Data-driven system identification and model predictive control of a multirotor with an unknown suspended payload

Thesis (MEng)--Stellenbosch University, 2022.ENGLISH ABSTRACT: This thesis considers the problem of stabilised control for a multirotor with an unknown suspended payload. The swinging payload negatively affects the multirotor flight dynamics by inducing oscillations in the system. An adaptive control architecture is proposed to damp these oscillations and produce stable flight with different unknown payloads. The architecture includes a data-driven system identification method that assumes no prior knowledge of the payload dynamics. This method is demonstrated in simulation and with practical flight data. Model Predictive Control (MPC) is applied for swing damping control and is verified with Hardware-in-the-Loop (HITL) simulations. A parameter estimator and Linear Quadratic Regulator (LQR) is used as a baseline control architecture. The LQR uses a predetermined model of the system, which is completed with estimates of the payload mass and cable length. The newly proposed architecture uses Dynamic Mode Decomposition with Control (DMDc) to estimate a linear state-space model and approximate the dynamics without using a predetermined model. The architecture was also tested with a Hankel Alternative View Of Koopman (HAVOK) algorithm which was extended in this work to account for control. An MPC uses the data-driven model to control the multirotor and damp the payload oscillations. A Simulink™ simulator was designed and verified with practical data. Within simulations both the baseline and proposed architectures produced near swing-free control with different payload masses and cable lengths. Even with a dynamic payload producing irregular oscillations, both methods achieved stabilised control. Both architectures also showed effective disturbance rejection. Despite the baseline method using an accurate predetermined model, the proposed method produced equal performances without prior knowledge of the dynamics. The baseline performance degraded significantly with a changed multirotor mass because this parameter was not considered as an unknown. In contrast, the proposed method consistently produced good performances. The accuracy of the DMDc models was verified with practical flight data. The proposed control architecture was also demonstrated in HITL simulations. The hardware executed the MPC at the desired frequency, producing near swing-free control within a Gazebo simulator. Overall, it was shown that the proposed control architecture is practically feasible. Without knowledge of the payload dynamics, a data-driven model can be used with MPC for effective swing damping control with a multirotor.AFRIKAANSE OPSOMMING: Hierdie tesis hanteer die probleem van gestabiliseerde beheer vir ’n multirotor hommeltuig met ’n onbekende hangende loonvrag. Die swaaiende loonvrag be¨ınvloed die vlugdin amika deur ossillasies in die stelsel te veroorsaak. ’n Aanpasbare beheerargitektuur word voorgestel om hierdie ossillasies te demp vir stabiele vlugte met verskillende onbekende loonvragte. Die argitektuur maak gebruik van ’n datagedrewe stelsel-identifikasiemetode wat geen voorafkennis van die loonvragdinamika gebruik nie. Hierdie metode word in simulasies en met praktiese vlugdata gedemonstreer. Model Voorspellende Beheer (MVB) word toegepas vir swaaidempingsbeheer en word geverifieer met Hardeware-in-die-Lus (HIDL) simulasies. ’n Parameter-afskatter en Lineˆere Kwadratiese Gaussiese (LKG) word in die basislyn beheerargitektuur gebruik. Die LKG gebruik ’n voorafbepaalde model van die sisteem wat voltooi word met afskattings van die loonvragmassa en kabellengte. Die nuwe voorgestelde argitektuur gebruik Dinamiese Modus Ontbinding met beheer (DMOb) om ’n lineˆere toestand-ruimte model te bereken en die dinamika af te skat sonder ’n voorafbepaalde model. Die argitektuur is ook getoets met ’n Hankel Alternatiewe Siening van Koopman (HASK)-algoritme wat in hierdie werk uitgebrei is om beheer in te sluit. ’n MVB gebruik die data-gedrewe model om die multirotor te beheer en die loonvrag se ossillasies te demp. ’n Simulink™-simululeerder is ontwerp en geverifieer met praktiese data. In simulasies het beide die basislyn en voorgestelde argitekture byna-swaaivrye beheer met verskillende loon vragmassas en kabellengtes geproduseer. Selfs met ’n dinamiese loonvrag wat onre¨elmatige ossillasies voortbring, het beide metodes gestabiliseerde beheer tot gevolg gehad. Beide ar gitekture het ook effektiewe versteuringsverwerping getoon. Al gebruik die basislynmetode ’n akkurate voorafbepaalde model, het die voorgestelde metode gelyke prestasies gelewer sonder voorafkennis van die dinamika. Die basislyn prestasie het aansienlik afgeneem vir ’n aangepaste multirotormassa omdat hierdie parameter nie as ’n onbekende beskou is nie. Daarteenoor het die voorgestelde metode deurgaans goeie prestasies gelewer. Die akkuraatheid van die DMOb modelle is geverifieer met praktiese vlugdata. Die voorgestelde beheerargitektuur is ook in HIDL-simulasies gedemonstreer. MVB is teen die verlangde frekwensie uitgevoer en het byna-swaaivrye beheer in ’n Gazebo-simululeerder gelewer. In die geheel is dit gewys dat die voorgestelde beheerargitektuur prakties uitvoerbaar is. Sonder kennis van die loonvragdinamika kan ’n data-gedrewe model met MVB gebruik word vir effektiewe swaaidempingsbeheer met ’n multirotor.Master

