A combined invariant-subspace and subspace identification method for continuous-time state–space models using slowly sampled multi-sine-wave data

C Huang - Automatica, 2022 - Elsevier
The problem of identification of linear continuous-time (CT) state–space (SS) models directly
from time-domain data is considered. Given multi-sine waves as excitation signals, this …

Disturbance-adaptive stochastic optimal control of energy harvesters, with application to ocean wave energy conversion

JT Scruggs, R Nie - Annual Reviews in Control, 2015 - Elsevier
This paper proposes a technique for optimizing the power generated from stationary
stochastic vibratory disturbances, using a resonant energy harvester. Although the theory is …

Optimal causal control of wave energy converters in stochastic waves–Accommodating nonlinear dynamic and loss models

R Nie, J Scruggs, A Chertok, D Clabby… - International Journal of …, 2016 - Elsevier
Recent research has shown that when constrained to causality, the optimal feedback
controller for an ocean wave energy converter (WEC) subjected to stochastic waves can be …

Spectral estimation in frequency-domain by subspace techniques

H Akçay - Signal Processing, 2014 - Elsevier
In this paper, frequency-domain subspace-based algorithms are proposed to estimate
discrete-time cross-power spectral density (cross-PSD) and auto-power spectral density …

Robust control of wave energy converters using unstructured uncertainty

Y Lao, JT Scruggs - 2020 American Control Conference (ACC), 2020 - ieeexplore.ieee.org
In the design of ocean wave energy converters, proper control design is essential to the
maximization of the power generation performance for the device. However, in realistic …

Positive realness in stochastic subspace identification: A regularized and reweighted nuclear norm minimization approach

H Akçay, S Türkay - 2015 European Control Conference (ECC), 2015 - ieeexplore.ieee.org
In this paper, we propose a method to transform a non-positive real transfer function matrix
into a positive real one. This problem is of engineering interest and arises when a linear time …

Subspace-based spectrum estimation in frequency-domain by regularized nuclear norm minimization

H Akçay - Signal Processing, 2014 - Elsevier
Subspace-based methods have been effectively used to estimate multi-input/multi-output,
discrete-time, linear-time-invariant systems from noisy spectrum samples. In these methods …

Discrete-time causal control of a wave energy converter with finite stroke in stochastic waves

Y Lao, JT Scruggs, A Karthikeyan… - IEEE Transactions on …, 2021 - ieeexplore.ieee.org
We consider feedback control design for a wave energy converter (WEC) for which the
power takeoff (PTO) system has a finite stroke limit. Stationary stochastic wave loading is …

Power spectrum estimation in innovation models

H Akçay, S Türkay - Mechanical Systems and Signal Processing, 2019 - Elsevier
In this paper, a regularized nuclear norm minimization-based subspace identification
algorithm is proposed to estimate discrete-time power spectra of multi-input/multi-out …

Frequency domain subspace-based identification of discrete-time singular power spectra

H Akçay - Signal Processing, 2012 - Elsevier
In this paper, we propose a subspace algorithm for the identification of linear-time-invariant
discrete-time systems with more outputs than inputs from measured power spectrum data …