Signal generation for switched reluctance motors using parallel genetic algorithms. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 8193-8198
Switched reluctance motors (SRM) are an inherent part in robotics and automation systems where energy and cost efficiency is required. This motor type has no windings and permanent magnets on the rotor which results in a simple and robust structure. However, SRMs require a complex electronic control system to generate a specified number of voltage pulses for each motor phase. This paper presents the signal generation of multiple phases using only one current sensor in an asymmetric half bridge (AHB). In addition to maintain the predetermined phase voltages, sufficient current measurement windows and a minimal current ripple for the individual phases are further optimization criteria for signal generation. The generation of a state vector which controls the individual semiconductor for each motor phase to achieve a required phase voltage and simultaneously fulfill the multi-objective optimization criteria is challenging. Due to the vast number of possible solutions, a genetic algorithm (GA) was used to find state combinations that are suitable for the formulated optimization criteria. The results were discussed and recommendations about the genotype representation and the used genetic operators were given. Interested readers will find detailed information about the software technical implementation using the Global Optimization Toolbox from MATLAB.
https://doi.org/10.1016/j.ifacol.2020.12.2328
A computation approach to chance constrained optimization of boundary-value parabolic partial differential equation systems. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 2435-2440
https://doi.org/10.1016/j.ifacol.2020.12.2517
Application of a nonovershooting tracking control method for the double buck converter. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 6151-6156
The problem of avoiding overshoot in tracking control problems has an extensive history, but only a few works have offered methods that are applicable to a nonlinear plant. The recent paper (Schmid, 2019) adapted some methods from the linear control systems literature to offer state feedback laws to deliver a nonovershooting response in all outputs of a multi-input multi-output feedback linearisable plant. A double-buck converter consists of cascaded buck converters connected to a single voltage supply. Taking the system outputs as the voltages across the two load resistors, we use dynamic averaging to obtain a nonlinear state model for the converter. We introduce suitable coordinates to show it has a well-defined vector relative degree and show the system is feedback linearisable. The methods of (Schmid, 2019) are then employed to obtain a state feedback law that ensures both outputs track arbitrary time-varying reference trajectories without overshoot.
https://doi.org/10.1016/j.ifacol.2020.12.1697
Soft sensor design for restricted variable sampling time. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 80-85
Difficult-to-obtain variables in industrial applications have led to the rise of soft sensors, which use prior system information and measurements to estimate these difficult-to-obtain variables. In real systems, the measurements that need to be estimated by a soft sensor are often infrequently measured or delayed. Sometimes, these delays and sampling time are variable in time. Though there are papers considering soft sensors in the presence of time delays and different sampling times, the variation of those parameters has not been considered when evaluating the adequacy of the soft sensors. Therefore, this paper will evaluate the impact of such variations for a data-driven soft sensor and propose modifications of the soft sensor that increase its robustness. The reliability of its estimate will be shown using the Bauer-Premaratne-Durán Theorem. Furthermore, the soft sensor will be simulated applying it to a continuous stirred tank reactor. Simulation showed that the modified soft sensor gives good estimates, whereas the traditional soft sensor gives an unstable estimate.
https://doi.org/10.1016/j.ifacol.2020.12.097
Analysis of sliding-mode control systems with unmatched disturbances altering the relative degree. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 5122-5128
We consider sliding-mode control systems subject to unmatched disturbances. Classical first-order sliding-mode techniques are capable to compensate unmatched disturbances if differentiations of the output of sufficiently high order are included in the sliding variable. For such disturbances it is commonly assumed that they do not affect the relative degree of the system. In this contribution we consider disturbances that alter the relative degree of the process and study their impact on the closed-loop control system with the classical first-order sliding-mode design. We analyse the reaching and sliding phase of the resulting closed-loop system. We show that uniqueness of the solution may be lost and derive conditions for such behaviour. We present conditions for the stability of the sliding-mode dynamics and analyse the disturbance rejection properties. A simulation case study of a two-mass spring-damper system illustrates the various closed-loop behaviours.
https://doi.org/10.1016/j.ifacol.2020.12.1149
Non-asymptotic state estimation of linear reaction diffusion equation using modulating functions. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 4196-4201
In this paper, we propose a non-asymptotic state estimation method for the linear reaction diffusion equation with general boundary conditions. The method is based on the modulating function approach utilizing a modulation functional in time and space. This results in a signal model control problem for a system of auxiliary PDEs in order to determine the modulation kernels. First, the algorithm is mathematically derived and then numerical simulations are presented for illustrating the good performance of the proposed approach and demonstrating the efficient implementation scheme.