Learning person-centred consultation skills in clinical medicine : a randomised controlled case study

BACKGROUND : Training institutions need to ensure that healthcare students learn the skills to conduct person-centred consultations. We studied changes in person-centred practice over time following a quality improvement (QI) intervention among Bachelor of Clinical Medical Practice undergraduate students. METHODS : Students were randomised to intervention and control groups. The intervention group received training and did a QI cycle on their own consultation skills. Consultations with simulated patients were recorded during structured clinical examinations in June (baseline) and November (post-intervention) 2015. RESULTS : Matched consultations for 64 students were analysed. The total SEGUE (Set the stage, Elicit information, Give information, Understand the patient’s perspective and End the encounter scores) were significantly higher in the final assessment compared to baseline for both the whole group and the intervention group (p = 0.005 and 0.015, respectively). The improvement did not differ significantly between intervention and control groups ( p = 0.778). Third-year students improved significantly more than second years (p = 0.007). CONCLUSION : The person-centred practice (including collaboration) of clinical associate students did improve over the period studied. The results show that students’ learning of personcentred practice also happened in ways other than through the QI intervention. There is a need to develop students’ collaborative skills during the medical consultation.The Faculty of Health Sciences, University of Pretoria’s Scholarship of Teaching and Learning fund.http://www.safpj.co.zaam2021Family Medicin

Home delivery of medication as part of reducing congestion in primary healthcare in Tshwane District Health Services

Congestion at health facilities poses the risk of extensive spread of the severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) to patients at high risk for severe illness and death due to this infection. During the lockdown to control the spread of the virus, many patients with chronic conditions are not visiting health facilities and not collecting their chronic medication. To improve adherence to medication, home delivery of medication was instituted for patients with chronic diseases who had been receiving care at the Skinner Street Clinic in Tshwane. To support patients with chronic diseases who were unable to collect their medication, by remotely consulting (telehealth) and delivering their medication during the lockdown due to the COVID-19 pandemic

A capability approach analysis of student perspectives of a medical consultation quality-improvement process

