Jun-ya Nagase

Design of a variable-stiffness robotic hand using pneumatic soft rubber actuators

In recent years, Japanese society has been ageing, engendering a labor shortage of young workers. Robots are therefore expected to be useful in performing tasks such as day-to-day support for elderly people. In particular, robots that are intended for use in the field of medical care and welfare are expected to be safe when operating in a human environment because they often come into contact with people. Furthermore, robots must perform various tasks such as regrasping, grasping of soft objects, and tasks using frictional force. Given these demands and circumstances, a tendon-driven robot hand with a stiffness changing finger has been developed. The finger surface stiffness can be altered by adjusting the input pressure depending on the task. Additionally, the coefficient of static friction can be altered by changing the surface stiffness merely by adjusting the input air pressure. This report describes the basic structure, driving mechanism, and basic properties of the proposed robot hand.

Development of a Tendon-Driven System Using a Pneumatic Balloon

The development of a robot which is gentle to people in nursing and welfare has been concerned about more and more toward the aged society. For a robot in often contact with people and requiring safety and flexibility in nursing and welfare, the development of a soft actuator that is compact and lightweight has been urged. In particular, robots, which are intended for use in the held of medical care and welfare, should be safe for the human environment as they often come into contact with people. The robot hands are required to have dexterity similar to human hands, and be able to perform complicated movements. Therefore, they differ from industrial robot hands in the weight, freedom of movement of joints, and flexibility. Then, we have devised a tendon drive system using flexible silicon rubber material aiming to develop a robot hand, which is lightweight and has the same degree of freedom as biological human hands. This study will report on the basic structure of the flexible and lightweight tendon drive system that we have developed as a soft actuator. It will also report on the basic properties of the system evaluated, as compared with the case of the biological human muscle.

Development and control of a multifingered robotic hand using a pneumatic tendon-driven actuator

Because of the rapid aging of the Japanese population and the acute decrease in young workers in Japan, robots are anticipated for use in performing rehabilitation and daily domestic tasks for nursing and welfare services. Use in environments with humans, safety, and human affinity are particularly important robot hand characteristics. Such robot hands must have flexible movements and be lightweight. Under these circumstances, this study specifically addresses the expansion of a silicone rubber, tendon-driven actuator, which has been developed using a pneumatic balloon. A multifingered robotic hand using the actuator is developed. Moreover, a fuzzy grasping control system is applied to the proposed robotic hand. The robot hand’s development is described incorporating pneumatic balloon actuator with the softness, size, and weight of a human hand. The fuzzy grasping control system is shown to be effective for the proposed robot hand, which can grasp soft objects easily.

Two Tendon-Driven Systems Using Pneumatic Balloons

In recent years, Japanese society has been aging, creating a shortage of young workers. Robots are expected to be useful to perform tasks such as rehabilitation therapy, nursing elderly people and day-to-day work support for elderly people. In particular, robots that are designed for use in the fields of medical care and welfare must be safe for the human environment because they often come into contact with humans. Furthermore, robots must have dexterity that is similar to that of humans. Under these circumstances, tendon-driven systems of two types using flexible silicone rubber materials have been developed. They are lightweight and have characteristics resembling those of human muscle. This paper describes the basic features and mechanisms of two tendon-driven systems that we have developed as a soft actuator. Furthermore, basic properties of the system are evaluated and compared with those of human muscles.

Function-selectable tactile sensing system with morphological change

This paper presents a novel approach for active tactile sensation that utilizes soft morphological deformation. This work is inspired by human fingers wrinkles, which appear after a long time soaking in water, and has been indicated as an efficient mean for enhancement of gripping in wet environment. We created a tactile sensing system that is an integration of actuation (pneumatic actuator) and sensing elements (strain gauges). This device can change its morphology (wrinkle patterns) so that the posture of embedded sensing elements can vary, then generate different responses depending on sensing tasks. As a result, this device can actively select its sensing function depending on sensing task. In this paper, the sensing device is both sensitive to contact action and sliding action by using only one types of strain gauges. This work can be extended to a wide range of sensing elements (not only strain gauges), and considered to give impact to the field.

