This paper describes a new method of walking speed estimation by a simple accelerometry of ambulatory movements, aimed at a precise quantification of energy consumption. It was postulated that walking speed variation reflects both strength and frequency of pelvis vibration during walking. Therefore, amplitudes of vertical acceleration that come along with walking speed variation were evaluated in terms of the signal energy in walking frequency band 1-3Hz. According to the Parseval's Theorem, signal energy can be applied both in time domain and frequency domain signal processing. The relationship between the walking speed and the signal energy was investigated considering aging. A portable instrument attaching on the waist measured vertical acceleration. Then, an estimate equation of walking speed as a function of signal energy was formulated from the experimental results of 199 subjects including young and elderly people. To validate the estimation, another 85 elderly people including 5 subjects who walked with the aid of sticks were investigated. The subjects were instructed to walk on a 16-meter strait level track at self-selected normal walking speed individually. Walking speed was estimated for 10 second continuous walking. Lap time was also measured to evaluate real walking speed. Results showed that the walking speed was accurately estimated by the proposed method (95%). It was also confirmed that this method could be applied to estimate the walking speed of both young and elderly people, but not those who walk with the aid of sticks.

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There are two problems to be solved for this study; first of all, emissivity change of a steel sheet caused by oxidation, and secondly background radiation noise filled in a furnace. In order to overcome these problems, we have achieved the following two methods. The one is the use of polarized radiances for emissivity compensation. This method enables to measure both emissivity and temperature of the object. The other is the installation of a pseudo-blackbody radiator into the furnace, which enables to remove background radiation noise filled in the furnace and to supply constant reference to a radiometer.
The measurements of emissivity and temperature have been achieved within the errors of 12% and 0.96%, respectively for stainless steel at the temperature range of 1300K. By installing the pseudo-blackbody into the furnace, background noise equivalent temperature error has been suppressed within 4K.

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This paper is concerned with the mixed H₂/H_∞ control problem. The purpose of this paper is to give iterative methods for obtaining a sub-optimal solution for the mixed H₂/H_∞ control problem. The key idea of our methods is to construct “controller sequences” that converge to the H₂ optimal controller. Using the controller sequences two iterative algorithms are proposed. The obtained controller is either the global optimal solution or a sub-optimal solution on the boundary of the H_∞ constraint. The effectiveness of the proposed methods is shown by numerical examples.

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This paper considers a synthesis problem of output feedback controllers for linear time-delay systems via infinite-dimensional Linear Matrix Inequality (LMI) approach. We first present a memory observer-based stabilizing output feedback controllers for linear time-delay systems. Based on this result, we derive an existence condition and an explicit formula of memoryless/memory observer-based output feedback controllers, which guarantee the internal stability of the closed loop systems and a prescribed level of L₂ gain of closed loop systems. Next, we introduce a technique to reduce conditions for synthesis in the form of infinite-dimensional LMIs to a finite number of LMIs, and present a feasible algorithm for synthesis of controllers based on the finite-dimensional LMIs. Finally we demonstrate the efficacy of the proposed output feedback controllers by numerical case studies.

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In this paper, Unfalsified control concept is applied to the parameter space design problem of PID gains for mixed sensitivity control problem, and a new method of drawing unfalsified region on the parameter plane is proposed. This method does not require constructing a mathematical model for design, but draws the unfalsified region directly from the input-output responses of the plant. Therefore, it is expected that this method can be applied to complex nonlinear plants. By numerical experiments, it is found that sufficiently large region cannot be falsified by using a step response data, but can be falsified by using the responses of the plant excited by sinusoidal inputs for many frequencies. If the unfalsified region is empty, it can be concluded that no solution exist. Usefulness is demonstrated by a numerical example for a nonlinear plant with backlash.

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The class of piecewise affine systems (PASs), which is a typical subclass of hybrid systems, is useful to describe dynamics of many kinds of real-world systems. Although the class has recently attracted much attention, there has not been enough results on analysis and control of the systems. This paper considers L₂-gain analysis problem for PASs whose dynamics switch depending not only on their states but also on exogenous inputs. The class of piecewise quadratic functions is adopted to construct storage functions, and an analysis condition is given via the functions.

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This paper proposes a new method of continuous-time model identification from sampled I/O data by using an adaptive observer. The boundedness of the parameter estimate and the exponential convergence of the parameter estimate error to 0 under the PE assumption are guaranteed. In order to identify the plant from a finite number of I/O data, an adaptive observer of a backward system is also proposed.

