Francis Adepoju

A Review and Adaptation of Methods of Object Tracking to Telemetry Capsules

Abstract This review considers techniques employing radio frequency (RF) as well as ultrasound signals for tracking. Medical capsules have been employed since the SOs to measure various physiological parameters in the human body. Examples are temperature, pH, or pressure inside the gastrointestinal (GI) tract. The development and subsequent incorporation of new technology into reasonably priced, commercially available devices have made ultrasound and RF devices readily accessible for medical diagnosis. Some applications for telemetry capsules are drug delivery, and collection of tissue/fluid samples. Samples are taken from the GI to understand or treat diseases where diagnosis can only be made by taking a biopsy from the intestinal walls. Such biopsies have traditionally been performed using customized endoscopes. In order for a telemetry capsule to be effective in the above named tasks, accurate knowledge of the location of the capsule within the body during tests is necessary. As such, methods for calcu...

Adaptive Linearized Methods for Tracking a Moving Telemetry Capsule

In this paper, we discuss system and method of determining the real-time location of an omni-directional diagnostic radio frequency (RF) system while the object (transmitter) is moving freely inside an inaccessible organ. A specific application to the human gastrointestinal (GI) organ is presented, showing the importance of the method in accessing a specific site for drug administration or for extracting fluid or tissue samples for biopsy and similar medical investigations. For practical purposes, omnidirectional antenna on the transmitter at 433 MHz, normalized transmitter power 1 W was modeled for simplicity, and Es/No = 20 dB (corresponding to the linear region of the target transceiver). A brief discussion of how the original analogue signals, after conversion to voltage, was adapted for position tracking. In the tracking algorithm, we employed a path loss scenario based on the popular log-normal model to simulate the effects of organs on signal quality between transmitter and receiver at various distances.

Capsule tracking in the GI tract: a novel microcontroller based solution

Telemetry capsules that will provide facilities for on-site drug delivery and those that are capable of taking tissue/fluid samples within the human gastro-intestinal (GI) are quite invaluable for diagnosing GI related diseases where diagnosis can only be made by taking a biopsy from the intestinal walls. Such biopsies have traditionally been preformed using custom endoscopes. To be effective in the above named tasks, accurate knowledge of the location of telemetry capsules within the GI tract is a necessity. This paper presents a method of tracking a capsule inside the human GI tract based on the application of a microcontroller to control the generation and transmission of ultrasonic pulses. The capsule, i.e. object, and the central receiver are capable of transmit and receive functions, others are receive-only stations. This ensures the collection of a reliable round-trip time of flight (TOF) data. Application of triangulation to the TOF data facilitates the determination of the real-time positions of the object with less than 10% aggregate measurement error

A Model for Estimating the Real-Time Positions of a moving Object in Wireless Telemetry Applications using RF Sensors.

In this paper, we discuss system and method of determining the real-time location of an omni-directional diagnostic radio frequency (RF) system while the object is moving freely inside an inaccessible organ. A target application to the human gastrointestinal (GI) organ is presented, showing the importance of the method in accessing a specific site for drug administration or for extracting fluid or tissue samples for biopsy and similar medical investigations. Unlike other commercially available solutions that are fraught with invasive procedures our method interfaces with wireless technology to provide non-invasive real-time acquisition of intestinal physiology data and also relay information about the objects whereabouts at all times during the entire period of diagnosis. The system consists of a miniature RF transceiver embedded in the GI tract and a set of receivers positioned external to the body. RF signal is transmitted at 433MHz to achieve half duplex communication between the transmitter and receiver. The frequency shift keying (FSK) modulation scheme was adopted to ensure a reliable and high-speed digital RF link. Undoubtedly, the novelty of the method will foster a strategic marketing advantage by virtue of the solutions ambulant nature targeted at patients suffering from intestinal disorders or irritable bowel syndrome (IBS).

Verification of Wireless Data Acquisition Radio Frequency System for Medical Telemetry Application

This paper presents an overview of simulated and custom models for a wireless data acquisition system. The output signal from the transmitter was encoded to digital signal based on one of the Pulse Coding Modulation (PCM) algorithms. At the receiver end, the signal is demodulated and processed to extract the spectrum of the original analogue signal which is subsequently converted to voltage primarily for position tracking purposes. We used a path loss scenario based on the log-normal model to investigate the relationship between signal power transmitted, distance between transmitter and receiver, and the bit error rate generated in the channel. The performance of the radio frequency (RF) unit through additive White Gaussian Noise (AWGN) channel was examined by estimating the average Bit Error Rate (BER). The effect of the multipath fading was also considered in the receiver model. The receiver was modeled to receive from an omnidirectional transmitter which is transmitting RF signals at 433MHz, Input power IW, and Es/No = 20dB (corresponding to the linear region of the target transceiver).

