We performed three-dimensional analysis of the conjoint changes of digit forces during prehension (prehension synergies) and tested applicability of the principle of superposition to three-dimensional tasks. Subjects performed 25 trials at statically holding a handle instrumented with six-component force/moment sensors under seven external torque conditions; -0.70, -0.47, -0.23, 0.00, 0.23, 0.4...

In humans, the caudal pole of the superior parietal lobule is involved in the control of both reaching and grasping movements, whereas in monkey it is reported to be involved only in the control of reaching. Using single-unit recordings from trained macaque monkeys, we investigated whether area V6A, a visuomotor area located in the caudal part of the posterior parietal cortex, is involved in bo...

It is important for robots to obtain appropriate grasp positions autonomously to make stable grasps. In this paper, we propose an algorithm for automatically generating an optimum planar grasp based on grasp stability. Every finger is replaced with a two-dimensional linear spring model. Grasp stability is evaluated by using the eigenvalues of the grasp stiffness matrix derived from the potentia...

Recently, a number of grasp detection methods have been proposed that can be used to localize robotic grasp configurations directly from sensor data without estimating object pose. The underlying idea is to treat grasp perception analogously to object detection in computer vision. These methods take as input a noisy and partially occluded RGBD image or point cloud and produce as output pose est...

Many of the tasks that are potential candidates for automation involve grasping. We are interested in the programming of robots to perform grasping tasks. To do this, we propose the notion of “perceptual programming,” where the key idea is to enable a system to observe a human performing a task, understand it, and perform the task with minimal human intervention. This allows the programmer to e...

The precise relationship of functional writing and pencil grasp has not been determined. Occupational therapists and educators have long recommended the mature dynamic tripod grasp. This grasp provides the most control of the pencil. Variations of this grasp (lateral tripod, dynamic quadrupod, adapted tripod) are common in children with legible handwriting. A grasp with an open web space betwee...

When manipulating parts, it is important to determine the orientation of the part with respect to thegripper. This orientation may not be known precisely or may be disturbed by the act of grasping. It isin some cases possible to use mechanical compliance to orient parts during grasping. It was recentlyshown [14] that any part with polygonal boundary can be oriented and grasped i...

With the goal of advancing the state of automatic robotic grasping, we present a novel approach that combines machine learning techniques and physical validation on a robotic platform to develop a comprehensive grasp predictor. After collecting a large grasp sample set (522 grasps), we first conduct a statistical analysis of the predictive ability of grasp quality metrics that are commonly used...

Path-relinking is a major enhancement to the basic greedy randomized adaptive search procedure (GRASP), leading to significant improvements in solution time and quality. Path-relinking adds a memory mechanism to GRASP by providing an intensification strategy that explores trajectories connecting GRASP solutions and the best elite solutions previously produced during the search. This paper revie...

We distinguish between two types of grasp stability, which we call spatial grasp stability and contact grasp stability. We show via examples that spatial stability cannot capture certain intuitive concepts of grasp stability and hence that any full understanding of grasp stability must include contact stability. We derive a model of how the positions of the points of contact evolve in time on t...