Sperm whales are known to prey on giant squids, but no one has ever seen the moment of predation because of behavior in the deep sea. To capture the predation scene, we are developing the whale rover expected to walk on the body surface. Until now, the seventh prototype achieved absorption on the whale for a period of time, but we had no way to know if the rover had walked. In this paper, we proposed a system that can count steps by measuring the number of rotations of the propeller. We applied the developed system to the results of field experiments in Ogasawara, and showed that the rover achieved adsorption walking on the body surface.

This paper reports a method of 3D pose estimation of sea turtles. The method that we have proposed in previous research can estimate 2D pose of sea turtles. However, because sea turtles move in 3D dimensions, the method cannot track them. In this report, we propose the improved method that can estimate the 3D position of sea turtles by tilt control of a imaging sonar. First, we recognize a sea turtle from a sonar image using deep learning, and transform the coordinates and calculate the 3D position. Second we estimate the 3D pose of a sea turtle by particles filter, and additionally, we control the tilt angle of the sonar so that the turtle is steadily captured by the sonar. The proposed method is verified through experiments using a turtle model and real turtles.

The aim of this study is to improve the efficiency of maintenance such as inspection on the underside of the pier. In this paper, we have developed an octa-thruster actuated vehicle that can automatically move along a route that passes through specified waypoints. Furthermore, we have shown that the developed robot is effective even in a wavy environment.

The aim of this study is to develop a fish-type robot that can swim underwater autonomously toward the marine environment and ecological research or entertainment in aquariums. In this study, we implemented a real-time self-localization method based on inertial navigation combined with Madgwick filter for autonomous swimming. Besides, we added a function for obstacle avoidance utilizing laser sensors. In the experiment, we confirmed that the fish-type robot can estimate the swimming route while avoiding obstacles with sufficient accuracy, but further improvements in both swimming route estimation and obstacle avoidance are required for practical use.

For long-term and non-invasive observation of underwater animals without attaching any tag to them, there have been researches on using AUV for detection and tracking methods with a multi-beam imaging sonar. The authors proposed the underwater pose estimator for underwater targets, especially for a sea turtle in this work. The method introduced a multi-beam imaging sonar mounted on the vertical scanning device, and an underwater pose estimating neural network with 3D convolutional layer and multi-ResNet could successfully estimate the yaw and pitch angle of the turtle replica. With the proposed method, the posture angle of the rotating target was predicted with a yaw mean error of 9.21 degrees and pitch mean error of 3.99 degrees.

With the increasing demand for energy, there is an expectation for the development of autonomous underwater robots for marine resource exploration. In this study, we aim to develop a small AUV that generates thrust by rotating itself. We developed a small spherical AUV whose moment of inertia is constant around any axis and whose rotation axis can be easily tilted, and verified its operation. As a result, we were able to rotate the spherical outer shell with the proposed drive mechanism. It was also found that as the rotation speed was increased, precessional motion was

A detachable omnidirectional movement mechanism for improving the work efficiency of a manual wheelchair is shown. As a detachable method, the drive wheel of a manual wheelchair can be attached by simply riding on the mechanism and applying the brake, which makes it possible to easily attach and detach without the need for an assistant. In addition, in order to use the riding method, a spherical wheel that requires at least two wheels for omnidirectional movement including turning is adopted as the omnidirectional movement mechanism. So far, we have prototyped Units 2 and 3 in which the arrangement of the two spherical wheels is different from left to right and front and back. In this paper, we show the moving performance of two prototypes and verify them from the viewpoint of practical use.

Care robots have yet to be widely adopted even though the demand for care robots is increasing with the aging of the population. Care robots are required to be small and simple for general household use as well as high functionality. We have developed a small robot that can assist the user in standing up, walking, and sitting down in daily life. By using the user’s center-of-gravity candidate, we were able to estimate the user’s condition and determine abnormalities with a small number of sensors. The experiments verify that the robot can switch the appropriate support according to the estimated state and prevent falls.

