With the increase in the aging population, the demand for healthcare devices has increased. Among the aging population, many experience joint pain, muscle weakness, or poor balance. Without external help, such persons may have difficulty walking, fall easily, or experience poor quality of life. To provide this category of the population with the opportunity to exercise and walk safely and take care of themselves in daily activities, a stepper motor-powered walking assistive device is proposed and built. The device enables users with different heights to walk in suitable gaits; assists users to stand up, sit down, and step up or down stairs; automatically detects user’s intention using pressure sensors and potentiometers; and can be used outdoors for long periods. In this study, the effectiveness of the device is verified using muscle-activity measurements.

Owing to aging populations, the number of elderly people with limb dysfunction affecting their daily lives will continue to increase. These populations have a great need for rehabilitation training to restore limb functions. However, the current numbers of rehabilitation hospitals and doctors are limited. Moreover, people often cannot go to a hospital owing to external conditions (e.g., the impacts of COVID-19). Thus, an urgent need exists for telerehabilitation system for allowing patients to have training at home. The purpose of this study is to develop an easy-to-use system for allowing target users to experience rehabilitation training at home and to remotely receive real-time guidance from doctors. The proposed system only needs a monocular camera to capture 3D motions. First, the 2D key joints of the human body are detected; then, a simple baseline network is used to reconstruct 3D key joints from the 2D key joints. The 2D detection only has an average angle error of 1.7% compared to that of a professional motion capture system. In addition, the 3D reconstruction has a mean per-joint position error of only 67.9 mm compared to the real coordinates. After acquiring the user’s 3D motions, the system synchronizes the 3D motions to a virtual human model in Unity, providing the user with a more intuitive and interactive experience. Generally, many telerehabilitation systems require professional motion capture cameras and wearable equipment, and the training target is a single body part. In contrast, the proposed system is low-cost and easier to use and only requires a monocular camera and computer to achieve real-time and intuitive telerehabilitation (even though the training target is the entire body). Furthermore, the system provides a similarity evaluation of the motions based on the dynamic time warping; this can provide more accurate and direct feedback to users. In addition, a series of evaluation experiments verify the system’s usability, convenience, feasibility, and accuracy, with the ultimate conclusion that the system can be used in practical rehabilitation applications.

As the population ages, the number of elderly people suffering from systemic diseases such as stroke increases. To address this problem, various wearable walking assistive robots have been developed to promote physical exercise for stroke prevention. Wearable assistive robots have shown the ability to improve human mobility. However, most of these robots are heavy, bulky, and impractical. In this study, we developed a compact ankle assistive robot for elderly users to promote walking exercise. By informing the user of correct motion and timing, the robot can guide the user to achieve a healthy gait by only assisting their ankle joint. The robot provides faster-than-ankle motion to allow the user to feel supported while walking. Users can adjust the robot’s assistance parameters through a graphical user interface (GUI) according to their needs. Furthermore, we proposed a gait-adaptive method for ankle assistive robots to adapt to the user’s changing gait. Hence, the robot can automatically adjust the parameters to provide more accurate walking assistance. Finally, the results of an evaluation experiment demonstrated the feasibility of human gait adaptation. The proposed methods have the advantages of low cost and easy implementation.

This paper proposes a three-layer elastic cloth fabric mechanism for an assistive suit with adjustable structure (based on a two-layer non-adjustable structure) to achieve different assistive force profiles. This increases the assistive force on the lower-back muscle group and alleviates the undesired pre-tension that acts on a user when the rubber belt located on the back is pulled to provide a higher assistive force. With the lower pre-tension, users would not encounter body fatigue as rapidly as in the past. The adjustable feature enables the structure to provide a force that increases gradually to a high level over a short distance without pre-tension. An experiment involving the measurement of muscle activities is conducted to evaluate the variation in assistive force in the lower back by comparing the three-layer suit to the two-layer non-adjustable suit. The experimental results show that the new three-layer structure successfully assists without pre-tension in the lower-back muscle group similar to the two-layer structure with pre-tension. A simple questionnaire is also administered to collect feedback from participants on the differences between the three-layer suit and two-layer suit in terms of wearing perception. Over half of the participants reported that the perception of pre-tension in the three-layer suit is lower than that in the two-layer suit.

