A cerebral aneurysm is a type of cerebrovascular disorder in which a balloon-like bulge develops in a part of an artery in the brain. The rupture of a cerebral aneurysm can cause subarachnoid hemorrhage, and the mortality rate after rupture is high, so cerebral aneurysms must be treated before they rupture. Flow-diverter stenting was developed for large cerebral aneurysms. Although analytical methods are available for the study of FDS, the current analytical methods require a large amount of time for modeling. Considering these circumstances, a coupled fluid-structure analysis method that applies DEM particles to FDS was conducted, and flow velocity and pressure were compared with models based on the boundary surfaces of conventional fluid analysis in this study. Although the coupling was confirmed, additional validation is required to apply the method to all vascular regions.

The donor shortage for organ transplantation is a serious problem. A machine perfusion(MP) is one of the solutions to the donor shortage with recovery and assessment futures. Development of the assessment method of the organ function during MP is the most important issues to expand the donor criteria. In this study, porcine livers, which were harvested after 45 min warm ischemia time(WIT), were evaluated for their functions with metabolic factors (pH, oxygen consumption) during the hypothermic oxygenated machine perfusion(HOPE)). Furthermore, the livers were perfused with autologous blood under body temperature conditions to mimic the reperfusion situation after transplantation. The pH and oxygen consumption during HOPE were compared with conventional biomedical markers( lactate clearance, enzyme, and FMN).

Sparse Bayesian learning implemented into electrical impedance tomography (SBL-EIT) has been used to image physiological swelling inside the human calf under stocking compression, aiming to evaluate the treatment effect of various compression pressures. Three categories of stockings, categorized as Strong, Weak, and Control according to the net pressure measured by the pressure sensor, were utilized to assess the calves of six subjects each during prolonged standing. The results revealed that 1) the spatial-mean conductivity 〈σ〉^α2 showed an increased trend for all subjects in the sequence of Control, Weak, and Strong, 2) 〈σ〉^α2 exhibited a significant negative correlation with conventional impedance Z^BIA by bioelectrical impedance analysis (BIA), and 3) SBL-EIT adequately reconstructed the conductivity distribution Δσ and exhibited varied responses to physiological swelling resulting from three different stocking compression pressures.

The purpose of this study is to investigate the effects of the bike exercise by confirming the conductive response of the thigh muscles. In this study, two types of experiments, HPLT (high pedal rate low torque) and LPHT (low pedal rate high torque), were performed at almost equal work rates. both types of bicycle exercise were performed for a total of 25 minutes, with power varying every 5 minutes for each. This experiment was conducted on one subject (Age : 28 years old, Height : 173 cm, Skeletal muscle mass : 29.5kg) who has no history of musculoskeletal or neurological disease. We acquired the conductivity distribution images of the right thigh before experiment and after the bike exercise by using electrical impedance tomography (EIT). EIT measurement was conducted using sixteen electrodes which has placed on the right thigh at regular intervals. We divided thigh muscles into three muscle compartments T1, T2, and T3. And then, we confirmed how the conductivity changed in each muscle compartment. As a result, T1 showed the largest conductivity change and after that T2 and T3 followed. Also, at almost equal work rates, the increase in conductivity was greater for HPLT than for LPHT.

Assessment of gastric emptying by gastric function monitoring is an essential parameter in many clinical conditions such as functional dyspepsia (FD), gastroptosis, reflux esophagitis, and resumption of eating after surgery. This study aims to demonstrate the utility of gastric electrical impedance tomography (gEIT) for monitoring for monitoring gastric function by noninvasively measuring gastric volume while measuring gastric function with the 13C acetic acid breath test. The proposed method consists of two steps: (1) estimation of gastric volume V_tm based on gastric conductivity distribution σ, and (2) evaluation of gEIT by liquid food volume and gastric volume changes. 5 subjects were tested drinking 200 mL of liquid food and 600 mL after fasting for more than 8 hours to measure changes in gastric volume. Simultaneous breath testing was used to determine if subjects had functional gastric impairment. gEIT gastric image reconstruction showed 1) an increase in gastric volume with liquid food and 2) an increase in gastric volume over time.

The rupture mechanism of cerebral aneurysms has not yet been elucidated. To elucidate the principle, we developed an aneurysm model in vivo in rats, in which thinning of necrotic reaction and thickening of proliferative reaction coexist, and analyzed it from the viewpoint of mechanics and histology.

