In this paper, we propose a model reduction method for linear systems evolving on large-scale complex networks, called dynamical networks. In this method, we construct a set of clusters (i.e., disjoint subsets of state variables) based on a notion of cluster controllability that characterizes local controllability of the state-space of the dynamical networks. We aggregate the constructed clusters to obtain a reduced model that preserves connection topology of the original system as well as the stability and some particular properties, such as steady-state characteristic and system positivity. In addition, we derive an H_∞-error bound of the state discrepancy caused by the aggregation. The efficiency of the proposed method is shown through a numerical example including a large-scale complex network.

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The objective of this paper is to analyze how children develop their spatial expression ability in 3-D space. We prepared a 3-D paint system that has “Translation-test”, “Rotation-test” and “Paper-layout-test”. As an experiment, we collected data by using our 3-D paint system for children between the ages of 4 and 6 in a pre-school in August 2009, January 2010, and August 2010. We conducted a survey on correlation between the system and WPPSI. The results are summarized as follows: 1) We classified children's spatial expressions into some expression patterns, 2) The data shows the trand that spatial expression ability in space becomes better with advancing ages; 3) We obtained correlations between the system and WPPSI. The system can analyze some abilities that are difficult for WPPSI.

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This paper describes a novel low-powered preamplifier for capacitive sensor using electret film such as a condenser microphone. Due to the expansion of sensor applications as ambient sensors such as the smart fire alarm, general purpose security sensor and vital sign detection sensor, it must work for at least one year with a small dry buttery. The conventional amplifier requires about 500µA current for the 3.0V voltage to make the sensor work stably. Even the recently developed capacitor-voltage transforming IC required the current in the range of 35µA to 530µA. In this paper, we present a preamplifier circuit combining the differential amplifier and the current miller transconductance amplifier which is robust to low frequency drift noise and the output is single (not differential) and low current driving circuit. The current required for stable operation of the sensor was 20µA, which is about one-twenty third of the conventional amplifier.

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This study proposes an idea that encourages driver's motivation to drive altruistically. We focus on an existing intersection that disturbs the throughput of upstream vehicles by right-turn vehicles waiting a gap acceptance to turn right. We investigated some scenarios that oncoming thru traffic mandatorily give a right-of-way to the right-turn vehicles to make enough time-gap for right turning. Here, it is assumed that the effects of giving a right-of-way to the right-turn vehicles are provided to a driver of approaching thru vehicle via onboard indicator. A verified traffic simulator examines the effects of prioritizing behavior on traffic flow. Numerical analysis showed that the traffic throughout in congested states was gradually improved when prioritized right-turn vehicles increases. Also, penetration of the prior right-turn vehicles is effective to mitigate not only the collision risk at the intersection but also the total CO₂ emission over the arterial road.

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The authors teach control engineering to the students in Mechanical Engineering Course, Osaka University. Although much effort has been devoted, the contents are not understood well. In particular, the essence of feedback control, i.e. the merits and the risks are not understood well. To ensure the understanding, this paper proposes to use an experimental control system to get personal experience in motivational lectures. The effectiveness of the proposed system and lecture is examined by a questionnaire survey.

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The Dynamic Positioning System(DPS) of a ship is evaluated by the capability to keep the position against the external disturbances as an important performacne index. Captains or DPS operaters usually decide the suitable heading direction while watching the thrust vectors producing to keep the position. In this paper, we present a DPS with an auto-turning function which automate such operations needed for experiences. The design strategy of the controller is derived by the stability in the sense of Lyapunov and L₂-gain performance analysis.

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This paper is concerned with the control problem of a class of nonholonomic systems having cross-chained structure. Cross-chained system is a class of nonholonomic driftless systems with two generators and second-order controllability, which are structurally incompatible with well-known chained systems. Feedback control for such a system requires us to find an entirely new control approaches different from the conventional ones designed for single generator driftless systems. In this paper, we propose a switched state feedback state which delivers the initial state to the origin in finite time using bounded control inputs, without infinitely high gain and frequent switchings in spite of the discontinuity of the feedback law. The effectiveness of the proposed method is shown by numerical simulations. Possible mechatronic applications of this class of systems include snake robots, rolling sphere control and the spherical ultrasonic motor.

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This paper deals with a fault-tolerant sensor network configuration by introducing a fault evaluation matrix and a compensation method of intermittent observation. A networked sensor system is designed by embedded local Distributed Kalman filters in each sensor, and the sensor agent has to estimate plant's state under the condition of sensor failure and intermittent observation. We propose two KF estimation algorithms which are based on a fault detection switching relies on a fault evaluation matrix and an imputation method by using estimate observation, respectively. Finally we show experimental results to analyze effectiveness of the proposed method.

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This paper considers a left-continuous dynamical system and exponential stability of periodic orbits in the system. Firstly, we introduce new continuity concepts with respect to initial conditions, and prove their equivalence conditions. Under the equivalence conditions, it is useful for analysis of exponential stability of hybrid periodic orbits to use those continuities differently according to where discontinuous jumps exist. Finally, we prove equivalence between exponential stability for a periodic orbit, and that for a fixed point of the generalized Poincaré map by applying the analysis method based on the proposed continuities.

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In this paper, we propose a trajectory tracking control law for snake robots on a cylindrical surface, which have passive wheels and active universal joints. It is necessary to avoid the sliding down for the robot to achieve locomotion on a cylindrical surface. Snake robots have two redundancies, one is dynamic redundancy and the other is kinematic redundancy. Dynamic redundancy means that control inputs are not determined uniquely since there are more inputs than the number of controlled variables based on dynamics. Kinematic redundancy is caused by introducing wheelless links and means that all joint velocities of the robot are not determined uniquely in order to achieve the desired velocity of the head of the snake robot. First, to consider the contact force and the frictional force between the robot and the cylindrical surface, we derive the dynamic model of the robot. Next, we indicate the conditions to achieve the avoidance of sliding down, and design the controller to satisfy the conditions by utilizing the redundancies. Simulation results demonstrate the validity of the proposed controller.

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This paper deals with the Simultaneous Localization and Mapping problem via H_∞ filter considering finite escape time. The estimation via H_∞ filter occurs finite escape time depending on the value of the parameter γ and then the estimation fails or deteriorates. In order to avoid it, we propose a novel algorithm of the update equation of the filter gain. The convergence of the error covariance matrices are proven. In simulation and experimental results, the avoidance of the finite escape time and the correctness of derived theorems for the convergence are confirmed and then we can show robot's state and environment information can be estimated.

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In this note, we treat the problem of estimating the initial value of a parallel-flow two-fluid heat exchange process with boundary outputs. We first state the observability results for the heat exchange process and discuss on the eigenvalues of the observability gramian, where the properties of self-adjoint compact operators play an important role. Next, we consider a finite-difference model for the process and show an estimation method of initial value of the approximated model using the Truncated Singular Value Decomposition (TSVD). We also give numerical simulation results.

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