Shunji Moromugi

Muscle stiffness sensor to control an assistance device for the disabled

An innovative sensor has been developed as a man–machine interface to control an assistance device for people with disabilities. This sensor is applied to a mechanical glove that has a grasping function, and its usefulness is demonstrated through experiments. The sensor is attached to the operator’s skin and detects noninvasively how much the muscle under the sensor has stiffened.

Noninvasive brain-computer interface driven hand orthosis

Neurological conditions, such as stroke, can leave the affected individual with hand motor impairment despite intensive treatments. Novel technologies, such as brain-computer interface (BCI), may be able to restore or augment impaired motor behaviors by engaging relevant cortical areas. Here, we developed and tested an electroencephalogram (EEG) based BCI system for control of hand orthosis. An able-bodied subject performed contralateral hand grasping to achieve continuous online control of the hand orthosis, suggesting that the integration of a noninvasive BCI with a hand orthosis is feasible. The adoption of this technology to stroke survivors may provide a novel neurorehabilitation therapy for hand motor impairment in this population.

Chewing number is related to incremental increases in body weight from 20 years of age in Japanese middle‐aged adults

BACKGROUND Eating habits are associated with both current obesity and incremental increases in body weight from young adulthood, but no study has focused on chewing number during meals among community residents. OBJECTIVE This study focused on the relationship between chewing number and incremental increases in body weight from 20 years of age. METHODS A total of 93 persons aged 35-61 years participated. The subjects were asked to set the device and record their chewing number during each meal on a particular day. They were also asked whether their body weight had increased by 10 kg or more since they were 20 years old. RESULTS The body weight of 28 subjects (30%) had increased more than 10 kg since the age of 20 years. Total chewing number showed a relationship with such body weight increases. The odds ratio of weight increments of more than 10 kg for the lowest tertile group was 4.6 [95% confidence interval (CI), 1.3-16.2] relative to the highest tertile group (Model 1). The odds ratio of weight increments for the lowest tertile group increased to 6.3 (95% CI, 1.6-25.4) in Model 2 and to 9.1 (95% CI, 1.7-49.8) in Model 3. CONCLUSION Although this study was limited because it did not consider all risk factors, categorical chewing number was related independently to body weight increments of more than 10 kg from 20 years of age.

Effect of head elevation on passive upper airway collapsibility in normal subjects during propofol anesthesia.

Background:Head elevation can restore airway patency during anesthesia, although its effect may be offset by concomitant bite opening or accidental neck flexion. The aim of this study is to examine the effect of head elevation on the passive upper airway collapsibility during propofol anesthesia. Method:Twenty male subjects were studied, randomized to one of two experimental groups: fixed-jaw or free-jaw. Propofol infusion was used for induction and to maintain blood at a constant target concentration between 1.5 and 2.0 &mgr;g/ml. Nasal mask pressure (PN) was intermittently reduced to evaluate the upper airway collapsibility (passive PCRIT) and upstream resistance (RUS) at each level of head elevation (0, 3, 6, and 9 cm). The authors measured the Frankfort plane (head flexion) and the mandible plane (jaw opening) angles at each level of head elevation. Analysis of variance was used to determine the effect of head elevation on PCRIT, head flexion, and jaw opening within each group. Results:In both groups the Frankfort plane and mandible plane angles increased with head elevation (P < 0.05), although the mandible plane angle was smaller in the free-jaw group (i.e., increased jaw opening). In the fixed-jaw group, head elevation decreased upper airway collapsibility (PCRIT ∼ −7 cm H2O at greater than 6 cm elevation) compared with the baseline position (PCRIT ∼ −3 cm H2O at 0 cm elevation; P < 0.05). Conclusion:Elevating the head position by 6 cm while ensuring mouth closure (centric occlusion) produces substantial decreases in upper airway collapsibility and maintains upper airway patency during anesthesia.

