The transformation of linear continuous-time system model into discrete-time one is amenable to direct solution for both deterministic and stochastic situations. In this paper, the reverse problem is investigated, and a procedure is developed for performing the transformation from an autoregressive moving-average (ARMA) model to an equivalent minimal order continuous-time system with a white noise input in the sense that the correlation function of the continuous-time model is identical at the samping instance with that of the corresponding ARMA process. The technique presented here is found useful in area where the systems are actually continuous, but the fact that the available data are discrete leads to identification of ARMA model.

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The solution of a steady-state error covariance equation is studied for a forward-pass fixed-interval smooter in discrete-time systems. From the view point of the detectability and stabilizability, a necessary and sufficient condition is derived to assure the existence of a unique stabilizing solution. A simple algorithm for constructing such a steady-state solution is also proposed by applying the Potter's eigenvector approach to the algebraic Riccati equation associated with a backward-pass information filter. Finally, it is illustrated from a numerical example that the algorithm is useful for smoother design purposes and for the analysis of bound estimate accuracies of the final convergence estimates.

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Matrix Riccati equations arising in optimal filtering and control problems of discrete time-invariant systems with possibly singular state transition matrices are considered in this paper.
An algebraic approach based on a formulation as a generalized rather than an ordinary eigenvalue problem is employed.
Existence conditions are derived of nonnegative definite steady-state solutions together with relevant properies to the generalized eigenvalue problem. Also, a construction method of all such solutions is given. It is seen that the results associated with nonsingular state transition matrices are generalized in a natural fashion.

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A stochastic approximation procedure is proposed for finding a point on a discrete set which gives the maximum of a function defined and observable only at points on the discrete set based on the noisy observations. Here, we call a discrete set as a set of points of integral multiples of some unit. It is proved by using the theorem of almost supermartingale that the estimate converges with probabilty one to the true maximum as the number of observation tends to infinity. A numerical example is presented for illustrating the convergence. The procedure can be applied to recursive identification of time serie model.

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Variable Structure Systems (VSS) change the structure on both sides of a switching surface, which is instituted in the state space, and its change gives rise to sliding motion. The Sliding Mode Control (SMC) utilizes this sliding motion and carries out the feedback control by variable structure feedback elements. While in sliding motion, the SMC system remains insensitive to parameter variations and disturbances.
In this paper, we deduce the condition of a control gain for the SMC system in a mean sense of the white noise and state-dependent noise respectively. The Sliding region is an overall switching surface on the regulation problem of the SMC system, however, on the follow-up control problem, in this paper, sliding motion doesn't occur in a limited region, given by a function of the reference input. Furthermore, we derive an equation of an optimal switching surface, which is based on a quadratic evaluation of the state, from the equivalent control method. Lastly, through digital simulations of several examples we confirm the above results.

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This paper proposes the partial state feedback control system synthesis method and the feedforward compensation method for the partial state or the output feedback control system. The partial state feedback control system synthesis method is useful because all of the state variables of the controlled object cannot be necessarily measured, end the output feedback control system is susceptible to noise because of including high difference actions in the controller. The feedforward compensation is beneficial for improvement on the transient response of the control system, but, until now, the feedforward compensation method for the partial state or the output feedback control system has not been proposed. In this paper, the feedforward compensation method which can be applied to all control system syntheses is proposed and the effectiveness is verified experimentally in the case of application to the efficiency optimized speed control system synthesis which is single-input and single-output and third order system. The influence of noise for each control system is also investigated experimentally.
The partial state feedback control system synthesis method and the feedforward compensation method proposed in this paper basically can be applied to multi-input and multi-output system.

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This paper considers how the output measurements have relation to the set of transfer functions from external inputs to controlled outputs achievable by stabilizing controllers.
For the design of control systems model-matching technique plays a fundamental role. Recently, several control problems concerning the above have been solved. Generally there is a degree of freedom in designing a controller with which a specified external characteristic is achieved. It is to be desired from the viewpoint of maintenance and economy that as few output-measuring terminals as possible be used. As a result we obtained a criterion for judging whether a particular subset taken from among the presupposed measuring terminals includes redundancy for the control objective or not, by using explicit characterization of all controllers that achieve the specified transfer function. In the case where some desired characteristic is not achievable, we utilize additional sensor outputs. A necessary and sufficient condition under which the inclusion of additional sensors strictly enlarges the class of achievable transfer functions is given.