Formation and progression of cerebral aneurysms are associated with vascular wall thinning, but the cause is still unclarified. We hypothesize that the cause is (1) microscopic change of vascular-wall mechanical fields, (2) erosion of elastic lamina (EL) by smooth muscle cells (SMCs), (3) elongational amplification and collective death of SMCs and (4) internal collapse of vascular structure associated with cell death, in order. We have validated it for a few years. When manipulating vascular-wall mechanical fields of rat abdominal aorta, disorder of the EL, collective death of SMCs and vascular wall thinning was observed. On the other hand, the formation of aneurysms couldn’t be found in this experiment. This result suggests that the cause is that the repair response is fast. Therefore, the same experiment was conducted in an aged rat. The study focused on 76 weeks old male SD rat abdominal aorta. Manipulating the mechanical field of the vascular wall by stenosing the artery by 35% and elongating the artery axis resulted in EL tears and EL structures resembling intimal thickening, which were not observed in both young and old control groups. These results suggested that the mobility of SMCs has been increased by changes in the vascular tissue structure due to aging and making it easier for them to migrate in response to mechanical stimuli.

This study explores the diverse factors contributing to the variability in reproducibility within life science research. Recognizing the potential impact of environmental and human factors, we focused on introducing laboratory automation. We designed an innovative automatic media exchange system employing a compact, multi-functional robotic arm equipped with image recognition capabilities for precise target object localization. The core enhancement involved the integration of an optimized 3D-printed hand into the robotic arm, facilitating seamless plate manipulation and pipette transport and eliminating the need for manual intervention. Furthermore, complementary peripheral devices such as tailored work stages and chip disposal stands were developed to streamline the exchange of culture media. Invalidating the efficacy of our automated media exchange system, we achieved a notable waste liquid removal rate exceeding 97%. Comparative trials with human operators demonstrated the system's exceptional consistency in executing complex exchange procedures, surpassing or achieving parity with human performance benchmarks.

Monitoring blood glucose levels is essential for patients with diabetes. In the previous study, blood glucose measurement has developed using near-infrared (NIR) imaging, we have found that the accuracy obtained by machine learning based model was reduced by adjustable positioning of the experimental setup and preprocessing techniques of the image. Therefore, in this study, we conducted in-vivo measurements by capturing images of light transmittance from a tunable pulse laser passing through the purlicue (the area between the index finger and thumb). For stable image capturing, an adjustable setup was designed to accommodate various hand sizes, 18 subjects underwent an Oral Glucose Tolerance Test (OGTT), providing input for predicting blood glucose levels. A Convolutional Neural Network (CNN) machine learning model was employed to predict blood glucose levels from absorbance difference images. The performance results to RMSE of 19.28 mg/dl and 0.50R². The results demonstrate the potential of using NIR imaging and image standardization preprocessing for non-invasive glucose monitoring, representing a significant leap forward in diabetes care management.

Recently, Micro Air Vehicle (MAV) has been actively developed. It’s used in various situations, such as checking the situation in the event of a disaster, exploration of Mars, intelligence gathering at the scene of a terrorist attack. In these situations, MAV needs to be able to keep flying in strong crosswinds and turbulence. These conditions can be seen during flight of flying animals such as birds and insects. Their flight has the characteristics of high maneuverability and robustness for disturbances such as high winds and gusts. The purpose of this study is to develop a flexible flapping wing more closely mimic the bird’s wing structure and to investigate the aerodynamic characteristics of this wing model by fluid force measurements. Using this wing, a small wireless bird-like flying robot will be fabricated, and a system for detecting flight conditions will be also developed to realize a stable flapping wing flight. From the results of fluid force measurement, the bird-type wing which mimic bird’s wing structure can reduce drag. And it was shown that the bird-type wing may reduce drag by slots effect and the opening and closing motion of primary feathers. Also, flying robot that has wingspan of about 300mm was fabricated. Thus, flight tests and fluid force measurement of flying robot were conducted, and it confirmed the robot can generation of lift.

Friction under energized conditions is a phenomenon that involves in various machine parts. This phenomenon not only causes more damage than normal friction due to the effects of arc discharge, but can also interfere with machine operation due to inadequate energization, leading to accidents in the worst case scenario. In particular, pantographs of railway vehicles are exposed to the outside and are easily affected by nature, such as rain, which may interfere with the operation of the vehicle. In addition, with the recent spread of electric vehicles, research on friction under energized conditions will be necessary for friction components such as wiring harnesses in the future. In this study, acoustic emission (AE) sensing was used to evaluate friction under energized conditions, assuming rainy weather, on specimens made of materials used in pantographs and overhead contact wires of railway vehicles. As a result, two types of wear modes were identified: a case with many discharge marks on the friction surface and a case with iridescent discoloration, and the characteristics of each were examined.

