Measurements, Models, Systems and Design

531 s.

Comparison of different repetitive control architectures: synthesis and comparison. Application to VSI Converters

Repetitive control is one of the most used control approaches to deal with periodic references/disturbances. It owes its properties to the inclusion of an internal model in the controller that corresponds to a periodic signal generator. However, there exist many different ways to include this internal model. This work presents a description of the different schemes by means of which repetitive control can be implemented. A complete analytic analysis and comparison is performed together with controller synthesis guidance. The voltage source inverter controller experimental results are included to illustrative conceptual developmentsPeer ReviewedPostprint (published version

Parameter identification and filter design for a repetitive controller of hot rolling mills

U výrobků válcoven za tepla se vyskytují periodické povrchové defekty v důsledku inherentní excentricity přítomné ve válcích. Tyto vady lze považovat za periodické rušení systému. Pro odstranění těchto závad je zkoumán návrh regulátoru založený na metodě opakované kontroly. První aproximací válcovacích tratí za tepla z experimentálních dat jako systémů s časovým zpožděním prvního řádu se získají potřebné podmínky regulátoru a vlastnosti, které musí být splněny pro periodické vyřazování poruch, pro konkrétní typ systémů s interním ovladačem modelu. S ohledem na tyto podmínky je pak navržena a testována metodika získávání filtrů, které mají klíčovou roli v opakované kontrole, pro její účinnost a robustnost při dosahování úspěšné kontroly při poruše a nesouladu mezi zařízeními a modely.In hot rolling mill products, periodic surface defects are encountered due to the inherent eccentricity present in the rolls. These defects can be considered as a periodic disturbance to the system. To remove these defects, a controller design based on Repetitive Control method is investigated. By first approximating hot rolling mills from experimental data as first-order time delayed systems, the necessary controller conditions and properties that need to be satisfied for periodic disturbance rejection are obtained for the particular type of systems with Internal Model Controller. Then with respect to these conditions, a methodology to obtain filters which hold a key part in Repetitive Control is proposed and tested for its effectiveness and robustness in achieving successful control under disturbance and plant/model mismatch

Hybrid computer Monte-Carlo techniques

Hybrid analog-digital computer systems for Monte Carlo method application

Robust gradient-based discrete-time iterative learning control algorithms

This paper considers the use of matrix models and the robustness of a gradient-based Iterative Learning Control (ILC) algorithm using both fixed learning gains and gains derived from parameter optimization. The philosophy of the paper is to ensure monotonic convergence with respect to the mean square value of the error time series. The paper provides a complete and rigorous analysis for the systematic use of matrix models in ILC. Matrix models make analysis clearer and provide necessary and sufficient conditions for robust monotonic convergence. They also permit the construction of sufficient frequency domain conditions for robust monotonic convergence on finite time intervals for both causal and non-causal controller dynamics. The results are compared with recent results for robust inverse-model based ILC algorithms and it is seen that the algorithm has the potential to improve robustness to high frequency modelling errors provided that resonances within the plant bandwidth have been suppressed by feedback or series compensation

Virtual Delay Unit Based Digital nk ± m-order Harmonic Repetitive Controller for PWM Converter

Repetitive control (RC) scheme presents an attractive solution to achieve excellent steady-state tracking error and low total harmonic distortion (THD) for periodic signals. RC can produce extremely large gains at fundamental and each harmonic frequency of reference signal to achieve all harmonics suppression. However, a DC-AC inverter always has uneven THD distribution, e.g. THD concentrates at 4fc ± 1 orders for signal-phase inverter, and 6k ± 1 orders for three-phase inverter. Furthermore, a digital RC requires a integral ratio of the sampling frequency and the reference frequency, whereas the digital control system cannot always meet this requirement. For example, (e.g. 60 Hz reference signal with a 5 kHz sampling frequency, or grid-connected converter under grid frequency fluctuation, etc.). In this paper, virtual delay unit (VDU) based digital nk ± m-order harmonic RC is presented to solve the problems above. The VDU produces a different virtual RC sampling frequency from the system sampling frequency. The virtual sampling frequency for digital RC can be flexibly adjusted based on the integral ratio requirement. The advantage of VDU is that it does not vary the system sampling frequency and it is easy to be realized. Furthermore, nk ± m-order harmonic repetitive controller is selected to provide a selective harmonic compensation (SHC). Experimental results of VDU based nk±m-order harmonic RC for 60 Hz single-phase DC/AC inverter with 5 kHz system sampling frequency are provided to show the effectiveness of the proposed VDU-based SHC

Triggered Repetitive Control:Application to Mechanically Ventilated Patients

Asymptotic rejection of a periodic disturbance can be achieved using repetitive control (RC). The aim of this article is to develop a triggered RC (TRC) framework that can handle repeating tasks that are initiated by an external disturbance induced trigger on varying intervals, which clearly violates the periodicity assumption in RC. A design method for this TRC framework is presented with a stability guarantee. Finally, through an experimental use-case, it is shown that pressure tracking performance for mechanically ventilated patients is improved significantly.</p