In this study, the motion while lifting a heavy object under wearing an endoskeleton-type power assist suit was captured by motion capture device, and the burdens on the lower back were analyzed using the musculoskeletal modeling software AnyBody Modeling System. Then, the muscle activity of the erector spinae muscles, and disc compression force and disc shear force between L4/L5 lumbar vertebrae in the state of no assist force, the state of wearing passive power assist suit and the state of wearing active power assist suit, were evaluated and compared. As a result, effectiveness of the power assist suit on reducing the burden on the lumbar region was verified. In addition, the assist effects of the passive power assist suit and the active power assist suit were almost equivalent.

In our previous study, a power assist suit that is available at high place in construction sites has been developed, in which the artificial muscles are attached to back of the full harness to assist lifting heavy object and maintaining half-sitting posture. However, there exist some drawbacks in the developed power assist suit as follows. When the full harness mode is switched to the power assist suit mode, it is troublesome to fasten harness belt, and sufficient assist force was not obtained since the adjustable range of the harness belt to tighten was too short. The purpose of this study is to improve these drawbacks. To this end, three new power assist suits, “M Co. type”, “Separation type” and “Interlocking type” were built. In addition, assist effect of newly built power assist suits was evaluated through experiments of holding the heavy object with half-sitting posture. The experimental results showed that the assist effect of the newly developed “Separation type” and “Interlocking type” is comparable to or more than that of the previous power assist suit.

In our previous study, the upper arm assist device was developed for assisting upward work such as fruit harvest and tension ceiling. In this study, the problems of the developed upper arm assist device were improved. In addition, to reduce the burden on the neck during the upward work, a headrest which can be attached to the upper arm assist device was developed. In order to evaluate assist effects of the improved assist device and the built headrest, experiments of measurement of electromyogram and muscular stiffness were conducted. From the experimental results, reduction of the burden on shoulders and neck during upward work was confirmed. Thus, the effectiveness of the improved upper arm assist device and the built headrest was verified.

We have developed the dorsiflexion support unit (DSU) to improve flail walking. The DSU utilizes flexibility and non-linearity of the elastomer-embedded flexible joints (EEFJ) to eliminate complex adjustment. In this study, we improved the shape and structure of the EEFJ to enhance the supporting force and usability of the DSU. Usability tests were conducted for four healthy female and males. The results show the improved structure successfully reduce the burden to exchange the elastomer cap. In addition, the assessments for the supporting effect were conducted for ten healthy male subjects. According to the results, the DSU successfully reduce the plantar flexion in swing phases and initial stances without additional burden.

The number of elderly product accidents is increasing. Conventionally, typical causes of main accidents have been classified as misuse of the product or user carelessness. However, some of the accidents stem from the lack of adequate body holding functions of daily consumer products. The purpose of this study is to develop a system that enables visualization of body holding force and location in everyday living space. The developed visualization system consists of RGB-D cameras and a wearable force sensor. The system verification experiment was conducted in a total of 5 rooms at the houses of 2 subjects (75 year-old female and 84 year-old male). Experimental results show that the development system is useful for visualizing body holding during taking force behavior of holding their surrounding items, when standing up from a sitting position, getting up from lying down, and so on.

There are many situations where wheelchairs feel inconvenient when traveling over steps or uneven terrain. Therefore, we developed a deformable wheel that can change the wheel radius to ensure stable traveling on uneven terrain and steps. Then, the performance of the developed wheel was evaluated by measuring the trajectory of the center of the wheel as it went over steps.

One of the reasons why myoelectric prostheses have not been widely used is the difficulty in improving the accuracy of myoelectric prostheses and the small number of facilities that can provide myoelectric prosthesis training. In this study, we aim to improve the poor response accuracy. For this purpose, we use muscle sound as a feature of muscle motion estimation, which has been attracting attention recently. In this paper, in order to develop a control method using the aforementioned muscle sound, we developed and verified a method for estimating muscle motion using an ultra-fine diameter piezoelectric wire sensor, which is low cost and easy to process.

In the previous study, we developed a polycentric biomimetic knee joint (PC-BKJ) for assisting human standing motion. However, the PC-BKJ is limited for use on level grounds. Therefore, we are developing a semi-active PC-BKJ (SA-BKJ) to assist walking on uneven terrains with a variable reaction force mechanism. In this study, the basic structures of the SA-BKJ were proposed and its first prototype was developed.