Because braking of railway vehicle involves human life, it is very important to understand the friction and wear characteristics of brake friction materials. There are various types of brake friction materials, and their properties vary greatly depending on the operating environment and other factors. In this study, an experimental investigation of brake shoes for railway vehicles using acoustic emission (AE) sensing, which measures and analyzes AE waves generated by deformation and fracture phenomena at the friction interface, was performed. Experiments were conducted using a pin-on-disk friction and wear tester to measure friction force and AE signal for different brake shoe materials. The measured AE signal waveforms were subjected to a short-time Fourier transform, and the friction and wear phenomena were discussed from their frequency changes. In addition, it was found that there is a correlation between the AE signal amplitude and the coefficient of friction. Therefore, AE sensing enables in situ measurement of friction and wear state and frictional properties of brake shoe materials.

Floating seals are used as seals around the shafts of bulldozers and other construction machinery with crawler tracks, and are mechanical elements that seal lubricating oil and prevent the intrusion of earth and sand from outside. In this study, we focused on the occurrence of oil leakage due to eccentricity between seal rings and investigated the relationship between the contact state between seal rings and the occurrence of oil leakage through experiments and analysis. As a result, it was found that oil leakage is more likely to occur when the eccentricity between the seal rings increases. The results of the contact analysis showed that as the eccentricity increased, a distribution of contact conditions on the seal surface occurred, and the location of the oil leakage coincided with the vicinity of the boundary position where the contact conditions changed. In order to clarify the occurrence of leakage, it is necessary to study in detail the changes in contact conditions near the boundary.

Gear pumps are used in dump trucks and other construction equipment, and can be regarded as the heart of construction machinery that produces hydraulic pressure driven by the engine. At present, gear pumps are required to have performance comparable to that of axial piston pumps, and it is essential to improve the efficiency of gear pumps to achieve this. There are several ways to improve efficiency, but oil leakage from the high pressure side to the low pressure side inside the gear pump is a critical issue, and true efficiency improvement cannot be expected without solving this problem. One of the oil leakage points inside the gear pump is around the side plate. However, there are few studies on the displacement of side plates, gear cases, brackets, and covers during operation. In this study, we obtained basic knowledge about the displacement around the side plates under gear pumps operation by analysing the displacement with a 3D model of the component around the side plates.

In this study, we proposed a mirror array with a mirror height distribution in a dihedral corner reflector array (DCRA) to expand the viewing angle in the elevation direction of floating images. We developed a design criteria of the height distribution for three design requirements, (i) in the case of that there are no restrictions on the type of height, (ii) in the case of that there are restrictions on the type of height, (iii) minimum height specified. We have shown that these design can achieve large viewing angle in elevation direction compared to that of conventional DCRA with constant height. We also studied the fabrication method of DCRA with height distribution. In detail, we fabricated a multi-stage pillar with a two-stage height distribution using photolithography technology and evaluated the shapes.

Our objective is to realize a suction cup with a low pressing force and high adhesion force by changing the stiffness of the suction cup during the adhesion process. Based on the tendency for a suction cup with higher Young's modulus to generate higher adhesion force but to need higher pressing force, we designed Young’s modulus of a suction cup to be low during pressing and high during pulling. Thermoplastic polyurethane, which can change Young's modulus with temperature, is used for changing the stiffness of suction cup. In other words, the stiffness change of the suction cup can be achieved by using a high temperature during pressing and a low temperature during pulling. We considered the structure and fabrication method of the suction cup with thermoplastic polyurethane. Then, we measured the pressing force and adhesion force for changing the temperature of the suction cup with thermoplastic polyurethane during the adhesion process. As a result, we achieved a high adhesion force and a low pressing force by changing the stiffness of the suction cup.

Cavitation is a formation of bubbles due to the phase transition from liquid to gas, which occurs under the condition that the pressure of the liquid falls to below the vapor pressure. It is known that a single bubble in an ultrasound field shows unsteady motions repeating the process of growth and collapse, which can be described by the Rayleigh-Plesset equation. In our previous experimental observations, the dynamics of such a single bubble in an ultrasound field includes some noises which are originated from the microscopic structures. In this study, we show the variational formulation of the stochastic Rayleigh–Plesset equation with a Wiener process. Finally, we perform our numerical simulation based on our model to show the reproducibility of fluctuations in bubble behaviors.

It is well known that a flexible space structure such as a beam antenna attached to spacecraft performs large deformations due to the overall motion of its base, and it is crucial to make a model that includes the effect of geometrical nonlinearity between displacements, rotations and strains. The geometrically exact model has been known as a powerful tool to analyze dynamics of such a flexible space structure. In this paper, we show the variational principle of Hamilton for the infinite dimensional dynamical system to apply to a flexible beam attached to its base undergoing large overall motions. Then, we develop a structure-preserving variational integrator which is known to be superior in long-term computations for energy. In particular, we examine two types of space discretization methods; namely, the trapezoidal rule that yields explicit difference equations and the midpoint rule that yields implicit equations. Finally we make comparisons of these two types of space discretization methods in the variational integrators.

