Busy agricultural seasons involve long-term continuous work and heavy labor. Particularly during overhead work, such as harvesting, gibberellin treatment, and bagging, workers need to consistently raise upper limb weights of approximately 2 to 4 kg with their own muscular strength, resulting in a high work burden. For long-duration work in the field, a passive and robust assist system is advantageous. Therefore, we propose an assistance device named TasKi that uses self-weight compensation mechanisms and horizontal link mechanisms to reduce the burden on a worker's upper limbs during overhead work. TasKi can compensate for upper limb weight by using the force of a spring in various postures of the upper limbs without battery support. In this report, we describe the design of the TasKi mechanisms that achieve the upward work assist in actual agriculture with a simple structure. The mechanism of self-weight compensation and the degree of freedom and parameters of the link mechanism are studied.

The cleaning of residential ventilation ducts is necessary to prevent damage to health. However, since residential ventilation ducts are usually thin and curved, cleaning them is difficult. It is also difficult to obtain thrust within the duct using a wheel or a snake type robot because it is hard to obtain an appropriate reaction force in a deformed pipe. Therefore, the pipe must be gripped stably even if it is flexible so that thrust can be generated to run the cleaning robot through the pipe. In this paper, we modeled a cleaning robot that uses peristaltic motion running through a flexible duct with an inner diameter of 50 mm. Then, the validity of the model was verified by experiment. Finally, a cleaning experiment was conducted and the cleaning rate was 98.7 %.

Recently, in the search for alternatives to conventional robots, various types of soft actuators and their applications have been studied. In particular, pneumatic soft actuators have the advantage of being lightweight and high power. One of the uses of these soft actuators is as a substitute for an electric motor to actuate the joint of a structure, such as a link mechanism. Another use involves their fusion with a flexible structure. The features of this concept are a simplified system, in which almost all interfaces can be configured as flexible structures. However, because these actuatable flexible structures are made with rubber, silicone, or flexible resin, it is difficult for them to support their own weight owing to the effect of the square-cube law in the case of increasing size. Hence, these structures are limited to a size of approximately 1 × 10-21 × 10-1m. If an actuatable flexible structure with a size of 1 × 100m can be realized, the concept of soft actuator-flexible structure fusion is expected to provide novel solutions and applications. Herein, as a feasibility study, large actuatable flexible structures were developed. The proposed structure, LayerCAKE, is a laminated open-cell and closed-cell foam structure; cell foam is a lightweight and flexible material that can be used to realize large actuatable flexible structures. LayerCAKE is actuated by using the concept that openand closed-cell foams contract differently when they are vacuumed. The bending-motion model and was experimentally verified, and different types of LayerCAKE models that could exhibit various types of motion were developed and tested. Furthermore, a complex-shaped LayerCAKE model (in the shape of a human hand) was developed. A large actuatable flexible structure of approximately 900 mm was realized. Furthermore, it was confirmed that the bending motion could be controlled by pressure.

Currently, serious accidents are caused frequently by the aging of sewer pipes. Therefore, to inspect sewer pipes, we developed a peristaltic crawling robot that reproduces the locomotion of an earthworm. This robot can drive for more than 100m, and it can be used for the maintenance of sewer pipes (100A pipes). However, the speed of the robot is low. There are two causes. First, the units of the previous robot have steps of artificial muscle fastening. These steps increase the diameter of the artificial muscles. A smaller diameter of the artificial muscles is advantageous for the speed of the robot inside the pipes. Second, the previous robot has slow air response. In this study, we used large-sized solenoid valves to overcome this drawback.

For unmanned rescue, observation, and/or research, vehicles with high terrain adaptability, high speed, and high reliability are needed to reach hard-to-reach-locations. In order to extend the areas that can be explored, we propose a method and a robot capable of running on the surface of water without having to bypass the puddles and streams that exist on uneven terrain. The method that enables the robot to run on the water surface is bio-inspired by the basilisk lizard that can walk on the surface of water. We developed a blade-type crawler robot with a simple and reliable mechanism, capable of traversing uneven terrain at high speed. The robot with the method was tested on a real water surface and the result confirmed the ability of the robot to run on the water surface.

In recent years in Japan, over half of all workers suffered from lower back pain. This has become a social problem that needs to be addressed. To reduce its occurrence, we developed a flexible, high-output waist assist suit called “AB-Wear” in a previous study. The AB-Wear suit can assist human motion and reduce muscular fatigue of the waist. However, the assistive forces of the device generate compressive forces on the backbone, which have adverse effects on the body. Hence, in this study, we propose an exoskeleton-type AB-Wear equipped with a compressive force reduction mechanism, called “semi-endoskeleton-type AB-Wear”. This device has a reduction mechanism similar to a flexible flat spring behind the upper body. Because of this structure, this device can generate an effective assistive force. First, we explain the difference between the semi-endoskeleton-type AB-Wear and the previous device. Then, we model the semi-endoskeleton-type AB-Wear because the model is used for its operation. Moreover, its effectiveness is confirmed using musculoskeletal simulation. Finally it is evaluated by measuring surface electromyography (EMG) on a subject's body to confirm its effectiveness with a real body. The EMGs of the wearer with and without the suit are compared. The usefulness of the AB-Wear is confirmed by simulation and experiment.

