Collinear acoustooptic (AO) switches are investigated for use in label recognition system in photonic routing systems. The optical label discussed in this paper uses optical codes which are encoded in the time domain. Short optical pulse trains representing the codes are processed with integrated AO devices. Some device configurations for label recognition are proposed with the basic operation mechanism. A numerical example for the code recognition is also presented.
The holographic information recording provides ultra-high density and fast read/write by using storage media in three-dimension. We developed the hologram multiplexing evaluation system to achieve ultra-high density recording. In this study, we investigated two methods of hologram optics, two-beam optics and collinear one. The two-beam optics gave a recording density of about 2.6 Mbit/mm2, however, this value is not enough for ultra-high density recording. This is because of the diffraction limit of objective lens induced by optical configuration. However, the collinear optics does not have the structural limitation because the optics of signal beam and reference beam is in co-axial. Furthermore, to increase the recording density we developed the method of the dynamic reference pattern recording. As the results, the recording density of 430 Mbit/mm2 was obtained, which corresponds to the recording capacity of 0.5 TByte for a disc with size of 12 cm.
An immunity testing method for electrostatic discharge (ESD) is being specified in IEC 61000-4-2, in which the contact discharge of an ESD-gun is being normally specified. Air discharge testing is known to be a severe immunity test compared to the contact discharge testing, while the discharge current injected is not well reproduced. Grasping the behavior of the current injected by the air discharge would be helpful in establishing the worst-case ESD immunity testing. We thus previously measured the discharge currents for air discharge testing onto the IEC recommended current transducer with a commercially available ESD-gun, and showed that there exists a specific relationship of Ip·trζ/VC=constant (ζ=0.75), between rise time tr and current peak Ip. The current transducer, however, has frequency dependent transfer impedance, which should affect the measured current waveform. In this study, we investigated if the above-mentioned specific relationship can be obtained for air discharge of an ESD-gun onto a ground that assumes a metal enclosure of electronic equipment under test. A method was presented for estimating the discharge current from simultaneously measured magnetic fields with two magnetic field probes regardless of the distance between the gun discharge-point and the probe position. This method was validated for contact discharge of an ESD-gun to a SMA connector. With this method, we estimated the discharge currents injected onto a ground for air discharge testing of an ESD-gun with intentionally fast and slow approaches. As a result, we could confirm a specific relationship between rise time tr and current peak Ip of Ip·trζ/VC=constant with ζ=0.57 independent of charge voltages and gun approaches.
In a city, roadside trees are regularly pruned. The pruning also not only changes the shape of the trees immediately but also changes subsequent growth of them. In addition, artificial illumination, which is caused by the light coming in through windows or caused by street lights, changes growth of the trees. Such conditions are not supported by the conventional tree growth models. Thus, we developed the growth simulation system of trees in city environment. The system has an interactive pruning interface including the functions for assisting the pruning. And the system grows trees after the pruning by referring the illumination environment of the city. In the experiment, a shape of a tree which has branches biased to the pavement side was generated by using the system. Moreover, the tree shape with a thin branch connected to a thick trunk was successfully generated by repeating the pruning and the growth. They are the features well seen to street trees.
Because something to think about and conversation with someone disturb the attention to the car driving, decentralization of attention by the cellular phone call tends to decrease safety in driving. This paper presents an experimental result of the relation between the attention concentration on the cellular phone call and the change in the facial expression such as eye movements and blinks. Moreover, this paper describes a method of detecting the depth of the attention concentration from the facial expression change.
The full-digital audio amplifiers have several merits such as a high power enabling a small size of the amplifier and digital implementation of the signal processing which allows desired precision of the processing except for the final stage switching amplifiers. Unfortunately, the pulse width modulation (PWM) causes signal distortions because of the non-linearity of the modulation from the viewpoint of the transient response. This paper proposes a compensation method of the PWM distortion with feedback approach. In the noise-shaping filter of the delta-sigma modulator to calculate the pulse codes for the PWM, the distortion caused by the PWM is evaluated and fed it back to compensate the distortion. Eventually the filter is implemented as a state-variable filter with non-linear feedback from the quantizer. The calculation of the filter elements is also described. By using proposed filters, PWM signals with small distortions and small floor noise can be obtained to realize high-fidelity audio amplifiers.
