• International Journal of Control, Automation, and Systems
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• 제4권2호
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• pp.217-226
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• 2006

Grasping and manipulation by hands can be considered as one of inevitable functions to achieve the performances desired in humanoid operations. When a humanoid robot manipulates an object by his hands, each finger should be well-controlled to accomplish a precise manipulation of the object grasped. So, the trajectory of each joint required for a precise finger motion is fundamentally necessary to be planned stably. In this sense, this paper proposes an effective joint motion planning method for humanoid fingers. The proposed method newly employs a bio-mimetic concept for joint motion planning. A suitable model that describes an interphalangeal coordination in a human finger is suggested and incorporated into the proposed joint motion planning method. The feature of the proposed method is illustrated by simulation results. As a result, the proposed method is useful for a facilitative finger motion. It can be applied to improve the control performance of humanoid fingers or prosthetic fingers.

• 로봇학회논문지
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• 제11권4호
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• pp.193-204
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• 2016

This paper presents an anthropomorphic finger prosthesis for amputees whose proximal phalanx is mutilated. The finger prosthesis to be proposed is able to make the amputees to perform the natural motion such as flexion/extension as well as self-adaptive grasping motion as if normal human finger does. The mechanism of finger prosthesis with three degrees-of-freedom (DOFs) consists of two five-bar and one four-bar linkages. Two passive components composed of torsional spring and mechanical stopper and only one active joint are employed in order to realize an underactuation. Each passive component is installed into the five-bar linkage. In order to activate the finger prosthesis, it is required for the user to flex and extend the remaining proximal phalanx on the metacarpophalangeal (MCP) joint, not an electric motor. Thus the finger prosthesis conducts not only the natural motion according to his/her intention but also the grasping motion through the deformation of springs by the object for human finger-like behavior. In order to reveal the operation principle of the proposed mechanism, kinematic analysis is performed for the linkage design. Finally both simulations and experiments are conducted in order to reveal the design feasibility of the proposed finger mechanism.

• 대한기계학회논문집A
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• 제29권2호
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• pp.176-187
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• 2005

This paper presents an evaluation of joint configurations of a robotic finger based on kinematic analysis. The evaluation is based on an assumption that the current control methods for the fingers require that the contact state specified by the motion planner be maintained during manipulation. Various finger-joint configurations have been evaluated for different contact motions. In the kinematic analysis, the surface of the manipulated object was represented by B-spline surface and the surface of the finger was represented by cylinders and a half ellipsoid. Three types of contact motion, namely, 1) pure rolling, 2) twist-roiling, and 3) slide-twist-rolling are assumed in this analysis. The finger-joint configuration best suited for manipulative motion is determined by the dimension of manipulation workspace. The evaluation has shown that the human-like fingers are suitable for maintaining twist-rolling and slide-twist-rolling but not for pure rolling. A finger with roll joint at its fingertip link, which is different from human fingers, proved to be better for pure rolling motion because it can accommodate sideway motions of the object. Several kinds of useful finger-joint configurations suited for manipulating objects by fingertip surface are proposed.

• Journal of Biosystems Engineering
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• 제22권4호
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• pp.411-420
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• 1997

The mechanization efficiency using high ability machines such as tractors or combines in a paddy field rice farm is high. Mechanization in harvesting fruits and vegetables is difficult, because they are easy to be damaged. Therefore, Advanced techniques for careful handling fruits and vegetables are necessary in automation and robotization. An apple harvesting robot must have a recognition device to detect the positioning of fruit, manipulators which function like human arms, and hand to take off the fruit. This study is related to the development of a rotatic hand as the first stage in developing the apple harvesting robot. The results are summarized as follows. 1. It was found that a hand that was eccentric in rotatory motion, was better than a hand of semicircular up-and-down motion in harvesting efficiency. 2. The hand was developed to control changes in grasp forces by using tape-type switch sensor which was attatched to fingers' inside. 3. Initial finger positioning was set up to control accurate harvesting by using a tow step fingering position. 4. This study showed the possibility of apple harvesting using the developed robot hand.