BACKGROUND. Research shows that person-centredness declines during medical education. This study examines the underlying assumptions and effects of clinical associate training interventions on person-centred practice. OBJECTIVES. To understand student experiences of a medical consultation quality-improvement (QI) process in terms of a capability approach to learning and the effects of this process on their person-centredness. METHODS. In a randomised controlled trial students from 8 clinical learning centres (CLCs) participated in a qualitative, medical consultation QI process. Qualitative data (focus group discussions and reflective reports) were analysed using a capability approach to the learning framework. RESULTS. Learning was triggered by disruptions to students’ abilities, knowledge, identity and relationships. Through facilitated review-read-reflectre/ action scaffolded by feedback and practical assessment tools they learnt new person-centred consultation skills. The QI process functioned as a learning cycle in which students reviewed disruptions, identified areas for improvement and developed improvement plans. Through it, awareness of themselves developed more deeply, their relationships with peers and patients grew and they improved their knowledge and consultation skills. CONCLUSIONS. Students demonstrated learning through their understanding of the skills and competencies required for person-centred practice. The study found students to be at different points along the directed/self-directed learning continuum, with most of them developing abilities to learn independently, work in groups, give and receive feedback and apply learning across different contexts. Facilitation is particularly important, given the uneven development of the ‘dimensions of a person’ at an individual level. Lastly, the capability approach is useful as an analytical framework and as a way of ‘doing learning’.The research for this study was done in partial fulfilment of the requirements for JML’s PhD (Family medicine) degree at the University of Pretoria. (http://hdl.handle.net/2263/72533)http://www.ajhpe.org.zaFamily Medicin

How to measure person-centred practice – an analysis of reviews of the literature

BACKGROUND: Facilitation and collaboration differentiates person-centred practice (PcP) from biomedical practice. In PcP, a person-centred consultation requires clinicians to juggle three processes: facilitation, clinical reasoning and collaboration. How best to measure PcP in these processes remains a challenge. AIM: To assess the measurement of facilitation and collaboration in selected reviews of PcP instruments. METHODS: Ovid Medline and Google Scholar were searched for review articles evaluating measurement instruments of patient-centredness or person-centredness in the medical consultation. RESULTS: Six of the nine review articles were selected for analysis. Those articles considered the psychometric properties and rigour of evaluation of reviewed instruments. Mostly, the articles did not find instruments with good evidence of reliability and validity. Evaluations in South Africa rendered poor psychometric properties. Tools were often not transferable to other sociocultural-linguistic contexts, both with and without adaptation. CONCLUSION: The multiplicity of measurement tools is a product of many dimensions of personcentredness, which can be approached from many perspectives and in many service scenarios inside and outside the medical consultation. Extensive research into the myriad instruments found no single valid and reliable measurement tool that can be recommended for general use. The best hope for developing one is to focus on a specific scenario, conduct a systematic literature review, combine the best items from existing tools, involve multiple disciplines and test the tool in real-life situations.http://www.phcfm.orgpm2020Family Medicin

Cost effectiveness of clinical associates : a case study for the Mpumalanga province in South Africa

BACKGROUND : The National Department of Health of South Africa decided to start a programme to train mid-level healthcare workers, called clinical associates, as one of the measures to increase healthcare workers at district level in rural areas. Unfortunately, very little is known about the cost effectiveness of clinical associates. AIMS : To determine, on a provincial level, the cost effectiveness of training and employing clinical associates and medical practitioners compared to the standard strategy of training and employing only more medical practitioners. METHODS : A literature study was performed to answer several sub questions regarding the costs and effectiveness of clinical associates. The results were used to present a case study. RESULTS : The total cost for a province to pay for the full training of a clinical associate is R 300 850. The average employment cost per year is R196 329 and for medical practitioners these costs are R 730 985 and R 559 397, respectively. EFFECTIVENESS : Clinical associates are likely to free up the time of a medical practitioner by 50–76%. They can provide the same quality of care as higher level workers, provided that they receive adequate training, support and supervision. Furthermore, they seem more willing to work in rural areas compared to medical practitioners. CONCLUSIONS : The case study showed that training and employing clinical associates is potentially a cost-effective strategy for a province to meet the increasing demand for rural healthcare workers. This strategy will only succeed when clinical associates receive adequate training, support and supervision and if the province keeps investing in them.http://www.phcfm.orgam2017Family Medicin

A new health care profession in rural district hospitals : a case study of the introduction of clinical associates in Shongwe hospital