Today, laser radar is widely studied as in-car radar. The laser radar has a characteristic that the received signal becomes to be buried in noise with increasing distance. When the long distance is measured, it needs a high power laser, or the repetitive process that uses multiplication and integration. Therefore, a new type of the chaos laser radar has been studied. This laser radar is relatively resistant to noise and can simply process because of using only additional process. But, the chaos laser radar has been off-line processing thus far. Then using FPGA in the signal processing, the on-line measurement system is developed. As a result, the distance up to 95m can be measured on-line.
We report on a position measurement system for a mobile miniature robot using moving marks. Three lasers mounted on three linear stages are used as moving marks, and three position sensitive detectors (PSDs) are installed on the robot. The position of the miniature robot is measured by the laser position and the PSD output. The position of the lasers determines the macro position of the robot, and the output of the PSDs detects the micro displacement of the robot. By using the moving marks, the measurement system can avoid an obstacle on the laser beam path.
The progress of digital audio technology enabled the familiar use of the products such as CD and DAT in the acoustic measurement. For example, a signal reproduced with CD player is inputted into a subject of measurement and DAT recorder records its response. However, the sampling cannot be synchronized completely with the input signal although both nominal sample rates are set up equally, because player and recorder work independently. It is the most popular software solution to perform the synchronous addition after converting the recorded signal into the original sampling rate. However, the rate conversion also has the error due to the windowing in the high frequency region of processed signal. This paper proposes a new method for averaging asynchronous sampling data to solve these problems. To evaluate performance, the transfer function of only measuring equipment estimated from asynchronous sampling data was compared with the measuring result in synchronous sampling condition. Both results agreed within 0.1dB, so the effectiveness of new method was confirmed. In measuring the frequency response of BPF under injecting white noise, the proposed method was compared with the method using rate conversion. As a result, the noise reduction was almost the same, and the processing time was reduced to about 1/4.
One of authors previously has proposed the Initial Value Compensation (IVC) method at mode switching for head positioning servo of magnetic disk drives. The basic consept of IVC is to cancel undesirable poles of the closed loop system by zeros. Zeros of the transfer function between the head position and the state variables of the plant and the compensator can be relocated by injecting suitable values to the state variables of the compensator at mode switching via the IVC gain. However, in the previous study, the class of relocatable zeros has not been clarified. Furthemore, the degree of freedom of the IVC gain has not been studied. In this paper, these problems are investigated. First, it is clarified that the class of relocatable zeros is concerned with zeros of the transfer function of the plant and poles of the transfer function of the compensator. Second, by using the degree of freedom of the IVC gain, the optimization method for zero-input responses is proposed. Finally, numerical results for the head-positioning servo system of the magnetic disk drives are given to show the effectiveness of our proposed method.
The “Ifbot” robot communicates with people by considering its own “emotions”. Ifbot has many facial expressions to communicate enjoyment. These are used to express its internal emotions, purposes, reactions caused by external stimulus, and entertainment such as singing songs. All these facial expressions are developed by designers manually. Using this approach, we must design all facial motions, if we want Ifbot to express them. It, however, is not realistic. We have therefore developed a system which convert Ifbot's emotions to its facial expressions automatically. In this paper, we propose a method for creating Ifbot's facial expressions from parameters, emotional parameters, which handle its internal emotions computationally.