In response to the shortage, uneven distribution, and high cost of rehabilitation resources in the context of the COVID-19 pandemic, we developed a low-cost, easy-to-use remote rehabilitation system that allows patients to perform rehabilitation training and receive real-time guidance from doctors at home. The proposed system uses Azure Kinect to capture motions with an error of just 3% compared to professional motion capture systems. In addition, the system provides an automatic evaluation function of rehabilitation training, including evaluation of motion angles and trajectories. After acquiring the user’s 3D motions, the system synchronizes the 3D motions to the virtual human body model in Unity with an average error of less than 1%, which gives the user a more intuitive and interactive experience. After a series of evaluation experiments, we verified the usability, convenience, and high accuracy of the system, finally concluding that the system can be used in practical rehabilitation applications.

The world’s aging population is increasing. The number of elderly individuals having walking impairments is also increasing. Adequate exercise is becoming necessary for them. Therefore, several walking assistive devices have been developed or are under development. However, elderly individuals may have low motivation for exercising, or they may experience physical damage by excessive fatigue. This study proposed a method to enable elderly individuals to exercise with a positive emotion and prevent damage such as muscle fatigue. We proposed a 3D human condition model to control the walking assistive device. It includes the arousal, pleasure, and fatigue dimensions. With regard to the arousal and pleasure dimensions, we used heartbeat and electromyography (EEG) signals to train a deep neural network (DNN) model to identify human emotions. For fatigue detection, we proposed a method based on near-infrared spectroscopy (NIRS) to detect muscle fatigue. All the sensors are portable. This implies that it can be used for outdoor activities. Then, we proposed a walking strategy based on a 3D human condition model to control the walking assistive device. Finally, we tested the effectiveness of the automatic control system. The wearing of the walking assistive device and implementation of the walking strategy can delay the fatigue time by approximately 24% and increase the walking distance by approximately 16%. In addition, we succeeded in visualizing the distribution of emotion during each walking method variation. It was verified that the walking strategy can improve the mental condition of a user to a certain extent. These results showed the effectiveness of the proposed system. It could help elderlies maintain higher levels of motivation and prevent muscle damage by walking exercise, using the walking assistive device.

Ankle foot orthoses are mainly applied to provide stability in the stance phase and adequate foot clearance in the swing phase; however, they do not sufficiently assist during the entire gait cycle. On the other hand, robotic-controlled orthoses can provide mechanical assistance throughout the phases of the gait cycle. This study investigated the effect of ankle control throughout the gait cycle using an ankle joint walking assistive device under five different robotic assistance conditions: uncontrolled, dorsiflexion, and plantar flexion controlled at high and low speeds in the initial loading phase. Compared with the no-control condition, the plantar flexion condition enhanced knee extension and delayed the timing of ankle dorsiflexion in the stance phase; however, the opposite effect occurred under the dorsiflexion condition. Significant differences in the trailing limb angle and minimum toe clearance were also observed, although the same assistance was applied from the mid-stance phase to the initial swing phase. Ankle assistance in the initial loading phase affected the knee extension and ankle dorsiflexion angle during the stance phase. The smooth weight shift obtained might have a positive effect on lifting the limb during the swing phase. Robotic ankle control may provide appropriate assistance throughout the gait cycle according to individual gait ability.

Extended roles of robots for activities of daily living (ADL) lead to researchers’ increasing attention to human-robot interaction. Emotional recognition has been regarded as an important issue from the human mental aspect. We are developing an assistive walking device which considers the correlation between physical assistance and mental conditions for the user. To connect the assistive device and user mental conditions, it is necessary to evaluate emotion in real-time. This study aims to develop a new method of two-dimensional valence-arousal model emotion evaluation with multiple physiological signals. We elicit users’ emotion change based on normative affective stimuli database, and further extract multiple physiological signals from the subjects. Moreover, we implement various algorithms (k-means, T method of MTS (Mahalanobis Taguchi System) and DNN (deep neural network)) for determining the emotional state from physiological data. Finally, the findings indicate that deep neural network method can precisely recognize the human emotional state.

