Hideo Makino

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.

Basic study on indoor location estimation using Visible Light Communication platform

A VLC (Visible Light Communication) system using fluorescent lights has been developed for indoor guidance of the visually impaired. While it is relatively straightforward to provide generalized location information for a blind user, precise location information is much more difficult to determine. We propose that the effective data reception range and the receivers precise location can be calculated using measured sensor angles. A series of experiments have been performed in a practical platform with 22 fluorescent lights, 39 measuring points (MP). The average distance error could reach as low as 10 cm. This development will provide greater accuracy and therefore less stress for blind users.

Design of an Indoor Self-Positioning System for the Visually Impaired - Simulation with RFID and Bluetooth in a Visible Light Communication System

After a public experiment of the indoor guidance system using FLC (fluorescent light communication), we found that FLC provides a promising medium for the installation of a guidance system for the visually impaired. However, precise self-positioning was not satisfactorily achieved. In this article, we propose a new self-positioning method, one that uses a combination of RFID (radio-frequency identification), Bluetooth and FLC. We analyzed the situation and developed a model that combined the three communication modes. Then we performed a series of experiments and get some results in the first step.

Indoor positioning using a high-speed, fish-eye lens-equipped camera in Visible Light Communication

We propose a method for determining the indoor position based on a Visible Light Communication (VLC) system that uses a high-speed fish-eye lens-equipped camera. In VLC, lights are used as data transmitters and users can receive location information using a receiving device. Since the lights are configured to meet a pre-determined illumination level, the system requires neither space nor additional power. The lights serve their usual function as sources of illumination, and as a means of transmitting digitized information. Up to now, photo sensors or a normal lens-equipped camera have been used as receiving devices. However, the number of lights that can be received by a photo sensor is limited, and the receiving angle of the image that a normal lens-equipped camera takes is also limited. Since a camera with a fish-eye lens commands a 180-degree view of the ceiling, the number of detectable LED lights increases and positioning accuracy is improved. In terms of data transmission in VLC, the LED lights transmit data at 9.6 kbps. Thus, we use a high-speed complementary metal-oxide-semiconductor image sensor to receive the digitized information. The sampling frequency of the image sensor is up to 48 kHz. The LED lights send ID frames containing a prefix, ID, and Cyclic Redundancy Check (CRC) code. The ID and CRC are modulated with 4 Pulse-Position Modulation. The receiver detects the LED lights from the ceiling image. Then, variations in intensity at the center of the LED lights are stored as light signals. Since received data can be separated into two segments within a small buffer, according to the measurement period, received data are occasionally swapped. The receiver obtains the world coordinates of the LED light from the received ID. Finally, self-location estimation is performed using the relationship between the fish-eye image coordinates and the world coordinates. We conducted an experiment using the VLC platform in Niigata University, with the receiver position fixed at 24 measuring points. The platform area measures 5.4 m by 7.5 m, and the ceiling height is 3 m.The results show that the maximum horizontal error is 10 cm.We conclude that it is possible to determine a horizontal position within merely 10 cm, using the proposed method.

A pulse-type hardware neuron model with beating, bursting excitation and plateau potential.

We proposed a pulse-type hardware neuron model. It could reproduce simple excitations, beating and bursting discharges as well as an action potential with a plateau potential observed in living membranes. The model exhibited one of these dynamics depending on parameter values of the models circuit. They include resistance, capacitance and externally injected DC current intensity. We studied the models dynamics based on hardware experiments and mathematical analyses. Our results showed that two inward currents introduced into the model and differences in their operating time scales determined dynamics of the model. In particular, we illustrated a mechanism of the bursting discharges generation in terms of bifurcation theory and time-dependent changes in the form of instantaneous current voltage characteristics of the model.

Optimal Pacemaker Sensing with Respect to Amplitude and Slew Rate of Intracardiac Electrograms: Theoretical Analysis by Computer Simulation

The optimal amplitude and slew rate of intracardiac electrograms for pacemaker sensing Here examined on a theoretical basis by computer simulation. The simulation was based on the concept that it is the voltage at the position of the pacing electrode in an electrical field of a moving electrical dipole. By changing the distance between the electrode and the myocardium and the moving velocity of the electrical dipole, simulated ECGs with arbitrary amplitudes and slew rates were generated by the computer and fed to a bandpass filter. This filter was equivalent to those assembled in some models of permanent pacemakers and had a center pass‐band frequency of 50 Hz and a Q of 1.0. The outputs of the filter were measured. The results showed that, for pacemaker sensing, simulated intracardiac electrograms with high amplitude should have high slew rates and those with low amplitudes should have low slew rates, although the absolute values depend on the characteristics of the bandpass filter and the sensing threshold of the pacemaker.

Research of Practical Indoor Guidance Platform Using Fluorescent Light Communication

This article presents an indoor positioning and communication platform, using fluorescent lights. We set up a practical implementation of a VLC (Visible Light Communication) system in a University building. To finalize this work, it is important that we analyze the properties of the reception signal, especially the length of the data string that can be received at different walking speed. In this paper, we present a model and a series of formulae for analyzing the relationship between positioning signal availability and other important parameters, such as sensor angle, walking speed, data transmission rate, etc. We report a series of real-life experiments using VLC system and compare the results with those generated by the formula. The outcome is an improved design for determination of the reception area with more than 97% accurate signals, and an optimal transmission data length, and transmission rate.

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.

Algorithm for extracting ellipses using weighted center points map

When a group of parallel lines pass through an ellipse, the center point between two intersecting points of each straight line is on another straight line passing through the center of the ellipse. Furthermore, a graphical plot of the distance between the two intersecting points vs. a coordinate value (either x or y) of the center point will form an elliptical shape. These two characteristics of the ellipse are exploited by an algorithm for ellipse extraction. Given an input image of ellipses, a center point map is constructed. Then a Hough transform is used to detect the center line that represents the ellipse. Next, the center line so detected is used to estimate the parameters and to obtain sample pixels of the ellipse. This is followed by a least-square fitting and high precision parameter value computation. Numerous experiments were conducted which demonstrated the effectiveness of our algorithm.

LED-tracking and ID-estimation for indoor positioning using visible light communication

We are focusing our research on indoor positioning technology; specifically, a type that uses Visible Light Communication (VLC); modulatable LED lights transmit data at 9600 bps, using 4 Pulse Position Modulation (4PPM), while a fish-eye lens-equipped camera receives the light signal over a 160-degree field-of-view. This type of lighting requires neither additional space nor-power. We assigned a unique ID to each LED, in order to recognize its position. Self-location is calculated from the relationship between the LED positions and coordinates on the image plane. In our previous research, we confirmed that self-location can be determined within 10 cm, using our system. However, we needed to attach dedicated transmitters to each LED used for positioning, especially in large buildings such as hospitals and shopping malls. So, in this paper, we propose LED-tracking and ID-estimation using LEDs with known IDs; doing so will significantly reduce the cost of installing- and running transmitters. Additionally, with the increased use of LEDs for positioning, accuracy naturally improves. We conducted experiments with the camera moving in 2 different environments: a) a small area, with just 4 LEDs; b) the VLC platform with a total of 24 LEDs, to demonstrate that as many as 13 LEDs can be identified. With 2 or more IDs detected beforehand, unidentified LEDs, as well as some that failed to be tracked, could be estimated, while the camera was in motion. Average positioning error in the smaller environment and the VLC platform were 3.78 cm and 6.96 cm, respectively. From this, location can be determined, even when some LEDs are offline.