In recent years, a rapid increase in bedridden elderly, due to cerebral strokes and other diseases, has become a social problem due to soaring medical costs and heavy burden of long term care support. Therefore, development of walk rehabilitation devices for the elderly, suffered from cerebral strokes, is strongly expected. In the research so far, the authors have developed a rollator with a chest support pad that can rotate freely with one degree of freedom, and the effectiveness of its walk assistance was evaluated. In this study, a novel rollator using a motor-driven chest support pad was developed. A compact system to combine data collect system and motor control was configured. Walk measurements for six subjects were conducted using the developed rollator. The relationship between the movements of the lower limbs and rotation of the motor driven chest support pad was investigated. Time series and power spectrum results were analyzed, and the effectiveness of the motor-driven chest support pad on movement of the lower limb during walking was discussed.

Impedance control is an important technology used in the grasping control of a robot hand. Numerous studies related to grasping algorithms have been reported in recent years, with the contact force between robot fingers and the object to be grasped being primarily discussed in most cases. Generally, a coupling effect occurs between the internal loop of the grasping operation and the external loop of the interaction with the environment when a multi-fingered robot hand is used to complete a contact task. Therefore, a robot hand cannot hold an object using a large external force to complete a wide range of tasks by applying the conventional method. In this paper, the coupling of the internal/external forces occurring in grasping operations using multiple fingers is analysed. Then, improved impedance control based on the previous method is proposed as an effective tool to solve the problem of grasping failure caused by single-finger contact. Furthermore, a method for applying the improved grasping algorithm to the admittance control of a robot hand-arm system is also proposed. The proposed method divides the impedance effect into the grasping control of the hand and the cooperative control of the arm, so that expanding the task space and increasing the flexibility of impedance adjustment can be achieved. Experiments were conducted to demonstrate the effectiveness of the proposed method.

Our previous studies proposed an admittance and an impedance control method of a finger-arm robot with a 3DOF finger and 6DOF arm robot to guarantee the finger manipulability under arm compensatory movement, whose results show that satiny movement of the finger-arm robot was realized in constrained space. Although these results were applied for one finger system, it is necessary to extend these methods for a multi-finger system. This paper shows an admittance control method and its results of multi-finger-arm robot to guarantee its finger's manipulability. Both averaging method and mini-max method are examined to evaluate its manipulability of multi-finger. Both results are discussed in the viewpoint of both stiffness and viscosity and finger's manipulability.

Multimedia services such as an audio and visual media have been advanced rapidly. And now we can employ several multimedia services via the Internet in which audio and visual information is exchanged. In addition to them, physical force information is expected as the next multimedia service. However, there are several fundamental issues for interactive force telecommunication, which do not appear in the conventional teleportation. We study on basic issues of force telecommunication from human sensory aspect by using two haptic interfaces with 3' DOF that have an orthodox parallel linkage, and propose a hybrid control of Master/Slave system for force telecommunication between Human beings, which has position/force feedback loop directly. Results show that both hybrid and compliance control of Master/Slave System are suitable candidates for the force telecommunication system because both force and position serve functions are essential for the system. Moreover, recognition of an operator coordinate system is clarified to be important because of force communication strong interaction, which is discussed from human sensory aspect.

A 3'DOF robot finger is fixed to the end-effector of a 6'DOF robot arm to construct a redundant macro-micro robot system that is able to emulate the finger-arm system of a human being. However, determining joint angles and velocities of a redundant robot system in a natural way remains a difficult issue. This paper describes a method to control the system so as to generate common motions emulating the hand-arm movement of a human. To achieve this purpose, the finger is primarily supposed to complete delicate local motions while the arm moves to assist the finger when the manipulability of the finger is too low and the system is about to miss the desired target. The effectiveness on motion generation and the relation between kinetic energy and manipulability by using the proposed method has been experimentally demonstrated and discussed.

With the rapid development of service robots, avoiding collisions with human beings is a most important requirement of robot control. This chapter proposes a control method by establishing a virtual potential field around a robot to avoid collisions between a human being and the robot by the redundant joints of the robot. The greatest advantage of the proposed method is that a possible collision can be avoided automatically without requiring any action by nearby human beings. A control method is also proposed for a redundant robot to simultaneously carry out a contact task with its hand and perform collision avoidance with its redundant joints. The effectiveness of the proposed method has been demonstrated by experiments. © 2005 Elsevier B.V. All rights reserved.

