Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

In this study, a tactile feedback method is proposed for virtual repulsive force based on non-contact impedance and applied to collision avoidance for a biological signal-controlled mobile robot. Virtual walls based on mechanical impedance are placed around the robot, it can avoid obstacles using virtual repulsive forces when obstacles meet the virtual walls. The proposed method provides tactile feedback about the force to the operator, which enables the operator to recognize the environment around the robot. In the experiments, a blindfolded participant controlled a mobile robot using myoelectric signals. The results demonstrated that the robot could be operated stably.

DOI： 10.1109/ESCI56872.2023.10099666

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ALife Robotics Corporation Ltd.  

In this paper, we aim to develop a new tactile feedback method for myoelectric prosthetic hands and model the relationship between delay time and sensation in vibration stimulation. For myoelectric prosthetic hands, the tactile sensation can be expressed by vibrating an oscillator attached to the socket based on information obtained from tactile sensors attached to the prosthesis's fingertips. In this case, if there is a time gap between the sensory input and the stimulus, there is a possibility of causing discomfort. Therefore, in the experiment performed, a delay time, 𝐷u [s], is set between the start of contact with an object and the start of vibration using a tactile sensor and conducted NRS evaluation. The results showed that the discomfort was generated up to 𝐷u = 0.4 [s] and then decreased according to the delay time. The results showed that the discomfort was induced by controlling the timing of the vibration stimulus.

DOI： 10.5954/icarob.2022.os14-2

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ALife Robotics Corporation Ltd.  

This paper proposes a monitoring system for a hamster that uses a video camera. The proposed system first processes the video image taken from the top of the cage, and then extracts features related to posture information and internal state. These features are used to discriminate between daily activities and other activities. This allows the system to alert when the hamster behaves differently from its daily routine. We analyzed the daily behavior of a hamster by using the proposed system. The results showed that the behaviors of a hamster changed when stimuli are given from outside the cage, and the system could discriminate them appropriately.

DOI： 10.5954/icarob.2022.os14-4

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ALife Robotics Corporation Ltd.  

In this paper, a mutual control method is proposed for multi-layered non-contact impedance model-based mobile robots. In the proposed system, the motion priority is set to the robot, and the stiffness, viscosity, and inertia parameters of the non-contact impedance model are changed appropriately according to the priority value allowing the robots to avoid collisions with each other and obstacles at the same time. In the experiment, two mobile robots one controlled by electromyogram signals were prepared and operated to intersect. The other mobile robot automatically stopped and resumed its movement in response to the EMG-controlled robot with high priority, indicating that the proposed method can be used to control multiple robots.

DOI： 10.5954/icarob.2022.os14-1

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ALife Robotics Corporation Ltd.  

This paper describes the effects of tactile stimulation near the auricles on body sway in during foot stamping. The system measures center of pressure, acceleration of upper body, and whole-body movements by skeleton tracking with a depth camera while the participant performs foot stamping on the stabilometer, and extracts evaluation indices based on four perspectives: the amplitude, variation of body sway, rhythm of body sway, and correlation between of each limb. In the prototype experiment conducted with one healthy male, the body sway during foot stamping for ten trials in non-stimulus condition is compared with that for two trials in stimulus condition that the constant tactile stimulus is applied. As a result, the variation of the movement of lower limb and upper body sway were significantly reduced. This result implies that applying the constant tactile stimulation near both of auricles may be effective in stabilizing posture during foot stamping.

DOI： 10.5954/icarob.2022.os14-3

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

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Authorship：Last author   Language：English   Publishing type：Research paper (international conference proceedings)  

Carts and carry bags are used to transport goods, however, they place a heavy burden on the user especially when ascending or descending stairs. Crawlers, often used for mobile robots, suffer from slippage on stairs. The driving unit of proposed cart with power-assist has a planetary gear mechanism with three drive wheels on each side, and it can move on a plane by rotating the wheels and climb stairs by rotating the arm part. Although the burden of the user was reduced at both flat floors and stairs, there was a problem of poor operability for descending stairs. In this study, we propose a new power-assist control method to solve the problem in descending stairs and evaluate the method through experiments.