Ultrasonic sensor disk for detecting muscular force

Many researchers are studying and developing various kinds of man-machine systems. Especially, a wearable robot, such as an exoskeleton power suit, is one of the most remarkable fields. In this field, more accurate and reliable sensing system for detecting human motion intention is strongly required. In most of conventional man-machine systems, torque sensors, tactile pressure sensors and EMG sensors are utilized in a man-machine interface to detect human motion intention. These sensors, however, have some limitations. For example, it is hard to install and secure torque sensors on the joints of a human body. It is not easy to correlate the data from a tactile pressure sensor to the human motion intention. Although the EMG sensor can detect human motion intention, the sensor system is complex and expensive, and suffers from electric noise. We have been developing an innovative sensor suit which, just like a wet suit, can be conveniently put on by an operator to detect his or her motion intention by non-invasively monitoring his or her muscle conditions such as the shape, the stiffness and the density. This sensor suit is made of soft and elastic fabrics embedded with arrays of MEMS sensors such as strain gauges, ultrasonic sensors and optical fiber sensors, to measure different kinds of human muscle conditions. In the previous paper, the muscle stiffness sensor for detecting muscular force was developed according to the fact that the muscle gains its stiffness as it is activated. Its superior performance was reported through experiments in which the sensor was applied for the assisting device for the disable. In this paper, the ultrasonic sensor disk is proposed as one of the sensor disks embedding the sensor suit. This sensor is based on an original principle and non-invasively detects activity of specific muscle. It is clear that the square of ultrasonic transmission speed is in proportion to the elasticity of the object and in inverse proportion to the density. It is estimated that the elasticity and density of the muscle increase or decrease as the muscle is energized. Then, it is hereby expected that the muscular activity is measured by the ultrasonic sensor. In this study, the feasibility of an ultrasonic sensor for detecting muscular force is shown through experiments.

Performance Assessment of a Brain–Computer Interface Driven Hand Orthosis

Stroke survivors are typically affected by hand motor impairment. Despite intensive rehabilitation and spontaneous recovery, improvements typically plateau a year after a stroke. Therefore, novel approaches capable of restoring or augmenting lost motor behaviors are needed. Brain–computer interfaces (BCIs) may offer one such approach by using neurophysiological activity underlying hand movements to control an upper extremity orthosis. To test the performance of such a system, we developed an electroencephalogram-based BCI controlled electrically actuated hand orthosis. Six able-bodied participants voluntarily grasped/relaxed one hand to elicit BCI-mediated closing/opening of the orthosis mounted on the opposite hand. Following a short training/calibration procedure, participants demonstrated real-time, online control of the orthosis by following computer cues. Their performances resulted in an average of 1.15 (standard deviation: 0.85) false alarms and 0.22 (0.36) omissions per minute. Analysis of signals from electrogoniometers mounted on both hands revealed an average correlation between voluntary and BCI-mediated movements of 0.58 (0.13), with all but one online performance being statistically significant. This suggests that a BCI driven hand orthosis is feasible, and therefore should be tested in stroke individuals with hand weakness. If proven viable, this technology may provide a novel approach to the neuro-rehabilitation of hand function after stroke.

A sensor to measure hardness of human tissue

An innovative sensor is developed to evaluate hardness of human soft tissue. This sensor provides easy and accurate hardness measurements based on a unique sensing mechanism. Hardness of soft materials is often evaluated by using international standards of hardness such as IRHD (International Rubber Hardness Degree) and durometer hardness. However the conventional scales based on these standards requires a stable pressuring condition to the target. Therefore, these scales cannot be used for targets that are in motion or targets that require quick measurement such as human muscles during exercises and a liver exposed at a surgery. The prototyped sensor has a compact body and allows continuous hardness measurement with an arbitrary pressing force. This sensor always monitors the force exerted on the sensor and automatically eliminates the unintended effect from the fluctuation of the pressing force. Therefore, continuous time series of the hardness data is real-timely available. This paper reports results of a test as well as the detail of the mechanism and data processing technique of the latest version of the sensor.

Vision based pointing device with slight body movement

It is widely acknowledged that computer is powerful tool to improve the quality of life of the people with disability. One problem is how the user manipulates the computer using suitable input device designed for him or her. This paper proposes tow pointing devices based on vision for the people with disability as input devices. These devices detect the position of the marks attached on the users head. According to the head movements, computer cursor on the computer display is moved in two-dimensionally. A distinct advantage of these devices is that various strategies could be installed based on the situation of the users. The pointing device was applied to a drawing tool of the painting software for an patients successfully.

Monitoring system of body movements for a bedridden patient

In this article a system to detect the physical behavior of bedridden elderly people is proposed. This system is used to prevent elderly people from falling down and injuring themselves. The basic idea of our approach is to measure the body movements of the person using an acceleration sensor. Based on the data measured, dangerous actions are recorded and warning signals to the care workers are generated via wireless signals. A feature of the system is that the sensor is compactly assembled as a wearable unit. Another feature of the system is that it adopts a simplified wireless network system. Owing to its network capability, the system can monitor the physical movements of many patients. The applicability of the system is now being examined at hospitals.

Electric-powered glove for CCI patients to extend their upper-extremity function

An electric-powered hand orthosis has been developed to support daily activities of people with motor impairment in hand fingers. This system is composed of an orthotic part, a head-mounted interface to detect users commands, and a controller. One major feature of this system is that the orthotic part is basically made of soft and lightweight materials only. It is expected that this feature allows users to frequently and continuously use the system in their daily life. A prototype has been made and tested. It was demonstrated that the system has an excellent operability and has promising performance to support daily activities of people with finger disability through the tests.