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The frequency characteristics and the input impedance of cavity-mounted pressure sensing systems have been derived by considering the tube impedance and the radiation impedance as well as the orifice resistance across the sensing hole. The system can be modeled as a L-R-C series circuit with the resistance affected by signal frequency and amplitude. The theoretical result has a good agreement with the experimental one for wide ranges of geometrical and signal parameters.
It is clarified that a smaller cavity volume and a larger sensing hole can realize a wider frequency band, a higher input impedance (smaller modification of flow), and a smaller nonlinearity.

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The initiation process of the human gait has been simulated for a wide range of walking speed. A simple model consisting of a rigid body and two massless legs was used in the simulation. Parameter values characterizing the process such as the motion of the point of application, supporting times, and step lengths were measured and analyzed by the regression method. The input data for the simulation were determined based on this experimental analysis.
It was assumed that a steady state was reached after the landing of a second-swinging leg. The simulation results are compared with the inverse motion of the point of application and the horizontal floor reaction forces measured experimentally. The comparison shows that the simulation gives satisfactory results.

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The digital image processing has been applied recently to flow measurement in order to obtain quantitative data from various visualized flow phenomena As an effective way for the measurement of flow velocity vector distribution, a tracer method has been usually adopted for flow visualization and also the velocity vectors have been calculated from the photographic pictures of tracer paths. This technique by using the photographs, however, needs some complicated procedures of the processing to determine the flow directions.
In this study, the authors propose and develop the image processing system to determine the flow directions more easily. This system consists mainly of a TV camera, an image frame memory, and a minicomputer. The image frame memory is specially capable of extracting the tracer paths. The minicomputer and its software system calculate the travelling distances of the tracer particles floating during a constant period in order to obtain the flow velocity vector distribution. And this system was actually applied to an open channel flow.
As a result of this study, the following facts were specifically confirmed:
(1) The travelling distance and direction of the tracer particles were determined precisely by matching the tracer particle image at the starting point to the tracer path image.
(2) The tracer path lines, the velocity vectors, and their distribution were obtained.

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In colder districts, water is not to be-used, because of the possible freezing hazard, as the heat transfer medium for a heat pump, which is operated with the solar and atmospheric heat as its high temperature source. Thus, the low pressure refrigerant after the expansion valve is directly sent to the outdoor heat collecting panel for evaporation. This results in an elongated pipe line and which, in turn, tends to cause cycling in the control system.
Such a pump is operated during colder seasons and the dynamic responses are observed. As the results, some of the seemingly important characteristics of the system in connection with the cycling are detected. The inverse response of the refrigerant flow rate to a sudden change in solar input and the unstable fluctuation of the state variables in the evaporator side of the refrigerant system are the most remarkable ones.
The conventional expansion valve is replaced by a needle valve manipulated by a microcomputer through a step motor. The temperature signal right after the evaporator is processed to cut the harmful fluctuation by a nonlinear digital filter. Direct measurement of the degree of superheat through the pressure sensor is avoided to suppress the inverse response of the refrigerant flow rate. Instead, use is made of a model for the static characteristics, extracted from the observed data, to estimate the drgree of superheat and to manipulate the valve based on it.

