制御工学ブログ / Control Engineering Blog

制御工学の基礎から専門まで、動画・MATLABコード付きで解説。20年以上の研究経験をもつ大学教員が運営。Control engineering tutorials, research articles, and MATLAB code by a university researcher. Topics: LMIs, state estimation, model error compensator, multirate systems, observer design.

Subspace System Identification: A Tutorial on N4SID, MOESP, and CVA with MATLAB

A tutorial on subspace identification methods for control systems. Explains N4SID, MOESP, and CVA algorithms, model order selection via SVD, and MATLAB implementation. Includes connections to multirate and LPTV system identification resear…

System Identification: From Data to Dynamical Models — A Comprehensive Guide

A comprehensive guide to system identification in control engineering. Covers parametric methods, subspace identification (N4SID), kernel-based estimation, multirate systems, and data-driven control. With MATLAB code and links to research …

Model Error Compensator vs Disturbance Observer: A Structural Comparison

A detailed comparison between Model Error Compensator (MEC) and Disturbance Observer (DOB) for robust control. Covers structural differences, inverse model requirements, applicability to non-minimum phase and nonlinear systems, and practic…

H-infinity Filter: Robust State Estimation Using LMI Optimization

A comprehensive guide to the H-infinity filter for robust state estimation. Covers the worst-case optimization formulation, LMI-based design with Bounded Real Lemma, comparison with Kalman filter, pole placement constraints, and extensions…

Kalman Filter: From Basic Algorithm to Multi-Rate Extensions

A comprehensive guide to the Kalman filter for state estimation. Covers the prediction-update algorithm, steady-state Kalman filter, Kalman-Bucy filter, tuning of Q and R, Extended and Unscented Kalman filters, and multi-rate Kalman filter…

State Observer and State Estimation: A Comprehensive Guide

A comprehensive guide to state observers and state estimation in control systems. Covers Luenberger observers, Kalman filters, H-infinity filters with LMI design, multi-rate state estimation, and outlier-robust MCV observers. Includes link…

Estimation of Robust Invariant Set for Switched Linear Systems Using Recursive State Updating and Robust Invariant Ellipsoid

Estimation of robust invariant set for discrete-time switched linear systems with peak-bounded disturbances. A novel method combining recursive state updating and robust invariant ellipsoid achieves less conservative estimation.

Design of Observer-Based Feedback Controller for Multi-Rate Systems With Various Sampling Periods Using Cyclic Reformulation

Observer-based feedback controller design for multi-rate systems where sensors and actuators operate at different sampling rates. Using cyclic reformulation and LMI optimization of the l2-induced norm, both observer gains and feedback gain…

System Identification Under Multirate Sensing Environments

System identification algorithm for multirate sensing environments using cyclic reformulation and subspace identification. Proposes a method to identify plant models from input-output data when sensors have different sampling rates, withou…

Cyclic Reformulation-Based System Identification for Periodically Time-Varying Systems

This article explains cyclic reformulation-based system identification for LPTV systems. A subspace identification method with state coordinate transformation recovers periodic time-varying parameters without requiring periodic inputs. Bas…

Tracking Performance Limitation for 1-DOF Control Systems Using a Set of Attainable Outputs

This article explains the tracking performance limitation for 1-DOF control systems with unstable plants, extending the achievable-output-set approach from 2-DOF systems. The closed-form result separates the contributions of unstable zeros…

MSCS2026 in 富山

MSCS 2026 で富山に来ています。今年度3回目です。 MSCS 2026 新幹線ができて以降、鉄道に乗ったのははじめてです。 小中の同級生8名で飲みました。 pic.twitter.com/tLZPTWHuJj — Hiroshi Okajima (@control_eng_ch) 2026年3月2日 ワークショップ前に、富…

Model Error Compensator Design for Continuous- and Discrete-Time Non-Minimum Phase Systems with Polytopic-Type Uncertainties

This article explains the MEC design with parallel feedforward compensator for MIMO non-minimum phase systems with polytopic uncertainties, based on SICE JCMSI 2022. LMI-based H-infinity analysis for both continuous- and discrete-time syst…

A Design Method of Model Error Compensator for Systems with Polytopic-Type Uncertainty and Disturbances

This article explains a design method for the Model Error Compensator (MEC) for systems with polytopic-type uncertainty and disturbances, based on SICE JCMSI 2021. LMI-based H-infinity analysis combined with particle swarm optimization ena…

Model Error Compensator with Parallel Feed-Forward Filter

This article explains the Model Error Compensator (MEC) with a parallel feed-forward filter (PFF) for non-minimum-phase plants with unstable zeros and time delays, based on SICE JCMSI 2017. Design methods for PFF and compensator using PSO …