Yusuke Ikemoto

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.

Force sensor system for structural health monitoring using passive RFID tags for structural health monitoring

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.

Forgetting curve of cricket, Gryllus bimaculatus, derived by using serotonin hypothesis

It is thought that the adjustment of intraspecific aggression is an essential factor in the development of a social structure. To understand the natural laws for organizing the social structure, we focus on the fighting behavior of crickets, Gryllus bimaculatus, and investigate the neuronal mechanisms to adjust aggressiveness associated with a neuromodulatory biological amine: serotonin (5-HT). In this paper, we present a working theory of a neurophysiological mechanism based on the past biological studies on the 5-HT hypothesis, and a mathematical model of the mechanism. We analyzed this model and concluded that this neurophysiological mechanism makes the forgetting process slower. Next, we fitted our theoretical forgetting curve to an experimental curve and estimated the parameters of our model. These estimated values were in agreement with common belief in biological science.

Analysis of Human Standing-Up Motion Based on Distributed Muscle Control

In developed countries, an aging society has become a serious issue; many activities of daily living (ADL) are impaired in the elderly. In order to improve this situation, it is necessary to develop an assisting method for the human standing up motion because it is considered to be an important factor to ADL. It is unclear, however, how humans coordinate their multiple distributed actuators, muscles, due to the ill-posed problem of redundant their body system. In this paper, we analyze the human standing-up motion based on muscle coordinations, called synergies. A simulation method was developed to make mappings between muscle activations, joint torque, and the human body trajectory; thus, it can be predicted how modular muscle coordinations contribute to the motion. As a result, two primary synergies were extracted and how they coordinate to achieve the motion was elucidated; one synergy strongly affected joint movements and speed of the motion while bending the back and lifting the body up, and the other synergy controls their posture after they lift up their body. These findings could be useful for development of an assisting robotic system for rehabilitative training based on extracted distributed synergies from complex redundant human motion.

Adaptive division of Labor Control for robot group

Division of Labor Control is advanced function for distributed autonomous robotic systems. Many studies focussing division of labor control inspired biological phenomenon have been reported. However, the optimality is not discussed because decentralized control is typically complicated. In this study, we propose the division of labor control method for robot group that enable adaptively select whether homogeneous state or heterogeneous state against working conditions and address the optimality by mathematical analysis. To evaluate the effectiveness of the proposed method, the computer simulations are carried out and we confirm that robot group implemented the proposed method inevitably organize the division of labor state with group performance improvement.

Thermodynamic implications of high Q10 of thermo-TRP channels in living cells

The activity of thermo-transient receptor potential (TRP) channels is highly dependent on temperature, and thus thermo-TRP reactions have a high temperature coefficient Q10. In thermodynamics, a high value of Q10 indicates the existence of a large activation energy (i.e., a large enthalpy) over a short period during the transition process between the closed and open states of the channels. The Gibbs free energy equation shows that a large entropy is required to compensate for this large enthalpy and permit activation of the channels, suggesting a large conformational change of the channels. These large values of enthalpy and entropy seem to be a match for the values of the unfolding process of globular proteins. We outline these thermodynamic issues in thermo-TRPs.

Muscle Synergy Analysis Between Young and Elderly People in Standing-Up Motion

Standing up is fundamental to daily activities of the elderly. It is necessary both to enhance muscle strength and to strengthen muscle coordination for improvement of their motor function. In this paper, we extract important data related to muscle coordination, called synergy, to perform standing motion by young and elderly participants. The contribution of muscle synergy to body kinematics is calculated through neural networks that estimate joint torque and body kinematics. To explain deficient motor function in elderly persons, extracted synergy is classified into 4 clusters based on how synergy contribute to body kinematics. Cluster analysis explains that elderly participants have weaker synergy than young persons in bending their backs to generate momentum. Compared to younger persons, older persons require additional muscle coordination to stabilize posture after standing-up in order to avoid falling.

Extraction of behavior primitives for understanding human standing-up motion

Recently the aging society is very rapid, and it has brought many problems to our society. In order to avoid these difficult situations, we focus on human standing up motion in our research because this motion is so important to our daily life that it is considered meaningful to support the motion. However, the way of human standing up is still unknown because the analysis of human motion is very difficult. Therefore, we develop integrated simulation methods to understanding the motion from human body data, such as muscle activations (EMG) and human joint torques. We carefully analyze human standing up motion based on muscle movements since muscles do move human body. Through our experiments and analysis, two important muscle coordinations (behavior primitives) are found out; one primitive has a function of generating dynamics of the motion by controlling hip, knee, and ankle and the other primitive controls posture of the body with their ankles. These behavior primitives are elucidated to be such an essential factor toward the motion that the way of standing up becomes unstable without them.

Modeling of Self-organized Competition Hierarchy with Body Weight Development in Larval Cricket, Gryllus bimaculatus

Larval crickets develop a big body and high aggressiveness under isolated conditions, but develop a small body and low aggression under crowded conditions. Furthermore, their ensemble variance increases. It is known that the heavier cricket tends to win. Therefore, the two growth processes affect competition. We constructed a mathematical model for intraspecific competition based on the Bonabeau model, showing bodyweight effects on the winning rate. Results show that the population mean of body weight decreases under the condition of specific memory enhancement that places more emphasis on losing than winning. Furthermore, hierarchical effects in foraging efficiency increase the ensemble variance.

Handshake request motion model with an approaching human for a handshake robot system

Humans shake hands as a sign of greeting when they first meet one another to express a feeling of rapport. A handshake is an embodied interaction that involves physical contact. For interactions involving a human and a robot, if the robot generates a handshake motion that is emotionally acceptable to humans, it will lessen any feeling of aversion that the human has when initiating an interaction with the robot. Thus, in our previous study, a handshake request motion model was proposed, in which the robot generates a handshake approaching motion before actually shaking hands with the human. In this model, the robot stretches its hand out to a human to request a handshake. Furthermore, the effectiveness of the model was demonstrated by experiments using a handshake robot system when the human and robot remained stationary. However, in handshakes between two humans, one of them usually requests to shake hands with the other who approaches him or her in order to promote an embodied interaction. Therefore, in this paper, a handshake request motion model with an approaching human is proposed, based on an analysis of human handshake motions. In this model, the robot generates the request motion for a handshake when a human approaches the robot. Furthermore, a switching handshake control is developed where the robot generates either the request motion, or the response motion, for a handshake according to the motion of the approaching human. The effectiveness was demonstrated by a sensory evaluation.