This paper proposes a double closed loop current-constrained finite-time controller for the buck converter circuit under current constraint. Firstly, the controller consists of an outer loop ...controller and an inner loop controller. The outer loop controller is dedicated to voltage tracking and enhances the speed of voltage convergence. Meanwhile, the inner loop controller employs the Barrier Lyapunov Function to ensure the current remains within a safe range. Secondly, homogeneous system method is used to demonstrate the finite-time stability of the double closed loop system. Finally, simulations and experiments validate the effectiveness and superiority of the proposed algorithm in the start-up stage and load mutation stage.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
DC–DC power supplies are playing significant role in different domains of engineering applications. Some converters such as boost, buck-boost, and fly-back have a right-half-plane zero (non-minimum ...phase system), hence it is difficult for the PID controller to exhibit good performance with load, line variations and parametric uncertainty. In this proposed work, design and implementation of type controllers have been performed by using k-factor approach and two different optimisation techniques (gravitational search algorithm and particle swarm optimisation) for obtaining better stability and performance for a closed loop DC–DC Switched mode boost converter. The closed loop control system has been implemented in real time dSPACE platform. The comparative closed-loop performances of a boost converter with classical, optimised PID and optimised type II/type III controllers have been produced. Simulations and experimental results are provided to demonstrate the effectiveness of optimised controllers for the proposed converter. Design and implementation of optimised type controller for switch mode converters has not been reported earlier in any literature.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This study considers the problem of adaptive sliding mode control for discrete-time Takagi–Sugeno (T–S) fuzzy systems with actuator faults and external disturbances via the delta operator method. The ...delta operator approach is used to represent the discrete-time non-linear systems described by T–S fuzzy models. The actuator fault considered in this study is unknown and its fault-deviation is also unknown. A reduced-order system is utilised to design the sliding mode surface subject to linear matrix inequality constraint. By constructing the sliding mode surface, a novel adaptive sliding mode controller is designed to guarantee that the closed-loop system is uniformly ultimately bounded. Finally, two practical examples are presented to show the effectiveness and applicability of the developed fault-tolerant control scheme.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Aims
First‐generation closed‐loop automated insulin delivery improves glycaemia and psychosocial outcomes among older adults with type 1 diabetes in clinical trials. However, no study has previously ...assessed real‐world lived experience of older adults using closed‐loop therapy outside a trial environment.
Methods
Semi‐structured interviews were conducted with older adults who were pre‐existing insulin pump users and previously completed the OldeR Adult Closed‐Loop (ORACL) randomised trial. Interviews focused on perceptions of diabetes technology use, and factors influencing decisions regarding continuation.
Results
Twenty‐eight participants, mean age 70 years (SD 5), were interviewed at median 650 days (IQR 608–694) after their final ORACL trial visit. At interview, 23 participants (82%) were still using a commercial closed‐loop system (requiring manual input for prandial insulin bolus doses). Themes discussed in interviews relating to closed‐loop system use included sustained psychosocial benefits, cost and retirement considerations and usability frustrations relating to sensor accuracy and system alarms. Of the five participants who had discontinued, reasons included cost, continuous glucose monitoring‐associated difficulties and usability frustrations. Cost was the largest consideration regarding continued use; most participants considered the increased ease of diabetes management to be worth the associated costs, though cost was prohibitive for some.
Conclusions
Almost 2 years after completing a closed‐loop clinical trial, closed‐loop automated insulin delivery remains the preferred type 1 diabetes therapy for the majority of older adult participants. Chronological age is not a barrier to real‐world successful use of diabetes technology. Identifying age‐related barriers, and solutions, to diabetes technology use among older adults is warranted.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Wind farm (WF) controllers adjust the control settings of individual turbines to enhance the total performance of a wind farm. Most WF controllers proposed in the literature assume a time-invariant ...inflow, whereas important quantities such as the wind direction and speed continuously change over time in reality. Furthermore, properties of the inflow are often assumed known, which is a fundamentally compromising assumption to make. This paper presents a novel, closed-loop WF controller that continuously estimates the inflow and maximizes the energy yield of the farm through yaw-based wake steering. The controller is tested in a high-fidelity simulation of a 6-turbine wind farm. The WF controller is stress-tested by subjecting it to strongly-time-varying inflow conditions over 5000 s of simulation. A time-averaged improvement in energy yield of 1.4% is achieved compared to a baseline, greedy controller. Moreover, the instantaneous energy gain is up to 11% for wake-loss-heavy situations. Note that this is the first closed-loop and model-based WF controller tested for time-varying inflow conditions (i.e., where the mean wind direction and wind speed change over time) at such fidelity. This solidifies the WF controller as the first realistic closed-loop control solution for yaw-based wake steering.
