Yuya Koyama

A Motion Monitor Using Hetero-Core Optical Fiber Sensors Sewed in Sportswear to Trace Trunk Motion

In this paper, a cameraless motion monitor has been described by introducing very thin sensor modules into sportswear, in which a single-mode hetero-core optical fiber sensor is fabricated. An elbow joint motion and a trunk motion are monitored by a sportswear on which the hetero-core optical fiber sensor modules are sewed so as to be sensitive to stretch on the wear. In order to get rid of the restriction to the human body, a two-plane model has been proposed in which only two sets of sensors simplify three kinds of motions at the trunk, which are anteflexion, lateral bending, and rotation. Additionally, the real-time monitoring system has been tested when golf swing motion is performed. As a result, it has been indicated that the motion, which consists of a composite of three motions, can be significantly analyzed by means of the two sensors. The developed system is viable to an unconstrained motion capture system intended for a teaching device in sports and rehabilitation fields.

Auditory golf coaching system using perceptive sportswear based on hetero-core optics

A sports motion support system for golf swing has been described by using a perceptive sportswear and a wireless mobile device with Android application, in which a trainee is given real-time auditory feedback to be informed the performance of the swing. The wireless mobile device receives motion data from the perceptive sportswear designed in form of shirts and shoes in which hetero-core optical fibers are fastened or embedded for monitoring the body motion without restraint. Real-time feedback experiment has been demonstrated based on the system, in which the trainee performing golf swings could efficiently improve his swing motion.

A tactile sensing element based on a hetero-core optical fiber for force measurement and texture detection

Tactile sensing technology can measure a given property of an object through physical contact between a sensing element and the object. Various tactile sensing techniques have been developed for several applications such as intelligent robots, tactile interface, medical support and nursing care support. A desirable tactile sensing element for supporting human daily life can be embedded in the soft material with high sensitivity and accuracy in order to prevent from damaging to human or object physically. This report describes a new tactile sensing element. Hetero-core optical fibers have high sensitivity of macro-bending at local sensor portion and temperature independency, including advantages of optical fiber itself; thin size, light weight, flexible transmission line, and immunity to electro-magnetic interference. The proposed tactile sensing element could detect textures of touched objects through the optical loss caused by the force applied to the sensing element. The characteristics of the sensing element have been evaluated, in which the sensing element has the monotonic and non-linear sensitivity against the normal force ranged from 0 to 5 N with lower accuracy than 0.25 dB. Additionally, texture detection have been successfully demonstrated in which small surface figures of 0.1 mm in height were detected with spatial resolution of 0.4 mm.

Hetero-core fiber optic tactile sensor for accurate discrimination of texture and hardness

This paper describes a novel tactile sensor using a hetero-core fiber optic sensor for detecting particular tactile information of surface texture and hardness. The hetero-core fiber optic sensor consists of two single-mode fibers with different core diameters, which can detect soft bending on a sensor portion, moreover being tolerant to several environmental fluctuation such as corrosion, temperature fluctuation and electromagnetic interference. The hetero-core fiber optic tactile sensor was designed in order to detect contact force by means of the hetero-core fiber optic sensor implanted in three-point bending structure. Force property of the tactile sensor was experimentally confirmed to be highly-sensitive in reaction to force given in the range of 0.01 - 5.0 N. Therefore, it was observed that the tactile sensor could detect minute level change of surface texture in the height of 0.01 mm with the spatial accuracy within 0.10 mm. In addition, the degree of hardness and the other physical property of viscoelasticity could be detected by pushing the tactile sensor on materials. As a result, it was successfully performed that the proposed tactile sensor could detect various kinds of tactile information with high sensitivity.

Multi-channel measurement for hetero-core optical fiber sensor by using CMOS camera

Fiber optic smart structures have been developed over several decades by the recent fiber optic sensor technology. Optical intensity-based sensors, which use LD or LEDs, can be suitable for the monitor system to be simple and cost effective. In this paper, a novel fiber optic smart structure with human-like perception has been demonstrated by using intensity-based hetero-core optical fiber sensors system with the CMOS detector. The optical intensity from the hetero-core optical fiber bend sensor is obtained as luminance spots indicated by the optical power distributions. A number of optical intensity spots are simultaneously readout by taking a picture of luminance pattern. To recognize the state of fiber optic smart structure with the hetero-core optical fibers, the template matching process is employed with Sum of Absolute Differences (SAD). A fiber optic smart glove having five optic fiber nerves have been employed to monitor hand postures. Three kinds of hand postures have been recognized by means of the template matching process. A body posture monitoring has also been developed by placing the wearable hetero-core optical fiber bend sensors on the body segments. In order for the CMOS system to be a human brain-like, the luminescent spots in the obtained picture were arranged to make the pattern corresponding to the position of body segments. As a result, it was successfully demonstrated that the proposed fiber optic smart structure could recognize eight kinds of body postures. The developed system will give a capability of human brain-like processing to the existing fiber optic smart structures.

