Haruhisa Kawasaki

Dexterous anthropomorphic robot hand with distributed tactile sensor: Gifu hand II

This paper presents an anthropomorphic robot hand, called the Gifu hand II, which has a thumb and four fingers, all the joints of which are driven by servomotors built into the fingers and the palm. The thumb has four joints with four-degrees-of-freedom (DOF), the other fingers have four joints with 3-DOF, and two axes of the joints near the palm cross orthogonally at one point, as is the case in the human hand. The Gifu hand II can be equipped with six-axes force sensor at each fingertip, and a developed distributed tactile sensor with 624 detecting points on its surface. The design concepts and specifications of the Gifu hand II, the basic characteristics of the tactile sensor, and the pressure distributions at the time of object grasping are described and discussed herein. Our results demonstrate that the Gifu hand II has a high potential to perform dexterous object manipulations like the human hand.

Development of a Hand Motion Assist Robot for Rehabilitation Therapy by Patient Self-Motion Control

This paper presents a new hand motion assist robot for rehabilitation therapy. The robot is an exoskeleton with 18 DOFs and a self-motion control, which allows the impaired hand of a patient to be driven by his or her healthy hand on the opposite side. To provide such potential that the impaired hand is able to recover its ability to the level of a functional hand, the hand motion assist robot is designed to support the flexion/extension and abduction/adduction motions of fingers and thumb independently as well as the opposability of the thumb. Moreover, it is designed to support a combination motion of the hand and the wrist. The design specifications and experimental results are shown.

Five-Fingered Haptic Interface Robot: HIRO III

This paper presents the design and characteristics of a five-fingered haptic interface robot: HIRO III. The aim of the paper is to provide a high-precision force representation at the five human fingertips. HIRO III consists of a 15-degree-of-freedom (DOF) haptic hand, a 6 DOF interface arm and a control system. The haptic interface, which consists of a robot arm and hand, can be used in a large workspace and can provide multipoint contact between the user and a virtual environment. However, the following problems peculiar to a multi-DOF robot have resulted: a backlash, a large amount of friction, many motors, and many sensors. In order to solve these problems, a new mechanism and a wire-saving control system have been designed and developed. Furthermore, experiments in both free space and constraint space have been carried out. In comparison with the previous HIRO, the force errors in free space and in constraint space have been reduced to 30% and 57%, respectively. These results show a high-precision force representation and the great potential of HIRO III.

Educational-industrial complex development of an anthropomorphic robot hand 'Gifu hand'

It is expected that forthcoming humanoid robots will execute various complicated tasks via communication with a human user. The humanoid robots will be equipped with anthropomorphic multi-fingered hands very like the human hand. We call this a humanoid hand robot. Humanoid hand robots will eventually supplant human labor in the execution of intricate and dangerous tasks in areas such as manufacturing, space, the seabed, etc. Our group, which consists of six members from small manufacturing companies in the Gifu prefecture, Japan and one member from Gifu University, has been developing the Gifu hand, a five-fingered hand driven by built-in servomotors as an educational-industrial complex development since 1996. We aimed to develop the robot hand which is used as the standard platform of the study on dexterous grasping and manipulation of objects.

Design and Control of Five-Fingered Haptic Interface Opposite to Human Hand

This paper presents the design and control of a newly developed five-fingered haptic interface robot named HIRO II. The developed haptic interface can present force and tactile feeling to the five fingertips of the human hand. Its mechanism consists of a 6 degree of freedom (DOF) arm and a 15 DOF hand. The interface is placed opposite the human hand, which ensures safety and freedom of movement, but this arrangement leads to difficulty in designing and controlling the haptic interface, which should accurately track the fingertip positions of the operator. A design concept and optimum haptic finger layout, which maximizes the design performance index is presented. The design performance index consists of the product space between the operators finger and the hapic finger, and the opposability of the thumb and fingers. Moreover, in order to reduce the feeling of uneasiness in the operator, a mixed control method consisting of a finger-force control and an arm position control intended to maximize the control performance index, which consists of the hand manipulability measure and the norm of the arm-joint angle vector is proposed. The experimental results demonstrate the high potential of the multifingered haptic interface robot HIRO II+ utilizing the mixed control method.

A design of fine motion assist equipment for disabled hand in robotic rehabilitation system

This paper reports a newly designed system intended to aid in hand rehabilitation. The motion assistance equipment consists of three parts: mechanisms for the fingers and thumb, a base of these mechanisms, and a motion assistance mechanism for the wrist. The structure of each mechanism is designed to achieve independent, fine motion assistance, especially, for the individual fingers. First, the features of each mechanism in the equipment are explained. Next, the control systems are introduced, which are constructed to realize a self-motion control strategy (i.e., the motion is controlled by its user). Using this control system, the transient response and steady state characteristics of the motion assistance mechanisms for the thumb are evaluated. Consequently, the possibility of practical application is found in regard to some improved points.

Developments of new anthropomorphic robot hand and its master slave system

This paper presents a newly developed anthropomorphic robot hand called KH Hand type S, which has high potential of dexterous manipulation and displaying hand shape, and its master slave system using the bilateral controller for five-fingers robot hand. The robot hand is improved by reducing the weight, the backlash of transmission, and the friction between gears by using elastic body. Expression of Japanese finger alphabet is shown. In order to demonstrate the dexterous grasping and manipulating an object, the experiment of peg-in-hole task controlled by bilateral controller is shown. These results denote that the KH Hand type S has a high potential to perform dexterous object manipulation like the human hand.

Simple Boundary Cooperative Control of Two One-Link Flexible Arms for Grasping

This paper considers a grasping task by means of two one-link flexible arms. To accomplish this task, we propose a simple boundary cooperative control based on a dynamic model, which consists of partial differential equations (PDEs) and ordinary differential equations (ODEs) subject to geometric constraints. Since the data which is needed for the implementation of the controller can be obtained by a strain gauge and a rotary encoder, it is easy to implement it. The asymptotic stability of a closed-loop system and the exponential stability of the system under some conditions are studied.

Novel climbing method of pruning robot

A novel climbing method of pruning robots is presented. The climbing method is similar to climbing approach of timberjacks in Japan. Main features include the optimal position of center of mass of the pruning robot that is located outside of tree and the innovative vertical climbing approach. Four active wheels are set at regular intervals around the tree, which one pair for upper side and the other for lower side. Each active wheel is driven by a DC servomotor through a worm gear that has no back drivability. This novel design brings both lightweight and high climbing speed features of the pruning robot. A basic theory of mechanism design for avoiding falling down from a tree and experimental results of climbing up for validating the theorem are presented.

Decentralized adaptive coordinated control of multiple robot arms without using a force sensor

This paper presents a distributed adaptive coordinated control method for multiple robot arms grasping a common object. The cases of rigid contact and rolling contact are analyzed. In the proposed controller, the dynamic parameters of both object and robot arms are estimated adaptively. The desired motions of the robot arms are generated by an estimated object reference model. The control method requires only the measurements of the positions and velocities of the object and robot arms, but not the measurements of forces and moments at contact points. The asymptotic convergence of trajectory is proven by the Lyapunov-like Lemma. Experiments involving two robot arms handling a common object are shown.