOA (time of arrival) approach, PDOA (phase difference of arrival), RSS (received signal strength), electromagnetic, DOA (direction of arrival) and video tracking approaches are developed to locate the WCE precisely. The current article introduces the acquisition concept of the GI medical images using the endoscopy with a comprehensive description of the endoscopy system components. Capsule localization and tracking are considered to be the most important features of the WCE system, thus the current article emphasizes the most common localization systems generally, highlighting the DOA-based localization systems and discusses the required significant research challenges to be addressed
Use of a 3-D Wireless Power Transfer Technique as a Method for Capsule Localization
Capsule endoscopy has been heralded as a technological milestone in the diagnosis and therapeutics of gastrointestinal (GI) pathologies. The location and position of the capsule within the GI tract are important information for subsequent surgical intervention or local drug delivery. Accurate information of capsule location is therefore required during endoscopy. Although radio frequency (RF)-based, magnetic tracking and video localization have been investigated in the past, the complexity of those systems and potential inaccuracy in the localization data necessitate the scope for further research. This article proposes the dual use of a wireless power transfer (WPT) configuration as a method to enable the determination of the location of an endoscopic capsule. Measurements conducted on a homogeneous agar-based liquid phantom predict a maximum error of 12% between the calculated and measured trajectories of the capsule in a working volume of 100 mm mm mm
A Survey on Subsurface Signal Propagation
Wireless Underground Communication (WUC) is an emerging field that is being developed continuously. It provides secure mechanism of deploying nodes underground which shields them from any outside temperament or harsh weather conditions. This paper works towards introducing WUC and give a detail overview of WUC. It discusses system architecture of WUC along with the anatomy of the underground sensor motes deployed in WUC systems. It also compares Over-the-Air and Underground and highlights the major differences between the both type of channels. Since, UG communication is an evolving field, this paper also presents the evolution of the field along with the components and example UG wireless communication systems. Finally, the current research challenges of the system are presented for further improvement of the WUCs
Hessian Estimation Based Adaptive and Cooperative Extremum Localization
The thesis is on Hessian estimation based adaptive and cooperative extremum localization via a single mobile sensory agent as well as a network of multiple such agents.
First, we develop a continuous time adaptive extremum localization of an arbitrary quadratic function F(·) based on Hessian estimation, using the measured signal intensity via a single mobile sensory agent. A gradient based adaptive Hessian parameter estimation and extremum localization scheme is developed considering a linear parametric model of field variations.
Next, we extend the proposed single agent based Hessian estimation and extremum localization scheme to consensus based cooperative distributed scheme to be implemented by a network of such sensory agents.For the networked multi-agent case, a consensus term is added to the base adaptive laws to obtain enhanced estimation cooperatively. Stability and convergence analysis of the proposed scheme is studied, establishing asymptotic convergence of the Hessian parameters and location estimates to their true values robustly, provided that the motion of agent(s) satisfies certain persistence of excitation(PE) conditions. Furthermore, we show that for a network of connected agents, the PE requirements can be distributed to the agents so that the requirement on each agent is more relaxed and feasible.
Later, we design an adaptive motion control scheme for steering a mobile sensory agent in 2D toward the source of a signal field F(·) using the signal intensity the agent continuously measures at its current location. The proposed adaptive control design is based on the Hessian estimation based adaptive extremum localization. Results are displayed to verify that the proposed scheme is stable, provides asymptotic convergence of the Hessian parameter and extremum location estimates to their true values and the agent location to the source location, robustly to signal measurement noises
Wide-Scale Small Unmanned Aircraft System Access to the National Airspace System
Expected revisions of federal policies and regulations for the operation and certification of small unmanned aircraft systems (sUAS) are anticipated to significantly increase the volume of traffic in the National Airspace System (NAS). By investigating critical needs of regulatory compliance and safety, as well as new advancements, it may be possible to identify strategies to address the most pressing concerns of sUAS integration. Findings and recommendations from this research are presented to highlight implications and possible solutions to urgent needs of UAS stakehold-ers, including industry, government, and academia
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