The paper estimates the uncertainty of discharge coefficients of sonic Venturi nozzles, which have toroidal throats complying with ISO 9300, measured at the atmospheric pressure by a constant volume tank system developed as the gas flow primary standard in Japan. Total uncertainties of the coefficients at 95% confidence level are estimated at 0.14% and 0.05%, for the smallest nozzle of Reynolds number of 0.5×10⁵ and for the largest one of 2.5×10⁵, respectively. More than half of the uncertainty of the smallest nozzle is caused by diameter measurement. Total uncertainty of mass flow rate, which is independent of the diameter measurement, is estimated at less than 0.05% for all nozzles.

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It is interesting and significant if sport players can detect their playing form by themselves and feed back it in their training. This paper describes a new up/down sports motion sensor which is compact, not heavy, economical, free in setting to humans.
The sensor detects the up/down speed by differentiating the atmospheric pressure decreasing in proportional to the height. The change in atmospheric pressure is detected by using condenser microphones as the fine pressure detectors. The fine pressure detectors by the microphones involve the problems of characteristic in the low frequency range. Further because of its high sensitivity, the condenser microphones detect not only the change in atmospheric pressure due to up/down motion but also the pressure disturbances of air in the microphone chamber especially due to the acceleration and the kinetic energy component accompanied with the sport motion.
Here we investigated how the various pressures acted to the pressure detection surface of the microphone when moving, influence to the measurement of the up/down motion in sports and presented a new up/down speed sensor that catches only the atmospheric pressure change. Validity of the method was examined by detecting the up/down speed of head of a golf player when swinging.

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In marine development and harbor construction works, it is becoming important to directly produce high-grade raw concrete on ships to shorten the construction periods.
This paper proposes an automatic measurement system which accurately measures the weight (time-variant) of the raw materials on the ships. That is, the measurement system which automatically compensates the indication by load sensors through on-line estimation of the heaving and rolling of ships which act as disturbances in measuring the weight of the raw materials.

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Remotely sensed images have different geometrical distortion caused by change of orbits or posture of platforms. Precise registration of these images is very important in multi-temporal processing. There have been reported a lot of registration methods for multi-temporal processing of images. These methods require ground control point (GCP) pairs for describing the relative geometrical discrepancy between images, and for determining the transform function from one to another. Selection of GCP pairs is essential in these methods. It is, however, difficult and time consuming to select them precisely. Inadequate selection of them causes registration error.
For reduction of error in registration and time for selecting GCP pairs, we propose an automatic registration method ART. In this method, we assume that only small change occurs in the scene during the period between the first and the second sensing. The proposed method ART consists of three stages of processing, that is, taking initial GCP pairs, detection and division, and local Affine transformation (ATF: Affine TransFormation).
In the first stage, we take three GCP pairs on both images for making initial triangles T₁ and T₂. In the second stage, residual discrepancy after ATF of T₂ to T₁ is evaluated in the detection procedure. We use spatial correlation as a key for measuring discrepancy in the sense of spatial structure. If the residual discrepancy is detected, T₁ and T₂ are divided into two sub-triangles. These procedures are iteratively applied to the triangles until the geometrical distortion between the images is sufficiently corrected by local ATF. The third stage of ART is application of local ATF to each divided triangle.
In this paper, we describe the principle and the procedures of the proposed method. The validity of this method is confirmed by numerical simulation and application to actual airborne images.

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A simple method is proposed for determining the frequency response function G(jω) of a system using a pair of characteristic M-sequences.
When a characteristic M-sequence is sampled with q₁ and q₂, both of which are coprime with N, where N is the period of the M-sequence, the obtained pair of sequences have conjugate complex frequency spectrum. Making use of this fact, two characteristic M-sequences having conjugate complex frequency spectrum are applied to a system to be identified, and the output spectrums are calculated.
Taking the average of the products of the output spectrums, we can obtain the frequency response function of the system. Experimental results show a good agreement with the theoretical considerations.

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In a discrete time control for multi-input multi-output systems, when the response speed of output differs greatly each other, it is better to use different sampling periods for each output in order to improve the robustness of the control system and decrease the effect of the S/N ratio. This paper proposes a multivariable generalized predictive control method with multirate sampling model. The sampling and holding actions are done in a single short sampling period for all loops, while the plant modeling is carried out by multirate sampling. First, the single-rate sampling model and the multirate sampling model of the plant are derived. Next, the predicted future value of each output is expressed using the single-rate and the multirate sampling model, respectively. Then the cost function is so modified that sampling interval for prediction of each output is set differently corresponding to the response speed of each output in order to ensure enough prediction interval using a small costing horizon. By using this cost function, the control law is determined. The dynamics from the reference trajectory to the plant output of the proposed method using the multirate sampling model is shown clearly to be the same as that using the single-rate sampling model. The simulation results illustrate that the proposed method using the multirate sampling model is superior to the method using the single-rate sampling model in terns of the effect of the observation noise.