Unmanned rescue, observation, and/or research vehicles with high terrain adaptability, high speed, and high reliability are needed in difficult-to-reach locations. However, for most vehicles, high performance over rough terrain reduces the travel speed and/or requires complex mechanisms. We have developed a blade-type crawler robot with a very simple and reliable mechanism, which traverses uneven terrain at high speed. Moreover, the gyro wheel design stabilizes the success of this approach in improving the motion, ensuring robust traversal. The improvement in traveling speed and robustness over uneven terrain by our approach was confirmed by experiment.

In this study, a variable viscoelastic joint system comprising antagonized artificial muscles and magneto-rheological fluid brakes is proposed. This system enables human assisting devices such as robotic exoskeletons to retain structural softness when compared with the existing devices driven by motors and reduction gears, which can only achieve superficial softness. The authors had proposed the system and showed its effectiveness via experiments using a prototype with one degree of freedom in their previous works. In this study, as the next step in designing the human assisting device, a lower body assistive prototype “Airsist” is introduced. In addition, a control method that can cooperate with the wearer without the need for an additional operation is proposed.

A range of pneumatically-driven devices have been developed. However, these require a large air compressor, making them heavy, bulky, and therefore inappropriate for use in portable devices. In this study, we proposed and tested a portable pneumatic power source using the chemical reaction between sodium bicarbonate and citric acid. The carbon dioxide generated in the reaction was used as a pneumatic power source. The chemicals used are inexpensive, nontoxic, and readily available. From the result of basic experiment demonstrated in this paper, we conclude that the method can provide enough high pressure (more than 1 MPa) for activating pneumatic actuators and the chemical reaction is safe since it is endothermic reaction. We also demonstrated a novel system that provides continuous mixing of the reagents, using a pressure booster. The system keeps a pressure inside of a tank moderate, and tank can become light weight because it doesn't need to endure high pressure.

Sub-seafloor exploration is an important area of biological and geological research, and often requires samples of seafloor mud to be recovered. The minerals and marine sediments trapped in this mud are also potentially valuable resources. However, seabed exploration has been limited by the complexity and cost of the traditional equipment used. Wide area exploration can be made possible by deploying multiple robots to autonomously search beneath the ocean floor. In this study, we prototyped a sub-seafloor excavation robot for use in seabed exploration. The key system comprised a propulsion unit and an excavation unit that allow the robot to move freely within the seabed. We experimentally demonstrated the ability of the excavation robot to produce curved boreholes with a diameter of 160 mm, a turning radius of 1.67 m, and a depth of 613 mm. Our experimental results confirm that nonlinear excavation is possible using the excavation robot developed.

Lower back pain is a major health concern worldwide. One cause of lower back pain is the burden on the lumbar region caused by the handling of heavy objects. To reduce this burden, the Ministry of Health, Labour and Welfare in Japan has recommended “squat lifting.” However, this technique, which supports a large force on lower limbs, is not very popular. Therefore, we aimed to develop a power assist suit for squat lifting. In this paper, we propose a gastrocnemius-reinforcing mechanism. Next, we discuss estimation of joint torque from motion analysis of squat lifting in order to construct a prototype. Finally, we describe the performance of the prototype mounted on a human body. The %MVC of the gastrocnemius while performing squat lifting was reduced by 40% using the prototype assist suit compared with the value without using the suit.

In this paper, permissible resistant torque considering back-drivability is verified to develop a wearable assist suit (WAS). The WAS has a clutch and a variable viscoelasticity joint. In this paper, permissible resistant torque is defined as torque that is acceptable in daily use. As first stage of the WAS development, the paper discusses the relationship between the resistant torque to the knee and the degree of discomfort experienced by the wearer as evaluated through a survey questionnaire experiment. In addition, the influence of the resistant torque on a muscle of the knee extension is considered and confirmed by measuring surface electromyography (surface-EMG).

Low back pain of workers is increased in workplaces that involve hard work. It is caused by excessive loading of the waist joint and muscle fatigue. Therefore, power-assist suits have been developed to decrease the load on the waist joint. However, previous power-assist suits have had problems such as low output or heaviness. Thus, we have developed an assist suit that is lightweight and exerts a large force. A balloon actuator and pneumatic artificial muscles are attached to assist suit as the actuators. The assist suit has various desirable features: lightweight, flexibility, and high output. First, human motion is analyzed for the development of the assist suit. The assist suit is developed to assist the waist joint torque. The assist suit is modeled, and the theoretical values of its generation force are estimated using an assist-suit model. Finally, the assist suit is evaluated by measuring the surface electromyography (EMG). The EMG of the wearer is compared with that without the suit. The effectiveness of the assist suit is confirmed by a decrease in EMG.