Emotion is an internal and subjective experience that plays a significant role in human life. There are several methods of recognizing emotions in people, the most authentic of which is using physiological signals, as they are beyond one's control and strongly correlated with human emotions. This study aims to develop an emotion recognition system based on three physiological signals, namely, brainwave, heartbeat, and facial muscular activity. It utilizes deep neural network (DNN) and the T method of Mahalanobis-Taguchi system (MTS) to process the multiple physiological signals and further recognize the states of human emotion. As such, nine emotions are effectively recognized on a two-dimensional model through the DNN, then compared against several other algorithms, such as MTS, SVM, Naive Bayes, and K-means, where its superior accuracy is validated. Moreover, although the T method only improves the classification accuracy on the valence state, it rather obtains the intensity of emotion in different states. Furthermore, in this study, the proposed DNN is implemented into a wide range of applications for an accurate understanding of the human emotional states, whereas the T method is utilized to respond to the emotional intensity in different states. Finally, a real-time emotion recognition system is developed with DNN as the classifier; this system can directly monitor the variation of the human emotion through reliable and objective emotion analysis results from the physiological signals. Thus, the method can provide useful treatment effect information for robots or assistive apparatus serving activities of daily living.

This chapter presents authors development work on walking assistant exoskeletons for gait training of patients and promotion exercise of the elderly. The first exoskeleton is a whole leg assisting device using a special parallel link mechanism. For gait training of motor palsy patients, a weight bearing lifter was attached, and an impedance control was tuned by using frequency entertainment. For the elderly, a torque controller taken into account the dynamics of both a user and the apparatus with real time acceleration data is developed. The second exoskeleton is a whole body assisting suit was developed by adding arm assistance to the whole leg apparatus. By assisting not only legs but also swinging arms, an increased cerebral activity of all areas can be expected via rehabilitation with the whole body exoskeleton. Finally, we developed a close-fitting type exoskeleton assisting only ankle joint, which leads to a product RE-Gait® in 2016. By utilizing the structure of bi-articular muscle and physiological phenomenon of stretch reflex, the user’s leg can be raised assisting only ankle joint. Experiments with by hemiplegic patients are enclosed, which show that abduct variation of the hip joint is decreased while the stride length is increased by using the device.

A walking assistance device for apoplexy patients has been developed. We developed a walking assistance device RE-Gait®, which assists the motion of the ankle joint while walking. The motor is controlled according to the walking phase grasped with the pressure sensors under the sole. It is already utilized as a product, for the gait training by so many hemiplegic patients. By using the technology of RE-Gait®, a new device for the able-bodied elderly to promote exercise was also developed. This is RE-Gait®Light, which is lower cost, very light, and easy to move. We proposed a new control method for this device, which is automatically tuned according to the condition of the emotion of the user. In this chapter, the evaluation results using this method are introduced.

Due to the growing elderly population in many developed countries like Japan, assistive devices are increasingly needed to overcome the difficulties of their activities of daily living (ADL). The motion of standing up places a particular burden on the ankle and knee joints and connects static motions (e.g., sitting and lying) and kinetic motions (e.g., walking and climbing up/down the stairs). In our previous research, two types of standing-up assistance apparatuses were introduced according to the suitable standing-up motions. However, these devices are bulky and cannot be widely used in practical settings such as bus terminals. Regarding the suitable standing-up motions of the elderly in the previous literature, a standing-up apparatus with a pantograph mechanism is introduced to diminish the size of the mechanism based on three design principles: (1) the trajectory of the user's COG is an arc
(2) the trajectory of the user's hip joint while standing up is a straight line at an angle of 45 [deg] from the horizon
and (3) the user is supported until the knee angle reaches 60 [deg]. Simulations showed that the load on knee and ankle joint is decreased, and user may stand up easily with our proposed apparatus. A prototype of the apparatus that may be installed on various chairs in public was fabricated. Considering that the apparatus may be used in places without electric power supply, the apparatus is made simply with links and a gas spring instead of electric actuators. Experimental measurements of the trajectories of the center of gravity (COG) and hip joints show that the proposed apparatus may help users to stand in a way that minimizes stress on their lower-body joints.