In recent space missions, methods utilizing invariant manifolds attract attention in designing low-energy transfer trajectories from the Earth to the Moon. However, these trajectories generally require long transfer times, and the relation between transfer times and the phase-space geometry of invariant manifolds is not fully understood. In this study, we apply particle swarm optimization to search for transfer trajectories of shortest possible times from the Earth to the Moon in the planar circular restricted three-body problem. The resulted transfer trajectories effectively utilize phase-space flows associated with invariant manifolds of Lyapunov orbits and resonant orbits. Specifically, the resulted trajectories are classified into no-transfer trajectories, transfer trajectories utilizing invariant manifolds of both Lyapunov and resonant orbits, and those utilizing invariant manifolds of Lyapunov orbits only, depending on the initial distance from the Earth.

With the recent development of novel spacecraft such as solar sails and microsatellites, active use of shape maneuvers has gained increasing interest for the purpose of attitude control. However, to use shape maneuvers effectively for attitude control, it is critically important and challenging to design the morphologies of spacecraft in an appropriate manner. In this study, we apply deep reinforcement learning to find shape maneuvers of an origami-inspired space robot that achieves attitude control under conditions of vanishing total angular momentum. The space robot consists of four triangular panels connected to the edges of a central square panel. We evolve the morphology of the space robot via particle swarm optimization, employing an objective function approximated by the Q-value function obtained from the deep reinforcement learning for attitude control. As a result of morphology evolution, the triangular panels of the space robot became narrower and longer. Moreover, the evolved space robot successfully reduced the control time for attitude changes.

In this study, the purpose is to develop a shark fish type drone which consists of the base drone hovering in the air, allowing the extension drone to takeoff and landing upon the base drone. However, there is a risk of collision with the base drone's propeller and the extension drone. To reduce this risk, an airflow control cover was made and attached to the upper part of the base drone. Additionally, flow simulations were conducted before and after attaching the airflow control cover. The results showed that without the cover, the airflow above the base drone was 8 m/s, which makes the extension drone unstable to takeoff and landing. However, after attaching the cover, the airflow above the base drone was reduced to 2 m/s, which makes the extension drone stable. Moreover, the actual takeoff and landing experiment was conducted. It was found that the development of a shark fish type drone has been successful.

Recently, the drone is unable to assist with cable installation indoors near ceilings or perform formation flight. To resolve this problem, we conducted a 3D fluid simulation to investigate stable flight conditions of a drone near a ceiling. We confirmed that the drone was not affected by surrounding pressure and flied stably when the distance between the drone and the ceiling is over 0.4 meters. To verify the simulation results, we conducted the experiment by flying a drone near the ceiling. The experiment confirmed that the drone could fly at the length of over 0.4 meters near the ceiling. Moreover, we fabricated the cable holding joints to assist with the cable installation near the ceiling by three drones flying in formation. We confirmed that the joints could be held and released using the cable holding joints. The joints allowed it to fly stably without interfering with the drone's sensors. Additionally, the cable can be released by the drone's rotational control. Flight verification experiments were conducted on a suspended ceiling component was at height of 2.0 meters and at length of 3.5 meters using these results. As a result, the installation of the cable to the suspended ceiling component was succeeded.

There are many needs for continuous water discharge operations from drones. However, drones recently face subjects with battery and water replenishment, preventing continuous water discharge. Therefore, the objective of this research is to develop a continuous water discharge drone using a supply port without battery changes and water replenishment. The target of the water discharge area was determined, and water discharge method, drone and supply method were designed. The used drone was a quad type with at the diameter propeller of 10 inch. The water discharge device used in this experiment was made of T junction joints and carbon pipe fixed with heat shrink tubing, and used was a power supply with at the output of 1200 W. The payload was 690 g under "load proportional to flight height" environment with the drone wired and hose connected. Finally, the water discharge area by flight experiment became within 86.2% at the target area of 100m².

