06-12-2012, 04:47 PM
biomechatronic -hand
[attachment=42823]
INTRODUCTION
The objective of the work describe in this paper is to develop an artificial hand aimed at replicating the appearance and performance of the natural hand the ultimate goal of this research is to obtain a complete functional substitution of the natural hand. This means that the artificial hand should be felt by the user as the part of his/her own body (extended physiological proprioception(EPP) ) and it should provide the user with the same functions of natural hand: tactile exploration, grasping , and manipulation (“cybernetic” prothesis). Commercially available prosthetic devices, as well as multifunctional hand designs have good (sometimes excellent) reliability and robustness, but their grasping capabilities can be improved. It has been demonstrated the methodologies and knowledge developed for robotic hands can be apologies and knowledge developed for robotic hands can be applied to the domain of prothestics to augment final performance. The first significant example of an artificial hand designed according to a robotic approach is the Belgrade/USC Hand. Afterwards, several robotic grippers and articulated hands have been developed, for example the Stanford/JPL hand and the Utah/MIT hand which have achived excellent results. An accurate description and a comparative analysis of state of the art of artificial hands can be found in . These hands have achived good performance in mimicking human capabilities, but they are complex devices requiring large controllers and their mass and size are not compatible with the strict requirements of prosthetic hands.
In fact, the artificial hands for prosthetics applications pose challenging specifications and problems, as is usually the case for devices to be used for functional replacement in clinical practice. These problems have forced the development of simple, robust, and reliable commercial prosthetic hands, as the Otto Brock SensorHand prothesis which is widely implanted and appreciated by users. The Otto Bock hand has only one degree of freedom(DOF), it can move the fingers at proportional speed from 15-130 mm/s and can generatea grip force up to 100 N.
DESIGN OF THE BIOMECHATRONIC HAND
Bio mechatronic Design
The main requirements to be considered since the very beginning of prosthetic hand design are the following: cosmetics, controllability, noiselessness, lightness, and low energy consumption. These requirements can be fulfilled by an integrated design approach aimed at embedding different functions within a housing closely replicating the shape, size and appearance of human hand.This approach can synthesized with the term: “biomechatronic” design.
B. Architecture of the Biomechatronic Hand
The design goal of the biomechatronic hand is to improve to some extent one of the most important limitations of current prosthetic hands (no dexterity and no adaptability),while preserving the main advantages of such hands, that is lightness and simplicity. This objective has been pursued by using small actuators(two of each finger) instead of one single large actuator( as in most current prosthetic hands) And by designing a kinematic architecture able to provide better adaptation to object shape during grasping. It turns out that the use of “micromotors” allows to augment functionality in grasping objects by means of “human-like” compliant movements of fingers. This result addresses the very basic requirements of “cosmetic” apperarance of the hand in static and dynamic conditions.
DESIGN OF HAND PROTOTYPE.
In order to demonstrate the feasibility of the described biomechatronic approach, we have developed a three fingered hand prototype with two identical fingers (index and middle) and thumb. Actuators, position sensors and a 2-D force sensor are integrated in the hand structure.
The index/middle finger has been designed by reproducing, as closely as possible, the size and kinematics of a human finger. Each finger consists of three phalanges and a palm needed to house the proximal actuator (see fig 5).
[attachment=42823]
INTRODUCTION
The objective of the work describe in this paper is to develop an artificial hand aimed at replicating the appearance and performance of the natural hand the ultimate goal of this research is to obtain a complete functional substitution of the natural hand. This means that the artificial hand should be felt by the user as the part of his/her own body (extended physiological proprioception(EPP) ) and it should provide the user with the same functions of natural hand: tactile exploration, grasping , and manipulation (“cybernetic” prothesis). Commercially available prosthetic devices, as well as multifunctional hand designs have good (sometimes excellent) reliability and robustness, but their grasping capabilities can be improved. It has been demonstrated the methodologies and knowledge developed for robotic hands can be apologies and knowledge developed for robotic hands can be applied to the domain of prothestics to augment final performance. The first significant example of an artificial hand designed according to a robotic approach is the Belgrade/USC Hand. Afterwards, several robotic grippers and articulated hands have been developed, for example the Stanford/JPL hand and the Utah/MIT hand which have achived excellent results. An accurate description and a comparative analysis of state of the art of artificial hands can be found in . These hands have achived good performance in mimicking human capabilities, but they are complex devices requiring large controllers and their mass and size are not compatible with the strict requirements of prosthetic hands.
In fact, the artificial hands for prosthetics applications pose challenging specifications and problems, as is usually the case for devices to be used for functional replacement in clinical practice. These problems have forced the development of simple, robust, and reliable commercial prosthetic hands, as the Otto Brock SensorHand prothesis which is widely implanted and appreciated by users. The Otto Bock hand has only one degree of freedom(DOF), it can move the fingers at proportional speed from 15-130 mm/s and can generatea grip force up to 100 N.
DESIGN OF THE BIOMECHATRONIC HAND
Bio mechatronic Design
The main requirements to be considered since the very beginning of prosthetic hand design are the following: cosmetics, controllability, noiselessness, lightness, and low energy consumption. These requirements can be fulfilled by an integrated design approach aimed at embedding different functions within a housing closely replicating the shape, size and appearance of human hand.This approach can synthesized with the term: “biomechatronic” design.
B. Architecture of the Biomechatronic Hand
The design goal of the biomechatronic hand is to improve to some extent one of the most important limitations of current prosthetic hands (no dexterity and no adaptability),while preserving the main advantages of such hands, that is lightness and simplicity. This objective has been pursued by using small actuators(two of each finger) instead of one single large actuator( as in most current prosthetic hands) And by designing a kinematic architecture able to provide better adaptation to object shape during grasping. It turns out that the use of “micromotors” allows to augment functionality in grasping objects by means of “human-like” compliant movements of fingers. This result addresses the very basic requirements of “cosmetic” apperarance of the hand in static and dynamic conditions.
DESIGN OF HAND PROTOTYPE.
In order to demonstrate the feasibility of the described biomechatronic approach, we have developed a three fingered hand prototype with two identical fingers (index and middle) and thumb. Actuators, position sensors and a 2-D force sensor are integrated in the hand structure.
The index/middle finger has been designed by reproducing, as closely as possible, the size and kinematics of a human finger. Each finger consists of three phalanges and a palm needed to house the proximal actuator (see fig 5).