Leader-follower robots are used to replace humans in hazardous environments. In this mode, the operator operates the leader robot accroding to the situation of the field, and the follower robot performs as same as the operation. In this study, we proposed a cockpit which is designed with comfortable seat to reduce operator’s fatigue under long-time working, also is able to carry devices such as sensors and the computer. Then, we used the cockpit to conduct a simulation experiment to verify reliability of the cockpit and effectiveness of the operating intention estimate method.

Recently, the demand for remote-controlled robots is increasing due to Covid-19, etc. In remote-controlled robots, safety is very important. We have developed a velocity-based mechanical safety brake. In this paper, we introduce a remote-controlled robot system with the safety brake by using only eye movements. Since the robot is controlled by eye movements, many people such as amyotrophic lateral sclerosis (ALS) patients can use this robot system. If the safety brake detects an unexpected driveshaft’s angular velocity, it switches all of the robot’s motors off, and then stop the driveshaft by gradually reducing the driveshaft’s velocity. The safety brake is composed of only passive mechanical components such as springs. First, we describe the remote-controlled robot system. Second, we explain the safety brake. Finally, we present experimental results to verify the effectiveness of the safety brake in the remote-controlled robot system.

The impact force applied to the human hand at the moment of collision between a step and the wheel of a wheeled walker varies greatly depending on the posture of the arm pushing the walker. However, there have been few studies in which the posture of the arm and the magnitude of the impact force have been evaluated. Therefore, the relationship between the posture of the human arm and the impact force has been analyzed with the ellipsoid of inertia at the tip of the hand by modeling the human arm as a 3-link manipulator.

The purpose of this study is to develop an evaluation index for the lateral reaching motion of elderly people using a simple measurement system with RGB-D sensors. Physical therapists often evaluate the motor function of elderly people visually. Therefore, if we can quantitatively evaluate motor functions, it is expected to reduce the workload of physical therapists and to allow elderly people to measure their own motor functions. In this study, we use DTW to extract features from time series data of movements. We propose an index that focuses on whether a person is able to perform actions equivalent to those of a healthy person by making judgments using the MT method based on the actions of a healthy person from multiple motion features.

In order to achieve efficient driving with less burden on wheeled chair users, it is necessary to design a wheeled chair that is easier to operate. In this paper, we design a wheeled chair based on a dynamical model of a human upper limbs to make it more user-friendly. Pulling motion is used to drive the proposed mechanism. To determine the shape of the mechanism, we first design a dynamical model of human upper limb motion. Data is obtained by motion capture. Then, we optimize the evaluation function to minimize the power and determine the parameters of the model. From that model, we will design a trajectory that allows the wheeled chair to be rowed more easily.

It is important for the patients with neurological difficulties such as ALS and SMA to improve their quality of life. Among them, we focused on a sport called Boccia that can be played even by people with relatively severe disabilities, and the ultimate goal is to construct a system for patients with intractable diseases. In this research, we examined the appropriate interface for the various patients with degree of hand mobility. We also developed a remote control system that allows the operator to determine the direction of the ramp, the height of the ball launch, and timing of the ball launch.

Swallow is an important for dietary process though, the number of the patients with swallowing disorder is increasing. The process of swallowing is a very fast reflex action and therefore the mechanism has not yet to be solved. The simulator “Swallow Vision” made by medical image, for example The MRI and CT scan make swallowing motion visible clearly. It supplies the fundamental information to analyze the actions that occurs inside the body. By using simulation as reference, we have been developing the swallowing robot which can mimic the human swallowing motion.

In a super-aging society, functional training of a lower body, especially the hip joint, is very important for extending healthy life expectancy. We therefore have development a “Functional Training Chair” that allows anyone to easily and safety flex and extend the hip joint.

