Makoto Nakashizuka

Development of navigation system for the blind using GPS and mobile phone combination

A single GPS (Global Positioning System) or differential GPS receiver is a useful tool for the blind for determining their location relative to the surrounding environment. However, each person needs to carry his/her own personal computer loaded with location data, and these data have to be updated periodically for each area. We therefore developed a new guidance system to solve these problems by using GPS receivers and a mobile phone. In the experiments on campus, we confirmed the automatic on-line personal guidance function. The maximum error of the determined position was 16 m. The weight of the mobile unit was under 2 kg.

Quaternary geomagnetic field intensity: Constant periodicity or variable period?

Paleomagnetic results are presented from a core, KH 90-3-5, in the Melanesia basin and are correlated with the previously obtained results from two cores, KH 73-4-7, KH 73-4-8, in the same basin in a period between 0.04 Ma and 1.1 Ma. The sediments in the three cores are composed mostly of calcareous ooze. It has been shown that the variation in the saturation isothermal remanent magnetization (SIRM) in the two cores is caused neither by deposition-rate variation of magnetic minerals nor by rock-magnetic inhomogeneity but almost solely by variations in CaCO3 dissolution. A close similarity between the variation in the SIRM in the two cores and the variation in the initial susceptibility (κ) in KH 90-3-5 has enabled us to correlate among the cores, and also means negligible rock-magnetic inhomogeneity in the core. A time versus depth correlation has been established from the δ18O record of KH 90-3-5. The relative paleointensity record estimated from the natural remanent magnetization (NRM) normalized by κ in KH 90-3-5 and those records in the other two cores are remarkably similar, implying that the records faithfully reflect variations in relative paleointensity of the geomagnetic field for the past 1.1 Ma. We examined on the periodicity of the paleointensity records with wavelets. It is shown that periods of major changes in the records reveal continuous shifts between about 50 Ka and 140 Ka over time. We offer an alternative viewpoint about the periodicity of the paleointensity in which periods of major changes shifted continuously within the time range instead of constant periodicities.

ECG data compression by multiscale peak analysis

The paper presents an ECG data compression technique using multiscale peak analysis. The authors define multiscale peak analysis as the wavelet maxima representation of which the basic wavelet is the second derivative of a symmetric smoothing function. The wavelet transform of an ECG shows maxima at the start, peak and stop points of five transient waves P through T. The number of wavelet maxima is expected to be less than the number of original data samples. The wavelet maxima can be enough to reconstruct original signals precisely. The wavelet maxima representation can lead to ECG data compression and analysis. The compressed data still keep the peaks of QRS waves, and abnormal behavior search will be feasible in practice. The result of the compression shows that a normal ECG data is compressed by a factor 10.

A method of measuring marker position/orientation for VR interface by monocular image processing

The method of measuring position/orientation in the real world determines the construction of the VR interface. This paper proposes a method of measuring marker position/orientation by image processing. The marker is rectangular. The position/orientation is measured using a single camera. The orientation of the marker is estimated by optimization, utilizing the information of two vanishing points obtained from an image. Then, the position of the marker is determined by calculations. This is facilitated because we have only to attach a marker to a target of measurements. n n n nThe expansion in the measurement of multiple objects is straightforward and the system can be constructed cheaply because no special circuitry is required. Also, the measurement range is easily modified by resetting the camera lens. The advantage of this method is shown by computer simulations and experimental results using a real image. The real-time measuring accuracy of the system, which was composed of ready-made devices and a highly distorted camera, was 0.5 degrees in directional deviations and 1 mm in depth deviation.

3-D object information system for the visually impaired using an infrared reflective bar code

We have produced a 3 dimensional object information system using a newly developed infrared reflection type pigment as an identifier. The system incorporates a video camera, which inputs the object image, a personal computer and speech synthesizer. In experiments, a bar code, using the IR reflection pigment, was attached to the surface of a pillar-shaped can, with the bar code matching the color of the object. The name of the object was then output within 1 second, using the image of the attached bar code. With this system, it is possible to identify objects without contact, and it is also possible to explain the positions of plural components on a table.<<ETX>>

ECG compression by multiple peak analysis

This paper proposes a method of compressing ECG data by using the wavelet maximum representation. This representation uses the second-order derivative of a symmetrical smoothing function for the basic wavelet function, and the characteristics of a peak of a waveform can be described since the maximum occurs at the inflection point of the waveform. This is defined as multiscale peak analysis. In such an analysis, five wavelet maxima occur at the start, peak, and end of the waveforms from P to T waves of an ECG. The original waveform can be reconstructed accurately by applying the convexity projection restoring method. Detection of the separating points and the compression of data in an ECG can be carried out at the same time in multiscale peak analysis. The results obtained by applying the proposed method to the MIY-BIH ECG database show that normal ECG data can be compressed to 1/12 with an accuracy of about 8% PRD, and abnormal ECG data can be compressed to 1/10 to 1/14 with a mean accuracy of about 9% PRD.

3D structure from multiple images and estimation of error distribution

This paper discusses a method in which multiple images are taken by a measuring system executing an arbitrary motion on a uniform trajectory, and the 3D information and the error distribution are extracted with high accuracy and high speed. Using the first two images, the initial coordinates are determined by a simple matching procedure. The coordinates are then corrected with later image information, and the 3D coordinates are extracted with high accuracy. In this method, it is not necessary to store the images or to define the measurement space beforehand. At each point in the course of measurement, the newest 3D information can be utilized. It is inevitable that false matching will be produced, but by counting the number of images in which the point appeared, the certainty of occurrence is quantitatively evaluated and the matching is discriminated. As to the error distribution, the equierror surface is assumed to be a spheroid, and the parameters are estimated from the error distribution of the feature points on the image plane, the disparity, and the number of images. By estimating the error distribution, the direction of maximum error and the spatial resolution can be estimated. As a result of simulations and the experiments on the actual image using a rotating table, it is verified that the spatial resolution is improved by approximately 60% compared to the stereo method when five images are used.