In the face of the aged society and a significant increase in mental disorders, this study proposes a novel therapeutic approach. Over the 15-year period from Heisei 14 to Heisei 29, the number of patients with mental disorders has approximately doubled. Conventional treatments such as pharmacotherapy and psychotherapy present challenges, prompting exploration of therapy robots as an alternative to pet therapy. However, existing therapy robots heavily incorporate animal features, making it unclear which elements contribute to their effectiveness. Therefore, this research aims to identify elements of a therapy robot focusing on human tactile sensation, using the Qoobo, a robot with animal features removed, as a base. Elements such as fur, tail, and breathing are selectively removed from the Qoobo, and variations in softness are examined to evaluate their impact on therapy. The State-Trait Anxiety Inventory (STAI) is employed to assess the effects, and a t-test analysis is conducted to identify essential therapy elements. This identification of necessary elements for therapy robots may contribute to facilitating patient treatment by easily incorporating these elements into robots designed for therapy, which was not achievable previously.

An interface robot was developed that uses smartphones. Smartphones have PC-like calculation power, large storage, extensive communication options (Wi-Fi, Bluetooth connect, etc.) and various sensors (camera, light, sound, accelerometer, gyroscope sensor, etc.). A smartphone works as the CPU and sensors for the interface robot. our robot equipped wheels controlled by motor driver for moving on a desk and gesture arms controlled by servo motor. The smartphone is connected to ESP32 embedded in the robot body using Bluetooth. The smartphone controls driving motors, servo motors and LED in as the interface robot eyes. The Camera and the light sensor in the smartphone were employed as interface robot sensors. The Camera detects the color of the object and gets RGB values and the smartphone recognizes red, green, and blue colors. The Light sensor detects lux of the room. The interface robot reacts action according to recognized object colors. Our interface robot was successfully fabricated and demonstrated

In a previous study, we developed an elbow joint mechanism that mimics a biological joint. In this paper, we developed a wire-driven mechanism that performs flexion and extension movements with a single motor as a driving mechanism for the elbow joint mechanism. In addition, a biomimetic upper limb robot was developed by combining the elbow joint mechanism and the shoulder joint mechanism developed in the previous study. Furthermore, we were able to estimate the maximum arm tip force by measuring the arm tip force of the robot. The robot was given a sinusoidal target trajectory and operated.

In this study, we propose a new round belt contraction force model to be used for estimating the fingertip force of robot fingers. In deriving this dynamic model, the approximation accuracy is improved by limiting the data range of the 5th order approximation. Furthermore, by correcting the problem of the contractile force being a negative value, the contractile force model is more suitable for the force control of the robot fingers. By applying this model to fingertip force control of a robot finger, we demonstrate force control with an upper limit of 5 N, which was difficult in previous research, using an actual machine, and clarify its usefulness.

While the aging society and declining birthrate problem has been progressed, the number of workers who provide care for elderly has been decreased. humanoid robot which can substitutes for human work is expected to solve this problem. In this study, a dislocation mechanism that also works at various parts of the fuselage is designed by improving the model of the previous study, which was based on the design concept of a "fragile robot". After prototyping the mechanism and confirming its operation, the upper body part of the robot model designed in the previous study was built and the mechanism mounted. Crash tests were then carried out to verify the effectiveness of the mechanism. This document reports the results of this research and development.

This paper presented a fabrication of a hand rehabilitation support device driven by pneumatic soft actuators. When damaging a finger, it’s difficult to take back usual movement. The rehabilitation added to the symptom is needed. We propose the new support device with which rehabilitation of a hand is supported. A support device for move winding and extension motions.

In this paper, we describe rehabilitation (hereafter referred to as "rehabilitation") is necessary to improve the quality of life (QOL) and reintegration into society for those who have lost the use of their hands and fingers due to accidents or diseases. Rehabilitation is performed in stages by qualified physical therapists and occupational therapists, and includes splint therapy to release contractures, joint range-of-motion exercises to normalize joint function, and muscle strengthening exercises to restore muscle strength necessary for daily activities. Ideally, these rehabilitation activities should be continued on a daily basis.

It is said that rehabilitation for the elderly should be conducted seamlessly in a familiar community with the patient at the center of the rehabilitation program. However, it is difficult for patients whose homes are located in remote areas or who require assistance for transportation to go to the hospital. Therefore, the authors are conducting research on a device that supports rehabilitation at home in order to improve the continuity of rehabilitation.

However, the rehabilitation support devices currently available are large and very heavy, with compressors, vacuum pumps, and other equipment, making it difficult to use them at home.

Therefore, this study aims to reduce the size and weight of the rehabilitation support device and to improve the rehabilitation glove accordingly.

In this paper, we describe the made of snake type in-intestinal traveling robot. To inspect the inside of the large intestine, a robot is inserted into the large intestine. But the large intestine is folds and has different internal diameters in different places. In order to realize a robot that can travel in pipes with different inner diameters, we have proposed the intestine traveling robot that mimics the accordion motion of snakes, which is a method of moving inside pipes and vertical holes. The snake type in-intestine traveling robot is composed of three body segments to realize accordion motion. The front and back body sections consist of actuators that can flex, and the flexing of the body sections serves as a braking section that can hold the tube. The center section consists of actuators that provide the displacement necessary to drive the robot and is configured as the displacement part.