We proposed a method that promotes walking which uses a two-dimensional emotion map. In this method, a subject listened to a beat sound while walking. The beat was adjusted according to the condition of the subject, based on his/her comfortable walking frequency. Simultaneously, the walking velocity, the stride length, and the heart beat of the subject while walking was measured, and LF/HF was calculated from the result of measured heart beat. Furthermore, we asked them to give information on the condition of their feelings, from pleasant or not by 5 levels in each case of the beat sound. By using these data, a two-dimensional walking condition map and two-dimensional emotion map were made and we found the relation between these two maps. Therefore, according to the emotional condition of the targeted person while walking, this method can promote or restrain walking adequately, only adjusting the beat sound.

In the current study, we formulated ontological descriptions for emotional states of users using motion assistance apparatus. In our previous studies, we developed apparatus that assists the ankle joints of patients in neuro-rehabilitation. Although we have confirmed the apparatus can improve the gait of the patient while walking, we have to capture and manage patients’ emotions as feedback of the usage. The ontological descriptions provide a feasible framework for common understanding while sharing and using this knowledge. In future work, we will develop a subset of this framework for more practical usage, in addition to expanding the descriptions of emotional states. After that, we will assess the validity and utility for design and implementation of software and hardware applications using this subset.

<p>We developed a new power assistance suit without the need for electricity. This suit is to support care worker's assistance behavior, e.g. lifting-up and holding motion. It is made of only rubber and nylon belts. This suit can assist the equipped person's arms and back with two kinds of equipped belts. One is for the waist, attached from the shoulder to the back of the knee via his/her back. The other is for the arms, attached from equipped person's forearm to the back of the knee via his/her back. To confirm the possibility of this suit, first, we interviewed medical doctors and physical therapists. Their comments were, it is important to adjust the length of each belt for an equipped person adequately, and it is effective for the assistance of motion in a half-sitting posture and in transfer motions between a bed and a wheel chair. Furthermore, we measured the variation of maximum output force and %MVC of the entire body muscles during lifting and holding motions using the suit and not. From the result, by using this suit, the maximum lifting weight of the equipped person was increased by over 8kg, and the arms and back of the equipped person were assisted effectively.</p>

We developed a device that promotes walking which uses a two-dimensional emotion map for the exercise of the elderly. This map was made with two axes, the horizontal axis was pleasant or unpleasant, with the vertical axis being arousal or not, same as the circumplex model of affect (J. A. Russell (1980)). This device has two means to promote walking. One is an ankle joint assistance system, which consists of a servo motor and a controller which can adjust the targeted walking cycle, the targeted angle of the ankle joint, and the sensitivity of the sensors which was attached under the sole. The other is a beat listening system. The beat listening system makes the beat sound, which is decided for the purpose of the user, and based on the walking cycle. The user listens to the beat sound using head phones. By combining and using these two means simultaneously, users can change their gait and emotion, therefore, they can continue to walk for a long time.

We developed a walking assistance apparatus RE-Gait® for not only the elderly but also apoplexy patients, which assist the ankle joint of the equipped person. By only assisting the ankle joint, the equipped person’s leg can be raised. To keep up the user’s motivation for exercise using this apparatus, it is necessary to assist not only physically but also mentally. Therefore we suggested the new method of promotion walking, using the walking assistance apparatus while listening to the beat sound, which was adjusted according to a two-dimensional emotion map. In this paper, the relation between emotion map and walking condition map is shown.

We developed a motion assistance apparatus which can be used for neuro-rehabilitation of patients and for the promotion of exercise for the elderly. This apparatus assists only the ankle joints of the equipped person according to the posture of him/her while walking, getting up, sitting, and standing. By using this apparatus, the dorsiflexion and plantarflexion of the ankle joint of the equipped person can increase while walking. Therefore, this apparatus can prevent stumbling and promote walking and various motions.

