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 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

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

Singular stress field near the edge of interface of bonded dissimilar materials with an interlayer

AbstractFor bonded dissimilar materials, the free-edge stress singularity usually prevails near the intersection of the free-surface and the interface. When two materials are bonded by using an adhesive, an interlayer develops between the two bonded materials. When a ceramic and a metal are bonded, the residual stress develops because of difference in the coefficient of thermal expansion. An interlayer may be inserted between the two materials to defuse the residual stress. Stress field near the intersection of the interface and free-surface in the presence of the interlayer is then very important for evaluating the strength of bonded dissimilar materials.In this study, stress distributions on the interface of bonded dissimilar materials with an interlayer were calculated by using the boundary element method to investigate the effect of the interlayer on the stress distribution. The relation between the free-edge singular stress fields of bonded dissimilar materials with and without an interlayer was investigated numerically. It was found that the influence of the interlayer on the stress distributions was confined within a small area of the order of interlayer thickness around the intersection of the interface and the free-surface when the interlayer was very thin. The stress distribution near the intersection of the interface and the free-surface was controlled by the free-edge stress singularity of the bonded dissimilar materials without the interlayer. In this case, the interlayer can be called free-edge singularity-controlled interlayer. If a stress distribution on the interface is known for one thickness of an interlayer h, stress distributions on the interface for other values of h can be estimated

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

IMPORTANCE OF VISUAL INFORMATION AT CHANGE IN MOTION DIRECTION ON DEPTH PERCEPTION

This paper demonstrates the importance of visual information on depth perception from monocular motion parallax presented at the time of change in the motion direction of head and stimulus movements. In head-tracking systems, a longer delay time between the head and stimulus movements degrades the depth perception from monocular motion parallax. Because this delay is noticeable at this time, we hypothesized that the visual information given at the time of the direction change plays a critical role in the depth perception from motion parallax. We evaluated depth perception from monocular motion parallax with and without a visual stimulus at the time of the motion direction change to confirm our hypothesis, and clarified that stable and unambiguous depth can be perceived by presenting the change of the stimulus motion direction. We also demonstrated that it is the change in motion direction itself that is important rather than the temporal stop between deceleration and acceleration of the stimulus motion

Quantum state tomography for Kerr parametric oscillators

Kerr parametric oscillators (KPOs) implemented in the circuit QED architecture can operate as qubits. Their applications to quantum annealing and universal quantum computation have been studied intensely. For these applications, the readout of the state of KPOs is of practical importance. We develop a scheme of state tomography for KPOs with reflection measurement. Although it is known that the reflection coefficient depends on the state of the KPO, it is unclear whether tomography of a qubit encoded into a KPO can be performed in a practical way mitigating decoherence during the measurement, and how accurate it is. We show that the reflection coefficient has a one-to-one correspondence with a diagonal element of the density matrix of the qubit when a probe frequency is properly chosen and an additional single-photon-drive is introduced. Thus, our scheme offers a novel way to readout the qubit along an axis of the Bloch sphere, and therefore the reflection measurement and single-qubit gates can constitute state tomography

A design method of multivariable model reference adaptive control system using coprime factorization approach

A design method for multivariable model reference adaptive control systems (MRACS) using a coprime factorization approach is proposed. First, a relation between the coprime factorization over RH&#8734; and the interactor matrix is derived. Using this relation, a method for design of multivariable MRACS over the ring of proper stable rational functions is obtained. Since the proposed method is based on the coprime factorization approach, the control structure in this paper is more simple. It is shown that the control structure of multivariable MRACS by other authors is included in the structure proposed in this paper. A robust MRAC scheme which achieves asymptotic rejection of unmeasurable disturbances is derived also </p