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This paper presents a discrete-time robust model reference adaptive control scheme for an uncertain plant with delay and shows the experimental results obtained by applying it to an actual air heating process.
The air heating process is described as a continuous-time system of first order with delay including parasitics. The adaptive control system is designed based on the discrete-time model, which is expressed in terms of δ-operator by combining the plant with a zero-order hold device, because the adaptive controller is intended to be implemented with a micro-computer. In the scheme, the dominant parameters of the discrete-time model are estimated by an adaptive law with relative dead zone taking account of the modeling errors and then the current estimates are used to determine the controller parameters. In the synthesis of the control input, the output error between the plant and the reference model is additionally fedback through a PI-type of fixed compensator to reduce the residual tracking error caused by the use of the dead zone. The proposed scheme worked well as expected in the experiment applied to the air heatig process and then it was verified that the scheme can be applied to practical plants with robust performance.

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This paper considers a tracking problem for a linear system with norm bounded time-varying uncertainties. The aim is to design a controller so that the system is quadratically stable for all allowable uncertainties and its output tracks the reference input which is represented as smoothly differentiable function as closely as possible. A controller having this property is given as a two-degrees of freedom controller. The feedback controller is designed by solving Riccati equations and the feedforward controller is designed as an inverse system of the nominal system. The conditions under which the system asymptotically tracks any constant reference input are considered. The method is applied succesfully to a position control system of a mechanical printing machine.

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This paper is concerned with determination of sampling frequencies for digital control of servo system such as industrial robots and industrial machines. Recently, digital control of servo system has been widely accepted in industrial fields. However, delay time caused by computational time of the digital control causes deterioration of control performances if the sampling frequency of the sampler is not appropriate one. We had proposed a method for a requisite sampling frequency for a single sampler system. The result was derived based on theoretical background and gave a reasonable one. We further developed the previous work of the sampling frequency. In this study, we investigated the determination of two sampling frequencies for position loop and velocity loop of multi-samplers servo system. The problem was analysed in S plane, but not in Z plane, then the derivation of the formula for appropriate sampling frequencies was successful. By using the formula and the given system parameters of an equipment such as gains, we can obtain appropriate sampling frequencies for position loop and velocity loop of the servo system easily. The obtained results were evaluated by an experiment with a personal computer of digital controller and analog computer of simulated servo system. We obtained satisfactory experimental results of sampling frequencies. The proposed method for determination of sampling frequencies will be applicable widely in industrial fields to determine the sampling frequencies of the digital servo systems.

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The purpose of the head positioning control of hard disk drives is to move the magnetic head onto the desired track swiftly and to keep it on track precisely against various disturbances and plant uncertainty at high frequency. In this paper, we apply H^∞ control to the head positioning of hard disk drives. The advantage of H^∞ control is that it yields robust feedback system and the trade-off between various specs is easily incorporated into the design. Further, to obtain a good transient response, we adopt the two-degree freedom control scheme. Experimental results are presented to demonstrate the control effects.

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There have been a lot of literature on the master-slave systems. Therein, the aim of control has been developed from an ancient and simpler one, i.e., from unilateral into bilateral servo, from manipulators with same configulations into ones with defferent ones, and so on.
In controlling the master-slave systems, however, ‘manipulating ability’ is very inportant. The good manipulating ability mean here that an operator can handle the master-slave robot arms and manipulate an object as if he directly manipulated the object.
In this paper, we propose a new control method of master-slave systems by using the model reference adaptive control (MRAC) which has ‘reference model estimation’. The reference model, which describes the object dynamics, is estimated from position and force at slave arm, and master and slave arm are controlled separately by MRAC to track the reference model output.
The advantages of this control method are 1) while the system is bilateral and the operator can feel the interactive force between slave arm and the object, he doesn't feel the dynamics of master-slave system, 2) as the reference model is estimated in real time, the system is adaptive to objects which have unknown or changing dynamics, 3) in case of presence of transmission delay between master and slave such as a space robot, the reference model on master site is considered as the model of slave site and the operator can manipulate the object without consciousness of delay.
First we describe the way to design the controller, and then numerical simulations and experiments illustlate these advantages.

