2019 |
Jisu Kim / Hyungbo Shim / Jin Heon Seo State Estimation and Tracking Control for Hybrid Systems by Gluing the Domains Journal Article In: IEEE Transactions on Automatic Control, 2019. Abstract | Links | BibTeX | Tags: Hybrid system, Observer, Tracking @article{KimShimSeo19, We study the design problems of state observers and tracking controllers for a class of hybrid systems whose state jumps. The idea is to utilize the well-known method of gluing the jump set (a part of domain where the jumps take place) onto its image, which converts the hybrid system into a continuous-time system whose state does not jump. Sufficient conditions for this idea to be implemented are listed and discussed with a few concrete examples. In particular, we present a structural condition for an observer design, and, for tracking control, we introduce a feedback to compensate residual discontinuity in the vector field after gluing. The benefits of the proposed approach include that the observer design does not require detection of the state jumps, and that the tracking control does not require the plant state jumps when the reference jumps. |
2017 |
Nam Hoon Jo / Chanyoung Jeon / Hyungbo Shim Noise Reduction Disturbance Observer for Disturbance Attenuation and Noise Suppression Journal Article In: IEEE Transactions on Industrial Electronics , vol. 64, no. 2, pp. 1381 - 1391, 2017. Abstract | Links | BibTeX | Tags: Motor drive, Observer @article{JoJeonShim17, In most research works on the disturbance observer (DOB)-based controller, stability conditions are only sufficient and not effective for handling large uncertainties. To deal with large uncertainties, a necessary and sufficient condition for robust stability has been recently provided by utilizing a novel design technique for the Q -filter. Although this design method can deal with large uncertainties, it is not capable of suppressing the effect of sensor noise. To achieve noise suppression as well as disturbance attenuation, this paper proposes a robust controller by utilizing a modified DOB structure. In contrast to the conventional DOB structure, noise suppression ability of the proposed controller can be adjusted by an appropriate choice of the Q-filter. Moreover, a necessary and sufficient condition for the modified DOB system to be robustly stable is newly presented. To show the effectiveness of the proposed controller, the performance is compared with other disturbance attenuation methods through simulation studies. Finally, in order to verify the validity of the proposed method, laboratory experiments are also conducted with brushless dc motor drives, which confirms that the proposed controller is quite useful for attenuating both input disturbance and sensor noise, while DOB controller is not capable of suppressing sensor noise. |
2016 |
Taekyoo Kim / Hyungbo Shim / Dong-il “Dan” Cho Distributed Luenberger Observer Design Proceedings Article In: Proc. of 2016 IEEE 55th Conference on Decision and Control, pp. 6928-6933, IEEE, Las Vegas, NV, USA, 2016. Abstract | Links | BibTeX | Tags: Observer @inproceedings{KimShimCho16, This paper presents a distributed design scheme of the Luenberger-type state observer for continuous-time linear dynamical systems. The proposed observer consists of networked local observers, and each local observer computes the estimate by the local measurements, which may not be sufficient to recover the full state. Therefore, by communicating with the neighboring observers, the proposed observer compensates for the insufficient information. The novelty of the proposed method is the design of two observer gains; one for local measurements and the other for the information exchange. By exploring the structure of gain matrices, our design can assign the injection gain only to “detectable” part of the estimate for the local measurements, and for the “undetectable” portion of the estimate, the gain of the information from neighboring observers is set to be relatively higher than others. It turns out that this intuitive idea leads to a simple design of distributed Luenberger-type observers. |
Youngjun Joo / Gyunghoon Park / Juhoon Back / Hyungbo Shim Embedding Internal Model in Disturbance Observer with Robust Stability Journal Article In: IEEE Transactions on Automatic Control, vol. 61, no. 10, pp. 3128-3133, 2016. Abstract | Links | BibTeX | Tags: Control system synthesis, Observer, Robustness @article{JooParkBackShim16, Abstract: The disturbance observer has been widely employed in applications due to its powerful ability for disturbance rejection and robustness under plant uncertainties. However, it rejects the disturbance approximately rather than exactly since it is usually designed without considering structural properties of disturbance. In order to improve the disturbance rejection performance, we propose a design method to embed the internal model of disturbance into the disturbance observer structure. Furthermore, a systematic design procedure is proposed so that one can always design the disturbance observer to guarantee robust stability of the closed-loop system even though uncertain parameters of the plant belong to an arbitrarily large (but bounded) set. |
2012 |
Hyungbo Shim / Aneel Tanwani / Zhaowu Ping Back-and-forth Operation of State Observers and Norm Estimation of Estimation Error Proceedings Article In: Proc. of 2012 IEEE 51st Annual Conference on Decision and Control (CDC), pp. 3221-3226, IEEE, Maui, HI, USA, 2012. Abstract | Links | BibTeX | Tags: Observer @inproceedings{ShimTanwaniPing12, In contrast to classical observers operating synchronously with the plant, this paper proposes a state estimation algorithm that executes Luenberger observers back-and-forth in time using the stored inputs and output signals. One benefit of this technique is to get rapid convergence of state estimation without relying on high injection gain, so that the amplification of measurement noise is much relieved. Moreover, by operating the observer in the proposed manner, we easily obtain an upper bound on the estimation error. Real-time applications of the proposed idea, and the effect of disturbances, are also discussed. |
Hansung Cho / Jongwook Yang / Jin Heon Seo Geometric Characterization of Reduced-Order Dynamic Observer Error Linearization for Uncontrolled Multi-Output Systems Proceedings Article In: Proc. of 2012 IEEE 51st Annual Conference on Decision and Control (CDC), pp. 338-343, IEEE, Maui, HI, USA, 2012. Abstract | Links | BibTeX | Tags: Lie algebra, Observer @inproceedings{ChoYangSeo12, In this paper, we introduce the concept of reduced-order dynamic observer error linearization (RDOEL) for uncontrolled multi-output systems, which is a natural extension of the (conventional) observer error linearization (OEL) as well as a modified version of dynamic observer error linearization (DOEL). We first state necessary conditions for RDOEL, and then provide a necessary and sufficient condition in terms of Lie algebras of vector fields, which has not yet been completely established even in OEL. |
List of English Publication
2019 |
State Estimation and Tracking Control for Hybrid Systems by Gluing the Domains Journal Article In: IEEE Transactions on Automatic Control, 2019. |
2017 |
Noise Reduction Disturbance Observer for Disturbance Attenuation and Noise Suppression Journal Article In: IEEE Transactions on Industrial Electronics , vol. 64, no. 2, pp. 1381 - 1391, 2017. |
2016 |
Distributed Luenberger Observer Design Proceedings Article In: Proc. of 2016 IEEE 55th Conference on Decision and Control, pp. 6928-6933, IEEE, Las Vegas, NV, USA, 2016. |
Embedding Internal Model in Disturbance Observer with Robust Stability Journal Article In: IEEE Transactions on Automatic Control, vol. 61, no. 10, pp. 3128-3133, 2016. |
2012 |
Back-and-forth Operation of State Observers and Norm Estimation of Estimation Error Proceedings Article In: Proc. of 2012 IEEE 51st Annual Conference on Decision and Control (CDC), pp. 3221-3226, IEEE, Maui, HI, USA, 2012. |
Geometric Characterization of Reduced-Order Dynamic Observer Error Linearization for Uncontrolled Multi-Output Systems Proceedings Article In: Proc. of 2012 IEEE 51st Annual Conference on Decision and Control (CDC), pp. 338-343, IEEE, Maui, HI, USA, 2012. |