DOI： 10.1109/ICMA54519.2022.9855966

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ALIFE ROBOTICS CO, LTD  

This paper describes the relationship between tactile stimulation and human body sway. We previously proposed a body sway mitigation system based on tactile stimulation and revealed that simultaneous stimulation behind both auricles were significantly improve human balance function, however, the mechanism of it were not fully discussed. In this paper, some stimulation patterns were applied to participants and COP distribution before/after stimulation was extracted. The results showed that COP values after stimulation could be inclined to the opposite of the stimulation site. It indicates that tactile stimuli can control human balance function.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Electrical and Electronics Engineers (IEEE)  

DOI： 10.1109/access.2021.3126348

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Springer Science and Business Media LLC  

<title>Abstract</title>
Various attempts have been made to elucidate the development patterns in the spontaneous movements of infants through longitudinal evaluations. Movement complexity has been found to demonstrate u-shaped changes in the measurements focusing on limb movements. However, researchers have not yet clarified how other characteristics, besides movement complexity, change over time. This paper presents a longitudinal evaluation of spontaneous movements in infants using evaluation indices calculated through markerless video analysis. Nine infants with corrected ages from <inline-formula><alternatives><tex-math>$$-1$$</tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
<mml:mrow>
<mml:mo>-</mml:mo>
<mml:mn>1</mml:mn>
</mml:mrow>
</mml:math></alternatives></inline-formula> to 15 weeks participated in the experiments. We confirmed the change in indices over time using statistical methods. Index changes can be classified as positively correlated, u-shaped, inverted u-shaped, and uncorrelated. We also confirmed that the u-shaped and inverted u-shaped indices are negatively correlated. Furthermore, the principal component analysis revealed that the first principal component had the inverted u-shaped changes with the corrected age. These results suggest that it is important to synchronize the inverted u-shaped variations in the movement and velocity with the u-shaped changes in the movement complexity for infant development.

DOI： 10.1038/s41598-020-74006-y

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Other Link： http://www.nature.com/articles/s41598-020-74006-y

Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)  

General movements (GMs), a type of spontaneous movement, have been used for the early diagnosis of infant disorders. In clinical practice, GMs are visually assessed by qualified licensees; however, this presents a difficulty in terms of quantitative evaluation. Various measurement systems for the quantitative evaluation of GMs track target markers attached to infants; however, these markers may disturb infants' spontaneous movements. This paper proposes a markerless movement measurement and evaluation system for GMs in infants. The proposed system calculates 25 indices related to GMs, including the magnitude and rhythm of movements, by video analysis, that is, by calculating background subtractions and frame differences. Movement classification is performed based on the clinical definition of GMs by using an artificial neural network with a stochastic structure. This supports the assessment of GMs and early diagnoses of disabilities in infants. In a series of experiments, the proposed system is applied to movement evaluation and classification in full-term infants and low-birth-weight infants. The experimental results confirm that the average agreement between four GMs classified by the proposed system and those identified by a licensee reaches up to 83.1 ± 1.84%. In addition, the classification accuracy of normal and abnormal movements reaches 90.2 ± 0.94%.

DOI： 10.1038/s41598-020-57580-z

PubMed

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© The Author(s) 2017. This article proposes a virtual hand and a virtual training system for controlling the MyoBock—the most commonly used myoelectric prosthetic hand worldwide. As the virtual hand is controlled using the method also adopted for the MyoBock hand, the proposed system provides upper-limb amputees with operation sensibilities similar to those experienced in MyoBock control. It can also display an additional virtual hand for the provision of instructions on hand operation, such as the recommended posture for object grasping and the trajectory desirable to reach a target. In virtual hand control experiments conducted with an amputee to evaluate the proposed virtual hand’s operability, the subject successfully performed stable opening and closing with high discrimination rates (89:3±6:65%), thanks to the virtual hand’s incorporation of the MyoBock’s operational characteristics. A training experiment using the proposed system was also conducted with eight healthy participants over a period of 5 days. The participants were asked to perform the box and block test using the MyoBock hand in a real environment on the first and final days. The results showed that the number of blocks transported in 1 min significantly increased and that the participants using the instruction virtual hand changed the orientation of the hand approaching blocks from vertical to lateral. The outcomes of the experiment indicate that the proposed system can be used to improve MyoBock hand control operation both quantitatively and qualitatively.

DOI： 10.1177/1729881417728452

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Robotics Society of Japan  

This paper proposes an interactive training system for control of myoelectric prostheses. The proposed training system is capable of selecting suitable motions (EMG patterns) for each user by eliminating ineffective ones, and can also provide consistency between user's motor images and the corresponding prosthetic movements using a virtual prosthetic hand (VH). In the experiments performed, a one-day training session using the proposed system was conducted with nine healthy males (including an experienced) and an upper limb amputee. In addition, EMG discrimination ability of each subject during VH control without any feedback information was evaluated before and after the training to verify the training effects of the proposed system. The results showed that the discrimination rates for selected motions were sufficiently high (98.9 &plusmn; 1.24%) by using the proposed selection method, and the accuracy in discrimination for VH control was significantly improved after training (for healthy subjects and the amputee at the 0.1% and 1% level, respectively). It is therefore confirmed that the proposed system can be used for myoelectric prosthesis control training.

