08-05-2013, 02:04 PM
Proceedings of the 2001 IEEE –RAS International Conference on Humanoid Robots
Proceedings of the 2001 IEEE.docx (Size: 23.3 KB / Downloads: 22)
Abstract
An “ideal” artificial hand should match the requirements of prosthetics and humanoid robotics. It can be wearable by the user which means that it can be perceived as part of the natural body and should replicate sensory-motor capabilities of the natural hand. However, such an ideal bionic prosthesis is still far from reality. This paper describes the design and fabrication of a novel artificial hand based on a “biomechatronic” and cybernetic approach. Our approach is aimed at providing “natural” sensory-motor co-ordination, by integrating biomimetic mechanisms, force and position sensors, actuators and control, and by interfacing the hand with the peripheral nervous system.
INTRODUCTION
The objective of the work described in this paper is to develop an artificial hand which can be used for functional substitution of the natural hand (prosthetics) and for humanoid robotics applications. The artificial hand is designed for replicating sensory-motor capabilities of human hand.
The work described in this paper is started from the analysis of state of the art artificial hands designed either for prosthetics or for robotics applications. Commercially available prosthetic devices, such as Otto Bock SensorHand™, as well as multifunctional hand designs [1,2,3,4,5,6,7] are far from providing the grasping capabilities of the human hand [8]. In prosthetic hands active bending is restricted to two or three joints, which are actuated by a single motor drive acting simultaneously on the metacarpo-phalangeal (MP) joints of the thumb, of the index and of the middle finger, while other joints can bend only passively. This limitation in dexterity is mainly due to the very basic requirement of limited size and weight necessary for prosthetic applications. On the other hand robotics hands have achieved high level performance in grasping and manipulation, but they make use of large controllers which are not applicable in prosthetics or humanoid robotics where it is necessary to provide the user with a wearable artificial hand.
In this paper we propose a novel design methodology, for design, development and fabrication of artificial hands, aimed at balancing the two opposite requirements of high dexterity and of natural size, weight and appearance. This process can be indicated with the word biomechatronic design, which indicates concurrent mechatronic design with a biomimetic approach, aimed at replicating as much as possible working principles and behavior of living systems. Starting from the considerations outlined above, we can summarize the basic specifications of the wearable artificial hand described in this paper: 1. natural grasping capability; 2. natural appearance (in prosthetics this is called cosmetic appearance); 3. secure grasping and sensory feedback; 4. ”natural” command interface.
DESIGN OF THE BIOMECHATRONIC HAND
Biomechatronic design The main requirements to be considered since the very beginning of a artificial hand design are the following: natural appearance, controllability, noiselessness, lightness and low energy consumption. These requirements can be fulfilled by implementing an integrated design approach
aimed at embedding different functions (mechanisms, actuation, sensing and control) within a housing closely replicating the shape, size and appearance of the human hand. This approach can be synthesized by the term: “biomechatronic” design [9].
CONCLUSIONS
A novel approach to the design and fabrication of innovative prosthetic hands, called biomechatronic design, has been presented. It is based on integrating together multiple degrees of freedom, multi-sensing capabilities, and distributed control in order to obtain “elegant” human-like appearance, simple and direct controllability, low weight, low energy consumption and noiselessness. Following this type of approach a first hand prototype with six DOFs has been designed and fabricated. In this paper we focused our attention on the design and development of a first implementation of an innovative hand, and in particular on the biomechatronic approach and on the integration of the position and force sensors.