In this study, a variable viscoelastic joint system with a clutch for a human assistance was proposed. The variable viscoelastic joint system comprised antagonized artificial muscles and magneto-rheological fluid brake (MR-brake). This system enabled the human assisting device such as exoskeletons to retain structural softness when compared with the existing devices driven by motor and reduction gear, which could only achieve superficial softness. In addition, a clutch system that provided high back-drivability to the wearer by structurally separating the device from the wearer was proposed. As an initial step in designing the human assisting device, a prototype with the proposed variable viscoelastic joint system for knee assistance is developed. Also, its control method were developed. Furthermore, experiments were conducted to confirm the influence of the proposed viscoelastic joint system on the wearer and the effectiveness of the clutch system.

A desktop force feedback device is able to render reaction force of virtual objects. However, the desktop type limits operator's motion. In contrast, a wearable force feedback device allows us to interact with virtual objects while moving in virtual space. In this study, we have developed a 1-DOF wearable force feedback device with MR brake and pneumatic artificial muscles. These actuators are lightweight, have a high power density, and are controlled by feed-forward control. This device is equipped with the operator's arm and renders various forces, such as friction, elasticity, and viscosity. In this paper, we improve the device to solve existing problems from previous studies. The proposed device is tested to confirm its basic properties. It is applied to augmented reality space and comparisons of subjective evaluations between virtual objects and actual objects.

Lower back pain accounts for more than half of all reported on-the-job ailments, escalating from a personal challenge to a broader societal challenge. Researchers have developed a power assist suit intended prototype to reduce the incidence of lower back pain in the workplace when process automation is not possible. Equipped with two pneumatic actuators, the prototype suit is lightweight, flexible, and efficient. The prototype suit can assist human motion using passive and active forces. In this study, researchers confirmed the effectiveness of passive assistive force. Two types of motion were considered: lifting and unloading in a crouching position and carrying. Researchers first analyzed the subject motions using video analysis software. Waist joint loads were estimated using motion analysis results and a human link model. Second, researchers determined the power assist suit's operational parameters and developed a power assist suit model. Lastly, researchers confirmed the passive force prototype suit's effectiveness based on measured changes in generated force and electromyography.

Recently, force feedback devices that intuitively achieve excellent operation have attracted attention in a wide range of fields such as remote operation, virtual reality, and medical training systems. However, it is difficult for conventional devices to widely display soft and hard objects because of driving motors. Moreover, they are likely to be hazardous in the event of delayed response to an unexpected external force. To solve these problems, we previously developed a force feedback device using pneumatic artificial muscles, which are structurally flexible and have wide a range of stiffness, and magnetorheological clutches. Furthermore, we confirmed that any three-dimensional virtual object can be displayed using the developed device. However, when the operation part of the force feedback device is moved away from the virtual object, it remains stuck to the virtual object. In this study, we propose a system to reduce the sticking phenomenon and experimentally confirm the reduction rate (85%). Moreover, we displayed viscous torque as a new application of the feedback device.

Bipedal robots capable of various dynamic motions such as walking, running, and jumping have been developed in recent years. In particular, these dynamic motions require the use of high power in a short time when the robot kicks off the ground. Furthermore, it is necessary to decrease the impact force that a robot is subjected to when landing during these motions. Unfortunately, rigid actuators tend to become heavier as their output increases. Therefore, we focus on the method for obtaining a high output using elastic energy. However, the use of the elastic element only leads to robot vibration. Therefore, to control the dynamic motion, we adopted the viscosity element to the robot joint. In this study, we focused on a straight-fiber-type artificial muscle for the elastic element and a magnetorheological brake for the viscosity and friction elements, respectively. A previously designed monopedal robot was able to jump 82.5 mm using a sliding rail and counter weights; however, the robot shook upon landing because of the presence of the elastic element in its artificial muscles. In this paper, we first proposed a dynamic model of the previously developed monopedal robot. We then performed vertical jumping simulations of the robot to confirm the model's utility.

Unmanned rescue, observation and/or research vehicles with high terrain adaptability, high speed, and high reliability are needed to reach difficult locations. However, most vehicles achieve improved performance over rough terrain at the expense of low speed and/or complex mechanisms. We developed a blade-type crawler robot with a very simple and reliable mechanism, capable of traversing uneven terrain at high speed, using aerodynamic devices. As these small devices are in the low Reynolds number region, we tested a wing that made use of the ground effect. We experimentally confirmed the success of this approach in improving the traveling speed and ability to traverse uneven terrain. The robot with aerodynamic lift was climbed 1.5 times higher obstacle than without wings.

Unmanned rescue, observation and/or research vehicles with high terrain adaptability, fast velocity and high reliability to reach difficult rough terrain locations are still demanded, but most vehicles increase rough terrain adapt ability at the expense of low velocity and/or complex mechanisms. We propose a novel vehicle consisting of a very simple blade-type crawler and active antennas with rollers, resembling a wharf roach. This configuration assures stable travelling over uneven terrain at high-speeds, with a very simple and reliable mechanism. This article presents the basic concept, mechanical design of the crawler and the antennas, and the basic motion control strategies. Moreover, we built and tested the first small mechanical prototype named KEIOS-I, and got successful results from experiments on uneven terrain at a high-speed traveling, and also lateral travelling and jumping motions. Future work will also implement roller skating mode using the active antennas equipped with rollers.