DOI： 10.7210/jrsj.34.404

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC  

This paper proposes a probabilistic neural network (NN) developed on the basis of time-series discriminant component analysis (TSDCA) that can be used to classify high-dimensional time-series patterns. TSDCA involves the compression of high-dimensional time series into a lower dimensional space using a set of orthogonal transformations and the calculation of posterior probabilities based on a continuous-density hidden Markov model with a Gaussian mixture model expressed in the reduced-dimensional space. The analysis can be incorporated into an NN, which is named a time-series discriminant component network (TSDCN), so that parameters of dimensionality reduction and classification can be obtained simultaneously as network coefficients according to a backpropagation through time-based learning algorithm with the Lagrange multiplier method. The TSDCN is considered to enable high-accuracy classification of high-dimensional time-series patterns and to reduce the computation time taken for network training. The validity of the TSDCN is demonstrated for high-dimensional artificial data and electroencephalogram signals in the experiments conducted during the study.

DOI： 10.1109/TNNLS.2015.2400448

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Human Growth and Development  

This paper proposes a behavior analysis system for quantitative evaluation of infants with attention deficit hyperactivity disorder (ADHD) using video images. The system records infantsʼ movements using video cameras without any markers, and quantitatively evaluates each infantʼs behavior using features extracted from video images based on the behavior model. In the experiments performed, behaviors of infants in nursery school were evaluated using the proposed system. The results showed that the behavior of a high-risk infant significantly different from those of normal infants. These outcomes indicated that the proposed system could discriminate the behavior of normal infants and high-risk infants.

DOI： 10.5332/hatsuhatsu.2014.65_1

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This paper introduces a motion and channel selection method based on a partial Kullback-Leibler (KL) information measure. In the proposed method, the probability density functions of recorded data are estimated through learning involving a probabilistic neural network based on the KL information theory. Partial KL information is defined to support evaluation of the contribution of each dimension and class for classification. Effective dimensions and classes can then be selected by eliminating ineffective choices one by one based on this information, respectively. In the experiments, effective channels for classification were first selected for each of the six subjects, and the number of channels was reduced by 32.1 ± 25.5%. After channel selection, appropriate motions for classification were chosen, and the average classification rate for the motions selected using the proposed method was found to be 91.7 ± 2.5%. These outcomes indicate that the proposed method can be used to select effective channels and motions for accurate classification. © 2012 IEEE.

DOI： 10.1109/ICCME.2012.6275609

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Event date： 2022

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Event date： 2015

Language：Japanese  

This paper proposes a training system for controlling the five-finger EMG-prosthetic hand that enables not only fast finger motions but also a strong grasping force. The proposed system is developed based on the control method equivalent to the five-finger prosthetic hand, and conducts three types of training: muscle contraction, muscle cooperation, and grip force training. In the contraction training and the cooperation training, the control ability of muscle force and the reproducibility of EMG patterns can be trained, respectively. Appropriate gripping force according to the hardness of an object can also be trained via the grip force training using a virtual prosthetic hand. The validity of the proposed system is demonstrated in the five-day experiments conducted for three subjects.

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Event date： 2014.5.24

Language：Japanese  

In this paper, we aim to develop a custom-made environment control system (ECS) in order to support daily living for physically handicapped persons. We modularized the ECS "Bio-remote" developed at Hiroshima University based on OpenRTM. The modularity enhanced flexibility and expandability of Bio-remote, and it made possible to operate by combining multiple input signals. In addition, we performed a trial test with an upper limb amputee in a room which was build to evaluate Bio-remote. We confirmed the operation of the prototype system and the advantage of the modularity that the system function can be easily modified and added.

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Event date： 2011.9.1

Language：Japanese  

This paper proposes a five-fingered EMG-prosthetic hand, which enables a quick motion and a secure grasp. In order to realize the natural feeling of control similar to that of human movements, the control system includes the impedance model of human forearms, and utilizes the muscle contraction level extracted from the user's EMG signals. To verify the effectiveness of the developed prosthetic hand, the control experiments of quick motion and secure grasp using EMG signals performed with a subject.

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