Since there exist a lot of deformable objects in our daily life, method of manipulation of a deformable object for a robot is expected not only in industrial manufacturing but also in life support. Generally, a force/torque sensor is used in playing a contact task for a rigid object by a robot. However, only a force/torque sensor is not enough in handling of a deformable object by a robot. In this paper, a fusion algorithm by integrating data from both a force/torque sensor and a visual sensor is proposed for a robot to play a contact task in which an aluminum peg fixed on the robot hand is inserted into a hole installed on a deformable plate. To complete the task, a high-speed camera is used and a real time processing algorithm is developed to detect deformation of the central line of the hole. Then, the results of visual processing are integrated with data of the force/torque sensor using the proposed compliance control algorithm for a robot in playing the task. The effectiveness of the proposed method has been demonstrated through experiments. © 2001, The Japan Society of Mechanical Engineers. All rights reserved.

In the previous papers, a sealing nozzle and a visual sensor were mounted on the end-effector of a manipulator, but control of nozzle position was only considered. As the results, the visual sensor would possibly lost the seam target at curved part of a sealing line during tracking. In order to improve tracking property of the sealing robot, both a visual sensor and a nozzle of a sealing robot must be real time controlled. In this paper, a fuzzy model based method for generating desired trajectory of the visual sensor is proposed. The fuzzy rules are obtained by applying neural network learning. Generated desired positions of nozzle are equivalently converted to rotation angles considered in the visual sensor coordinate. Then, a visual feedback algorithm for simultaneously controlling the nozzle and the visual sensor is also developed. Using the proposed method, positions of the sealing nozzle and the visual sensor can be controlled at every sampling instant in the robot control system. Therefore, both the nozzle and the visual sensor can move along a sealing line without losing the target during tracking. Tracking experiments for sealing objects with different type of sealing lines are carried out, and the effectiveness of proposed method has been demonstrated. © 2000, The Japan Society of Mechanical Engineers. All rights reserved.

Imaging of skin thermal properties was attempted by successive thermographic measurements of the skin surface with a stepwise change in ambient radiation temperature. In order to produce the stepwise change in ambient radiation temperature, two hoods maintained at different temperatures, 20 degrees C and 60 degrees C, were mechanically switched. A total of 65 thermograms were taken from 2 s before to 32 s seconds after the hood switching. Images of skin emissivity, emissivity-corrected skin temperature and thermal inertia were obtained by least-squares fitting at each pixel of 64 thermograms. Measurements were performed on the forehead, cheek, forearm, palm and back of the hand of 10 healthy male subjects. Differences in emissivity between sites and subjects were insignificant. Significant differences were observed in thermal inertia values between sites. Great improvements in the imaging of thermal inertia have been achieved by applying least-squares fitting to 64 thermograms instead of by computations from only two thermograms as in the previous study. Non-contact measurement and visualization of skin thermal properties are significant advantages of this method.

Cooperative control algorithms for a redundant finger-arm robot were proposed in a previous study, based on the movement of the human hand-arm system. With these algorithms, the finger-arm robot arm was able to complete a constrained task by integrating admittance control and impedance control with the manipulability control of the fingers. The manipulability of the fingers was controlled using both an approximate global search (i.e., the top search method) and a local optimization method. However, the dynamic characteristics of these methods have not yet been studied. In this study, the conventional cooperative control algorithms were developed further by extending them to dynamic movement in the admittance control of a redundant multi-finger-arm robot with manipulability control of the fingers. We clarified the relationship between the feasibility of the virtual dynamics and the motion speed, as well as the range of the achievable virtual dynamics. This paper evaluates and discusses the proposed methods in terms of the finger manipulability control. The experimental results show that the algorithms responded to more dynamic movement, and a broader range of virtual dynamics was achievable.

This paper deliberates the spatial cognitive ability of the moving distance of the human hand, which is measured by using motion capture. Before the movement begins, the subject is shown a standard length. Then, both horizontal and vertical blindfold hand movements were measured using the proposed protocol for six right handed subjects in order to investigate the cognitive ability of the moving distance of the human hand. The experimental results show that the average moving distances obtained in both directions were quite smaller than the standard length an inverse "V" pattern in percentage result was observed only in the horizontal movement. The experimental result also demonstrated an interesting relationship between the hand moving distance and manipulability of the upper limb. © 2007 IEEE.

