Improved multi model predictive control for distillation column

Model predictive control (MPC) strategy is known to provide effective control of chemical processes including distillation. As illustration, when the control scheme was applied to three linear distillation columns, i.e., Wood-Berry (2x2), Ogunnaike-Lemaire-Morari-Ray (3x3) and Alatiqi (4x4), the results obtained proved the superiority of linear MPC over the conventional PI controller. This is however, not the case when nonlinear process dynamics are involved, and better controllers are needed. As an attempt to address this issue, a new multi model predictive control (MMPC) framework known as Representative Model Predictive Control (RMPC) is proposed. The control scheme selects the most suitable local linear model to be implemented in control computations. Simulation studies were conducted on a nonlinear distillation column commonly known as Column A using MATLAB® and SIMULINK® software. The controllers were compared in terms of their ability in tracking set points and rejecting disturbances. Using three local models, RMPC was proven to be more efficient in servo control. It was however, not able to cope with disturbance rejection requirement. This limitation was overcome by introducing two controller output configurations: Maximizing MMPC and PI controller output (called hybrid controller, HC), and a MMPC and PI controller output switching (called MMPCPIS). When compared to the PI controller, HC provided better control performances for disturbance changes of 1% and 20% with an average improvement of 12% and 20% of the integral square error (ISE), respectively. It was however, not able to handle large disturbance of + 50% in feed composition. This limitation was overcome by MMPCPIS, which provided improvements by 17% and 20% of the ISE for all of types and magnitudes of disturbance change. The application of MMPCPIS on a single model MPC strategy produced almost similar performance for both types of disturbances, while its application on MMPC yielded better results. Based on the results obtained, it can be concluded that the proposed HC and MMPCPIS deserve further detailed investigations to serve as linear control approaches for solving complex nonlinear control problems commonly found in chemical industr

An open source patient simulator for design and evaluation of computer based multiple drug dosing control for anesthetic and hemodynamic variables

We are witnessing a notable rise in the translational use of information technology and control systems engineering tools in clinical practice. This paper empowers the computer based drug dosing optimization of general anesthesia management by means of multiple variables for patient state stabilization. The patient simulator platform is designed through an interdisciplinary combination of medical, clinical practice and systems engineering expertise gathered in the last decades by our team. The result is an open source patient simulator in Matlab/Simulink from Mathworks(R). Simulator features include complex synergic and antagonistic interaction aspects between general anesthesia and hemodynamic stabilization variables. The anesthetic system includes the hypnosis, analgesia and neuromuscular blockade states, while the hemodynamic system includes the cardiac output and mean arterial pressure. Nociceptor stimulation is also described and acts as a disturbance together with predefined surgery profiles from a translation into signal form of most commonly encountered events in clinical practice. A broad population set of pharmacokinetic and pharmacodynamic (PKPD) variables are available for the user to describe both intra- and inter-patient variability. This simulator has some unique features, such as: i) additional bolus administration from anesthesiologist, ii) variable time-delays introduced by data window averaging when poor signal quality is detected, iii) drug trapping from heterogeneous tissue diffusion in high body mass index patients. We successfully reproduced the clinical expected effects of various drugs interacting among the anesthetic and hemodynamic states. Our work is uniquely defined in current state of the art and first of its kind for this application of dose management problem in anesthesia. This simulator provides the research community with accessible tools to allow a systematic design, evaluation and comparison of various control algorithms for multi-drug dosing optimization objectives in anesthesia

A continuum robotic platform for endoscopic non-contact laser surgery: design, control, and preclinical evaluation

