In this paper, discrimination of material and detection of the thickness and distance between the sensor and the material are presented by the proposed sensor. The proposed sensor uses a pair of CdS cells as the electrodes of the plane type capacitance sensor and measures capacitance by changing the strength of emission of the light emitting diode (LED). Several capacitance values are obtained by the proposed sensor because the resistance of CdS changes. Accordingly, the optical and electrical properties of the object are obtained from capacitance values. In this experiment, discrimination of two kinds of sample materials and detection of the thickness and distance between the sensor and the material were demonstrated by the proposed sensor. As a result, it was suggested that discrimination of insulating and conductive materials including detection of the thickness between 2 mm and 10 mm and the distance between 1 mm and 4 mm were possible by the proposed sensor.

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The method of paired comparisons is one of the most effective methods to scale an ambiguous quantity in the sensory evaluation. It is relatively easier to compare and choose one from two samples than to choose directly. Good results can be obtained easily even when examinees are not specialists. However, the number of comparison becomes an issue of this method. It is required to compare n (n-1)/2times to make the complete paired comparison table. When the number of the samples becomes larger, the number of comparison becomes too huge to compare all pairs. A band function model paired comparison (BMPC) method is one of the paired comparison methods. Since BMPC method uses inequalities to solve the paired comparison table, not all comparison is needed. In this paper, the new sequential solution method to solve paired comparison method is proposed. By the method, not n (n-1)/2times compares are required to solve n samples paired comparison. The validity of proposed method are confirmed by simulation, and it becomes clear that it is possible to set scale values to each samples without30% comparison on avarage. We applied the proposed method to the actual pitch comparison experiment. Consequently, we succeeded to obtain the result which is absolutly same as complete result by an incomplete paired comparison by using the sequential comparison method.

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Opt-acoustical measurement is a potential candidate of non-invasive measurement over the acoustic wave field. In this paper, a novel method for grading vector measurement of the sound pressure field which is based on the Fraunhofer diffraction is proposed. The proposed method has an ability to capture the projection of the gradient vector of acoustic wave field through the eccentricity of the zeroth-order Fraunhofer diffraction. In this study, the theoretical analysis of the process of the above projection is discussed and their physical meanings are investigated through numerical experiments and acousto-optical experiments.

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This paper characterizes easily controllable single-input-single-output (marginally) stable continuous-time plants in a quantitative manner by way of best achievable performance in H∞ loop shaping design. The characterization is based on a finite frequency phase/gain property, which we call Condition (π), and the achievable performance level for any 2nd order system satisfying this condition is proven to be bounded from above by the value γDI=√4+2√2. A simple procedure for the choice of a weighting function in H∞ loop shaping design is proposed based on the obtained knowledge, and its effectiveness is confirmed by a numerical example.

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This paper considers less conservative control design of gain-scheduled controllers on matrix polytopes. To achive this aim, first we use extended LMI representation which allows for parameter-dependent Lyapunov functions. Second, we focus on the time derivative of the Lyapunov variables and consider how this term can be sharply evaluated to reduce the conservatism of design. A numerical example illustrates the effectiveness of the proposed method.

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In industrial production processes, important variables such as product quality are not always measured on-line. Therefore, to reduce of specification products and enhance productivity, the development of accurate softsensors (virtual sensors) is crucial. Softsensors enable us to estimate unmeasured key variables and use the estimates for feedback control, which is referred to as inferential control. In the present work, two-stage subspace identification (SSID) is proposed to develop highly accurate softsensors that can take into account the influence of unmeasured disturbances on estimated key variables. The procedure of two-stage SSID is as follows: 1) identify a state space model by using measured input and output variables, 2) estimate unmeasured disturbance variables from residual variables, and 3) identify a state space model to estimate key variables from the estimated disturbance variables and the other measured input variables. The proposed two-stage SSID can estimate unmeasured disturbances without assumptions that the conventional Kalman filtering technique must make; thus it can outperform the Kalman filtering technique when innovations are not Gaussian white noises or the characteristics of disturbances do not stay constant with time. The superiority of the proposed method over the conventional method is demonstrated through numerical examples.

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This paper presents a new framework for closed-loop identification of linear continuous-time systems directly from the sampled I/O data based on trial iterations. The method achieves identification through ILC (iterative learning control) concepts without any knowledge of compensators in the loop. The robustness against measurement noise is achieved through both projection of continuous-time I/O signals onto a finite dimensional space and noise tolerant learning algorithms. Its effectiveness is demonstrated through numerical examples for a linear, non-minimum phase and unstable plant.

