Port-Hamiltonian formulation of nonlinear electrical circuits. - In: Journal of geometry and physics, Bd. 159 (2021), 103959, insges. 15 S.
We consider nonlinear electrical circuits for which we derive a port-Hamiltonian formulation. After recalling a framework for nonlinear port-Hamiltonian systems, we model each circuit component as an individual port-Hamiltonian system. The overall circuit model is then derived by considering a port-Hamiltonian interconnection of the components. We further compare this modeling approach with standard formulations of nonlinear electrical circuits.
https://doi.org/10.1016/j.geomphys.2020.103959
Coordinate transformation and its uncertainty under consideration of a non-orthogonal coordinate base. - In: Measurement science and technology, ISSN 1361-6501, Bd. 32 (2021), 4, 045001, insges. 6 S.
Nanopositioning and nanomeasuring machines are 3D coordinate measuring systems with nanometer precision at measurement volumes in the cubic centimeter range. The coordinate base is formed by an interferometer system with a common mirror corner. The orthogonality deviations of the mirror corner require a coordinate transformation of the measuring axes. The uncertainty of the coordinate transformation must be taken into account in the overall measurement uncertainty budget. Starting from a complete transformation model, the result of model simplications on the transformation behaviour is analysed and discussed.
https://doi.org/10.1088/1361-6501/aba3f5
Partitions of hypergraphs under variable degeneracy constraints. - In: Journal of graph theory, ISSN 1097-0118, Bd. 96 (2021), 1, S. 7-33
https://doi.org/10.1002/jgt.22575
Recursive feasibility of continuous-time model predictive control without stabilising constraints. - In: IEEE control systems letters, ISSN 2475-1456, Bd. 5 (2021), 1, S. 265-270
https://doi.org/10.1109/LCSYS.2020.3001514
Invariance of the essential spectra of operator pencils. - In: Operator theory, operator algebras and their interactions with geometry and topology, (2020), S. 203-219
Distributed control enforcing group sparsity in smart grids. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 13269-13274
In modern smart grids, charging of local energy storage devices is coordinated within the distribution grid to compensate the volatile aggregated power demand on the time interval of interest. However, this results in a perpetual usage of all batteries which in return reduces their lifetime. In this paper, we enforce group sparsity by using an lp,q-regularization on the control to counteract this phenomenon. This leads to a non-smooth convex optimization problem, for which a tailored Alternating Direction Method of Multipliers algorithm is proposed. Furthermore, the algorithm is embedded in a Model Predictive Control framework. Numerical simulations show that the proposed scheme yields sparse control while achieving reasonable overall peak shaving.
https://doi.org/10.1016/j.ifacol.2020.12.156
Learning-based funnel-MPC for output-constrained nonlinear systems. - In: IFAC-PapersOnLine, ISSN 2405-8963, Bd. 53 (2020), 2, S. 5177-5182
We exploit an adaptive control technique, namely funnel control, to establish both initial and recursive feasibility in Model Predictive Control (MPC) for output-constrained nonlinear systems. Moreover, we show that the resulting feedback controller outperforms the funnel controller both w.r.t. the required sampling rate for a zero-order-hold implementation and required control action. We further propose a combination of funnel control and MPC, exploiting the performance guarantees of the model-free funnel controller during a learning phase and the advantages of the model-based MPC scheme thereafter.
https://doi.org/10.1016/j.ifacol.2020.12.1186
Modelling of heat diffusion for temperature-controlled retinal photocoagulation. - In: Proceedings on automation in medical engineering, Vol. 1 (2020), no. 1, paperID: 006, 2 Seiten
https://doi.org/10.18416/AUTOMED.2020
Model predictive control, cost controllability, and homogeneity. - In: SIAM journal on control and optimization, ISSN 1095-7138, Bd. 58 (2020), 5, S. 2979-2996
We are concerned with the design of Model Predictive Control (MPC) schemes such that asymptotic stability of the resulting closed loop is guaranteed - even if the linearization at the desired set point fails to be stabilizable. Therefore, we propose constructing the stage cost based on the homogeneous approximation and rigorously show that applying MPC yields an asymptotically stable closed-loop behavior if the homogeneous approximation is asymptotically null controllable. To this end, we verify cost controllability - a condition relating the current state, the stage cost, and the growth of the value function with respect to time - for this class of systems in order to provide stability and performance guarantees for the proposed MPC scheme without stabilizing terminal costs or constraints.
https://doi.org/10.1137/19M1265995
Mathematical innovations fostering the energy transition - control and optimization. - In: Automatisierungstechnik, ISSN 2196-677X, Bd. 68 (2020), 12, S. 982-984
https://doi.org/10.1515/auto-2020-0152