The application of laser technologies in surgical interventions has been accepted in the clinical domain due to their atraumatic properties. In addition to manual application of fibre-guided lasers with tissue contact, non-contact transoral laser microsurgery (TLM) of laryngeal tumours has been prevailed in ENT surgery. However, TLM requires many years of surgical training for tumour resection in order to preserve the function of adjacent organs and thus preserve the patient’s quality of life. The positioning of the microscopic laser applicator outside the patient can also impede a direct line-of-sight to the target area due to anatomical variability and limit the working space. Further clinical challenges include positioning the laser focus on the tissue surface, imaging, planning and performing laser ablation, and motion of the target area during surgery. This dissertation aims to address the limitations of TLM through robotic approaches and intraoperative assistance. Although a trend towards minimally invasive surgery is apparent, no highly integrated platform for endoscopic delivery of focused laser radiation is available to date. Likewise, there are no known devices that incorporate scene information from endoscopic imaging into ablation planning and execution. For focusing of the laser beam close to the target tissue, this work first presents miniaturised focusing optics that can be integrated into endoscopic systems. Experimental trials characterise the optical properties and the ablation performance. A robotic platform is realised for manipulation of the focusing optics. This is based on a variable-length continuum manipulator. The latter enables movements of the endoscopic end effector in five degrees of freedom with a mechatronic actuation unit. The kinematic modelling and control of the robot are integrated into a modular framework that is evaluated experimentally. The manipulation of focused laser radiation also requires precise adjustment of the focal position on the tissue. For this purpose, visual, haptic and visual-haptic assistance functions are presented. These support the operator during teleoperation to set an optimal working distance. Advantages of visual-haptic assistance are demonstrated in a user study. The system performance and usability of the overall robotic system are assessed in an additional user study. Analogous to a clinical scenario, the subjects follow predefined target patterns with a laser spot. The mean positioning accuracy of the spot is 0.5 mm. Finally, methods of image-guided robot control are introduced to automate laser ablation. Experiments confirm a positive effect of proposed automation concepts on non-contact laser surgery.Die Anwendung von Lasertechnologien in chirurgischen Interventionen hat sich aufgrund der atraumatischen Eigenschaften in der Klinik etabliert. Neben manueller Applikation von fasergeführten Lasern mit Gewebekontakt hat sich die kontaktfreie transorale Lasermikrochirurgie (TLM) von Tumoren des Larynx in der HNO-Chirurgie durchgesetzt. Die TLM erfordert zur Tumorresektion jedoch ein langjähriges chirurgisches Training, um die Funktion der angrenzenden Organe zu sichern und damit die Lebensqualität der Patienten zu erhalten. Die Positionierung des mikroskopis chen Laserapplikators außerhalb des Patienten kann zudem die direkte Sicht auf das Zielgebiet durch anatomische Variabilität erschweren und den Arbeitsraum einschränken. Weitere klinische Herausforderungen betreffen die Positionierung des Laserfokus auf der Gewebeoberfläche, die Bildgebung, die Planung und Ausführung der Laserablation sowie intraoperative Bewegungen des Zielgebietes. Die vorliegende Dissertation zielt darauf ab, die Limitierungen der TLM durch robotische Ansätze und intraoperative Assistenz zu adressieren. Obwohl ein Trend zur minimal invasiven Chirurgie besteht, sind bislang keine hochintegrierten Plattformen für die endoskopische Applikation fokussierter Laserstrahlung verfügbar. Ebenfalls sind keine Systeme bekannt, die Szeneninformationen aus der endoskopischen Bildgebung in die Ablationsplanung und -ausführung einbeziehen. Für eine situsnahe Fokussierung des Laserstrahls wird in dieser Arbeit zunächst eine miniaturisierte Fokussieroptik zur Integration in endoskopische Systeme vorgestellt. Experimentelle Versuche charakterisieren die optischen Eigenschaften und das Ablationsverhalten. Zur Manipulation der Fokussieroptik wird eine robotische Plattform realisiert. Diese basiert auf einem längenveränderlichen Kontinuumsmanipulator. Letzterer ermöglicht in Kombination mit einer mechatronischen Aktuierungseinheit Bewegungen des Endoskopkopfes in fünf Freiheitsgraden. Die kinematische Modellierung und Regelung des Systems werden in ein modulares Framework eingebunden und evaluiert. Die Manipulation fokussierter Laserstrahlung erfordert zudem eine präzise Anpassung der Fokuslage auf das Gewebe. Dafür werden visuelle, haptische und visuell haptische Assistenzfunktionen eingeführt. Diese unterstützen den Anwender bei Teleoperation zur Einstellung eines optimalen Arbeitsabstandes. In einer Anwenderstudie werden Vorteile der visuell-haptischen Assistenz nachgewiesen. Die Systemperformanz und Gebrauchstauglichkeit des robotischen Gesamtsystems werden in einer weiteren Anwenderstudie untersucht. Analog zu einem klinischen Einsatz verfolgen die Probanden mit einem Laserspot vorgegebene Sollpfade. Die mittlere Positioniergenauigkeit des Spots beträgt dabei 0,5 mm. Zur Automatisierung der Ablation werden abschließend Methoden der bildgestützten Regelung vorgestellt. Experimente bestätigen einen positiven Effekt der Automationskonzepte für die kontaktfreie Laserchirurgie

