A Magnetic Localization Technique Designed for use with Magnetic Levitation Systems.

M.S. Thesis. University of Hawaiʻi at Mānoa 2017

Characterisation and State Estimation of Magnetic Soft Continuum Robots

Minimally invasive surgery has become more popular as it leads to less bleeding, scarring, pain, and shorter recovery time. However, this has come with counter-intuitive devices and steep surgeon learning curves. Magnetically actuated Soft Continuum Robots (SCR) have the potential to replace these devices, providing high dexterity together with the ability to conform to complex environments and safe human interactions without the cognitive burden for the clinician. Despite considerable progress in the past decade in their development, several challenges still plague SCR hindering their full realisation. This thesis aims at improving magnetically actuated SCR by addressing some of these challenges, such as material characterisation and modelling, and sensing feedback and localisation. Material characterisation for SCR is essential for understanding their behaviour and designing effective modelling and simulation strategies. In this work, the material properties of commonly employed materials in magnetically actuated SCR, such as elastic modulus, hyper-elastic model parameters, and magnetic moment were determined. Additionally, the effect these parameters have on modelling and simulating these devices was investigated. Due to the nature of magnetic actuation, localisation is of utmost importance to ensure accurate control and delivery of functionality. As such, two localisation strategies for magnetically actuated SCR were developed, one capable of estimating the full 6 degrees of freedom (DOFs) pose without any prior pose information, and another capable of accurately tracking the full 6-DOFs in real-time with positional errors lower than 4~mm. These will contribute to the development of autonomous navigation and closed-loop control of magnetically actuated SCR

Challenges of continuum robots in clinical context: a review

With the maturity of surgical robotic systems based on traditional rigid-link principles, the rate of progress slowed as limits of size and controllable degrees of freedom were reached. Continuum robots came with the potential to deliver a step change in the next generation of medical devices, by providing better access, safer interactions and making new procedures possible. Over the last few years, several continuum robotic systems have been launched commercially and have been increasingly adopted in hospitals. Despite the clear progress achieved, continuum robots still suffer from design complexity hindering their dexterity and scalability. Recent advances in actuation methods have looked to address this issue, offering alternatives to commonly employed approaches. Additionally, continuum structures introduce significant complexity in modelling, sensing, control and fabrication; topics which are of particular focus in the robotics community. It is, therefore, the aim of the presented work to highlight the pertinent areas of active research and to discuss the challenges to be addressed before the potential of continuum robots as medical devices may be fully realised

Modern Telemetry

Telemetry is based on knowledge of various disciplines like Electronics, Measurement, Control and Communication along with their combination. This fact leads to a need of studying and understanding of these principles before the usage of Telemetry on selected problem solving. Spending time is however many times returned in form of obtained data or knowledge which telemetry system can provide. Usage of telemetry can be found in many areas from military through biomedical to real medical applications. Modern way to create a wireless sensors remotely connected to central system with artificial intelligence provide many new, sometimes unusual ways to get a knowledge about remote objects behaviour. This book is intended to present some new up to date accesses to telemetry problems solving by use of new sensors conceptions, new wireless transfer or communication techniques, data collection or processing techniques as well as several real use case scenarios describing model examples. Most of book chapters deals with many real cases of telemetry issues which can be used as a cookbooks for your own telemetry related problems

Control of Magnetic Continuum Robots for Endoscopy

The present thesis discusses the problem of magnetic actuation and control applied to millimetre-scale robots for endoluminal procedures. Magnetic actuation, given its remote manipulation capabilities, has the potential to overcome several limitations of current endoluminal procedures, such as the relatively large size, high sti�ness and limited dexterity of existing tools. The application of functional forces remotely facilitates the development of softer and more dexterous endoscopes, which can navigate with reduced discomfort for the patient. However, the solutions presented in literature are not always able to guarantee smooth navigation in complex and convoluted anatomical structures. This thesis aims at improving the navigational capabilities of magnetic endoluminal robots, towards achieving full autonomy. This is realized by introducing novel design, sensing and control approaches for magnetically actuated soft endoscopes and catheters. First, the application of accurate closed-loop control to a 1 Internal Permanent Magnet (IPM) endoscope was analysed. The proposed approach can guarantee better navigation capabilities, thanks to the manipulation of every mechanical Degree of Freedom (DOF) - 5 DOFs. Speci�cally, it was demonstrated that gravity can be balanced with su�cient accuracy to guarantee tip levitation. In this way contact is minimized and obstacle avoidance improved. Consequently, the overall navigation capabilities of the endoscope were enhanced for given application. To improve exploration of convoluted anatomical pathways, the design of magnetic endoscopes with multiple magnetic elements along their length was introduced. This approach to endoluminal device design can ideally allow manipulation along the full length; facilitating full shape manipulation, as compared to tip-only control. To facilitate the control of multiple magneto-mechanical DOFs along the catheters' length, a magnetic actuation method was developed based on the collaborative robotic manipulation of 2 External Permanent Magnets (EPMs). This method, compared to the state-of-the-art, facilitates large workspace and applied �eld, while guaranteeing dexterous actuation. Using this approach, it was demonstrated that it is possible to actuate up to 8 independent magnetic DOFs. In the present thesis, two di�erent applications are discussed and evaluated, namely: colonoscopy and navigational bronchoscopy. In the former, a single-IPM endoscopic approach is utilized. In this case, the anatomy is large enough to permit equipping the endoscope with a camera; allowing navigation by direct vision. Navigational bronchoscopy, on-the-other-hand, is performed in very narrow peripheral lumina, and navigation is informed via pre-operative imaging. The presented work demonstrates how the design of the magnetic catheters, informed by a pre-operative Computed Tomography (CT) scan, can mitigate the need for intra-operative imaging and, consequently, reduce radiation exposure for patients and healthcare workers. Speci�cally, an optimization routine to design the catheters is presented, with the aim of achieving follow-the-leader navigation without supervision. In both scenarios, analysis of how magnetic endoluminal devices can improve the current practice and revolutionize the future of medical diagnostics and treatment is presented and discussed