In this paper ,we describe the made of an In-pipe Mobile Microrobot for the Intestine.The drag force applied to the tube wall by the robot was measured to estimate the frictional force. We also compared the running speed of the robot with the running time in the colon model to confirm the effect of the running environment.Among various testing methods for early detection of colorectal cancer, endoscopy is said to be the most accurate. However, endoscopy has problems such as infection by resistant bacteria and deformation of the intestine. To solve these problems, our laboratory proposes the use of an examination robot that moves inside the intestines. We did the following. We fabricated a robot body using bellows rubber and a nitrile butyl rubber friction brake plate. We measured the drag force on the friction brake plate with a force gauge. Measured and compared the running time of the robot in the gut model.

In this paper, we describe the basic development of an easy-to-handle pipeline-traveling robot that can adapt to changes in pipe inner diameters and improve robot recoverability. With a water supply penetration rate of over 98%, there is an urgent need to maintain the reliability of existing water pipelines. Efforts to evaluate the condition of pipelines generally use nondestructive testing methods such as infrared, elastic wave, X-ray, and radar in order to reduce costs. However, these methods have the disadvantage of potentially overlooking microscopic surface damage and cracks. To solve this problem, this study proposes an inspection method for pipeline interiors using a traveling robot with soft actuators. In addition, by using a small camera, visual inspection in real time will be possible, aiming for more reliable pipeline evaluation.

Soft actuators have advantages over conventional rigid actuators for their light weight and flexibility. Although various soft actuators that can extend or contract were developed in these days, only a few actuators can extend and contract under load. Then, we believe that developing the actuator mentioned above will expand the applications of soft actuators, and we are aiming to develop them. Our proposed actuator is composed of an inflatable tube body and inflatable stopper. Some oval plates are arranged inside the tube in a zigzag pattern. Oval plates induce the tube to fold and deform in a zigzag manner during contraction, and plates and stoppers enable provide for gradual extension of the tube. These mechanisms enable the actuator to actuate under load conditions. From experiments, we confirmed that proposed actuator can extend with the load applied to the tip of the tube. Then, experimental results also showed that the actuator can contract with the load applied to the bottom of it. We are convinced our proposed actuator have some advantages over other soft actuators for extending and contracting motion.

Topology optimization is a method for determining the optimal structure for a particular objective based on physical equations and optimization mathematics. It has been applied to a wide variety of physical and engineering problems, and its application to soft robot design has attracted much attention in recent years. We specifically focus on the use of topology optimization in the design of musculoskeletal robots. In this study, we first propose a simple representation model of musculoskeletal structures suitable for topology optimization. This model represents an artificial muscle that behaves differently in time due to multiple expanding domains. Then, we present topological derivatives, which are design sensitivities for optimizing the robot’s structure. An optimization method using these topological derivatives is applied to the design of a mechanism that creates elliptical trajectories, and a reasonable optimal solution is obtained. This provides a promising direction for future research in the field of soft robotics.

We propose a 2DOF manipulator in which two gear-link mechanisms replace the two active joints of a standard five-bar linkage. Due to the effect of the various curves produced by the gear-link mechanism, this mechanism has many inverse kinematics solutions, and the kinematic properties can be easily changed by the choice of solutions. This manipulator is expected to be able to handle a wide variety of tasks by appropriately selecting an inverse kinematics solution for each task. First, we show how to solve the inverse kinematics problem for the manipulator. Next, the characteristics mentioned above were confirmed by computer simulations such as drawing manipulability polytopes which depend on the solutions, calculating the distribution of the number of solutions in the movable range, graphically expressing configuration space, and searching for a path to move to another solution while avoiding singular configurations. Furthermore, we developed prototype model and confirmed that the manipulator can actually move between inverse kinematics solutions.

If noncircular gears are incorporated into the active joints of manipulators, it is expected that the distribution of the basic kinematic properties such as force and velocity that can be generated at hand can be changed without modifying the mechanism. This paper takes the case of incorporating noncircular gears into the active joints of a 2DOF manipulator consisting of a five-bar linkage as an example. First, the design method of noncircular gears to realize the above effects is discussed. Specifically, manipulability polytopes are used as the evaluation index, and their shapes are deformed in a specified direction by introducing noncircular gears. Next, the system for making noncircular gears is described, and two pairs of noncircular gears produced by this system are shown. The system automatically outputs data representing noncircular gear geometry by inputting the change in reduction ratio during one rotation, distance between rotating axes, and module. Finally, a prototype model of a 2DOF manipulator with noncircular gears is shown to demonstrate that a controllable mechanical model is feasible.