Identifikation und Mehrgrößenregelung von isolierten Organen in Perfusionssystemen mit nichtlinear dynamischen und wissensbasierten Methoden

Die Transplantation eines Organes ist in der Medizin oftmals die letzte Möglichkeit zur Behandlung einer terminalen Organinsuffizienz. Das grundlegende Problem der internationalen Transplantationsmedizin ist die stetig wachsende Diskrepanz zwischen Bedarf und Angebot von Transplantaten. Die Situation wird dramatisiert durch einen Trend der Marginalisierung von Spenderorganen. Marginale Spenderorgane werden häufig aufgrund mangelnder Möglichkeiten zur Funktionsbewertung verworfen. Die Technik der ex-vivo Organperfusion kann maschinell physiologienahe Bedingungen bereitstellen, um ein isoliertes Transplantat zu rekonditionieren und sogar eine Bewertung seines Zustands zu ermöglichen. Perfusionsprozesse sind organsystemindividuell durch eine hohe Komplexität ihrer biologisch-technisch verkoppelten Vorgänge gekennzeichnet. Für nutzer- und sicherheitsorientierte, klinisch taugliche Perfusionssysteme ist eine Prozessautomatisierung unumgänglich. Hier sind in klassischer anwendungsindividueller Entwicklung hohe Kosten die Folge. Auf Basis von Recherchen zum aktuellen Stand von Medizin und Technik konnten Eigenschaften von Perfusionsprozessen für die Organsysteme Herz, Lunge, Leber und Niere bestimmt werden. Aus ähnlichen Anwendungen der extrakoporalen Lebensunterstützung sind Erkenntnisse zur Systemautomatisierung zusammengetragen worden. In Fortführung der Arbeit sind die Organperfusionsprozesse abstrahiert und verallgemeinert worden. Beteiligte Prozessgrößen, sowie deren funktioneller Verkopplungen wurden identifiziert und evaluiert, um schließlich eine generalisierte, organunabhängige Strategie zur dezentralen Mehrgrößenregelung abzuleiten. Die abgeleitete Regelungsstrategie wurde folgend speziell für die ex-vivo Nierenperfusion umgesetzt. Dazu wurde zunächst auf Basis des generalisierten Organperfusionsprozesses ein Gerätesystem zur Nierenperfusion abgeleitet, entwickelt und aufgebaut. Für das entstandene Perfusionssystem wurden Modellbildungen und Parameteridentifikationen des Temperatursystems, des hämodynamischen Systems und des Blutgassystems durchgeführt. Die entstandenen Zustandsraummodelle wurden jeweils in Simulink implementiert und mittels realer Perfusionsexperimente an Schweinenieren im Tiermodell validiert. Simulativ und analytisch wurden für die drei Subsysteme Regelungsstrategien zur robusten Einzelgrößenregelung entwickelt und im realen Perfusionssystem implementiert. Im Zuge von weiteren Perfusionsexperimenten im Tiermodell konnten die Regelungen ebenfalls validiert und deren Robustheit im Mehrgrößenfall evaluiert werden. Die Erkenntnisse der speziellen Umsetzung des generalisierten Mehrgrößenregelungsansatzes zur Organperfusion wurden auf die Organsysteme Herz, Lunge und Leber projiziert. Die Hypothese dieser Arbeit, dass eine organübergreifende generalisierte Regelungsstrategie zur ex-vivo Perfusion bei Nutzung mit verschiedenen speziellen Organsystemen tauglich ist, konnte bestätigt werden. Auf dieser Basis ist eine vereinfachte und kostenreduzierte Entwicklung von Perfusionssystemen für verschiedene Organsysteme möglich.In many cases the transplantation of an organ is the last way to treat a terminal organ insuffiency. The basic problem of international transplant medicine is a continiously increasing gap between the demand and the proposal of sufficient organ grafts. The situation is compounded by the actual trend of marginalization of organ grafts. Marginal donor grafts often are discarded due to absent options to test their vitality and viability. The technique of ex-vivo organ perfusion provides near physiologic conditions in order to recondition and even to evaluate the state of an isolated organ graft. Perfusion processes are organ individual characterized by highly complex coupled biological-technical processes. For achieving an user- and safety-focussed, clinical suitable perfusion system, an automation of the system is inavoidable. Within classical development of technologies, high costs were following. On the base of research according to the actual status quo of medicine and technology, characteristics of the perfusion processes for the heart, the lungs, the liver and the kidneys could be determined. Knowledge about similar processes of extracorporeal life support were gathered. Subsequently the organ perfusion processes were abstracted and generalized. Participating process values, as well as their couplings, were identified and evaluated in order to extract a generalized, organ independent strategy for decentral multivariable control. The extracted control strategy was then transfered specificly for ex-vivo kidney perfusion. Therefore a device for ex-vivo kidney perfusion was developed and built from the generalized organ perfusion process. According to the implemented device, the temperature system, the hemodynamic system and the blood gas system were modelled mathematically and parameter estimations were performed. The resulted state space models were implemented to Simulink and validated by comparing simulations to the results of experiments on real procine kidneys. Within the simulations and based on analytical methods, robust single variable control strategies for the control of the three subsystems temperature, hemodynamic and blood gases were developed and implemented into the real kidney perfusion device. During further perfusion experiments within the large animal model, the control strategies could be validated an their robustness could be evaluated in the multivariable case. The findings of the special implementation of the generalized multivariableapproach for organ perfusion were projected on the organ systems heart, lungs and liver. The hypothesis of this work, in detail, that a generalized, organ independent control strategy for organ perfusion processes is suitable for the use with several special organ systems, could be confirmed. On this basis, simplified and cost reduced developments of perfusion systems for different organ systems are possible