Market entry in the German pharmaceutical market : a framework for business intelligence measures

Pharmaceutical companies today are under great pressure to successfully launch new specialty drugs, high-tech products for small patient populations with cost intensive R&D and complex mechanisms of effect. At the same time, increasing privacy regulation limits the availability of data for market research in the medical markets, forcing pharmaceutical companies to find ways of creating transparency. Researchers can draw from a large, yet disperse body of literature investigating the factors that favour early adoption of a drug. The thesis introduces Roger’s Diffusion of Innovation framework to organize literature on factors that speed up new product adoption among physicians. The framework is expanded to suit the pharmaceutical markets, especially to differentiate between fixed variables and such that are subject to change during an adoption process. Afterwards different approaches to quantitative diffusion modelling are introduced with an exemplary paper each. The different levels of modelling, from macro-level (national sales) down to micro-level (individual behaviour) are explained. Subsequently, the limitations through German privacy regulation as well as through market specific features on data availability for pharmaceutical market research are presented. A comparison between quantitative diffusion models on different levels with the current privacy regulation shows which analysis approaches might still be feasible. Based on the prior analysis, a quantitative model for drug adoption in the German pharmaceutical market is developed, using Multiple Regression Analysis as the statistical tool. It is found that under some conditions, a very simple two-variable model using the salesforce visits’ and their assessment of a doctor’s adoption behaviour can explain more than 40% of the variance in sales between hospitals. Limited availability of independent data causes the model to be largely influenced through the sales force’s agenda in reporting. Although this data is naturally biased, it seems unlikely that data availability from independent sources will improve in the future. Pharmaceutical companies will need to further utilize their sales force to collaborate with physicians and adapt their incentive systems to live up to the new requirements.nhhma

Design and implementation of DSP-based magnetic control system for capsule endoscope

