This paper describes a structural analysis of rehabilitation robots intended for upper-limb post-stroke therapy. First, the functions of the robots required for restoration of motor function are explained and the according conditions that should be satisfied by the robots are introduced. Second, the analytical methods to judge if the conditions are satisfied for a given robot structure are proposed, and they are explained by using a planer robot. Then, the methods are applied to the structure of the proposed escort type rehabilitation robot for spatial motions and their validity is investigated.
In this paper, a compact high-speed range image sensor that can acquire a range image mapped with a color texture is constructed. The sensor consists of only commercially available products: a monochrome CCD camera, a color CCD camera, a laser projector, and two optical filters. The laser projector projects 19×19 multi-spot lights. Using the laser projector and the monochrome CCD camera with the optical filters, range images with 19×19, totally 361 points are measured. As fast as 100[Hz] measurement of a range image mapped with a color texture is achieved. Additionally, a three-dimensional (3D) mapping method using the constructed sensor is introduced. The performance of the constructed sensor and the 3D mapping method are evaluated by experiments. It is shown that the constructed sensing system can acquire 100[Hz] real-time textured range images and that it can be applied to 3D mapping by using range and color information.
This paper proposes a novel control method for stable grasping and attitude regulation of an object using a multi-fingered hand-arm system. This method is based on a task space sensory-feedback control using real time information of an object attitude. A unified control signal is designed for a whole hand-arm system. Firstly, nonholonomic rolling constraints between a multi-fingered hand-arm system and a grasped object are formulated. Secondly, a novel control signal to accomplish stable grasping and attitude regulation of the grasped object is proposed. To design the control signal, it is assumed that sensory information of the attitude of the grasped object is available in real time through some external sensors, such as vision, force, tactile sensors, and so on. Next, stability of the overall closed-loop dynamics and convergence of the object attitude to a desired attitude are given based on the passivity theory. Finally, several numerical simulations are conducted, and it is demonstrated that an arbitrary polyhedral object can be grasped, and its attitude converges to the desired one stably using proposed method.
A 3D measurement system of a tunnel shape is being developed. This system is composed of a mobile robot equipped with a 2D laser scanner and a three-axis fiber optic gyro, integrated software, and a total station placed in the tunnel. Measured data by the robot is transformed to the tunnel's coordinates system using the position information measured by the total station and the optic gyro. The integrated software is able to load the design data of 3D CAD system via LandXML format, and compare with the measured data. The error of the measured data is displayed in the software interface on-site. This paper describes the basic system architecture and the results of the measuring experiments in a simulated tunnel.
The purpose of this study is to develop novel training system for medical skills using robot technology. We have developed Waseda Kyotokagaku Airway No.4 (WKA-4) as a novel training simulator for airway management. This robot reproduces several different patients with actuators. For instance, this robot has a unique mechanism in its temporomandibular joint that consists of a set of warm gears and force sensors, hence reproduces a patient with TMJ disorder. This robot also has the tongue that is able to change its shape using air pressure, hence reproduces the difficulty of airway management. We then asked the medical doctors to evaluate the robot using a questionnaire and confirmed that WKA-4 had enough property to use in the training of anesthesiologists.
This paper proposes a novel high-backdrivable parallel-link manipulator with Continuously Variable Transmission (CVT) mechanism using several shaft actuators. The backdrivability is quite important and necessary for robots working around our living space to ensure the safety of us and environment. As for such robots, using a rotational actuator with a high reduction ratio reducer which has been commonly used is not adequate to realize the high backdrivability from the viewpoint of mechanical configuration. In this study, several high-backdrivable linear shaft actuators are utilized instead of it. Furthermore, the CVT mechanism which is provided by a novel configuration of the parallel mechanism is employed effectively. Using multiple linear shaft actuators and the CVT mechanism is able to surmount a drawback of the linear shaft actuator whose output force is relatively small compared with that of commonly used geared motors. As the first step of the study, a simple 1 DOF manipulator is proposed, and its kinematic and dynamic models are given. Next, a PD type feedback control signal to regulate both the arm's angle and its force/velocity ratio simultaneously is designed. A statical relation between the end-point output force of the manipulator and the CVT mechanism is illustrated. Finally, several fundamental experiments are performed using a prototype to demonstrate the effectiveness of proposed mechanism.
This paper investigates passive dynamic walking and its efficiency of a combined rimless wheel (CRW) that consists of two identical 8-legged rimless wheels. First, we introduce a mathematical model of the CRW and develop the system equations. We then numerically show that stable passive-dynamic gaits can be generated regardless of the phase difference between the fore and rear legs. Second, we show that the walking speed is maximized when the phase difference is nearly equal to the half inter-leg angle through numerical analysis, and experimentally verify the validity using our prototype CRW machine. Furthermore, we discuss the inherent speeding-up mechanism from the potential barrier point of view.