QUADROCOPTER CONTROL

V delu je opisana izdelava računalniškega vmesnika za vodenje kvadrokopterja, preko brezžično dostopne točke in uporabo UDP protokola. Vodenje je izvedeno v programu LabVIEW, proizvajalca National Instruments. Identifikacije sistemov in načrtovanje regulatorjev smo izvedli v programskem okolju Matlab. Predstavljeno je delovanje kvadrokopterja AR.drone Parrot, kot tudi računalniškega vmesnika, obdelane so težave in rešitve vse od vzpostavitve komunikacije, identifikacije sistemov, regulacije sistemov in sledenja krivulji.This work describes the development of a computer interface for quadrocopter control via wireless access point using UDP protocol. Control is implemented in LabVIEW software, which is produced by National Instruments. For systems identifications to get the proper mathematical models and regulators, we helped with MATLAB sofware. We \u27ll describe the operation of a quadrocopter AR.drone Parrot, computer interface, the problems and solutions of establishing communication from beginning, all the way through system identification, system control to curve tracking at the end

Optimal design of a nonlinear system dynamics based on robust adaptive backstepping controller

Disertacija predstavlja novo metodo optimalnega načrtovanja dinamike nelinearnega sistema na osnovi nelinearnega robustnega adaptivnega sestopnega regulatorja (backstepping regulatorja). Metoda temelji na obstoječi sestopni metodi vodenja (backstepping control) z uvedbo vrednotenja dinamičnega obnašanja zaprto-zančnega sistema. Takšno vrednotenje temelji na povezavi med prostimi parametri sestopnega regulatorja in parametri referenčne linearne prenosne funkcije. Z vrednotenjem dinamičnega obnašanja v kombinaciji s pristopi linearne teorije, sta predstavljena dva pristopa načrtovanja prostih parametrov regulatorja. Prvi pristop zajema načrtovanje prostih parametrov sestopnega regulatorja na osnovi želenih položajev zaprto-zančnih polov in drugi pristop na osnovi želenega dušenja ter lastne frekvence sistema. V primeru parametričnih odstopanj in motenj nelinearnega sistema je predlagana uporaba adaptivnega sestopnega regulatorja. Adaptacija takšnega regulatorja ohranja navzven linearen značaj zaprto-zančnega sistema. Parametrična odstopanja nelinearnega sistema se odražajo tudi v odstopanju parametrov linearne zaprto-zančne prenosne funkcije. V ta namen predlagana metoda vključuje postopke vrednotenja robustnosti iz linearne robustne teorije. Na osnovi kriterijev robustne stabilnosti in robustnega učinka je definirana cenilna funkcija, pri čemer je celoten problem sinteze prostih parametrov regulatorja predstavljen kot optimizacijski problem. Takšen pristop omogoča načrtovanje optimalnega dinamičnega obnašanja nelinearnega sistema.This dissertation describes a new method of optimal dynamical behavior design of a nonlinear system based on nonlinear robust adaptive backstepping controller. The method is based on standard backstepping control procedure with an additional evaluation of closed-loop dynamical behavior. This evaluation is based on a connection between backstepping control parameters and reference linear system parameters. The dissertation presents two backstepping parameter design approaches based on dynamical behavior evaluation and certain linear theory procedures in order to define reference linear dynamics. The first approach of backstepping parameter design is based on reference pole positions, and the second approach is based on reference damping and natural frequency. An adaptive backstepping controller is proposed for cases when parameter uncertainties and external disturbances are present in a nonlinear system. Adaptation properties of such controller preserve a linear nature of a closed-loop system. Parametric uncertainties of a nonlinear system are also reflected in parametric uncertainties of a closed-loop transfer function. Therefore, robust stability and robust effect evaluation procedures, derived from linear robust control theory, are used in such case. An objective function is defined based on robustness evaluation procedures. Thus, the entire backstepping parameter design problem is defined as an optimization problem. Such parameter design approach allows the design of optimal dynamical behavior of a nonlinear system