PhD ThesisEarly detection methods are key to reducing morbidity rates from digestive tract cancer which is currently one of the fastest growing cancers in the World. Capsule endoscopes (CEs) are a new technology that can be used to improve early detection of the gastrointestinal (GI) tract disorder. The device integrates the technologies such as image processing, optoelectronic engineering, information communication, and biomedical engineering. The capsule is the size and shape of a pill and contains an optoelectronic camera, antenna, transmitter, battery and optoelectronic illuminating light emitting diodes (LEDs). The small size of these devices enables them to offer many advantages over conventional endoscopes such as accessibility to the entire intestine and minimising the risk of perforation, particularly for patients with difficult anatomy (e.g. post-operative scar tissue). Currently used devices are passive and can only follow the natural transit of the intestines, and hence there is considerable interest in methods of controlled actuation for these devices. In this thesis, a novel actuation system based on magnetic levitation is designed, developed and implemented, utilizing a small permanent magnet embedded within the capsule and an arrangement of digitally controlled electromagnets outside the body. The proposed approach is that the magnet can be moved and oriented by DC magnetic force and torque produced by coils placed outside of the human body, with a suitable position feedback sensor enabling closed-loop control. Theoretical analyses of the proposed actuation system are presented which model the magnetic field, force and torque exerted by electromagnetic coil on the embedded magnet. Based on the distribution of the magnetic field, an optimal geometry for the coils is proposed in order to achieve a levitation distance which is realistic for the inspection of the GI tract. Two types of systems are investigated in the thesis, namely single-input single-output (SISO) and multi-input multi-output (MIMO), and the dynamics of these systems are modelled in state space form and hence linear controllers are designed for capsule actuation. The controllers are simulated using Matlab/ Simulink tools to realize the mathematical analysis of the system, and then implemented digitally in real-time using Texas Instruments (TI) TMS320F2812 Digital Signal Processor (DSP) to validate the proposed actuation system. In the SISO system, a linear one degree of freedom (1DOF) proportionalintegral- derivative (PID) controller is designed to move the inserted magnet in the vertical dimension within an area around the operating point and to maintain it at a desired position. A realistic simulation model is designed and implemented to evaluate the proposed controller. Simulation results have shown that the controller is able to successfully hold the embedded magnet in the desired position. For practical validation, the PID controller is implemented in real-time on the DSP system, where pulse width modulation (PWM) is generated to control the coil current, and Hall effect sensors are used for position feedback. Experimental results are obtained under step and square wave input demand. In the proposed system, high frequency noise on the position sensor is initially rejected by hardware implementation of resistor capacitor-low pass filter (RC-LPF) circuit. The accuracy of the position feedback is increased by calibrating the DSP’s on-chip analogue-digital converter (ADC) in order to reduce conversion error due to inherent gain and offset errors. To further reduce the influence of the position feedback noise, an average of ten repeated samples based on mean filter is implemented by the DSP in order to reduce the influctuation of the sensor reading. The tracking performance of the actuation system based on two Hall effect sensors on the opposite coil’s poles is investigated under step trajectory input. In an improved actuation system, position feedback is provided by using an AC magnetic field to obtain the capsule position information, decoupling this from the DC actuation field. The noise of the position feedback in the improved system is reduced by replacing the PWM current drive with a linear power amplifier driven from a digital to analogue converter (DAC), hence reducing AC interference. Positioning sensor noise was found to be further reduced by implementing digital filtering based on a coherent detector using the DSP, without increasing response time. The performance of the actuation system using these position sensors is compared based on settling time, overshoot, steady-state error, and control input parameters in order to validate the proposed improvement in the position feedback. The experimental results have shown that the controller based on both sensing strategies satisfactory control of the magnet’s position. However, the response of the system based on AC position sensing has the shortest settling time, smallest overshoot value and steady-state error. In the MIMO system, several linear controllers such as pole placement (PP), Entire Eigenstructure Assignment (EEA), and linear Quadratic regulator (LQR) techniques are designed and their tracking performances are compared. Simulation results have shown that, based on acceptable control inputs, the LQR controller has the fastest response with minimal overshoot value and steady state error. However, the LQR controller based on 2DOF is unable to maintain stable control of the magnet due to the insufficient position feedback from the two coil sensors. Specifically, it is not possible to achieve a stable 2D system since the orientation angle of the magnet is not resolvable. Therefore, the position feedback is improved by obtaining the device position and orientation information from a pair of 3-axis orthogonal coils. A realistic simulation model for the 3DOF LQR controller is designed and implemented to evaluate the developed system. Simulation results have shown that this controller is can achieve the necessary stability. In conclusion, based on the results from the 1D control system, the thesis shows that the DC magnetic field, which is used for capsule movement, can be also used to provide the controller acceptable position feedback. However, the use of AC magnetic field for positioning purpose provides more accurate position information. In order to implement 2DOF control system successfully, two 3-axis orthogonal coil sensors are considered which are used to provide the actuation algorithm with more accurate feedback of position and orientation information.Ministry of Higher Education, Iraq

Effect of curing conditions and harvesting stage of maturity on Ethiopian onion bulb drying properties

The study was conducted to investigate the impact of curing conditions and harvesting stageson the drying quality of onion bulbs. The onion bulbs (Bombay Red cultivar) were harvested at three harvesting stages (early, optimum, and late maturity) and cured at three different temperatures (30, 40 and 50 oC) and relative humidity (30, 50 and 70%). The results revealed that curing temperature, RH, and maturity stage had significant effects on all measuredattributesexcept total soluble solids

New Techniques in Gastrointestinal Endoscopy

As result of progress, endoscopy has became more complex, using more sophisticated devices and has claimed a special form. In this moment, the gastroenterologist performing endoscopy has to be an expert in macroscopic view of the lesions in the gut, with good skills for using standard endoscopes, with good experience in ultrasound (for performing endoscopic ultrasound), with pathology experience for confocal examination. It is compulsory to get experience and to have patience and attention for the follow-up of thousands of images transmitted during capsule endoscopy or to have knowledge in physics necessary for autofluorescence imaging endoscopy. Therefore, the idea of an endoscopist has changed. Examinations mentioned need a special formation, a superior level of instruction, accessible to those who have already gained enough experience in basic diagnostic endoscopy. This is the reason for what these new issues of endoscopy are presented in this book of New techniques in Gastrointestinal Endoscopy