Wireless communication with mobile inspection robots while submerged inside oil storage tanks

Data acquisition during storage tank inspection is one of the most important aspects for petrochemical storage tank owners. Mobile inspection robots designed to enter inside a storage tank without taking the tank out of service are required to enter through manholes on the roof of the tank with openings as small as 300-millimetre diameter. These robots are controlled via an umbilical cable which supplies power to the robot, sends and receives signals to control robot motion, and transfers inspection data acquired by non-destructive testing (NDT) sensors back to NDT inspectors. It is important to localize a robot inside the tank so that NDT data indicating a defect such as corrosion pitting in tank floors or weld cracks can be mapped for subsequent monitoring and repair. Wireless communication with the robot for NDT data acquisition and localization would enable the minimization of umbilical size and its effective management which is important when a small mobile robot is supplied with a very long umbilical. This paper presents results of a study to develop a wireless communication system that uses radio frequency (RF) signals with low power (<1W) sent by a transceiver on a robot operating inside an oil storage tank which travel through an oil medium, are transmitted through steel tank walls and are captured by receivers placed in air outside the tank. Simulations using Feko software have been performed to assess the feasibility of using RF for communication in oil storage tanks with laboratory experiments conducted using vegetable oil to validate the simulations. RF signals transmitted by a robot operating inside an oil tank and received by a number of receivers placed in air around the tank has potential application as a robot localization system

Performance of electromagnetic communication in underwater wireless sensor networks

Underwater wireless sensor networks (WSNs) composed of a number of sensor nodes that are deployed to conduct a collaborative monitoring task. Wireless signals are used for communication between the sensor nodes. Acoustic signals are the dominant signals used as a wireless communication medium in underwater WSNs due to the relatively low absorption in the underwater environments. Acoustic signals face a lot of challenges such as ambient noise, manmade noise, limited bandwidth, multipath and low propagation speed. Some of these challenges become more severe in shallow water environment where a high level of ambient and mankind noise, turbidity and multipath propagation are available. Therefore, electromagnetic signals can be applied as an alternative communication signal for underwater WSNs in the shallow water. In this project, the performance of EM communication in underwater WSNs is investigated for the shallow water environment. Theoretical calculations and practical experiments are conducted in fresh and seawater. It is shown that signals propagate for longer ranges in freshwater comparing to seawater. Theoretical results show that attenuation of electromagnetic communication in seawater is much higher than in fresh water. The attenuation is increasing with the increasing of frequency. In addition, velocity of the signal is increasing as the frequency is increasing while loss tangent is decreasing as the frequency increasing. Based on practical experiments, freshwater medium permits short ranges EM communication that does not exceed 25.1 cm for 2.4 GHz frequency. On the other hand, communication in seawater is very difficult to achieve for the same high frequency. Path loss exponent was estimated for freshwater environment based on logdistance path loss model. The estimation was achieved through a comparison between theoretical calculations and practical measurements. The path loss exponent for EM communication in fresh water was estimated to be in the range of 2.3 to 2.4

Measuring the underwater received power behavior for 433 mhz radio frequency based on different distance and depth for the development of an underwater wireless sensor network

Underwater wireless sensor network (UWSN) important to enhance the widely use of the application of the Internet of things (IoT) for underwater. Uses of the acoustics base of wave propagations are the best ways to establish the UWSN. But the unpracticality of the hardware due to the size and cost has limited the application of UWSN. Radio frequency (RF) wave propagation is the best way to overcome this situation. Low frequency of the RF wave is proven feasible and suitable for underwater communication. 433 MHz RF were chosen to measuring the underwater received power behavior between the transmitter node and receiver node based on different distance and depth. HC12 transceiver module was used as a transmitter and spectrum analyzer with the telescopic antenna was used as a receiver. The received power give a good reading when the transmitter note was at 0.5-meter depth with a maximum operating range within 12 meters from the receiver

An Energy and Spectral Efficient In Underwater Communication Using Magneto Inductive Channel

Abstract: The analysis of Magneto Inductive communication technique due to underwater communication having multipath fading, dynamic channel and high propagation delay . The performance studies of 3D network covering 100 of meter of sea depth and few km square area show fully connected multi coil network with communication bandwidth extending from few to tens of kHz. The low speed of sound in water, different attenuation characteristics and time varying multi-path fading make use of regular communication methods impractical. To get large area coverage and more bandwidth from sea area . In this work, highly power efficient and fully connected fuzzy scheduling is presented. It allows underwater channel more fair and efficient communication over larger distances

