Ikuo Yamano

Five-fingered Robot Hand using Ultrasonic Motors and Elastic Elements

A five-fingered robot hand having almost an equal number of DOF to the human hand is developed. The robot hand is driven by a unique method using ultrasonic motors and elastic elements. The method makes use of restoring force as driving power in grasping objects, which enables the hand to perform stable and compliant grasping motion without power supply. In addition, all the components are placed inside the hand because the ultrasonic motors have characteristics of high torque at low speed and compact size. Applying the driving method to a multi-DOF mechanism, a five-fingered robot hand is designed. The robot hand has twenty joints and DOF. It is almost equal in size to the hand of an average grown-up man. The robot hand is produced, and control experiments are conducted. As a result, the potential of the robot hand is confirmed.

Multi-fingered exoskeleton haptic device using passive force feedback for dexterous teleoperation

A novel control methodology for master-slave systems using passive force feedback has been proposed by the authors. The methodology solves the conventional problems of previously developed master-slave systems with force feedback, such as oscillations, complex structures and complicated control algorithm. In the present paper a multi-fingered exoskeleton haptic device (master hand) with passive force feedback function is developed. First, the exoskeleton master hand with three fingers (12 degrees of freedom) is designed and implemented. Each finger of the master hand consists of a link mechanism with elastic-shaft joints and clutches. Using link mechanisms, the master hand measures fingertip positions and angles of index finger middle finger and thumb. Furthermore, it also enables passive force feedback to an operator by the same link mechanism used for the geometric measurements. Then, a virtual reality system of human hand is constructed using the master hand and the control methodology. Using the system, sensory evaluations are conducted on human subjects to confirm the usability of the developed master hand and the possibility of the control methodology in the virtual reality system. As a result, the subjects possibly recognize the stiffness of the objects in the virtual environment.

Development of a robot finger for five-fingered hand using ultrasonic motors

A robot finger is developed for five-fingered robot hand having equal number of DOF to human hand. The robot hand is driven by a new method proposed by authors using ultrasonic motors and elastic elements. The method utilizes restoring force of elastic element as driving power for grasping an object, so that the hand can perform the soft and stable grasping motion with no power supply. In addition, all the components are placed inside the hand thanks to the ultrasonic motors with compact size and high torque at low speed. Applying the driving method to multi-DOF mechanism, a robot index finger is designed and implemented. It has equal number of joints and DOF to human index finger, and it is also equal in size to the finger of average adult male. The performance of the robot finger is confirmed by fundamental driving test.

Method for controlling master-slave robots using switching and elastic elements

A new type of master-slave control methodology, which has the merits of both unilateral and bilateral ones, is proposed. The methodology is built on switching the unilateral feedback controls of position and force as required using switching and elastic elements. Proposed methodology not only eliminates the demerits of bilateral control, but also supplies the mechanical force feedback to the operator. It utilizes a feature of human factor that direct displacement feedback is not as important as visual and force feedback. Effectiveness of the proposed method is confirmed by experiments using a developed simple single axis master-slave arm system. Driving test of the experimental devices and sensory evaluations are conducted. As a result, it is confirmed that the methodology successfully provides the sense of touch to the operator of the system.