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Recently, a pneumatic servo system is expected to be applied to various automation systems, because it has some advantages such as high power/weight ratio, functions of impact absorption and rigorous force control owing to air compressibility. However, the compressibility makes it a high order and nonlinear system, so its exact modelling and parameter estimation are not easy. To cope with this problem, the development of the control scheme with the robustness for disturbances and parameter changes are required.
We apply a disturbance observer, which is one of methods to attain the robust control, to the position and force control of a pneumatic servo system comprising a bellofram type pneumatic cylinder and a PCM digital control valve. The content of this paper is summarized as follows.
1) To compare the robustness of some types of control systems, we propose a estimation function being the ratio between open loop transfer functions included in the sensitivity function. Referring to this estimation function, control parameters can be rationally adjusted to improve the robustness of control system.
2) Comparing dynamic responses of the control system using a disturbance observer with the usual PI control system, it is proved that a disturbance observer is more effective to lower the sensitivity to both disturbances and plant parameter changes.
3) To avoid the trade-off problem between the low sensitivity and the high stability in the conventional control system using a disturbance observer, we add a compensator in the feedback loop of control input. The improved control system can provide the sufficient stability without sacrificing the low sensitivity to parameter changes.
4) The robust control system using a disturbance observer can achieve the satisfactory position and force control. Its availability to a pneumatic servo system is confirmed.

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Bearings are the components of rotary machinery, which are easiest to fall into faults. This paper describes how to identify standard numbers of the ball bearings and diagnose their failure modes from scream when they are rotating.
We apply techniques of the neural networks to the identification and the diagnosis. Here we present an architecture of the hierarchically structured multi-layer neural networks. The tasks of identification of the number of bearing and diagnosis of the failure mode are allotted to each hierarchical stages, by which the efficiency of learning and recognition by the network can be improved.
The standard number of a bearing is identified by directly feeding the line power spectrum under the frequency normalized by the revolution frequency to the first stage of the network. The revolution frequency is estimated from the sound of scream. Failure is diagnosed by the networks in the second stage by the information of the standard number of ball bearing, the repetitive frequency of the spectrum and the stationary or nonstationary of the scream.
The ability of associative memory of the neural network can reduce the effect of noise and error in the signal.
The identification and diagnosis of bearings were carried out both by simulation and experiment. We found the hierarchical neural network proposed could effectively identify the standard number and diagnose the faults.

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A computer-based operation system for a cyclotron which assists inexperienced operators has been developed. Cyclotron start-up operations require dozens of adjustable parameters to be finely tuned to maximize extracted beam current. The human interfaces of the system provide a visual environment designed to enhance beam parameter adjustments.
First, the mental model of operators is analyzed. It is supposed to be composed of five partial mental models: beam behavior model, feasible setting regions model, parameter sensitivity model, parameter mutual relation model, and status map model.
Next, based on these models, three visual interfaces are developed, i.e.,
(1) Beam trajectory is rapidly calculated and graphically displayed whenever the operators change the cyclotron parameters.
(2) Feasible setting regions (FSR) of the parameters that satisfy the cyclotron's beam acceptance criteria are indicated.
(3) Search traces, being a historical visual map of beam current values, are superimposed on the FSRs.
Finally, to evaluate system effectiveness, the search time required to reach maximum beam current conditions was measured. In addition, system operability was evaluated using written questionnaires. Results of the experiment showed that the search time to reach specific beam conditions was reduced by approximately 65% using these interfaces. The written questionnaires survey showed the operators highly evaluate system operability.

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We propose the concept of Active Human Interface (AHI) that makes the machine (computer and/or robot) respond to human being more actively and for establishing the new paradigm to realize the AHI, as the first step of this study, we investigate the method of machine recognition of human emotions.
This paper deals with the neural network method of human emotion recognition from facial expressions. Facial expressions were categorized into 6 groups (Surprise, Fear, Disgust, Anger, Happiness and Sadness), and obtained CCD camera-acquired data with respect to facial characteristic points relating to 3 components of face (Eyebrows, Eyes and Mouth). Then we generated the position information and shape information about the 6 basic facial expressions for 30 clients. These information were input into the Input units of the 4-layered neural network and network learning was carried out by back propagation algorithm. The neural network recognition system of facial expressions showed a high recognition rate up to 80% to 6 basic facial expressions for both the position and shape information and particularly the system showed a smaller rate of mis-recognition between some of 6 basic expressions.

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In this paper degrees of fixed modes are characterized in terms of nullities of subsystem matrices and rank deficiencies of corresponding feedback structured submatrices. The obtained results enable us to eliminate plural fixed modes effectively.

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This paper presents a local modification method for a manipulator trajectory to avoid moving obstacles in the work space. The initial joint trajectories described by B-spline curves are modified to satisfy the condition that none of links of the manipulator collide with the obstacles.

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