We developed a method which can diagnose damage on a gear tooth surface by using laser beam without a rotary encoder. This method is as follows: 1) The tooth bottom, the tooth tip and their two medians are detected by the differentials of the laser reflection data. 2) The gear rotation speed is calculated with these four positions, and interpolated according to the rotation fluctuation. 3) By using the calculated gear rotation speed, the measured data can be converted corresponding to the gear rotation angle. Thus we diagnose gear tooth surface damage without being influenced by rotational fluctuation. We did diagnosis experiments and we made contour maps show diagnosis accuracy. From these maps, we got the following conclusions: 1) The accuracy of damage diagnosis is the same level regardless of the presence or absence of a rotary encoder. 2) The cycle of rotational fluctuation hardly affects the accuracy. 3) Bigger fluctuation amplitude makes the range accuracy worse, however the position accuracy improves.

We developed a new whole body motion support type mobile suit. This suit can be used separately for supporting the upper and/or lower limbs, for assisting in ADL (Activities of Daily Living). We also developed a mobile lifter system which can bear both the equipped person and the suit. This suit and the lifter can be used by motor palsy patients, people who have suffered a stroke, spinal-cord-injury patients, and people with central nerve disorders. Using this device, these patients can recover normal gait with no risk of falling. In this paper, the cerebral activity during walking using the suit and normal gait without the suit are compared. According to multiple trials with the suit on a treadmill, the activities of the premotor area sensory motor cortex decreased. Especially, while walking using the suit for supporting lower limbs without swinging arms, the cerebral activities of most of the areas decreased. This data shows that it bcomes ineffective for patients accustomed to the suit in rehabilitation. However, on the contrary, by walking while swinging bilateral arms (even though these arms were assisted by the suit), the activity in the supplementary motor area increased (this area of the brain is related with memory of motion). Furthermore, the cerebral activities while walking on a treadmill and while walking in a corridor with an outside view were compared using NIRS (Near-Infrared Spectroscopy). From the results of this experiment, we found it is most effective for gait training to actually walk and not stay fixed in one location. We also found it is important for patients to swing their arms during gait training in rehabilitation.

We developed a new diagnostic method by using a laser beam. A tooth surface is irradiated by the zonal laser beam from an oblique direction, and then the irradiated laser beam line is shifted along the height of the tooth according to gear rotation. The variation of the voltage proportional to laser reflection between initial and present conditions are compared, and the condition of the tooth surface can be diagnosed for things such as initial or abnormal abrasion, pitting, etc. Furthermore, we developed a method of automatic and remote damage diagnosis on a gear tooth surface according to various gear specifications by using the angle-distance relation map which made from pre-measured data of same material and heat treatment, and taking into account the influence of adjacent teeth. The measured data agreed well with the predicted data made with this method, therefore we can diagnosis the condition of various products automatically.

We have developed a prototype for a walking-assistance apparatus that serves as a next-generation vehicle or a movable neuro-rehabilitation training appliance for the elderly or motor palsy patients. Our prototype uses a novel spatial parallel link mechanism with a weight-bearing lift. Flat steps of the apparatus move in parallel with the ground
the apparatus supports the entire leg alignment (including soles of the feet) and assists walking behavior at the ankle, knee, and hip joints simultaneously. To estimate the walking phase of each leg of the equipped person, pressure sensors were attached under the thenar eminence and the heel of the sole and the pressure variation at each sensing point was measured. To determine the direction in which the equipped person is walking, a pressure sensor was attached to the flexible crural link. Motor palsy patients and those with muscle weakness can walk with the assistance of the apparatus. Patients who have ambulation difficulty can also use the apparatus with a weight-bearing lift that we developed. Using the apparatus with the weight-bearing lift prevents stumbling and enables input of walking movement to the brain motor area. The validity of the weight-bearing lift can be confirmed from the results of the measured % maximum voluntary contraction (MVC). © (2012) Trans Tech Publications, Switzerland.