In this paper, we describe the made of a crawler type of omni directional mobile robot that can climb up steps. Omnidirectional mobile mechanisms are often used in robots that perform complex movements.However, omnidirectional mobile mechanisms require the wheels to be in contact with the ground, so will not operate accurately in environments where the ground surface is unstable.Therefore, by incorporating an omnidirectional mobile mechanism into the track vehicle and also incorporating a mechanism for climbing up steps, the robot can operate stably even if the ground surface is unstable.The robot consists of four crawlers that can move in all directions, a mechanism for climbing up steps, a loading platform, and electrical circuits for control and status monitoring.

Normal wheeled mobile systems have a low ability to overcome obstacles, and combined wheel-crawler and wheel-leg mobile systems are complex in structure and difficult to control. In this study, we propose a new moving system for conveyance equipment. The system can be adapted to complex natural or man-made scenes, and its design objective is to improve the flexibility, stability, and safety of the transport device to meet complex and hazardous transport needs.

In this paper, we describe fabrication of a cylinder type gas-liquid phase change actuator．Pneumatic actuator is used for endoscopic surgery support robot．However pneumatic actuator have some faults．Its peripheral equipment is large and makes oscillation and electromagnetic noise．These adversely affect medical equipments．We think that new actuator which does not have those faults is necessary．We suggest a gas-liquid phase change actuator．It is an actuator which big power is got from in the small size．And it can work only with DC power supply such as dry cells．Its device is small and has a small influence to give medical equipments．In this study，we aim to improve the cooling characteristics of the actuator by comparing and examining several working fluids in the actuator．We created a cylinder-type actuator that can move a piston using a gas-liquid phase change．Actuators and a DC power supply were used to apply voltages to three different working fluids and check their displacement response．As a result，it was determined that the best fluid at present is liquid．

This paper describes a work path planning using deep reinforcement learning study to derive the optimal work path for a paddy weed suppression robot with an automatic driving function to efficiently perform weed suppression work. In addition to the paths obtained by learning, simulations were performed using the robot's equations of motion to evaluate the paths for a simple path that repeats reciprocation in the vertical and horizontal directions. As a result, we were able to derive the work path using deep reinforcement learning. The path of the proposed method was characterized by a spiral shape. Therefore, it was found to be superior in terrain that can be divided into several rectangles. Compared with the conventional path, the tracking accuracy of the robot on the spiral path was improved.

In recent years, various approaches have been made in the control of robots using machine learning. Among them, research on deep reinforcement learning, which combines deep learning and reinforcement learning, has progressed. This learning method enables the learning of continuous behaviors by storing discretized Q-tables in neural networks. Examples of its application include tripod gait generation for quadruped robots and trajectory planning for industrial manipulators, contributing to learning complex behaviors. In this study, we focus on deep reinforcement learning for gait generation, specifically aiming to achieve forward locomotion in a hexapod robot using the tripod gait with three-point support．

This paper presents the hardware configuration of a four-wheeled autonomous mobile robot with a newly designed and developed thermal array sensor integrated into the human detection function. The person-following algorithm divides the pixel area acquired by the thermal array sensor into specific areas, sorts the highest temperatures, and determines the robot's motion based on the area where the highest temperature is located. Finally, we conducted an experiment using this algorithm to make the robot follow a person by walking a circular course and realized that the robot follows the person.

In recent years, unmanned autonomous vehicles have been playing a vital role in various fields due to technological development. LiDAR technology, in particular, has been widely and rapidly expanding its applications for automatic driving, transportation, delivery, mapping and so on. Drone is definitely one of the promising applications which can benefit from LiDAR technology. For Japan, as a country well-known for natural disasters, LiDAR can be a key technology for disaster to observe a damage situation. The objective of this study is to develop a drone system equipped with 3D-LiDAR sensor for search and rescue missions of disaster victims at the early stage of a large-scale natural disaster such as earthquake, tsunami, or landslide. In this paper, one of the most advanced sensors, Zenmuse L1, is mounted on DJI Matrice 300 RTK to complete the missions. The paper validates the possibility of observing the human body shape laid on ground while measuring the overall topography of the disaster hit area by means of 3D-LiDAR.