Simulation and Characterization of Wireless Data Acquisition RF Systems for Medical Diagnostic Application

This paper presents an aggregation of simulated models for a wireless data acquisition system. The model consists of key units that were simulated using SIMULINK. The output signal from the transmitter was encoded to digital signal based on one of the pulse coding modulation (PCM) algorithms. At the receiver end, the signal is demodulated and processed to extract the spectrum of the original analogue signal which is converted to voltage for position tracking purposes. The performance of the radio frequency (RF) unit through additive white Gaussian noise (AWGN) channel was examined by estimating the average bit error rate (BER) for different carrier frequencies. The effect of the multi-path fading in a lossy medium was also considered. The receiver model was based on the assumption that the transmitter is omnidirectional and is transmitting at 433 MHz.

Simulation, Design and Testing of Wireless Data Acquisition RF Systems for Capsule Endoscopy

This paper presents an aggregation of simulated and designed radio frequency (RF)-based models for a wireless data acquisition system. The model consists of key units that were simulated with SIMULINK. We employed a path loss scenario based on the popular log-normal model to investigate the relationship between signal power transmitted, distance between transmitter and receiver, and the bit error rate generated in the channel. The performance of the RF unit through additive white Gaussian noise (AWGN) channel was examined by estimating the average bit error rate (BER) for a certain carrier frequency. The effect of the multi-path fading in a lossy medium (applicable to the human gastro intestinal (GI) tract) was also considered. The receiver model was operating about 10-20 cm from the transmitter whereby the power emanating from the transmitter antenna is essentially omnidirectional. Taking advantage of the 433 MHz free band, input power 1 W, and signal energy-noise power spectral density (Es/No) = 20 dB corresponding to the linear region of the target transceiver. Finally a laboratory model was built in order to confirm the simulated results.

A Method for Estimating the Geometric Position of a Wireless Telemetry Capsule in Real-Time

In this paper, we present a discussion of work done in tracking an embedded object. A special application to telemetry capsules in the gastrointestinal (GI) tract using radio frequency (RF) signals is highlighted. We present the mathematical analysis of the procedure and consequently, an experimental validation of the concept from data captures to position determination using non linear least squares approximation. Finite difference time domain (FDTD) simulation of a suitable dipole antenna employed in the work is also presented to show that within the test range, the radiation pattern of a dipole at about 433 MHz is suitable for detecting an embedded object that is subject to the characteristics of tissue and other related structures.

Linearized Transformation of RF Data for Capsule Tracking in Wireless Telemetry

In this paper, we discuss system and method of determining the real-time location of an omnidirectional diagnostic radio frequency (RF) system while the object (transmitter) is moving freely inside an inaccessible organ. A specific application to the human gastrointestinal (GI) organ is presented, showing the importance of the method in accessing a specific site for drug administration or for extracting fluid or tissue samples for biopsy and similar medical investigations. For practical purposes, we assume omnidirectional transmitter transmitting at 433 MHz, Input power 1 W, and Es/No = 20 dB (corresponding to the linear region of the target transceiver). We also discuss the method for using the original analogue signal, after conversion to voltage, for position tracking. In our algorithm, we employed a path loss scenario based on the popular log-normal model to simulate the effects of organs on signal quality between transmitter and receiver at various distances.

A mathematical model for localization and tracking of telemetry capsules using RSSI signals

In this paper we consider the problem of tracking the real-time positions of a diagnostic capsule in the gastrointestinal (GI) tract. Our solution is a fully developed estimation algorithm that utilizes radio frequency signals converted to voltage on the received signal strength indicator (RSSI) output of an array of transceivers. We employed a modified form of the traditional radio-map based deterministic model that requires an estimate of initial position vector. Data capture was implemented with commercial off-the-shelf transceivers featuring RSSI outputs. At the intermediate processing stages, trilateration was employed as a mathematical tool to determine the approximate 2-D coordinates of unknown capsule locations by linearizing the resulting equations. This approach facilitates a PC-based implementation of fully automated real-time position measurements by eliminating the need to measure angles. In the final algorithm based on non linear least squares approximations, the Newtons iteration of the resulting Jacobian matrices were used to generate a more accurate position coordinates. Test Results from laboratory experiments demonstrate the accuracy of the solution in the centimeter range. This results in a position tracking measurements with an average value error of less than 25%. This kind of results guarantees that our solution can be adapted into telemetry capsules for use in diagnosing intestinal malfunctions.