This paper investigates the motion forms of robots generated by the Q-Learning algorithm during the learning process. We analyzed the manner in which a caterpillar robot, which performs looping motions using two actuators, acquires advance actions by focusing on the process. By observing a series of processes, we confirmed that various motion forms appeared or disappeared as a result of their interactions with the learning process and approach an optimum motion form. In most algorithms, such motion forms cannot appear in the learning process because its framework is almost predetermined by the teacher data, and the cost functions for learning cannot be usually considered as a continuous process. The characteristics of reinforcement learning are very interesting from the viewpoint of biological evolution. This paper describes the effects of the interaction between the robot kinematics and the environment as a direct result of changing the environment. In addition, this study challenged the acquisition of two-dimensional motions with a starfish robot having four actuators. The result demonstrates that the robot can obtain a reasonable motion from the complicated relationships with the environment by skillfully employing its structure. Moreover, this paper implies that the reward manipulation may give a new insight for the learning process by the investigations performed in this study. This paper examines the possibility of the reward combinations for generating arbitrary motions.

The advancement of multimedia services including audio/visual media has been rapid. The applications of cellular phones, in particular, have increased by using these technologies. In addition, if force telecommunication were realized, force information would become a next leading factor in the multimedia service. In this field, a robotic master/slave system is a leading candidate. This system has been studied as a teleoperation system between an operator and an environment; the operator controls only the master device whereas the slave device is never controlled. For multimedia applications, such systems require flexibility and bidirectionatity because force telecommunication must consider the interactions between users. This paper details the fundamental issues of force communication from a viewpoint of human perception. With regard to the control system, this study uses an integrated hybrid control master/slave system that helps to find a key factor of equal bilateral force telecommunication in the sensory aspect. The employed system has a function to change the proportion of force display to position display by varying a weight parameter. We discuss the basic control performance of a force telecommunication system and evaluate qualitative feelings of users by using a psychological evaluation method.

The main advantage of Reinforcement Learning is that it provides unexpected solutions for a designer. This study shows how a mobile robot can obtain unexpected motion forms by using Reinforcement Learning. Results show the the mobile robot with two-dimensional mobile ability can obtain unexpected motion forms for both advance motion and rotation motion. The mechanisms for these motions were investigated in order to understand how to obtain these motions. Moreover, since this system has a two-dimensional factor, this study examines the learning characteristic for the oblivion of the learning knowledge. In addition, this study examines the learning of the knowledge manipulation method to obtain new learning results with respect to the two-dimensional factor.

脳卒中患者のリハビリテーションとしてトレッドミルによる歩行訓練を行うという手法は臨床的に広く用いられてきたが、現行の歩行訓練機器のほとんどは利用者下肢部に注目し、下肢部の反復強制運動を行うものである。一方、申請者らはこれまでに１自由度回転機構付きの胸部支持パッドを有する歩行車を試作し、歩行運動の特徴を定量的に評価した。利用者は提案の歩行車で歩行する際に、胸部支持パッドの回転により利用者腰部のスイングが自然に引き出され、ベルトを介して足が引っ張られることによって利用者の歩行意欲の向上を図りながら、歩行のリズム感をつかめやすいという特徴がある。そこで本研究は、これまでの研究成果を活かして、回転型胸部支持パッドを有するトレッドミル型歩行訓練機の開発を行い、その効果を評価することを目的とする。 本年度は研究計画の初年度であり、まずハードウェアの設計製作を含めたシステムの開発に取り組む。従来の研究成果を参考しながら、身長180cm、体重100kgまでの人が利用可能な回転型胸部支持パッドとその周辺支持機構を設計・試作したのち、市販品のトレッドミルに取り付けることによって回転型支持パッドを有するトレッドミル歩行訓練機器のハードウェアを製作した。また、歩行中利用者の運動情報を測定するため、支持パッドへの圧力を測る力センサと、歩行者下肢部の運動を測定するゴニオメータなどのセンサを用いており、これらのセンサ情報を集計するための計測系を構築した。本年度の研究内容に係わる研究発表については、学術講演会で２件の発表実績があった。

本研究では、利用者の歩行意欲を能動的に促進できる駆動型胸部支持パッドを有する歩行車の開発を行った。試作した歩行車では、身長180cm、体重100kgまでの利用者を想定して設計されており、支持パッドに力センサ4個を取り付けることで体重による圧力を計測できる。また、駆動モータの制御系とセンサ計測系を連動するためのシステム構築を行い、さらに外部電源のコードレス化を実現した。歩行車補助効果の評価としては、膝伸展角および足首回転角度の変動が胸部支持パッドの回転と連動していることがパワースペクトル解析によって明らかになっており、相関係数の結果から下肢部の運動が支持パッドの回転と強く関連したことが示された。