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Model predictive sampled-data control of constrained, linear, time-invariant, continuous-time plants is considered. The time-discretization of the prediction horizon may be non-linear, in order to reduce the computational complexity of online MPC methods by lowering the number of optimization variables for a given prediction horizon length. The main contribution of this paper is to propose two closed-loop performance measures in order to evaluate the salient performance properties of non-linearly time-discretized prediction horizons. A numerical motivating example comparing two prediction horizon time-discretizations with an order of magnitude difference in the number of optimization variables is discussed, and subsequently the results of a sensitivity analysis of the two proposed performance measures with respect to the prediction horizon time-discretization are presented. The use of non-linearly time-discretized prediction horizons is also shown to be relevant for complexity reduction in offline MPC strategies.

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In this paper, structural decomposition of linear periodic continuous-time systems is discussed. It was conjectured by Bittanti and Bolzeron that there exists a periodically time-varying coordinate transformation with the same period of a given linear periodic continuous-time system that splits the system into its controllable and uncontrollable parts. However we have shown that there is a counterexample to this conjecture. In this paper, we firstly study basic properties of controllable/reachable subspaces for linear periodic continuous-time systems. Then we derive a necessary and sufficient condition for the existence of a periodically time-varying coordinate transformation with the same period of the system that splits the system into its controllable and uncontrollable parts.

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This paper proposes a design method of stabilizing state feedback for distributed parameter systems of parabolic type with adaptive observers. The distributed parameter system with unknown coefficients is described by evolution equations in Hilbert space. The structure of adaptive observer using filtered values generated from input and output is stated. Moreover, control law using estimates of unknown coefficients is derived. Finally, by assuming the persistency of excitation, stability of the proposed control system is shown.

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This paper discusses a design problem of robust control systems with adaptive gain controllers for a class of uncertain linear systems. The uncertainties under consideration which are composed of matched part and unmatched one are bounded, but its upper bounds are unknown, and the proposed controller consists of a fixed gain controller and a variable gain controller. In this paper, on the basis of piecewise Lyapunov functions, we show sufficient conditions for the existence of the proposed robust control system with the adaptive gain controller. Finally, numerical examples are presented to demonstrate the effectiveness of the proposed controller.

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This paper presents a method for acquiring control rules for autonomous mobile robots by the Boosting algorithm. This algorithm is to search a set of rules with a high control performance by assembling simple low performing control rules one by one using teaching results by teaching play back. In this search process, the rules that contribute to the improvement of the control performance are found and they can be applied to a tuning of control rules described and given beforehand by a designer. This algorithm achieves a combination of merits of teaching play back and those of rule description, i. e. the given rules by the designer work fairly well against environmental/task changes, and the performance improving rules obtained by the boosting algorithm are effective for enhancing the control performance under limited conditions. The proposed method is applies to a corridor passage problem for a mobile robot. It is shown that the extraction of performance improving rules is easier by the proposed method than by the conventional method, and the performance improvement of the existing rules under a limited environment is achieved by adding the obtained rules, and against a change of the corridor the control performance of the rules is kept by the existing rules.

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This paper examines effects of risk compensating changes in behavior when an automated safety system is introduced and when the levels of the automation are varied. Two experiments were conducted using a microworld. The first experiment clarified the differences in the human's operation method and the operation risks among three control modes:(1) no aid is given to the human,(2) a warning signal appears when necessary, and (3) a warning signal appears and then the automation intervenes into control to prevent an accident. The results show significant risk compensatory changes in behavior when the safety system not only provides a warning, but also performs safety control actions, when necessary. It was also discovered that even if the automation system functions properly, new types of accidents arise, resulting in an equivalent number of accidents. The second experiment examined whether the change in behavior when the level of automation changes depends on the direction of the automation level shift. The results show that the risk reducing behavior change that occurs when the level of automation is decreased is not as significant as the risk compensatory change that occurs when the level of automation is increased.

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Synchronization tapping is a psychological task for studying timing control mechanism. In this timing mechanism, negative feedback in phase error correction and period error correction has been assumed. The effect of phase error was already measured and its negative feedback process was studied, however the effect of period error has not been clarified yet. Therefore, we directly controlled the period error in synchronization tapping task to study the feedback mechanism. And Dual task method was further applied to analyze the influence from attention. As a result, it is suggested that the period error correction is a negative feedback process and the role of attention is also clarified. This new observation will contribute not only for the basic psychological research but also for the human interface application.

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Vol. 43 (2007) No. 9 p. 782
修正箇所：その他

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