Advances of Italian Machine Design

This 2028 Special Issue presents recent developments and achievements in the field of Mechanism and Machine Science coming from the Italian community with international collaborations and ranging from theoretical contributions to experimental and practical applications. It contains selected contributions that were accepted for presentation at the Second International Conference of IFToMM Italy, IFIT2018, that has been held in Cassino on 29 and 30 November 2018. This IFIT conference is the second event of a series that was established in 2016 by IFToMM Italy in Vicenza. IFIT was established to bring together researchers, industry professionals and students, from the Italian and the international community in an intimate, collegial and stimulating environment

Aerospace medicine and biology: A cumulative index to a continuing bibliography (supplement 306)

This publication is a cumulative index to the abstracts contained in the Supplements 294 through 305 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes seven indexes - subject, personal author, corporate source, foreign technology, contract number, report number, and accession number

Self-aware reliable monitoring

Cyber-Physical Systems (CPSs) can be found in almost all technical areas where they constitute a key enabler for anticipated autonomous machines and devices. They are used in a wide range of applications such as autonomous driving, traffic control, manufacturing plants, telecommunication systems, smart grids, and portable health monitoring systems. CPSs are facing steadily increasing requirements such as autonomy, adaptability, reliability, robustness, efficiency, and performance. A CPS necessitates comprehensive knowledge about itself and its environment to meet these requirements as well as make rational, well-informed decisions, manage its objectives in a sophisticated way, and adapt to a possibly changing environment. To gain such comprehensive knowledge, a CPS must monitor itself and its environment. However, the data obtained during this process comes from physical properties measured by sensors and may differ from the ground truth. Sensors are neither completely accurate nor precise. Even if they were, they could still be used incorrectly or break while operating. Besides, it is possible that not all characteristics of physical quantities in the environment are entirely known. Furthermore, some input data may be meaningless as long as they are not transferred to a domain understandable to the CPS. Regardless of the reason, whether erroneous data, incomplete knowledge or unintelligibility of data, such circumstances can result in a CPS that has an incomplete or inaccurate picture of itself and its environment, which can lead to wrong decisions with possible negative consequences. Therefore, a CPS must know the obtained data’s reliability and may need to abstract information of it to fulfill its tasks. Besides, a CPS should base its decisions on a measure that reflects its confidence about certain circumstances. Computational Self-Awareness (CSA) is a promising solution for providing a CPS with a monitoring ability that is reliable and robust — even in the presence of erroneous data. This dissertation proves that CSA, especially the properties abstraction, data reliability, and confidence, can improve a system’s monitoring capabilities regarding its robustness and reliability. The extensive experiments conducted are based on two case studies from different fields: the health- and industrial sectors