ROBUST CONTROL OF DC-DC BOOST CONVERTER WITH CHANGEABLE LOAD IMPEDANCE

V sledečem magistrskem delu, smo se posvetili izdelavi eksperimentalnega sistema za izvedbo in testiranje robustnega vodenja DC-DC pretvornika navzgor, s pomočjo programirljivega polja logičnih vrat (FPGA – Field Programmable Gate Array). Robustnost pretvornika, se kaže v stabilni izhodni napetosti ob spreminjajoči impedanci bremena. Pri načrtovanju vodenja, smo uporabili linearni matematični modela pretvornika z dano nominalno karakteristiko bremena. Eksperimentalni sistem zajema DC-DC pretvornik ter nelinearno impedančno spremenljivo breme, s katerim smo pretvornik obremenili. Breme je načrtovano tako, da je mogoče spreminjati značaj bremena med induktivnim, kapacitivnim in uporovnim značajem.In this thesis, focus was on designing and creating of an experimental system, which will allow us to design and test all kind of robust control algorithms of DC-DC boost converter with FPGA (Field Programmable Gate Array). Robustness of such a converter is reflected in output voltage stability, when load with changeable impedance in specified limits, is turned on and off. In control design, a known linear model of converter has been used. Experimental system covers a DC-DC boost converter and load with changeable impedance. Load has been designed in such way, it is possible to change between resistive, capacitive and inductive load characteristics

Global variation in postoperative mortality and complications after cancer surgery: a multicentre, prospective cohort study in 82 countries

© 2021 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY-NC-ND 4.0 licenseBackground: 80% of individuals with cancer will require a surgical procedure, yet little comparative data exist on early outcomes in low-income and middle-income countries (LMICs). We compared postoperative outcomes in breast, colorectal, and gastric cancer surgery in hospitals worldwide, focusing on the effect of disease stage and complications on postoperative mortality. Methods: This was a multicentre, international prospective cohort study of consecutive adult patients undergoing surgery for primary breast, colorectal, or gastric cancer requiring a skin incision done under general or neuraxial anaesthesia. The primary outcome was death or major complication within 30 days of surgery. Multilevel logistic regression determined relationships within three-level nested models of patients within hospitals and countries. Hospital-level infrastructure effects were explored with three-way mediation analyses. This study was registered with ClinicalTrials.gov, NCT03471494. Findings: Between April 1, 2018, and Jan 31, 2019, we enrolled 15 958 patients from 428 hospitals in 82 countries (high income 9106 patients, 31 countries; upper-middle income 2721 patients, 23 countries; or lower-middle income 4131 patients, 28 countries). Patients in LMICs presented with more advanced disease compared with patients in high-income countries. 30-day mortality was higher for gastric cancer in low-income or lower-middle-income countries (adjusted odds ratio 3·72, 95% CI 1·70–8·16) and for colorectal cancer in low-income or lower-middle-income countries (4·59, 2·39–8·80) and upper-middle-income countries (2·06, 1·11–3·83). No difference in 30-day mortality was seen in breast cancer. The proportion of patients who died after a major complication was greatest in low-income or lower-middle-income countries (6·15, 3·26–11·59) and upper-middle-income countries (3·89, 2·08–7·29). Postoperative death after complications was partly explained by patient factors (60%) and partly by hospital or country (40%). The absence of consistently available postoperative care facilities was associated with seven to 10 more deaths per 100 major complications in LMICs. Cancer stage alone explained little of the early variation in mortality or postoperative complications. Interpretation: Higher levels of mortality after cancer surgery in LMICs was not fully explained by later presentation of disease. The capacity to rescue patients from surgical complications is a tangible opportunity for meaningful intervention. Early death after cancer surgery might be reduced by policies focusing on strengthening perioperative care systems to detect and intervene in common complications. Funding: National Institute for Health Research Global Health Research Unit

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

© 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licenseBackground: Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide. Methods: A multimethods analysis was performed as part of the GlobalSurg 3 study—a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital. Findings: Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3·85 [95% CI 2·58–5·75]; p<0·0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63·0% vs 82·7%; OR 0·35 [0·23–0·53]; p<0·0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer. Interpretation: Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised. Funding: National Institute for Health and Care Research