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In the casting industry, self-transfer-type automatic pouring system, such as synchronizes the movement of the ladle to than of the mold line and pours the molten metal to a pouring basin in the mold has been developed. However, this system has the problem that sloshing (liquid vibration) of molten metal in the ladle occurs when the ladle transfer accelerates. Consequently, when the pouring stream of molten metal behaves violently by sloshing of molten metal in the ladle, molten metal cannot be poured into the mold accurately. And, since contamination is generated in the molten metal by sloshing, the quality of casting products is degraded. Therefore, this paper proposes a new control design concerning with the tracking control to a moving mold and sloshing suppression control to the liquid in the ladle. In the proposed system, 2-DOF control system is applied to track the ladle to the moving mold. The time varying gain filter is given in the 2-DOF control system in order not to occur the sloshing at the beginning of tracking to the mold line and after that, track smoothly to mold line. Furthermore, for sloshing suppression control, controllers are designed by Hybrid Shape Approach that considers both time and frequency characteristics. The controller designed by Hybrid Shape Approach has a notch filter corresponding to natural frequency of sloshing of liquid in the container without direct feedback of sloshing in order to suppress the sloshing. The effectiveness of the proposed control system is shown through experiments in a liquid container transfer.

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In this paper, we discuss control of contact coordinates between a sphere and a plane with pure rolling contact by using iterative closed paths on the sphere. First, we show that there exist two lines with fixed-length interval on reachable area by the closed path. Utilizing the result, we propose a method which brings all the contact coordinates to a target point by the iteration of a finite number of the closed paths. A numerical example shows the effectiveness of the proposed method.

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In this paper, we propose a high-performance VLSI architecture for very high-order FIR filters based on distributed arithmetic. By using the distributed arithmetic of which the processing time depends only on word length, small latency can be realized in high-order FIR filters. Also, to decrease drastically power dissipation, the optimum function circuit which we have previously proposed is utilized. Further, the proposed architecture attempts to realize simultaneously smaller latency and lower power dissipation while sampling rate is kept constant. To achieve this objective, we propose newly two methods to utilize linear-phase characteristic using SFA(Serial Full Adder) and a high-speed 4-2 adder. Finally, we evaluate a 240-tap processor based on the proposed architecture. Consequently, we show that the proposed VLSI architecture is very effectively for very high order FIR filters.

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In this paper, we propose a new genetic local search named GLSDC (a Genetic Local Search with distance independent Diversity Control) by extending the basic idea of DIDC (a genetic algorithm with Distance Independent Diversity Control) to coarse grained parallelization. GLSDC employs a local search method as a search operator. GLSDC also uses genetic operators, i.e., a crossover operator and a generation alternation model. However, in GLSDC, the crossover operator is not used as a search operator, but is used only for converging the population. GLSDC has an ability to find multiple optima simultaneously by stacking good individuals that have been found by the local search. Finding multiple optima is often required when we try to solve real world problems. The effectiveness of the proposed method is verified through numerical experiments on several benchmark problems.

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The mechanical characteristics of materials are described by appropriate mathematical models as a basic technique for the manipulation of their corresponding virtual objects. In this study, virtual objects are assumed to consist of combinations of viscoelastic elements. Their dynamic characteristics are given within and beyond the range of elastic limitation of the edges of the elements by the calculation of their discrete-time models. Then, a sheet-type virtual solid object with various physical properties is theoretically cut by knives where their cutting mechanism is analyzed under some assumption. The resistance moment to the grips of knives on their cutting of synthesized material is confirmed similar to the actual one on the cutting of its corresponding actual material.

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Recent progress in linear motor and mechanical technologies shows the possibility of constructing multi-car elevators (MCE) that have several elevator cars in a single shaft. While remarkable improvement of performance of vertical transportation in high-rise buildings is expected with MCE, we have to develop not only the hardware of MCE but also a control strategy for them to achieve such expectation. Because of the complexity of MCE, applicability of control techniques for conventional elevators to the MCE is limited, and we need to start the research of control strategy from scratch. This paper discusses development of controllers for MCE through simulation-based optimization using a genetic alrogithm. First, a simulator of MCE that has sufficient precision to discuss realistic MCE is developed. Second, the effect of a simple control strategy for MCE is examined with the developed simulator. Finally, a genetic algorithm is applied to refine the control strategy of MCE through simulation-based optimization.

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By using velocity estimation a new robust trajectory tracking control scheme is developed in this paper for wheeled mobile robots. The developed controller has the following features; i) The proposed controller has robustness not only for the weight and the moment of inertia but also for radius of wheels and distance from the reference point to both wheels. ii) It is easy by using design parameters to improve tracking performance.

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A result is presented suggesting a robustness property of the LQ regulator. We consider such a situation that the full state is accessible but accompanied by unexpected observation error or noise. In the noise-free case, the minimum cost J₀ makes a trivial upper bound on the state-regulation error, and there is some margine because of the control power inclued in J₀. This margine plays a role of absorbing the loss caused by the state-observation error. In other words, the state-regulation error never exceeds J₀ as long as the power spectral density of the state-observation noise is bounded by a certain constant matrix.

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