In order to measure 3D coordinate values of a object to be manipulated by a support robot, we have been developing a "Real-World Clicker (RWC)" using a TOF-type laser distance sensor mounted on a pan-tilt actuator [1][2]. With this RWC the mobile robot can automatically grip and bring any object that user click in a real world. Our conventional robot system, however, used only its odometry to control the mobile robot, which resulted in low accuracy and low success rate in grasping distant objects. In this paper, we propose a method to solve this problem by taking advantage of the RWC not only to indicate the object but also to guide the mobile robot. The key idea is an automatic guidance by laser spots on the floor, illuminated by the laser sensor.

In this paper, to reduce the burden of caregivers, we develop a moving handrail-type device that supports the standing-up motion of a person based on the Assist-As-Needed concept. The trajectory of the moving handrail is optimized to minimize the power of the user’s whole body based on a human dynamical model, using the motion of a person who stands up naturally as a reference. The evaluation function is designed based on the human power, and the design parameters are set by the handrail velocity with initial and final position constraints. Based on the chained form of the partial differential, the gradient of the evaluation function with respect to the design parameters are introduced, and the trajectory of the handrail is optimized.

We developed motor-less and small type of a walking assistive device. Most of previous walking assistive devices were motored type. However, when the motor is used, computer and buttery must be equipped, then it makes heavy weight and expensive. On the other hand, some motor-less type devices are mainly for plantarflexion assistance and used by able body people. To address this problem, we utilized spring and rachet mechanism, and equipped not only plantarflexion but also dorsiflexion assistance in one device. By using this device, we had an experiment to measure the trajectory and angle variation of ankle joint. From the results, it could be confirmed this device could be improved user’s gait for safety.

In this study, we developed the first prototype of an endoskeleton-type knee joint assistive orthosis to assist in maintaining a half-sitting posture during agricultural work. We fabricated a long McKibben-type artificial muscle as the actuator of the orthosis, and proposed a method of arranging the artificial muscles along the wearer's body. After that, we conducted an evaluation test of the first prototype orthosis by measuring the surface EMG potential. From the results of the evaluation test, we found that there are some points that need to be improved in the assistance method of the orthosis and the evaluation test method. Therefore, we improved the orthosis based on the evaluation test. In the future, we plan to further improve the orthosis, improve the evaluation tests, and study better methods of assistance.

In order to assist stair climbing movement for ALS patients and patients with spinal cord injury, we are developing a stair climbing machine. Although most stair climbing machine adopt crawler mechanism, crawler system has some problems such as damaging floor and slip dropping. Therefore, we adopt linkage mechanism for stair climbing. This device also has advantage that users can keep their posture horizontally．In this paper, we describe development of real size device which user can ride on.

The impulsive motion generator mimicking the unique joint of the claw of Alpheus brevicristatus, which was developed in our previous study, is improved so that the movement speed in water is comparable to the original biological joint. The improved device is then subject to the statics analysis of the release and charge of energy for motion generation. The experiments are carried out to measure the movement speed and the actuating forces. The improved device performs at a superior speed to the claw of Alpheus brevicristatus. Also, the static analysis is consistent with the measured actuating forces.

The design and control of multifunctional soft robots that can operate in various environmental conditions is a major issue. One such challenge is to design hardware that can walk on floors and walls and can grasp objects. In this research, I designed a multi-degree-of freedom soft actuator with suction capability and fabricated an octopus-type soft robot equipped with these actuators redundantly. The octopus-type robot can walk on the floor, adsorb on the wall, and wipe the floor and wall by grasping a sponge.

We propose a micro-gel robot having a flagella-like structure. We design and fabricate robots that have a same Reynolds number as microorganisms, especially Chlamydomonas. Flagella-like actuator is made of a hydrogel, which has a thermo-responsive characteristic. The hydrogel actuator is mixed with light absorber materials so that the actuator can be driven by light irradiation. We selected carbon nanotube (CNT) as a light absorber by comparing absorbance efficiencies. To determine design values, we evaluated pattern-ability of CNT-mixed hydrogels. The minimum width of flagella-like structure was 6 μm . By making Reynolds number of the hydrogel actuator same as that of microorganisms, it is thought that the robot can swim with same principle as microorganisms. Therefore, we designed robots considering Reynolds number and succeeded in driving the robot with light irradiation.