A Static Multi-hop Underwater Wireless Sensor Network Using RF Electromagnetic Communications

Most underwater sensor networks choose acoustics as the medium for wireless transmission. However, electromagnetic waves also offer great merits for transmission in special underwater environment. A small scale wireless sensor network is deployed using electromagnetic waves with a multi-hop static topology under shallow water conditions where there is a high level of sediment and aeration in the water column. Data delivery is scheduled via daily cycles of sleeping and waking up to transmit. Due to the unique features of the network, ad-hoc on-demand distance vector (AODV) is chosen as the routing protocol. Modeling and simulations are conducted to evaluate network performance in terms of failure tolerance, congestion handling, and optimal grid arrangements. The results demonstrate the likely effectiveness of the designated network for this and similar scenarios

Analysis of the Possibilities of Using IoT Technologies under Water, Including Demonstration Tasks

Diplomová práce se zabývá možnou aplikací technologií IoT pod hladinou vody. Popisuje IoT technologie LoRa, IQRF, NB-IoT, jejich základní vlastnosti a principy funkce. Následně definuje pojem RSSI. V práci je obecně popsán přenos vysokofrekvenčního signálu pod vodou, jeho vlastnosti, výhody a nevýhody uplatnění. Vysokofrekvenční přenos dat porovnává s ověřenými metodami přenosu dat pod vodou. Teoretická analýza se zabývá přenosem signálu o frekvencích 868 a 433 MHz pod vodou a výpočtem dosahu jednotlivých technologií při přenosu signálu z vody na vzduch. Dále navrhuje a realizuje experimentální měření RSSI pro technologie LoRa, IQRF a NB-IoT pod vodou. Praktická analýza vyhodnocuje naměřená data a v závěrečném zhodnocení porovnává naměřená data s teoretickým předpokladem. Závěr práce sumarizuje možnost využití technologií IoT pod hladinou vody, ve kterých případech je vhodné uplatnit tyto technologie a ve kterých by bylo na místě zvolit odlišné způsoby přenosu dat.The thesis investigates the possible application of IoT technologies underwater. It describes IoT technologies LoRa, IQRF, NB-IoT, their basic features and principles of operation. Then it defines the concept of RSSI. The paper describes in general terms the transmission of high frequency signal underwater, its characteristics, advantages and disadvantages of application. It compares RF data transmission with proven methods of underwater data transmission. The theoretical analysis deals with the transmission of 868 and 433 MHz signals underwater and calculation the range of each technology when transmitting the signal from water to air. It also designs and implements experimental RSSI measurements for LoRa, IQRF and NB-IoT technologies underwater. The practical analysis evaluates the measured data and in the final evaluation compares the measured data with the theoretical assumption. The conclusion of the paper summarizes the possibility of using IoT technologies under water, in which cases it is reasonable to apply these technologies and in which cases it would be appropriate to choose different data transmission methods.450 - Katedra kybernetiky a biomedicínského inženýrstvívelmi dobř

Finite element method based simulations of low frequency magnetic field in seawater

Ankara : The Department of Electrical and Electronics Engineering and the Graduate School of Engineering and Science of Bilkent University, 2013.Thesis (Master's) -- Bilkent University, 2013.Includes bibliographical references leaves 91-95.Propagation properties of the electromagnetic waves in seawater are different than in air (vacuum) due to electrical conductivity (σ) and high relative permittivity (εr) of the seawater. Numerically it is hard to solve the electromagnetic waves in seawater for the complex geometries. With the help of the advances in the Finite Element Method (FEM) tools as well as the personal computers, we have chance to analyze magnetic field of the complicated and complex geometries of physical systems in seawater. In this thesis; an air-cored multilayer transmitting coil is designed. Then the low frequency magnetic flux density of this coil in different studies in seawater in COMSOL Multiphysics is solved. In the first study; the magnetic flux density of the coil in air and in seawater for different frequencies on different observation points is solved. In the second study; the shielding effect of the material of the case of the coil as well as the thickness of the case is analyzed. Specific materials as well as thickness for the case are proposed. In the third study; the perturbation of the magnetic flux density of the coil due to a metal plate is analyzed. The material of the metal plate is taken iron and copper. Iron has high relative permeability ( r) and high electrical conductivity (σ). Copper has unity permeability ( 0) and high electrical conductivity (σ). Effect of the high electrical conductivity on the perturbation of the magnetic flux density on the observation point is analyzed. Effect of high relative permeability on the phase shift of the field on the observation point is observed. A detection region for the plate and coil geometries according to the attenuation of the secondary fields caused by the eddy currents on the metal plate is proposed. In the last study; perturbation of ambient Earth magnetic field due to a submarine is solved and how this perturbation can be imitated by an underwater system, which tows a DC current carrying wire is analyzed. These underwater systems are used to test detection performance of magnetic anomaly detector (MAD) equipped aircrafts.Şimşek, Fatih EmreM.S