Wearable motion capturing with the flexing and turning based on a hetero-core fiber optic stretching sensor

In recent years, motion capturing technologies have been applied to the service of the rehabilitation for the physically challenged people and practicing sports in human daily life. In these application fields, it is important that a measurement system does not prevent human from doing natural activity for unrestricted motion capture in daily-life. The hetero-core optic fiber sensor that we developed is suited for the unconstrained motion capturing because of optical intensity-based measurement with excellent stability and repeatability using single-mode transmission fibers and needless of any compensation. In this paper, we propose the development of wearable sensor enables unconstrained motion capture systems using the hetero-core fiber optic stretching sensor in real time, which satisfy users requirements of comfort and ubiquitous. The experiments of motion capturing were demonstrated by setting the hetero-core fiber optic stretching sensor on the elbow, the back of the body and the waist. As a result, the hetero-core fiber optic stretching sensor was able to detect the displacement of expansion and contraction in the optical loss by flexion motion of the arm and the trunk motion. The optical loss performance of the hetero-core fiber optic stretching sensor reveals monotonic characteristics with the displacement. The optical loss changes at the full scale of motion were 1.45dB for the motion of anteflexion and 1.99 dB for the motion of turn. The real-time motion capturing was demonstrated by means of the proposed hetero-core fiber optic stretching sensor without restricting natural human behavior.

Multipoint real-time displacement sensing method employing multi-wavelength by intensity-based hetero-core fiber optics sensors

The intensity-based measurement could be necessary to smart structures embedding multipoint fiber optic sensors for real-time monitoring such as the human motion in daily activity. Hetero-core fiber optic displacement sensor has great advantage to the intensity-based measurement because the sensitivities of hetero-core fiber optic displacement sensors change by different of the hetero-core insertion length and the transmission wavelength. This paper proposed the new approach for multipoint real-time measurement of hetero-core fiber optic intensity-based sensors. The bending optical loss characteristics of hetero-core fiber optic sensor were measured about four kinds of hetero-core insertion lengths at the two wavelengths, 0.85 μm and 1.31 μm. The bending displacement of two sensors on a single transmission line could be successfully detected by using two hetero-core fiber optic sensors to have the different hetero-core insertion lengths at the two wavelengths of 0.85 μm and 1.31 μm. The accuracies of two sensors, which had the hetero-core insertion lengths of 0.5 and 1.0 mm, with tandem connection were ±0.003 mm and ±0.003 mm of the displacement, ±2.87 % and ±0.63 % for the full-scale displacement of 2 and 0.5 mm, respectively.

Unconstrained wrist rotating motion capture using sensitive tape based on hetero-core fiber optics

Motion capture techniques have attracted rising attention in the fields of cooking and traditional arts, with which fine finger action could be preserved. In this paper, we have put forward a flexible and unconstrained sensitive tape based on hetero-core fiber optics. The sensitive tape can detect the stretch resulting from body movement. Two sensitive tapes placed on forearm were combined to detect wrist rotation in real time. As a result, we experimentally confirmed that wrist rotations were monitored by means of the developed sensitive tape.

Gait monitoring for human activity recognition using perceptive shoe based on hetero-core fiber optics

Gait monitoring system for human activity recognition is demonstrated using a perceptive shoe based on hetero-core fiber optics. The insole with hetero-core fiber monitors foot pressure without temperature dependency and constraint to human body. Monitoring test was performed by a human subject doing basic activities which are walking, walking on the spot, running, standing, and sitting on a chair. The human activities were successfully monitored by means of perceptive shoe using hetero-core fiber optics. In addition, walking on the spot and standing were identified using only front weight response.

Extraction of natural weight shift and foot rolling in gait based on hetero-core optical fiber load sensor

Gait in daily activity affects human health because it may cause physical problems such as asymmetric pelvis, flat foot and bowlegs. Monitoring natural weight shift and foot rolling on plantar has been employed in order for researchers to analyze gait characteristics. Conventional gait monitoring systems have been developed using camera, acceleration sensor, gyro sensor and electrical load sensors. They have some problems such as limited measurement place, temperature dependence and electric leakage. On the other hand, a hetero-core optical fiber sensor has many advantages such as high sensitivity for macro-bending, light weight sensor element, independency on temperature fluctuations, and no electric contact. This paper describes extraction of natural weight shift and foot rolling for gait evaluation by using a sensitive shoe, in the insole of which hetero-core optical load sensors are embedded for detecting plantar pressure. Plantar pressure of three subjects who wear the sensitive shoe and walk on the treadmill was monitored. As a result, weight shift and foot rolling for three subjects were extracted using the proposed sensitive shoe in terms of centroid movement and positions. Additionally, these extracted data are compared to that of electric load sensor to ensure consistency. For these results, it was successfully demonstrated that hetero-core optical fiber load sensor performed in unconstraint gait monitoring as well as electric load sensor.