•Demonstrate model-based wind farm control in LES under time-varying inflow.•Ambient condition estimation with a novel theoretical measure of observability.•Provide a detailed tuning of FLORIS to LES data of the DTU 10MW wind turbine.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Aim
To compare the efficacy of the closed‐loop Diabeloop for highly unstable diabetes (DBLHU) system with the open‐loop predictive low glucose suspend (PLGS) system in patients with highly unstable ...type 1 diabetes (T1D) who experience acute metabolic events.
Methods
DBLHU‐WP10 was an interventional, controlled, randomized, open‐label study that comprised two cycles of N‐of‐1 trials (2‐of‐1 trials). Each trial consisted of two crossover 4‐week periods of treatment with either DBLHU or PLGS in randomized order. The primary outcome was the percentage of time spent in the 70‐180 mg/dL glucose range (time in range TIR).
Results
Five out of seven randomized patients completed the aggregated 2‐of‐1 trials. TIR was significantly higher with DBLHU (73.3% ± 1.7%) compared with PLGS (43.5% ± 1.7%; P < .0001). The percentage of time below 70 mg/dL was significantly lower with DBLHU (0.9% ± 0.4%) versus PLGS (3.7% ± 0.4%; P < .0001). DBLHU was also significantly superior to PLGS in reducing hyperglycaemic excursions and improving almost all other secondary outcomes, including glucose variability and satisfaction score. No adverse event could be related to the experimental treatment.
Conclusions
DBLHU was superior to PLGS in improving the metabolic control of patients with highly unstable T1D who require an islet or pancreas transplant but who either have a contraindication or refuse to consent.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This study proposes a systematic control design approach to consider jointly the event-triggered communication mechanism and state-feedback control for switched linear systems. The systems determine ...the necessary samplings of the feedback signal by constructing predefined events that can reduce redundant signal transmission and updates. Specifically, the first main step in the design is to construct sufficient conditions for stability analysis in the form of linear matrix inequalities to utilise fully the idea of average dwell time. With the proposed event-triggering mechanism, the design renders the resulting switched closed-loop system finite-time bounded. Subsequently, the authors present the conditions for finding the parameter of the event-triggered sampling mechanism and the state-feedback sub-controller gains. Then, the results for the full state feedback control case are further extended to systems incorporating observer-based state-feedback control motivated by practical applications. For each case, an estimate of the positive lower bound on the inter-execution times is further derived to avoid Zeno behaviour. A numerical example is presented to illustrate the effectiveness of the proposed methods.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Background
Hybrid closed‐loop (HCL) therapy is rarely studied in pregnancy. We present three cases of women with type 1 diabetes who used the Medtronic 670G HCL system for most or all of gestation.
...Methods
The Medtronic 670G system has a manual mode (no automated insulin delivery) and an auto mode (AM, HCL therapy). Women in this case series used AM off‐label in gestation.
Results
Case 1 started HCL therapy in the second trimester, her sensor glucose time spent <3.9 and >10 mmol/L improved thereafter. Case 1 had average sensor glucose (ASG) levels of 6.4 ± 2.4 mmol/L in the first trimester, 7.0 ± 2.7 mmol/L in the second trimester before HCL use, 7.1 ± 2.1 mmol/L in the second trimester after HCL use, and 6.8 ± 1.9 mmol/L in the third trimester. Case 1 continued AM during operative delivery and post‐partum. Cases 2 and 3 used HCL therapy throughout gestation but with inconsistent time in AM. When they increased time in AM their glycaemic indices improved. Case 2 had ASG of 9.5 ± 3.4, 8.6 ± 2.9, and 7.9 ± 2.5 mmol/L in the first through third trimesters, respectively. Case 3 had ASG of 11.1 ± 4.8 and 3.9 to 10 mmol/L in the first and second trimesters, respectively. Case 2 continued HCL therapy post‐partum, Case 3 did not.
Conclusions
CareLink® Clinical Software only reports the non‐pregnant time in range. Nonetheless, this represents the first report of HCL therapy in pregnancy with a system approved by the Food and Drug Administration in non‐pregnant populations.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
This paper studies the tracking control problem for an uncertain <inline-formula> <tex-math notation="LaTeX">{n} </tex-math></inline-formula>-link robot with full-state constraints. The rigid robotic ...manipulator is described as a multiinput and multioutput system. Adaptive neural network (NN) control for the robotic system with full-state constraints is designed. In the control design, the adaptive NNs are adopted to handle system uncertainties and disturbances. The Moore-Penrose inverse term is employed in order to prevent the violation of the full-state constraints. A barrier Lyapunov function is used to guarantee the uniform ultimate boundedness of the closed-loop system. The control performance of the closed-loop system is guaranteed by appropriately choosing the design parameters. Simulation studies are performed to illustrate the effectiveness of the proposed control.
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