Acquisition of earthworm-like movement patterns of many-segmented peristaltic crawling robots:

In recent years, attention has been increasingly devoted to the development of rescue robots that can protect humans from the inherent risks of rescue work. Particularly, anticipated is the development of a robot that can move deeply through small spaces. We have devoted our attention to peristalsis, the movement mechanism used by earthworms. A reinforcement learning technique used for the derivation of the robot movement pattern, Q-learning, was used to develop a three-segmented peristaltic crawling robot with a motor drive. Characteristically, peristalsis can provide movement capability if at least three segments work, even if a segmented part does not function. Therefore, we had intended to derive the movement pattern of many-segmented peristaltic crawling robots using Q-learning. However, because of the necessary increase in calculations, in the case of many segments, Q-learning cannot be used because of insufficient memory. Therefore, we devoted our attention to a learning method called Actor–Critic, which can be implemented with low memory. Because Actor-Critic methods are TD methods that have a separate memory structure to explicitly represent the policy independent of the value function. Using it, we examined the movement patterns of six-segmented peristaltic crawling robots.

Design of a peristaltic crawling robot using 3-D link mechanisms

In disaster areas, rescue work conducted by humans is extremely difficult. Therefore, rescue work using rescue robots in place of humans is attracting attention. This study specifically examines peristaltic crawling, the movement mechanism of an earthworm, because it can enable movement through narrow spaces and because it can provide stable movement according to various difficult environments. We developed a robot using peristalsis characteristics and derived a robot motion pattern using Q-learning, a mode of reinforcement learning. Moreover, we designed each part of the robot based on required specifications and thereby developed a real robot. We present results of motion experiments assessing the robot’s level ground movement.

Development and control of support function for upper limb support device

In recent years, the world has been confronting issues related to an aging society, population decrease, and shortages of young workers. Those trends point to the increased development of devices to support human. A device that involves any contact with people must be safe, lightweight, and flexible. Therefore, we developed a device using a pneumatic cylinder to support a patients upper limb motion. This supporting device has three modes corresponding to living activity support mode, rehabilitation and meal support. We designed control systems for these modes. We describe construction of our device and details of support functions. Then we use some experiments to evaluate function control systems. Results show that each control system provides good performance for supporting devices.

Cylindrical elastic crawler mechanism for pipe inspection inspired by amoeba locomotion

The diverse pipe installations used today include pipelines in chemical plants, water pipes, and gas pipes. Severe accidents at such pipe installations must be prevented by regular pipe inspection and repair. As described herein, a novel tracked crawler mechanism is proposed for pipe inspection. This simple and compact cylindrical elastic tracked crawler has multiple crawler belts in axial symmetry to a cylindrical frame, driven solely by a single motor via a single worm. It is suitable for propulsion through a narrow pipe. It can propel itself upward in a pipe using elastic force generated by deforming the crawler belt passively. Moreover, the proposed tracked crawler can cross over a level difference and pass an elbow by deforming the crawler belt passively along the pipe shape. For a prototype tracked crawler, running performance experiments conducted in various pipe conditions yielded good results. This study clarified the relation between belt rigidity and traction force in theory and experiment respectively.

Development of a novel crawler mechanism for pipe inspection

In this paper, we propose in-pipe cylindrical crawler mechanism. Our proposed cylindrical tracked-crawler robot has six rubber crawler belts in axial symmetry to a cylindrical frame. The robot drives by only a single geared motor through a single worm gear. It can run in a narrow pipe. Also, it can move upward inside vertical pipe while holding itself by the elastic force of the crawler belts. Moreover, the proposed crawler mechanism can propel steps and pass elbows, by deforming the crawler belt passively along the pipe shape. In experiments, the prototyped crawler robot had good running performance in various pipe conditions.