The repletion rate of guide dogs for visually handicapped persons is roughly 10% nationwide. The reasons for this low rate are the long training period and the expense for obtaining a guide dog in Japan. Motivated by these two reasons, we are developing guide-dog robots. The major objective is to develop an intelligent human-robot interface. This paper describes two novel interface algorithms and strategy to guide visually handicapped person. We developed new leading edge searching method, which uses a single laser range finder (LRF) developed to find the center of the corridor in an indoor environment. We also developed a new twin cluster trace method that can recognize the led-person's walking conditions measured by the LRF. The algorithm allows the guide-dog robot to accurately estimate and anticipate the led-person's next move. We experimentally verified these algorithms. The results show that the algorithms are reliable enough to enable the guide-dog robot and the led-person to maneuver in a complex corridor environment. © 2011 Springer-Verlag.

A prototype for a walking assistance apparatus for the elderly or rehabilitants of motor palsy patients was developed as a next-generation vehicle or movable neuro-rehabilitation training appliance, using a novel spatial parallel link mechanism and a bearing lift. The flat steps of the apparatus move in parallel with the ground
the apparatus can support entire leg alignment (including soles) and assist
walking behavior at ankle, knee and hip joints simultaneously. To respond to the variation of equipped person's walking velocity, the length of stride and walking cycle while walking with wearing the apparatus were compensated by using walking ratio. Therefore the apparatus can be controlled in response to equipped person's will. Next, we developed a control method of the apparatus by using impedance control, taking into account the dynamics of the apparatus and the legs of an equipped person, and assist ratio for the equipped person. By adjusting the value of natural angular frequency of the desired dynamic equation for the equipped person, this apparatus can assist walking according to the equipped person's desired response of the apparatus. Furthermore, motor palsy and muscle weakness patients can walk by themselves by using the apparatus
patients who have ambulation difficulty can use the apparatus with weight bearing lift that we developed. Using the apparatus with the weight bearing lift prevents stumbling and enables input of walking movement to the brain motor area. From the results of measured %MVC, the validity of the weight bearing lift was shown. Copyright © 2011 by ASME.

A prototype for a walking assistance apparatus for the elderly or motor palsy patients was developed as a next-generation vehicle or movable neuro-rehabilitation training appliance, using a novel spatial parallel link mechanism and a bearing lift. The flat steps of the apparatus move in parallel with the ground
the apparatus can support entire leg alignment (including soles) and assist
walking behavior at ankle, knee and hip joints simultaneously. In order to respond the variation of equipped person's walking velocity, the length of stride and walking cycle while walking with wearing the apparatus were compensated by using the relation of walking ratio. Therefore the apparatus can be controlled in response to equipped person's will. Motor palsy and muscle weakness patients can walk by themselves by using the apparatus
patients who have ambulation difficulty can use the apparatus with weight bearing lift that we developed. Using the apparatus with the weight bearing lift prevents stumbling and enables input of walking movement to the brain motor area. It is very effective for rehabilitation to use the apparatus with the weight bearing lift. This newly developed system facilitates motor palsy and muscle weakness patients in the rehabilitation program. © 2011 IEEE.

本研究では、乳母車利用時における安全性の向上を念頭に、乳児用バギーの新機能開発をおこなった。乳児用バギーの新機能開発のため、乳母車利用者へのアンケート調査に基づき新機能を開発する改善点を抽出した。アンケート調査は東京都荒川区南千住駅前ショッピングモール周辺でおこなった。調査地点の特徴として、自動車の交通量が多いこと、鉄道利用者の往来が多いこと、また歩道上での自転車と乳母車の同時通行がおこなわれていることがあげられる。調査の結果、片手開閉機能や片手推進時の直進性の向上など、「片手操作性の向上」に強い希望が示された。片手操作性の向上は、利用者が乳幼児を確実に確保することを確実にする。同時に、利用者が乳幼児に十分な注意力を確保することに効果が期待される。そこで、既存の乳児用バギーを基に、片手収納機能、直進性の向上、新たな自立機能の各追加機能を開発した。第1に、新たにキックバーを取り付け、片手での収納を容易にした。本機能は同時に自立機能のための追加動作を不要とした。第2に、ハンドル回転機構を開発し、左右に分かれたハンドルの疑似的な一体化を可能とした。本機能により、片手操作時における直進性の向上が期待できる。