In this study, we propose a reconfigurable microgel robot which can be assembled and disassembled by light irradiation. As the soft microrobot uses a soft actuator, it can realize highly efficient and unique movements that mimics living organisms. However, the previous studies of soft microrobots are composed of a single unit. Therefore, there is problem that it has only a single function. By adding assembly and disassembly functions to soft microrobots, it can realize multiple functions. The module is the smallest unit of assembling and disassembling, and it is required to have “drive” and “assemble/ disassemble” functions. For driving the robot, we use a volume change of thermoresponsive gel (PNIPAAm) driven by a light irradiation. For assembly and disassembly of the robots, we use a molecular recognition technology using β-cyclodextrin and azobenzene. We succeeded in performing the two basic functions of “drive” and “assemble/ disassemble” by using the proposed module of the microrobot.

The clarity of the position of eyes and pupils in canid species varies depending on their sociality. On the other hand, existing social robots have a wide range of uses, such as education, medical care, and customer service, while most of the robots have had a simple design of eyes with white base and black iris. However, it is conceivable that the degree of appropriate communication intensity varies depending on the purpose of a robot, and that there is a suitable eye design depending on its use, as in canid species. In this study, we propose the appropriate gaze clarity of a robot to three situations where the avatar speaks to the human, the avatar listens to human’s talk, and the avatar is near by the human during the task requiring concentration.

Gobies achieve hovering and agile swimming such as sudden turn from a stationary state, sudden acceleration, and sudden stop by using pectoral fins. The motion and deformation of their pectoral fins seems to be different from the conventional classification of swimming forms in fish. Understanding the swimming mechanism of a goby can inspire new fish-mimetic swimming robots fully utilizing pectoral fins. In this study, we attached fluorescent markers to a goby and recorded right turns with multiple video cameras, followed by three-dimensional motion analysis to quantify bending deformation of the pectoral fins during downstroke. As a result, it was found that the left pectoral fin notably bent, while the bending of the right pectoral fin was smaller than the left fin.

We develop a small jumping mechanism that mimics the unique joint of Issus coleoptratus and Alpheus brevicristatus.Issus coleoptratus nymphs have a gear-like mechanism on the hip joint of the hind legs, which enables them to synchronize the leg motion of a jump to maintain the posture. Alpheus brevicristatus has a cocking-slip joint on its claw, which enables to close the claw instantaneously in water. Mimicking and integrating these unique joints, we design a simple jumping mechanism. The experimental results show that the designed mechanism jumps up to 140 cm with maintaining the posture, which is a good and unique performance compared with conventional jump robots. Also, while the leg synchronization is slightly inferior, the takeoff speed is calculated as 5.2 m/s, which is on par with the best record of Issus coleoptratus nymphs.

In this study, We propose a new concept to approach Chemical Plume Tracing (CPT) problems in complex environments expected in emergencies such as disasters and terrorism as data-driven models. CPT, which uses odor information to plan the robot’s movement in preparation for obstacles and noise in emergencies, has been actively studied recently as it has huge engineering value. Since Considering all the factors in a complex environment in which robots equipped with a data-driven model are expected to be deployed takes high engineering costs, it aims to reduce the cost by dividing the complex environment into element environments with different spatial characteristics, conducting CPT experiments in each element environment, building an independent model with that data, and switching between the models autonomously to determine the next step action.

The concept of the sensory nervous system is proposed for service robots. Three key modules, i.e., sensor units, nerve cables, and spinal cord units, are employed to build a dedicated system to sense external / internal events and changes of the robot. Such units make modification of the sensory system, implementation of redundant one, and addition of built-in self-testing functions relatively easier. Addition of the sensor units is made easy because of unique unit constructions, such as terminal-type, insertion-type, and harness-type constructions. The sensor units send data to and receive power supplied from the spinal cord units through the nerve cables.