https://doi.org/10.1016/j.ifacol.2020.12.2570
Extended fractional-order memory reset control for integer-order LTI systems and experimental demonstration. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 7683-7690
In this work we extend the concept of fractional-order memory reset control. A fractional-order controller is applied to an integer-order plant and its memory is deleted periodically. As an extension, the controller state itself is reset, based on the reference and the error signal. The closed loop can be represented by a fractional-order hybrid system with induced discrete dynamics. These are used to tune the reset law and to prove exponential stability. By means of the extended reset strategy the reset intervals can be reduced, such that less memory is needed to implement the fractional-order operators. Furthermore, a new approach for the real-time implementation of memory reset controllers is presented that achieves a decrease of the numerical error. All results are validated by simulations and experimentally.
https://doi.org/10.1016/j.ifacol.2020.12.1512
Sensitivity analysis of bias in satellite sea surface temperature measurements. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 764-771
The satellite sea surface temperature (SST) measurement is based on the detection of ocean radiation using microwave or infrared wavelengths within the electromagnetic spectrum. The radiance of individual wavelengths can be converted into brightness temperatures for using in SST determination. The calibration and validation of the determined SST data require reference measurements from in-situ observations. These in-situ observations are from various platforms such as ships, drifters, floats and mooring buoys and require a high measurement accuracy. This paper presents an investigation about the possibility of using a glider as in-situ platform. A glider is a type of autonomous underwater vehicle (AUV) which can log oceanographic data over a period of up to one year by following predetermined routes. In contrast to buoys, a glider allows a targeted investigation of regional anomalies in SST circulations. To assess the quality of SST observations from a glider, logged data from a glider mission in the Atlantic Ocean from 2018 to 2019 and corresponding satellite SST data were used. The influence of variables (e.g. measurement depth, latitude, view zenith angle, local solar time) of the bias between satellite and glider SST data was investigated using sensitivity analysis. A new and efficient distribution-based method for global sensitivity analyzes, called PAWN, was used successfully. Interested readers will find information about its operation principle and the usage for passive observations where only given-data are available.
https://doi.org/10.1016/j.ifacol.2020.12.828
Explicit and implicit IDA-PBC design and implementation for a portal crane. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 5592-5597
The interconnection and damping assignment passivity-based control (IDA-PBC) is well-known for regulating the behavior of nonlinear systems. In underactuated mechanical systems (UMSs), its application requires the satisfaction of matching conditions, which in many cases demands to solve partial differential equations (PDEs). Only recently, the IDA-PBC method has been extended to UMSs in implicit representation, where the system dynamics are described by a set of differential-algebraic equations. In some system classes, this implicit model allows to circumvent the PDE obstacle and to construct an output-feedback law. This paper discusses the design and real-system implementation of the total energy shaping IDA-PBC with an optimal local performance for a portal crane system in implicit port-Hamiltonian representation. The implicit controller is compared with the simplified (explicit) IDA-PBC, introduced by Xue and Zhiyong (2017), which also shapes the total energy and avoids PDEs.
https://doi.org/10.1016/j.ifacol.2020.12.1572
Event-triggered discrete-time sliding mode control for high-order systems via reduced-order model approach. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 6207-6212
We propose the design of event-triggered (ET) discrete-time sliding mode (DTSM) control for a high-order discrete-time system via a reduced-order model-based approach. This design includes a triggering mechanism using a reduced-order state vector and a controller based on the modified Bartoszewicz' reaching law for a reduced-order model of the system, to stabilize the uncertain high-order system. The main advantages of using a reduced-order vector in the event condition are the low-order synthesis of the controller and the sampling pattern, which may be sparser than the full vector-based design. This motivation arises from the fact that relaxing a few components of the state vector in the triggering mechanism may decrease its rate of violation. An added advantage of the proposal is that the transmission of the reduced-order vector, particularly in a network-based implementation, can outperform the full-order based design due to the severe challenges that exist in the data network. The robust performance for the closed-loop system is achieved using the DTSM control. We show that our proposal guarantees the stability of the full-order plant with the reduced-order triggering mechanism. The control execution is Zeno-free because of the inherent discrete nature of the control. The efficiency of the proposed method is shown using the simulation results of a numerical example.
https://doi.org/10.1016/j.ifacol.2020.12.1716