Shogo Tanaka

Unconstrained and non-invasive measurement of heart-beat and respiration periods using a phonocardiographic sensor

Witthe rapid growth in the number of elderly people in the population, interest in health monitoring is increasing. Therefore the development of an unconstrained and non-invasive vital signs measurement system could be important for monitoring health status at home or in hospitals or nursing facilities. A simple system is proposed for measuring heart-beat and respiration periods for home healthcare. This was achieved with a phonocardiographic (PCG) sensor set on a water-mat or air-mat. The PCG sensor was an acceleration sensor that extracted the vibration of the mat caused by heart-beat and respiration. By calculating an autocorelation function of the fully rectifiedsensor output or by local pattern matching between the rectifiecbutput and a reference signal (pre-memorised for each subject), the system measured the average and instantaneous periods of both heart-beat and respiratin. Results showed that these periods were measured to a similar level of accuracy as for the electrocardiogram and thermistor respiration pickup. The comparative accuracies were within the following ranges: average heartbeat 0.19% to 0.67%, instantaneous heartbeat 0.53%to 1.15%, average respiration 0.51% to 2.17% and instantaneous respiration 2.51% to 5.20%.

Automatic measurement and control of the attitude of crane lifters: Lifter-attitude measurement and control

Abstract The spreaders and lifters on cranes are usually controlled to stop at the same time as their trolleys are stopped. Despite the use of adequate control systems, however, the lifters usually have comparatively large sway movements, due to their free suspension from the trolleys through pulleys, hooks and cables. It is therefore important to accurately measure the attitude of the lifters, in order to suppress such sways by means of secondary control. The authors have previously proposed a maintenance-free automatic measurement and control system which accurately measures the lifter’s attitude, using a servo-type accelerometer and a double-rigid-body pendulum model for the system, and completely eliminates the sway of the lifter. However, the measurement/control system takes action only after the trolleys are stopped. This paper extends the previous approach, and presents an on-line automatic measurement and control system that enables the lifters to stop at the same time as the trolleys are first stopped.

Dynamic model based length measurement using stationary waves

A highly accurate pipe length on-line measurement with acoustic sensor is considered. Stationary waves in straight pipes are modeled with a finite-dimensional linear dynamic system including unknown parameters. Posteriori probabilities of the candidates for the unknown parameters are calculated and pipe length measurement is obtained by taking expectation of the candidates. In order to realize a highly accurate on-line measurement, a criterion to select the optimal modes of the stationary wave is also presented.

Automatic on-line measurement of ship's attitude by use of a servo-type accelerometer and inclinometers

For an accurate automatic on-line measurement of the ships attitude the paper develops an intelligent sensing system which uses one servo-type accelerometer and two servo-type inclinometers which are appropriately located on the ship. By considering the dynamics of the servo-controlled rigid pendulums of the inclinometers, linear observation equations are derived on the rolling and pitching signals of the ship. Moreover, one accelerometer is utilized to extract the heaving signal. Through the introduction of linear dynamic models and the linear observation equations for the three signals, their online measurement is reduced to the state estimation of the linear dynamic systems. A bank of Kalman filters is used to execute the on-line state estimation and to overcome changes in parameters in the dynamic models with time lapse.

Fault detection in linear discrete dynamic systems by a reduced order generalized-likelihood-ratio method

Abstract The detectability by conventional step-hypothesized generalized-likelihood-ratio (SHGLR) method for detection of a parameter change (fault detection) in a linear discrete dynamic system is analysed and it is shown that a weakly-diagnosable-space (WDS) exists for dynamics and sensor faults. Based on the fault detectability, a reduced order SHGLR method is then developed which highly improves the detection rate and speed. In the same framework of the GLR method, another reduced order detection scheme is given, which makes the most use of the information about the input and the state of the system to raise the detectability for faults for the case where the step hypothesis cannot be applied effectively.

Unconstrained and noninvasive measurement of heartbeat and respiration for drivers using a strain gauge

This paper proposes an unconstrained and noninvasive measurement system of heartbeat and respiration for drivers. The system makes use of a wire-type strain gauge set on a seat belt and measures instantaneous heartbeat and respiration periods efficiently based on their dynamic models and maximum likelihood method.

Non-Destructive Inspection of Multiple Concrete Cracks Using Ultrasonic Sensor

Non-destructive testing (NDT) of concrete cracks are very important for the maintenance and safeguard of concrete structures. Numerous methods with varying detecting devices have already been developed for this purpose. Although detection of a single crack within the concrete is somewhat easy, simultaneous detection of multiple numbers of cracks in the direction of depth is extremely difficult due to the fact that many reflected waves are often overlapped and that the reflected waves are spindle oscillatory types. The present paper proposes a method to identify multiple numbers of cracks inside the concrete using a multi-reflected wave model and a pattern matching technique. The method uses the pattern matching technique to detect the optimum times of flights (TOEs) of the reflected waves from multiple cracks and thus determines the crack depths. Using this method, not only the depths of the multiple cracks but the attenuation of the reflected waves relative to each other can also be determined. Experiments will show that the method is effective

Volume measurement of the pulverulent body carried by a conveyor belt using range sensors

Measuring the volume of a pulverulent body carried by a conveyor is important in many construction fields. We propose using range sensors to obtain information on the shape of the pulverulent body. We attain high accuracy and precision in the measurement by considering the number and shape of basis functions to express the body surface, since the variance of the observation noise varies with the number of observation points in the use of range sensors. It is shown that there exist optimal numbers of observation points and basis functions corresponding to the relation between the noise variance and the observation number.

Brief paper: Optimal timing of observations for state estimation in a one-dimensional linear continuous system

This paper considers the optimal timing of observations for the state estimation in a one-dimensional linear continuous stochastic system which is corrupted by white Gaussian noise. The criterion adopted ia a min-max one. The optimal observation times are analytically shown to be located periodically including the terminal time, irrespective of the values of the variances of both the observation noise and the system noise. Finally, the relation between the min-max solution and MSE (mean-square error) solution is considered, and the method of obtaining a suboptimal MSE solution with a little computational cost is presented.

On Measurement of the Depth and the Diameter of Steel Bars in Reinforced Concrete Using Electromagnetic Wave (Radar)

The present paper analyzes the propagation paths of the electromagnetic wave of a radar in reinforced concrete using Snells law. Using the derived paths, the depth and the diameter of the reinforcing bars are measured by making a pattern matching between the modeled received wave signal and the actual received wave signal of the radar. The dielectric constant of the concrete is also measured together with the depth and the diameter, because the propagation speed is a function of the dielectric constant. Lastly, the effectiveness of the method is demonstrated by experiments. Especially, a high accuracy of measurement is achieved for the depth, while concerning the diameter one or two units in JIS standard is obtained and thus a new additional device is also suggested