Soichiro Morishita

Force sensor system for structural health monitoring using passive RFID tags

For this study, we developed a contactless loading sensor system that can measure the internal loading of an object structure through several covering materials for the purpose of structural health monitoring. The developed system can be inserted into objects without a battery because the system consists of passive RFID for data communication and a power supply. The system uses little electric power because the power supply with RFID is generally very low. We propose an architecture by which two RFID tags are used in the system. The functions of the tags are separated for communication and for the power supply as a circuit design contraption to solve the problem. First, we explain how the developed system is useful in an actual environment and introduce details of the developed sensor system. Second, the sensor system performance is evaluated through comparison of calculated results and experimental results. Based on those evaluations, the practical utility for structural health monitoring of the system is described.

Brain-machine interface to control a prosthetic arm with monkey ECoGs during periodic movements

Brain–machine interfaces (BMIs) are promising technologies for rehabilitation of upper limb functions in patients with severe paralysis. We previously developed a BMI prosthetic arm for a monkey implanted with electrocorticography (ECoG) electrodes, and trained it in a reaching task. The stability of the BMI prevented incorrect movements due to misclassification of ECoG patterns. As a trade-off for the stability, however, the latency (the time gap between the monkeys actual motion and the prosthetic arm movement) was about 200 ms. Therefore, in this study, we aimed to improve the response time of the BMI prosthetic arm. We focused on the generation of a trigger event by decoding muscle activity in order to predict integrated electromyograms (iEMGs) from the ECoGs. We verified the achievability of our method by conducting a performance test of the proposed method with actual achieved iEMGs instead of predicted iEMGs. Our results confirmed that the proposed method with predicted iEMGs eliminated the time delay. In addition, we found that motor intention is better reflected by muscle activity estimated from brain activity rather than actual muscle activity. Therefore, we propose that using predicted iEMGs to guide prosthetic arm movement results in minimal delay and excellent performance.

A three-dimensional silicon shadowmask for patterning on trenches with vertical walls

This paper proposes a direct metal patterning method on three-dimensional structures with vertical side walls. It uses a 3-D multi-height silicon shadow mask made by doubleside Deep Reactive Ion Etching (DRIE). Aluminum has been successfully patterned on the top, bottom and vertical side walls of 280mm wide trench with a depth of 250mm by sequentially tilting the wafer at three different angles during evaporation. The resulting tracks exhibited good isolation between adjacent metal patterns and with the resistance of the track between top and bottom of trench measured at 3.4ࡎ.

Walking assistance by functional clothes with highly elastic fabric

We proposed a novel approach to walking assistance by using functional clothes with highly elastic fabric. This strategy can achieve walking assistance without external forces generated by an actuator. In order to examine the effectiveness of the proposed approach, we produced a functional girdle and assessed the extent to which it assisted the hip flexor muscles. We confirmed that the load on the hip flexor muscles decreased during hip flexion while subjects wore the functional clothes.

Development of mobile controller for EMG prosthetic hand with tactile feedback

In this paper, we introduce a mobile controller for a five-fingered myoelectric prosthetic hand with tactile feedback. When constructing a system for use in daily life, the following design requirements should be satisfied: 1) limitations on the total weight of the system; 2) sufficient degrees of freedom of motion; and 3) sufficient sensory feedback information for the result of the interaction with circumstance. At first, we limited the degrees of operations for the wrist motion and switching operations, because too many degrees of freedom cause an increase in overall weight. Next, we constructed the controller, which has a suitable processing performance with mobile PC and microcomputer. Moreover, for lightweight tactile feedback system, we employed the technique of Phantom Sensation (PS) with only two electrodes. Finally, we discuss the appropriate parameter combinations for PS.

Development of an Automated Microscope for Supporting Qualitative Asbestos Analysis by Dispersion Staining

This paper introduces automated microscopic observation supporting qualitative asbestos analysis. Visual qualitative asbestos evaluation generally involves dispersion staining. Operators conventionally check and count asbestos fibers visually by microscope. We are developing automated microscopic observation to support qualitative asbestos analysis. The system images fibers by microscope and saves them automatically to a database. We introduce system concepts and performance using the prototype we developed.

Accuracy improvement of counting asbestos in particles using a noise redacted background subtraction

Increased health damage caused by asbestos has become a problem recently. Removal of asbestos contained in building materials and rendering it harmless is a common means of alleviating asbestos hazards, but that process necessitates a judgment of whether asbestos is included in building materials. According to an official method, particles and asbestos must be counted in a sample to judge whether it contains asbestos. This work is performed visually and requires enormous amounts of time and effort. Consequently, automated counting using background subtraction is proposed for rapid, highly accurate analysis. However, the method does not enable accurate counting because of noise included in a background image. This study is intended to improve the accuracy of counting particles through noise removal using a Gaussian filter.

Selective Linear-Regression Model for hand posture discrimination and grip force estimation using surface electromyogram signals

This paper proposes the method of hand posture discrimination and grip force estimation by means of Selective Linear-Regression Model. Generally, myoelectric hands which discriminate hand posture and estimate grip force at the same time result in unsatisfying results because of complication of EMG signals. Therefore, most of myoelectric hands can control either the force or the posture. However, the proposed method is able to discriminate hand posture and to estimate grip force simultaneously while the accuracy results are achieved. In experiments, EMG signals were measured while hand posture and grip force were changing. As a result, it appears that EMG features increase monotonically with grip force. In addition, increasing forms of EMG features are different on each posture. Based on these experimental results, the authors propose the method for both discriminating hand posture and estimating grip force by means of several linear-regression models which utilize the relationship between the grip force and EMG features on each posture. To evaluate the effectiveness of this method, the failure rates of discrimination and the estimation errors of the proposed method were employed. The results indicate that failure rates and estimation errors are improved significantly.

Integration of EWOD pumping device in deep microfluidic channels using a three-dimensional shadowmask

A droplet propulsion system based on the electrowetting-on-dielectric (EWOD) is integrated in deep-trench microfluidic channels. Due to the unique three-dimensional multi-height silicon shadowmask, electrodes are simultaneously fabricated on the top, bottom and vertical walls of deep channels, thus enabling three-face EWOD driving by both the bottom and sidewalls. We have successfully moved a water droplet in a 230μm-deep, 750μm-wide trench by EWOD.

Structure design for a Two-DoF myoelectric prosthetic hand to realize basic hand functions in ADLs

Prosthetic hands are desired by those who have lost a hand or both hands not only for decoration but also for the functions to help them with their activities of daily living (ADL). Prosthetic robotic hands that are developed to fully realize the function of a human hand are usually too expensive to be economically available, difficult to operate and maintain, or over heavy for longtime wearing. The aim of this study is therefore to develop a simplified prosthetic hand (sim-PH), which is to be controlled by myoelectric signals from the user, to realize the most important grasp motions in ADL by trading off the cost and performance. This paper reports the structure design of a two-DoF sim-PH with two motors to drive the CM joint of the thumb and the interlocked MP joints of the other four fingers. In order to optimize the structure, the model of the sim-PH was proposed based on which 7 sim-PHs with different structural parameters were manufactured and tested in a pick-and-place experiment. Correspondence analysis of the experimental results clarified the relationship between the hand functions and the shapes of fingers.