モビルスーツ型自立歩行支援ロボットを使って，免荷時のロボット使用時の歩行と通常歩行の健常者における脳活動を比較し，脳機能の視点から月面歩行のシミュレーションとしての可能性を検討した．月面歩行のシミュレーションを歩行と捉えるか，ジャンプと捉えるかでシミュレーションの方法が変わってくるものと考えられる．月面歩行のシミュレーションの技術開発は，ニューロリハビリテーションやスポーツ医学等の隣接学術領域にも多くの知見を与えるものと思われる．

An apparatus to assist elderly patients to stand up, as well as leaning forward the upper body, has been developed. The mechanism of the apparatus enables to shift the person's center of gravity along an adequate trajectory during the standing up process, so as not to cause strain on the joints of the user's leg. The apparatus also assists a person to alter from a standing or sitting posture to lying posture. Although the mechanism has multiple links and joints, only one actuator is required to transform the apparatus between aforementioned three postures. The length of each link of the mechanism has been determined from their effect on the backrest angle when each link in the mechanism length is changed. The torque of the hip and knee joints while using the apparatus can be calculated and compared with the data of a user not using the apparatus. We hypothesize that the output torque of the user while standing is decreased by using the apparatus.Mechanical Design

We have developed a walking assistance apparatus using a spatial parallel link mechanism. This apparatus was designed to assist in the rehabilitation of patients who have difficulty walking. The apparatus utilizes a compensating gravity mechanism that helps center gravity during the stance phase of walking. To confirm the effectiveness the mechanism, we compared the measured data of the height of the hip joint on the apparatus while walking between with the mechanism and without the mechanism, and measured the value of the force which lifted the upper body with the mechanism. From these results, it can be verified that the mechanism output the lifting force during the stance phase of walking, and the hip joint kept the adequate height while walking by using the mechanism.

We have developed two kinds of power assistance suits. One is for support a patient's activities of daily living, which was united two apparatuses between for the upper limbs and for the legs; these were driven with a motor. These apparatuses were already developed, and characterized in that equipped person can be assisted for arms and legs without fixation with the apparatuses. By using this suit, we can input the entire body motion to the equipped patient for the neuro-rehabilitation. The other is for support a helper's assistance behavior, which was made with rubber belt, and without electricity. This suit can assist lifting motion, especially for equipped person's arms and waist. To confirm the validity of this suit, we measured the variation of maximum output force, IEMG and %MVC of the entire body while lifting and holding motion. By using this suit, the maximum lifting weight of equipped person was increased by 8kg, and the arm and leg of the equipped person were assisted effectively.

A conceptual Guide-Dog Robot prototype to lead and to recognize a visually-handicapped person is developed and discussed in this paper. Key design features of the robot include a movable platform, human-machine interface, and capability of avoiding obstacles. A novel algorithm enabling the robot to recognize its follower's locomotion as well to detect the center of corridor is proposed and implemented in the robot's human-machine interface. It is demonstrated that using the proposed novel leading and detecting algorithm along with a rapid scanning laser range finder (LRF) sensor, the robot is able to successfully and effectively lead a human walking in corridor without running into obstacles such as trash boxes or adjacent walking persons. Position and trajectory of the robot leading a human maneuvering in common corridor environment are measured by an independent LRF observer. The measured data suggest that the proposed algorithms are effective to enable the robot to detect center of the corridor and position of its follower correctly.

