With the aging population trends in developed countries, there is an increased expectation of the application of assistive robots. A variety of robots have been developed to address this challenge. Although there are many technical problems to be solved, the lack of objective evaluation indexes for evaluating the benefit to the users is one of the important problems to be addressed before the commercialization of the assistive robots can be realized. The ICF (International Classification of Functioning, Disability and Health) is a classification of the health components of functioning and disability, and is being utilized in medical, healthcare, and welfare fields. The ICF has a basic framework to evaluate healthcare and welfare equipment, including robots, and it will be the basis of the evaluation indexes for assistive robots. In this paper, we present the development of evaluation indexes, and provide the results of preliminary experiments which were conducted using iARM and RAPUDA robots performing a certain lifting task. The experiments illustrate the issues involved in the development of ICF-based indexes for assitive robots.

This paper proposes an analytical methodology of inverse kinematic computation for 7 DOF redundant manipulators with joint limits. Specifically, the paper focuses on how to obtain all feasible inverse kinematic solutions in the global configuration space where joint movable ranges are limited. First, a closed-form inverse kinematic solution is derived based on a parameterization method. Second, how the joint limits affect the feasibility of the inverse solution is investigated to develop an analytical method for computing feasible solutions under the joint limits. Third, how to apply the method to the redundancy resolution problem is discussed and analytical methods to avoid joint limits are developed in the position domain. Lastly, the validity of the methods is verified by kinematic simulations.

This paper proposes a practical redundancy resolution for 7 DOF redundant manipulators with joint limits. The primary concern of the paper is how to resolve the redundancy in the global configuration space when the movable joint angles are considerably restricted. First, a parameterized inverse kinematic solution for a 7 DOF manipulator model is derived. Second, how the joint limits affect the inverse kinematic solution is examined to explicitly identify the feasible solution under the joint limits. Then, an analytical redundancy resolution method for avoiding the joint limits is developed. Finally, kinematic simulations show that the method is effective for avoiding the joint limits as well as expanding the reachable region of the manipulator's tip.

In this paper, we propose a task skill transfer method using a bilateral teleoperation. We assume that a task skill for a complicated motion is described by the suitable trajectory of the impedance center. Thus, a important point is how to get the suitable trajectory of the impedance center. In our method, the suitable trajectory is got from results of bilateral teleoperation. In the bilateral teleoperation, an operator constructs a motion procedure able to execute the task. The suitable trajectory of the impedance center is calculated from the position and the force data in the teleoperation experiment. A basic element of the task skill is composed of an initial condition, a task skill motion and a final condition. The initial and final conditions are described by values of both sensor and tip position. The task skill motion is described by a hybrid impedance/force control. To demonstrate how to use of our method, we choose the nut attachment task as an example

In this paper, we propose RT-middleware for robot system integration. "RT" means "robot technology", which is applied not only to industrial field but also to nonindustrial field such as human daily life support systems. RT-middleware which is proposed in this paper is a software platform for RT systems. We have studied modularization of RT elements and have developed RT-middleware, which promotes application of RT in various fields. Robotic system development methodology and our RT-middleware concepts are discussed. The RT-component, which is a basic software unit of RT-middleware based system integration, is derived from this discussion. A methodology of system development by using RT-components, and a framework for component development are proposed. Evaluations of some RT-component based systems are performed. Finally, conclusions and future work is described.

In our previous research, we developed space robot teleoperation technology to achieve control from the ground of effective manual manipulations in orbit. To solve the communication time delay in the space robot teleoperation, we propose a mixed force and motion command-based space robot teleoperation system that is a model-based teleoperation. Moreover, we have also developed a compact 6-degree-of-freedom haptic interface as a master device. The important features of our teleoperation system are its robustness against modeling errors and its ability to realize the force exerted by the operator at the remote site. We introduce a new control method, which modified our model-based teleoperation system, to control the real robotic system Engineering Test Satellite VII manipulator. Surface-tracking and peg-in-hole tasks have been performed to confirm the effectiveness of our system. The experimental results obtained with our system including the haptic interface demonstrate its ability to perform these tasks in space without any major problems. We also evaluated different master device approaches for the model-based space teleoperation system. For this purpose, we used two methods, which are a master-slave (MS) approach and a force-joystick approach. Our results show that the MS approach is the best control method for contact tasks in which the directions of motion of the slave arm and of the operator's input force are different, as in the surface-tracking task.

During teleoperation, when the operator's attention is focused on controlling the end-effector's motion, it is very difficult to recognize possible link collisions. Such collisions may damage the environment or the links seriously, because usually the links have no sensors. We propose a so-called "virtual radar" which displays the collision information related to the motion of the whole manipulator at the end-effector level. The computer checks for unreachable areas due to the presence of obstacles and displays the appropriate information mapped on the task space using 3D graphics. This would enhance the reliability of the system. When applied to a 6-DOF manipulator, the possible collision space must also be 6-dimensional. Hence it is difficult to visualized and comprehend by the operator. To tackle this problem, the virtual radar displays the collision information by means of a deformable sphere and various patterns on it. The effectiveness of this method has been verified by experiments with a real telerobotic system.

In this paper, we present a method for analyzing parallel mechanism stiffness including elastic deformations in the structure. In our previous works, we developed a compact 6-DOF haptic interface as a master device which achieved an effective manual teleoperation. The haptic interface contains a modified Delta parallel-link positioning mechanism. Parallel mechanism is usually characterized by a high stiffness, however, it is reduced by elastic deformations of both parts and bearings. Therefore, to study such a parallel mechanism, we analyzed stiffness in a parallel mechanism, including elastic deformation of both parts and bearings. Key points of our method are a modeling of bearings, a modeling of a elasticity coefficient of a passive axis in a bearing and a modeling of a parallel mechanism. Finally, we show that our stiffness analysis method of a parallel mechanism is high reliability and precision.

In our previous works, we have proposed a mixed force and motion commands-based space robot teleoperation system and a compact 6-DOF haptic interface to achieve an effective manual teleoperation. Until now, the effectiveness of this system and the haptic interface has been confirmed by the experiments in our laboratory. The most important features of this teleoperation system are robustness against modeling errors and ability to realize the operator exerted force at a remote site. In this paper, elements of this system and the haptic interface have been employed to teleoperate the 6-DOF manipulator mounted on the Engineering Test Satellite VII (ETS-VII) which is a real space robotic system. Surface-tracking and peg-in-hole tasks with modeling errors have been executed in this experiment. The results show that our space robot teleoperation system including the haptic interface has been able to execute these tasks in real space environment without any big problems.