BACKGROUND : One of the reasons to develop training courses for medical mid-level workers in South Africa is a shortage of doctors. The introduction of this new profession has led to task sharing and redefining of professional boundaries. The primary aim of this study is to evaluate the introduction of new healthcare professionals in a rural hospital district. METHODS : This multi-method qualitative research study used a semi-structured questionnaire to assess the effectiveness of Clinical Associates. A review of documents from 2012 to 2015 was done including a longitudinal study of the development of the Bachelor in Clinical Medical Practice (BCMP) programme at Shongwe hospital. RESULTS : Three Clinical Associates in 2011 and six Clinical Associates in 2014 completed questionnaires. Student satisfaction increased as measured with the Med IQ tool. At the end of 2013 Shongwe Clinical Learning Centre (CLC) had improved from last position out of 17 CLCs in 2011 to position number eight in 2014. Casualty was run by Clinical Associates and during observations it became clear that Clinical Associates were able to take responsibility for outpatient departments (OPDs), the emergency unit and some wards with supervision by a doctor. CONCLUSION : The introduction of the BCMP programme and the establishment of a Clinical Learning Centre in Shongwe hospital have led to improved patient care and a more conducive environment for teaching and learning. With the availability of more Clinical Associates vacant medical officer posts can be converted to employ Clinical Associates to serve patients without an increase in the cost of total human resources.The University of Pretoriahttp://www.tandfonline.com/loi/ojfp20http://www.safpj.co.za/index.php/safpjam2018Family Medicin

Blood-borne infections in healthcare workers in South Africa

The risks associated with infection of healthcare workers and students with blood-borne pathogens, specifically HIV, hepatitis B virus and hepatitis C virus, are often neglected. South Africa (SA) currently has no official policies or guidelines in place for the prevention and management of these infections. This article reviews the available data and international guidelines with regard to infected healthcare practitioners and makes minimum recommendations for the SA setting.http://www.samj.org.zahb201

Students’ perceptions of the instructional quality of district hospital-based training

BACKGROUND : An innovative, three-year training programme, the Bachelor of Clinical Medical Practice (BCMP), for mid-level medical healthcare workers was started in 2009 by the Department of Family Medicine, University of Pretoria. AIM : To measure the students’ perceptions of the instructional quality of district hospitalbased training. SETTING : Training of students took place at clinical learning centres in rural district hospitals in the Mpumalanga and Gauteng provinces. METHODS : A survey using the MedEd IQ questionnaire was performed in 2010 and 2011 to measure BCMP second- and third-year students’ perceptions of instructional quality of district hospital-based training. The MedEd IQ questionnaire is composed of four subscales: preceptor activities, learning opportunities, learner involvement and the learning environment. Composite scores of instructional quality were used to present results. RESULTS : The preceptor activities, learning opportunities and the learning environment were considered by second- and third-year BCMP students to be of consistently high instructional quality. In the area of learner involvement, instructional quality increased significantly from second to third year. CONCLUSION : Overall, instructional quality of district hospital-based training was high for both second- and third-year BCMP students, and the instructional quality of learner involvement being significantly higher in third year students. The MedEd IQ tool was a useful tool for measuring instructional quality and to inform programme quality improvement.http://www.phcfm.orgam2016Family Medicin

The clinical associate curriculum ‒ the learning theory underpinning the BCMP programme at the University of Pretoria

The Bachelor of Clinical Medical Practice (BCMP) is a new degree at the University of Pretoria (UP), designed to create a new category of mid-level medical workers, namely clinical associates. UP produced its first 44 graduates in 2011. The BCMP created the opportunity to innovate learning and teaching through designing, monitoring and evaluating the transformation of the curriculum as action research. Drawing on the theories and practices of authentic learning, self-directed learning, whole-brain learning and collaborative learning, the curriculum has been transformed. The potential of this curriculum extends beyond the formal education part of the programme ‒ into clinical associate practice, healthcare practice and, potentially, general medical and healthcare education.http://www.ajhpe.org.za/index.php/ajhpeam201