In Japan, repletion rate of guide dogs for visually-handicapped persons is at very low percentage of roughly 10% nationwide due to required long training period as well as uneconomic price in obtaining a guide dog. Motivated by these two reasons, we are currently developing a Guide-Dog Robot with major objective given to developing intelligence in human-guide-dog robot interface. In this paper, novel human-machine interface algorithm and strategy to lead visually-handicapped people is proposed. A new leading edge searching method intelligently incorporated with one leaser range finder (LRF) is developed and implemented in our prototype guide-dog robot. It is demonstrated in our experiment that with the new method, the robot not only is able to effectively recognize the led-person's walking conditions but also is able to accurately estimate the person's next move. With the new method and a LRF, robustness is improved and validated to allow the guide-dog robot and the led-person to maneuver in complex corridor environment.

There are many persons who lost their sight or hearing. And They want to get more flexibility for their activities. But there are very low supply assistance-dog. So, we started to serve a assistance-dog robot for handicap persons. In this paper, algorithm of obstacle detection with image processing and avoidance are proposed. Especially, the potential method is applied to Bar-Shape obstacles for estimating the coordinate. These validity of methods are shown with simulation and also experiment by using prototype robot with real-time processing. As a result, we found the choice of getting around Bar or not is easily to control with height of Bar with persons safety.

We developed a walking assist machine, which machine used a spatial parallel link mechanism for the elderly or workers. The flat steps of the assist machine move in parallel with the ground and can support the legs of a person including the soles. The machine was equipped various sensors, could turn around during walking and walk in a slope or stairs. Furthermore, the machine was mounted self-contained control system used a SH-4 microcomputer and Lithium-ion batteries. As a result, the equipped person can walk without limitation of the area where the machine can be used. The EMG while the equipped person walked on the stairs was measured, and the ratio of IEMG between the data while wearing and without wearing the machine, and MVC were calculated. As a result, the machine was effective to use during walking on the stairs for the lower leg (crural leg) of the equipped person.

Ankle-foot orthoses (AFOs) are used in people who have difficulty of working as ankle contracture splints and foot drop splints. Although utilization of AFOs has been expanding, it is still questionable if functions and structures of AFOs are suitable. In this paper, a new active ankle-foot orthosis (AAFO), which is dynamically controlled linked with muscle activities, is proposed. To discuss functions of the AAFO, using the electromyographies (EMGs), muscle activities during dynamic balancing of a body and changing of muscle activities with fatigue are considered. As the results, it's shown that to assist femoris muscles additionally to the tibialis anterior muscle is important as the function of the AAFO.

Ankle-foot orthoses (AFOs) are used in people who have difficulty of working as ankle contracture splints and foot drop splints. Although utilization of AFOs has been expanding, it is still questionable if functions and structures of AFOs are suitable. In this paper, a new active ankle-foot orthosis (AAFO), which is dynamically controlled linked with muscle activities, is proposed. To discuss functions of the AAFO, using the electromyographies (EMGs), muscle activities during dynamic balancing of a body and changing of muscle activities during fatigue are considered. As the results, it's shown that to assist femoris muscles additionally to the tibialis anterior muscle is important as the function of the AAFO.

A method for predicting gear noise from the vibration step to the sound-generation step of a complete gear system, including a gearbox, was developed. This method consists of three separate steps: gear-vibration analysis by an in-house program, gearbox-vibration analysis by an FEA program, and sound-radiation analysis by a commercial software. By using this method, it can obtain the vibration behavior of the gear and gearbox, and the distribution of the sound-pressure around the gearbox and identify the areas from which noise radiates intensely. To validate the method, we measured the displacement of a gear shaft, the acceleration of points on the surface of the gearbox, and the sound-pressure levels around the gearbox. The measured results agreed well with the corresponding calculations. According to the calculated noise, a low-noise gearbox was designed by adding ribs near the antinodes of the gearbox's vibration mode.

We have developed a new method for building a vibration model of an actual gear-drive system. Each gear has six degrees of freedom: three translational and three rotational motions. Stiffness matrixes representing each gear shaft and tooth meshing were made and overlapped into one stiffness matrix for the whole system. This enabled easy modelling of complex gear-drive systems such as multi-stage gears and branched gears. The results are in good agreement with experimental results with respect to the major resonance frequencies and vibration modes.