A forward-propagation learning rule (FPL) has been proposed for Neural Network (NN) to learn an inverse model of a controlled object. A feature of FPL is that the trajectory error propagates forward in NN and appropriate values of two learning parameters are required to be set. FPL has been only simulated to several kinds of controlled objects such as a 2-link arm in a horizontal plane. In this work, we applied FPL to AIBO so that we showed validity of FPL on a real controlled object. At first, we tested a learning experiment of an inverse dynamics of a 2-link arm in a sagittal plane with viscosity and coulomb friction by computer simulation. In this simulation, low pass filter (LPF) was applied to realized trajectories because coulomb friction vibrates them. From results of simulation, we found that the learning process is stable by some adequate sets of the learning parameters although it is more sensitive to the values of the parameters owing to friction and gravity terms. Finally, we tested applying FPL to motor control of AIBO's leg. The inverse dynamics model was acquired by FPL with only about 150 learning iterations. From these results, the validity of the FPL was confirmed by the real robot control experiments.
This paper concerns fault diagnosis for sequential control systems controlled by logic controllers. Incompleteness of the system model is regarded as nondeterministic. The considered systems are modeled by set-valued functions. Thus, the system model has more than one transition in each state of it. We propose a state space generation algorithm of the closed loop system of the plant model and the corresponding logic controller. Then, we show that the proposed algorithm yields only expected normal operation. Finally, we apply it to fault diagnosis for sequential control systems based on an idea that a nonexistent state and/or transition is faulty.
Recently it became very common to use information devices such as PCs during presentations and discussions. In these situations, a need arises for techniques that allow a smooth switch of presenters without changing cables, or an easy screen sharing in case of remote videoconferences. In this paper, we propose a desktop screen sharing system that can be used for such purposes and situations. For that, we designed an automatic control of connections in the VNC system that can be operated remotely over the network. We also suggested an interface that assigns a role such as “Screen sender" or “Screen receiver" to each terminal. In the proposed system, while sharing a screen between multiple terminals, one can easily display and browse the screen without having to understand how the others are connected. We also implemented a “role card" using contactless IC card, where roles are assigned only by placing the card in the IC reader.
We discuss a realization method of basic 1-bit signal processing based on Delta-Sigma modulation in this paper. Additionally, we show the characteristics of basic 1-bit processor and an effective design method from the view point of SNR. As the application of the 1-bit signal processing, we proposed a realization method of high-order filters based on Delta-Sigma modulation. We applied the effective design method to decide coefficients of a 4th-order butterworth low pass filter. We show that the filter designed by using the proposed method achieves the highest SNR.
In authors programming practice class, students create animation as programming practice because this type of practice will make students interested in learning programming. This type of animation creation practice is well received by students. For the animation creation, we provide students with material such as fundamentals for creating basic animation, explanations, there of usage of the information, basic animation creation method, its application and its programming example in printed form (black and white). However, it is difficult for students to see the actual color or motion in printed material, because some of the animation is only shown on the screen and it is difficult for the students to actually reproduce the motion or examine the source program by themselves. In order to overcome those problems, we have developed teaching material on the web and actually used them in programming practice class. In this paper, we give the general description of programming practice, the objective of developing the teaching material on the web and guidelines, for it, a general description of the material, their its effectiveness.
In order to fabricate the three-dimensional magnetophotonic crystals (3D-MPCs), we prepared the artificial opals composed by amorphous SiO2 spheres with diameter of 500 nm using gravitational sedimentation. These artificial opals had continuous net of voids between a-SiO2 spheres, which was filled with different type of magnetic materials. Characteristic properties of 3D-MPCs were studied by different experimental techniques. We found that magnetic and optical properties of opal-magnetic material composites retained the features of 3D-PC.
We cannot record biological signals, e.g., neural signals, over long time, because of biological tiredness and adaptation property. We often adopt the average over plural estimates obtained from samples recorded in different trials as a final estimate to improve the estimation accuracy. For minimizing mean squared error of the entropy estimation, we should optimally balance between bias error and mean squared error of individual estimations, however the optimal balance is unknown. This paper derivates the optimal balance between bias error and mean squared error of individual estimations.
The production of animations was made the subject of a university programming course in order to make students understand the process of program creation, and so that students could tackle programming with interest. In this paper, the formats and composition of the programs which students produced were investigated. As a result, it was found that there were a lot of problems related to such matters as how to use indent, how to apply comments and functions etc. for the format and the composition of the source codes.