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A novel method to reduce the fixed error of the FMCW radar measuring the distance to single target is proposed and has been studied both theoretically and experimentally. This method determines the distance from the weighted sum of the zero crossings of the beat signal in the FMCW radar, and is named the weighted counting method (WCM). The WCM is a generalized concept of the double modulation method (DMM) which was formerly proposed by the authors; the DMM is equivalent to the WCM employing the triangular weighting function. Applying the Poisson's formula, it has been shown that the fixed error is effectively reduced by employing the weighting function of which the Fourier transform has a low side-lobe level. The weighted counting errors for typical weighting functions: the rectangular function and its convolutions, cosⁿ functions, (1/4-t²)ⁿ functions and finite trigonometric serieses have been estimated. Many weightning functions show more accurate results than the DMM does. The effects of the non-linear frequency modulation on the accuracy of the WCM was studied by numerical simulation. It has been clarified that the WCM is scarcely affected by non-linear frequency modulation. The weighted counting FMCW radar employing cos⁴ weighting function has been realized by a simple analog signal processing circuit, and the experimental measurements were carried out. The position of aluminum plate located at approximately 1m distance was determined with the accuracy of 1.5mm. Based on the experimental results, it has been shown that the accuracy of the FMCW radar is restricted by the mismatches in the microwave circuit, when the fixed error is sufficiently reduced.

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In this report, we discuss the weight control of the hopper by using a microcomputer. As for the control algorithm, the “Model Reference Adaptive Control” method is used.
The model reference adaptive control system (MRACS) is constructed with Ohkawa's algorithm based on the Lyapunov's direct method. And the MRACS is extended to permit application to non-minimum phase systems by compensating zero-points of the system because the hopper system is non-minimum phase system.
The validity of the extended adaptive algorithm is confirmed by simulations, further the algorithm is applyed to the real hopper system.
As for the results, it is shown that the proposed algorithm is very useful for the process with a deterministic disturbance input and with time variant parameters through the simulations and experiments.

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Interactions in multi-joint manipulator dynamics must be eliminated for the prospective control of improved robots. The high-gain effect of sliding mode control suppresses such interactions as inertia variations, Coriolis force and centrifugal force between joints without any stability problem. The resulting system is robust in the sliding mode. In this paper, a time-varying hypersurface is introduced in order to ensure sliding motion throughout the entire response, and a nonlinear compensator is also used to reduce the chattering caused by switching input. The experimental results for a two-linkage manipulator show the validity of this technique for noninteracting control.

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A new algorithm for force feedback control of a robot hand is presented. Using this algorithm, a programmable 6-d.o.f. compliance (translational: 3, rotational: 3) at the robot wrist can be implemented with a 6-d.o.f. robot and a 6-axis force and torque sensor. The hand velocity is determined using virtual mass, virtual spring const., virtual dashpot const. and force/position feedback signals. The control command to each actuator of the robot is computed from the hand velocity. It is shown that these computations can be performed in 55ms or less.

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In this paper, we deal with the problem of designing an adaptive control system using the relay-type adjustment law.
First, three adaptive control schemes are proposed. The design method-1 is the scheme which utilizes the (2n_p+1) st-order adjustable parameter vector, the time functions of the number of 2n_p+1 and output error as the switching functions. The design method-2 is the scheme which utilizes the scalar adjustable parameter and the output error as the switching function. The design method-3 is the reduced order adaptive control system which is constructed by introducing the 1st-order filters.
Then, the proposed schemes are applied to solve the problem of constructing the C*-adaptive flight control system for a super-sonic aircraft. Simulation studies are presented in order to show the effectiveness and features of the proposed schemes.

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We treat a scheduling problem as follows: We have n jobs which are to be processed by any of m parallel facilities in a shop. It takes time Ti for any facility to process job i (i=1, 2, …, n), and a cost of c_ij is incurred during the changeover from job i to job j. Furthermore, each job i has a due-date D_i, and all jobs on each facility must be completed within a horizon of length H. The purpose is to find an optimal schedule, which is to partition the set J of n jobs into m subsets and to sequence the elements of each subset so that the due-date and horizon constraints are met and the total changeover cost is minimized. In this paper, we formulate this problem as a 0-1 integer problem, and present an efficient algorithm which makes use of the branch-and-bound method. It is shown that the algorithm can work efficiently, and, in particular, it can be apllied to some problems having upto 25 jobs. Furthermore, we propose a method of treating an extended problem that has no feasible solution satisfying the due-date constraint.

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