This paper describes a swimming robot that imitates a flatworm. The model was made with a length of 20 cm, which is about twice the size of a flatworm. As for the folds, they were reproduced by flat wing waves that mimicked the flatworm using a single motor and a phase-shifting slider-crank mechanism. In this way, the phase speed of the folds can be freely changed by changing the phase difference of the crank. The performance of the fabricated robot was evaluated using a high-speed camera and tracking software. For the flapping amplitude, the ornithopter showed no significant errors other than misalignment of parts.

In this project, we aimed to imitate the musculoskeletal system of a dog’s hindlimb and investigate the effect of constraints by the fascia in locomotion. Thin McKibben pneumatic artificial muscles were attached to the dog’s hindlimb skeleton model, referred to as its anatomical structure. A musculoskeletal robot with an animal-like driving system is expected to perform more animal-like movements than existing robots. Therefore, it may enhance the likeability of a robot, which is a crucial factor in Human-robot interaction(HRI). This project suggests the possibility of developing such a robot. The robot’s locomotion was performed under various constraint conditions. It was confirmed that the loose and ambiguous constraints by the fascia, affect the movement of musculoskeletal robots. In the aspect of constraints, the fascia would be a significant factor in a musculoskeletal robot with an animal-like driving structure.

In this paper, we propose a method for generating continuous traveling waves using a flexible sheet actuator. This sheet is pneumatically powered, flexible and extremely thin. Since it has a discrete structure, its continuous waveforms have not been realized so far. In our study, we focused on the transition process where waves move to neighboring chambers, and succeeded in making the waves travel continuously while always keeping almost the same amplitude. In addition, this paper discusses methods of preventing pressure ulcers by applying Sheet's waveform, and considers future perspectives.

Biped control method of the musculoskeletal model by hardware neural networks using CMOS circuit that does not depend on conventional digital control is reported. By using electronic circuits, the development of robotic systems that are similar to the nervous system of living organisms can be expected. Humans have many muscles in our body, but we do not control them independently. Humans have many muscles in their bodies. However, they are not controlled independently of each other. Humans operate by coordinating the muscles necessary for leg motion through control signals generated by the central pattern generator localized in the spinal cord. We proposed a CPG model that uses a pulse-type hardware neural networks to generate signals to control human walking and running. Using the proposed CPG model, the gait control method of the musculoskeletal model was proposed.

Flying insects perform remarkable flapping flights of hovering and rapid maneuvers under complex natural environments. The flapping flight of insects is achieved through a complex musculoskeletal system to transmit the thorax vibration/deformation to the wing hinge, which is considered as the most complicated dynamic system in biological systems but remains poorly understood. In this study, we aimed to uncover the underlying mechanisms associated with the musculoskeletal system of insects by developing an insect-inspired artificial system. We built up a prototype flexible and redundant flapping mechanism composed of an electromagnetic actuator capable of generating sustained or instantaneous force over a broad range of magnitude with various signal duty ratios or input voltages. The actuator was verified to be capable of altering the wing-beat trajectory owing to deforming a wing root structure. Our experimental model may provide new insights into the insect flight mechanisms.

In recent years, interruptions in communication due to disasters have become a problem for monitoring, reporting, and transmitting information on the damage. Butterflies are thought to be applicable to small drones because they have a low flapping frequency and can both glide and flap. Although butterfly-shaped small flying robots can fly away, they have not yet achieved free flight. In order to realize free flight, it is necessary to understand the flight mechanism of butterflies. The purpose of this study is to determine the flapping angle from the motion analysis and to compare the flight characteristics of Papilio xuthus and Idea leuconoe. We also aim to compare the wing shapes of the two butterfly species. The results suggest that butterflies with a lower frequency tend to have a higher lift-drag ratio.

Avian wings are composed of flexible feathers, which can deflect during flapping and gliding flights owing to its flexibility and change its shape passively in response to wind gust. While the crucial role that the feathers play in passive flow control during various flights and in detecting wind variations, it remains yet poorly studied. In this study, we developed and fabricated flexible sensors inspired by the avian feathers, which are designed capable of deforming and deflecting in response to wind variations. These sensors were placed on the upper surface of a wing, and their dynamic characteristics under various wind-speeds were analyzed through wind tunnel experiments. It was observed that the sensors located at various positions respond differently at different angles of attack. The bioinspired sensors may provide an effective sensing system in achieving high flight robustness of next-generations drones in the future.

