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This paper presents the design and fabrication process of a soft-bodied gripper with integrated curvature sensors for shape control. The soft gripper contains three identical fingers based on the principle of fluid elastomer actuator. Each of the finger is made of silicon rubber, named Dragon Skin, and is connected to a robotic arm by a snap-lock mechanism. Grasping ability of the soft-bodied gripper...
In our research, we have developed a Gripper with Multi Joint Fingers (MJF) that achieves envelope grasping adapting to shape of objects. In this paper, we discuss grasping motion using two or three MJFs. The MJF has 4 serially connected joints controlled by only two actuators, one for driving all joints at the same time for envelope grasping, the other for controlling the stiffness of every joint...
The paper presents a model and an algorithm for recognizing and handling articulated objects using industrial robots. The model is based on the skeleton of the object and it is used for recognition and to associate multiple grasping positions for robot handling. The object skeleton is a shape descriptor which preserves the topology of the object, even if the shape is changing. The model can associate...
This paper describes a hanging work, which is one of the work related to cloth products. By using deformability and stretchability of clothes successfully, it is possible to efficiently proceed with a hanging work. We focus on cloth wrinkles and superimposed relation of objects, and propose a method to recognize the progress of hanging work on-line. In a detection processing of wrinkles, after using...
We report on a novel low-computation object grasping method that can classify complex objects into primitive shapes and then select the object grasping posture based on predefined grasping postures associated with the approximated primitive shapes. In this approach, the object is not precisely modeled, and the grasping posture is selected from a small number of candidates without massive search; thus,...
In this work, we propose a method to compute the stiffness of flexible joints and its realization in order to let the fingers track a certain predefined trajectory. We refer to tendon-driven, underactuated and passively compliant hands composed of deformable joints and rigid links. Specific stiffness and pre-form shapes can be assigned to the finger joints can be given s such that a single-cable actuation...
This paper addresses the problem of grasping unknown objects with a humanoid robot. Conventional approaches fail when the shape, dimension or pose of the objects are missing. We propose a novel approach in which the grasping problem is solved by modeling the object and the volume graspable by the hand with superquadric functions. The object model is computed in real-time using stereo vision. Pose...
Most objects are designed for certain functionalities. For example, a knife is designed for cutting, and a hammer for pounding. Indeed, functionalities are not related to the objects themselves but to certain object parts, e.g., the blade of a knife affords cutting. A part can have different shapes and can exist in different objects such as a scraper or a peeler, but it carries the same functional...
This paper demonstrates manipulation, workspace and dimensional synthesis process of a novel gripper named Dexclar (DEXterous reConfigurable moduLAR), which is capable to manipulate plurality of object. The aim to develop such gripper is to address some current industrial issues particularly the rising in-hand manipulation problem. Operations like twisting, flipping, altering orientation of an object,...
Reducing the grasp candidates for unknown object grasping while maintaining grasp stability is the goal of this paper. In this paper, we propose an efficient and straight forward unknown object grasping method by using concavities of the unknown objects to significantly reduce the grasp candidates. Shortest path concavity is first employed to work out the concavity value for every vertex of the unknown...
To realize the shape adaptability and stable grasping for fruit mechanical picking, a design scheme of end-effector with tendon-driving is proposed based on the underactuated principle. The statics analysis of finger and the design rules for improving grasp stability is researched, as well as the main structure parameters of the end-effector are determined. Analysis and calculation results show that...
We propose a formalism for the hierarchical representation of affordances. Starting with a perceived model of the environment consisting of geometric primitives like planes or cylinders, we define a hierarchical system for affordance extraction whose foundation are elementary power grasp affordances. Higher-level affordances, e.g. bimanual affordances, result from combining lower-level affordances...
Stably grasping objects for a specific task is a hot research topic in robotics due to multiple degrees of freedom of hand kinematics, incomplete visual sensing of objects, and various shapes of objects. This paper proposes an effective grasp planning method by integrating the crucial grasp cues (positions and orientations of thumb fingertips and the wrist) from human experience. This approach greatly...
In this paper we propose an approach to robot grasp prioritization based on a combined arm-and-hand metric. Most traditional approaches evaluate grasps based on hand-centric metrics such as force-closure, finger spread, contact surface area and similar measures. While these are certainly important factors to predict the robustness of a grasp, they do not carry information on the feasibility of the...
Some simulation results of the grasping of an under-actuated finger driven by un-extendible tendons are presented. The finger is one of the ones of a mechanical hand based on a self-adaptive mechanism that permits the use of un-extendible tendons. The simulations were carried on by means of a model made by WM 2D" multibody code and permitted to save time and number of prototypes in the prototyping...
Complex steel structures such as power transmission towers require regular inspection and maintenance during their lifetime. This work is currently completed by teams of human workers who climb the live structures. The exposure of these workers to the risks of climbing and completing work on towers provides motivation for developing a robotic substitute. There are many complex elements of climbing...
This study aims to develop a fingertip in order to improve the manipulation performance of posture interpolation control for a multifingered robot hand. Increasing the contact area between the fingertips and object is one solution for improving grasping and manipulation stability. A reasonable fingertip shape design and material selection can increase the contact area. In this paper, we compare an...
In our previous study we have developed the seven axes multi joint gripper (MJG) having a variable stiffness mechanism and have showed it achieves some dexterous grasping. The mechanism mainly consists of a serially connected differential gear system (DGS) controlled by only two actuators: one for driving all of the joints simultaneously and the other for adjusting stiffness of every joints all together...
Folding clothes is a current trend in robotics. Previously to folding clothes, they have to be unfolded. It is not realistic to perform model-based unfolding, as every garment has a different shape, size, color, texture, etc. In this paper we present a garment-agnostic algorithm to unfold clothes that works using 3D sensor information. The depth information provided by the sensor is converted into...
In this paper, we present a method to classify the category of clothing item. When visually recognizing clothing items based on their shapes, two types of shape variations make the recognition difficult: physical deformation and the variety of size and design. In order to lessen the effect of deformation, first, the item of interest is reshaped into one of a small number of limited shapes. To absorb...
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