Internal in-service inspection of petrochemical storage tank floors to detect underside corrosion with Non-Destructive Testing Robot

This research develops a new robotics technology for the in-service inspection of floor plates of the majority for the world’s petrochemical storage tanks. The new robotic system aims to decrease inspection cost, reduce human inspector exposure to chemical and hazard environment during the inspection and eliminate tank outage entirely if the floor is found to contain no corrosion. The research focus is on the design and development of a Non-Destructive Testing Robot (NDTBOT) prototype that uses active buoyancy control for its locomotion mechanism and uses NDT ultrasound to measure floor plate thickness as an indication of corrosion thinning. The NDTBOT hops from one location of the floor to another location to make ultrasound thickness measurements of a tank floor, thus avoiding issues of motion on a dirty tank floor (due to oil sludge). Also, a novel radio frequency (RF) data communication system is investigated and developed that can operate while submerged in oil. This system allows control commands to be sent to the NDTBOT by an operator outside the tank and NDT data to be recovered for analysis. To evaluate the performance of the NDTBOT making thickness measurement in the tank, three types of measurement techniques were used. First, the real thickness was measured using a Vernier caliper, the second method used a standard hand-held ultrasonic thickness measurement instrument and finally the in-service inspection thickness measurements were made with the NDTBOT operating in a water tank. The NDTBOT thickness measurements with an immersion ultrasound probe obtained more accurate results than hand-held contact ultrasonic testing. Petrochemical storage tank size varies from 20 to 200 meters in diameter, rapid corrosion inspection in such tanks with a swarm of robots requires that a number of NDTBOTs be deployed inside the tank to perform the NDT. Such deployment needs coordination and control work between the robots to send the NDT data to the NDT inspector. Therefore, an investigation and experimental radio frequency wireless transmission is done in order to compare different radio frequency communication. Simulation with commercial software CADFEKO is used to perform simulation of RF wave transmission in petroleum and vegetable oil with selected radio frequencies of 200 MHz, 300 MHz, and 433 MHz. The experimental work and simulation results give confidence. The RF communication in petroleum medium is feasible for both control of NDTBOTs inside the tank and NDT data transmission back to a technician’s console placed outside the tank

EFFICIENT DYNAMIC ADDRESSING BASED ROUTING FOR UNDERWATER WIRELESS SENSOR NETWORKS

This thesis presents a study about the problem of data gathering in the inhospitable underwater environment. Besides long propagation delays and high error probability, continuous node movement also makes it difficult to manage the routing information during the process of data forwarding. In order to overcome the problem of large propagation delays and unreliable link quality, many algorithms have been proposed and some of them provide good solutions for these issues, yet continuous node movements still need attention. Considering the node mobility as a challenging task, a distributed routing scheme called Hop-by-Hop Dynamic Addressing Based (H2- DAB) routing protocol is proposed where every node in the network will be assigned a routable address quickly and efficiently without any explicit configuration or any dimensional location information. According to our best knowledge, H2-DAB is first addressing based routing approach for underwater wireless sensor networks (UWSNs) and not only has it helped to choose the routing path faster but also efficiently enables a recovery procedure in case of smooth forwarding failure. The proposed scheme provides an option where nodes is able to communicate without any centralized infrastructure, and a mechanism furthermore is available where nodes can come and leave the network without having any serious effect on the rest of the network. Moreover, another serious issue in UWSNs is that acoustic links are subject to high transmission power with high channel impairments that result in higher error rates and temporary path losses, which accordingly restrict the efficiency of these networks. The limited resources have made it difficult to design a protocol which is capable of maximizing the reliability of these networks. For this purpose, a Two-Hop Acknowledgement (2H-ACK) reliability model where two copies of the same data packet are maintained in the network without extra burden on the available resources is proposed. Simulation results show that H2-DAB can easily manage during the quick routing changes where node movements are very frequent yet it requires little or no overhead to efficiently complete its tasks