This paper presents diffuser stall inception in a centrifugal compressor with fishtail diffuser investigated by experimental and numerical analyses. The numerical simulation showed that the diffuser stall was the two-cell rotating stall originating from the low-speed region that occurred at opposing positions. When the mass flow rate was stable, the separation was observed on the suction side wall at the upstream of the diffuser bend and the secondary flow was observed at the downstream of the bend. Before the stall, the blockage increased due to the suction side boundary layer separation. Because of the separation extending to the throat, the mass flow rate on the throat decreased, leading to stall. The secondary flow crawled under the suction side separation at the bend. In near stall condition, the secondary flow that contributed to the suction side separation was developed at the bend. From these observations, it was concluded that the diffuser stall inception was caused by the suction side boundary layer separation due to the secondary flow development.

Experiments were conducted to investigate the characteristics of a low-speed 1.5-stage axial compressor under conditions where the blade tip clearance is large and using two different types of blades．The kink point that occurred in the blade total pressure rise characteristic moved to the lower flow rate，and the performance was confirmed to be improved by using modified rotor with an open inlet metal angle．Modified rotor had the effect of improving the flow field inside the rotor blade and delaying the occurring flow rate of rotating instability．On the other hand，at low flow rates，the diffusion factor at the blade tips was increased．These results suggest that opening the inlet metal angle has a positive effect in the high flow rate but has the effect of reducing the stall margin in the low flow rate．

Unsteady flow structure of a rotating instability (RI) in a 1.5-stage axial compressor was investigated through numerical analyses. The unsteady flow structure during RI occurrence was investigated at two flow rates, conditions φ = 0.42 and 0.38. At φ = 0.42, RI was formed by repeated collision and segmentation of a tip leakage vortex on the pressure surface of the adjacent blade. RI propagated because of the impact of the blockage region resulting from the collision on the blade loading of the adjacent blade. Then, RI was caused by the vortex breakdown of the tip leakage vortex as the mass flow rate was decreased at φ = 0.38. The fluctuation of vortex breakdown influenced on blade loading near the tip side of the next blade and propagated to the next blade passage. Therefore, the cause of RI occurrence shifted from collision and segmentation to vortex breakdown with a reduction in the mass flow rate.

The impeller stall inception in a transonic centrifugal compressor with bleed slots was investigated by the experiments and the unsteady numerical analysis. Both the experimental and CFD results showed that the impeller stall inception occurred first at the leading edge of the splitter blade before that of the main blade. Then, the numerical results revealed also that the blockage development of both pressure and suction side passage of the splitter blade was the main cause of the stall inception. The blockage development within the pressure side was caused by the expansion of the stagnation region, following the development of suction side due to the leading-edge separation. It is because the low momentum fluid was no longer discharged due to the decreasing of bleed air at the inlet of pressure side passage, while the increasing at the inlet of suction side passage. Therefore, while bleed air restrained the blockage development within the suction side passage, it induced the blockage development within the pressure side passage, which affected impeller stall inception.

In a centrifugal compressor with a vane diffuser, unsteady behavior indicating the precursor phenomena of impeller and diffuser stall in the flow range where the performance curve shows a local maximum value takes place. Within the diffuser passages, five non-swirling stall regions are formed, and they slowly begin to rotate as the compressor flow rate decreases. With a further decrease in compressor flow rate, the five cells grow into one large stall cell rotating at higher speed, but the mechanism of this growth has remained largely unclear until now. In this study, therefore, a detailed numerical analysis using DES (Detached Eddy Simulation) was employed to understand the internal flow field, identify the low-speed regions occurring in the impeller and diffuser passages, and elucidate the growth and merging mechanisms of the rotating stall cells.

Increasing the blade turning angle for axial turbine increases blade loading. However, it also increases the secondary losses caused by the intensifications of the horseshoe vortex, the passage vortex, and the leakage vortex, and consequently leads to the significant degradation in the aerodynamic performance of turbine. Therefore, the applications of any useful techniques to reduce the increase of aerodynamic losses are absolutely required for the development of the highly loaded turbine cascade in practical use. The bowed blade with curvature in spanwise is one of the techniques to reduce the secondly flow and has been verified to be effective for the conventional turbine cascade. In this study, the performance tests were carried out for the ultra-highly loaded turbine cascades (UHLTC) with the bowed shape by using the small sized wind tunnel test rig for an annular cascade. The four types bowed shape were applied to the UHLTC, which have the convex surface on the pressure surface (termed positive bowed) or the suction surface (negative bowed) and are characterized by the bow angle. The test results showed that turbine efficiency of the positive bowed blade decreased due to lower torque and higher enthalpy drop. The negative bowed blade showed a decrease in enthalpy drop in the low flow coefficient region, but the efficiency did not increase due to the decrease in torque. In addition, an increase in bow angle further reduced efficiency for both the positive and negative bowed blades.