Biomimetic soft robots followed by marine creatures morphology and propulsion mechanics expected to possess high adaptability and maneuverability in underwater world where conventional rigid robots are hardly utilized. Our research group aims to develop an underwater soft robot inspired by marine flatworms which shows a unique and well-organized swimming behavior. Among several types of soft actuators for realizing both robotic softness and flexibility, we focus on an ionic polymer–metal composite (IPMC) as a membranous actuator. This paper mainly introduces a manufacturing process of the IPMC and experimental tests of different types of the IPMC actuators. We found that mean electric resistance of the IPMC increases as decreasing the voltage induced to the IPMC, regardless of the size of the IPMC. The relationship between the voltage and resistance of the IPMC may be correlated with the capacitor component of a simplified RC circuit model of IPMC.

Flying snake has no limbs or wings, but it can glide by deforming its body into a flat shape and making it undulate. By implementing this gliding behavior in the search robot, I thought that it would be possible to make it glide. In this study, I investigate the effects of the cross-sectional shape of the body and the gliding posture of the snake on the gliding performance by using a three-dimensional model of the snake. The research includes the analysis of lift and drag coefficients using five different rectangular angles of attack and models of the cross-sectional shape of the flying snake. A comparison of the analysis results shows that the angle of attack has the effect of increasing the lift coefficient and lift-drag ratio and decreasing the drag coefficient as the snake deforms its body during gliding.

We are conducting the analysis of dolphins' tail stand to realize the water lift-up operation of the aquatic propulsion mechanism modeled on the tail flukes of the dolphin. Motion of tail fluke of the dolphin (Lagenorhynchus obliquidens) during a tail stand, were analyzed from the images recorded by multiple high-speed cameras. We discussed the relationship between velocity and deformation of a tail fluke.

Cursorial quadrupeds have flexible connectivity between the forelimbs and the trunk. Although the complex muscular network in the shoulder allows the basement of the forelimb (i.e., scapula) to exhibit three-dimensional movement, it is unclear how the complex movement of the scapula affects locomotor tasks. To elucidate the functionality of the animal’s flexible shoulder region, we developed a legged robot that mimics complex anatomical features of the musculoskeletal system of house cats by using elastic sheet elements. In the experiment, the robot’s shoulder unit moves upward-and-downward depending on the body supporting as cursorial quadruped does, suggesting that the passive flexible sheet in the robot’s shoulder region would implement the essential interference between body parts in the animal’s shoulder region.

In this study, we tried to control the behavior of Medaka (Japanese Killifish) by applying their phototaxis. First, we investigated Medaka’s general phototaxis by irradiating the light of the LCD display to a portion of the pool. We examined various lighting patterns such like half portion irradiation, center irradiation, peripheral irradiation, gradation pattern irradiation, etc. We recorded the Medaka’s swimming path and analyzed the abundance ratio by brightness. Medaka, however, did not show the typical positive/negative phototaxis to the LCD display light clearly. Medaka showed negative phototaxis to the irradiation of the strong light over 20,000 lx. Therefore, the irradiation of strong light is necessary to control Medaka’s behavior by general phototaxis. On the other hand, however, Medaka showed typical reaction patterns to the flow movies of the black/white stripe irradiated by LCD display. When Medaka showed these stripe flow patterns, (1) Medaka always tried to get on and follow the stripe flow, (2) Medaka stopped swimming when the pool wall would approach, Medaka never contact the wall, (3) Medaka turned to the backflow direction, (4) Medaka swam to the upstream side with slower speed and intermittent swimming. (5) Medaka turned to the flow direction again then back to (1). The medaka seemed to misunderstand that there was actually a stream of water. We call this reaction pattern of Medaka “Stripe flow phototaxis”. The stripe condition that Medaka showed typical reaction is that the stripe width is near the body length of Medaka, and the flow speed is about the half of the Medaka’s maximum swimming speed. We found Medaka can be controlled their behaviors by showing the stripe flow to the desired direction.