Variable structure model reference adaptive control based on two-degree-of-freedom compensators scheme

In this paper, a variable structure model reference adaptive control system (MRACS) based an two-degree-of-freedom compensators scheme (2 DOF) is proposed. First, a MRACS with fixed compensator is constructed using the 2 DOF proposed in Masuda et al. (1994). Second, the fixed compensator is replaced by a switching compensator. The switching algorithm is determined in order that the estimated parameter can converge more rapidly. Since the Proposed method is based on the 2 DOF structure, the switching compensator works only when the parameter uncertainties are large. The boundedness of all signals in the closed-loop system and the convergence of the output error are proved. Finally, simulation results are illustrated to show the effectiveness of the proposed method </p

Transient performance improvement in dynamic certainty equivalent adaptive controllers by including a fixed compensator

We propose a modified Morse's dynamic certainty equivalent (DyCE) adaptive controllers in the continuous-time, single-input single-output linear time-invariant plant for the purpose of improving the transient performance. In the new scheme the additive feedback loop through a fixed compensator, which means a non-adaptive one, is included. Furthermore a design method for the fixed compensator is also given, and performance analysis for the proposed DyCE adaptive controller is examined in terms of the mean square tracking error criterion and the &Lscr;&#8734; tracking error bound. According to the results of the paper the transient performance can be improved arbitrarily by the properly designed fixed compensator. Finally a numerical example is illustrated in order to show the effectiveness of the proposed method </p

A direct algorithm for state deadbeat control

The authors propose a novel method for computing state deadbeat feedback gains from systems given in the staircase form. The proposed method uses only manipulations of given matrices, and hence is more direct than the existing method, which requires orthogonal transformations repeatedly. It is shown that the obtained gain is linear quadratic optimal for some weighting matrices </p

A construction of multivariable MRACS with fixed compensator using coprime factorization approach

A multivariable model reference adaptive control system (MRACS) with a fixed compensator is proposed. First, a new two-degree-of-freedom (2DOF) compensator with disturbance estimator is derived. Using this structure, a multivariable MRACS with fixed compensator is constructed. Since the proposed method is based on the 2 DOF structure, the fixed compensator is chosen independently of specifications for reference commands. The boundedness of all signals in the closed-loop system and the convergence of the output error are proved. A design method of the fixed compensator for MRACS with low sensitivity is also given. Finally, numerical examples are illustrated in order to show the effectiveness of the proposed method </p

A direct computation of state deadbeat feedback gains

A method for computing a feedback gain that achieves state deadbeat control is given. From systems given in the staircase form, this method derives the deadbeat gain in a numerically reliable way. It is shown that the gain turns out to be LQ optimal for some weightings

渦度の話 : その変化の仕組みと渦度力

九州大学応用力学研究所研究集会報告 No.22AO-S8 「非線形波動研究の新たな展開 : 現象とモデル化」Report of RIAM Symposium No.22AO-S8 Development in Nonlinear Wave: Phenomena and Modeling流体力学では渦度変化の仕組みを渦線の傾きと渦線の伸長で説明する．海洋学や気象学でもこの説明を踏襲する．しかし実は剛体にかかる偶力に類した説明が可能である．本講演ではまず「渦度力」を導入する．渦度力とは局所併進自転系におけるコリオリ力に他ならない．そうして流体にかかる「渦度力の捻り」が渦度を変えると解釈する．この考え方は厳密で一般性を持ちしかも因果的なので，渦度発展の仕組みを無理なく直観的に理解できる．但し渦度力の捻り以外にも渦度を変えるものがある．そこで渦度発展の仕組みの全体像を直観的に分かり易い形で説明する．応用例として北半球の海洋の鉛直渦度の変化をもたらす仕組みを図解する．最後に傾圧捻りの意味および，その温度風平衡・ブシネスク流体近似との関係を明らかにする

Design of an Adaptive Observer to Estimate Unknown Periodical Disturbances

This report deals with the problem of designing an adaptive observer for estimating unknown periodical disturbances. This is very practical problem because in the area of control of servomechanisms such disturbances are always encountered. When the disturbance cannot be directly measured or eliminated at the source it is necessary to perform a prediction. When a periodical disturbance is present the frequencies appear as unknown parameters and they have to be identified. In order to identify the unknown parameters, it is necessary to transform the composite system model, which contains the models of the controlled system and the disturbances, into observable canonical form. In addition, an inverse transformation is required to calculate the estimates of the present disturbances. In this report, firstly, a review of an adaptive observer for estimation of unknown periodical disturbances is presented. Later a calculation of the disturbance estimate is derived using the algebraic programming system REDUCE. The proposed method here allows to perform all the necessary transformations and to obtain the disturbance estimation without using the transformation matrix. The calculations of these transformations are complicated and, hitherto, there is no simple method to perform them. The results of disturbance estimation are illustrated by two examples

Interferon-free Anti-hepatitis C Virus Treatment for Long-term Liver Transplantation Recipients with Failed Interferon Therapy

Article信州医学雑誌 67(6): 417-423(2019)journal articl