Microgripper-Embedded Fluid Fingertip-Enhancing Positioning and Holding Abilities for Versatile Grasping

2017 ◽  
Vol 9 (6) ◽  
Author(s):  
Toshihiro Nishimura ◽  
Yoshinori Fujihira ◽  
Tetsuyou Watanabe
Keyword(s):  
Position Control ◽  
Layer Structure ◽  
Outer Part ◽  
Robotic Hand ◽  
Mechanical Constraints ◽  
Grasping Forces ◽  
Geometrical Constraints ◽  
Grasping Force ◽  
Object Shapes ◽  
Contact Position

This paper presents a novel fingertip system with a two-layer structure for robotic hands. The outer part of the structure consists of a rubber bag filled with fluid, called the “fluid fingertip,” while the inner part consists of a rigid link mechanism called a “microgripper.” The fingertip thus is a rigid/fluid hybrid system. The fluid fingertip is effective for grasping delicate objects, that is, it can decrease the impulsive force upon contact, and absorb uncertainties in object shapes and contact force. However, it can only apply a small grasping force such that holding a heavy object with a robotic hand with fluid fingertips is difficult. Additionally, contact uncertainties including inaccuracies in the contact position control cannot be avoided. In contrast, rigid fingertips can apply considerable grasping forces and thus grasp heavy objects effectively, although this makes delicate grasping difficult. To maintain the benefits of the fluid fingertip while overcoming its disadvantages, the present study examines passively operable microgripper-embedded fluid fingertips. Our goal is to use the gripper to enhance the positioning accuracy and increase the grasping force by adding geometrical constraints to the existing mechanical constraints. Grasping tests showed that the gripper with the developed fingertips can grasp a wide variety of objects, both fragile and heavy.

A Novel Theory on Grasping Force Control in a Multifingered Robotic Hand

1992 ◽  
Author(s):  
Xiaochun Gao ◽  
Shin-Min Song
Keyword(s):  
Force Control ◽  
Control Method ◽  
Robotic Hand ◽  
Promising Alternative ◽  
Grasping Forces ◽  
Novel Theory ◽  
Small Joint ◽  
Grasping Force ◽  
Compliance Model ◽  
Joint Motions

Abstract Based on inspiration of human grasping activities, a new idea is developed in this paper that grasping forces in a multifingered robotic hand can be regulated and controlled through its compliance by actively coordinating small joint motions in its fingers. According to this idea, a grasping force control model is formulated by means of a compliance model developed by the authors before, and a novel theory is then developed for grasping force control in a multifingered robot hand. The developed theory is expected to lead to a new force control method which could serve as a promising alternative for the active stiffness method. As an application of the developed theory, a two-fingered planar robotic hand is also analyzed, and the simulation results verify the developed theory.

Controlling force variations during soft-tissue grasping

2009 ◽  
Vol 223 (6) ◽  
pp. 749-753 ◽  
Author(s):  
T Alja'afreh
Keyword(s):  
Soft Tissue ◽  
Basis Set ◽  
Grasping Forces ◽  
Grasp Stability ◽  
Grasping Force ◽  
Frictional Forces ◽  
Major Criterion ◽  
Model Independent ◽  
Limited Basis ◽  
Tissue Relaxation

This paper develops a mechatronic grasper that can be used to investigate a preliminary experiment of a simple model-independent approach to control soft-tissue grasping based on, first, measurement of the total tangential grasp force and, second, discrimination of relaxation and frictional forces by imposing a limited basis set of grasper motions. The main motivation for this work is that tissue grasping is an important component of surgical procedures. However, there is a major criterion which should be achieved: maintaining grasp stability while avoiding damage due to excessive grip force. Thus, the automation of grasping force control requires a controller to apply grasping forces just sufficient to maintain grasp stability. This task is complicated by the serially connected dynamics of grasp friction and tissue relaxation.

Two-Dimensional Team Lifting Prediction With Different Box Weights

2020 ◽  
Author(s):  
Asif Arefeen ◽  
Yujiang Xiang
Keyword(s):  
Joint Angle ◽  
Inverse Dynamics ◽  
Reaction Force ◽  
Optimization Method ◽  
Two Dimensional ◽  
Dynamics Modeling ◽  
Floating Base ◽  
Grasping Forces ◽  
Design Variables ◽  
Grasping Force

Abstract A novel multibody dynamics modeling method is proposed for two-dimensional (2D) team lifting prediction. The box itself is modeled as a floating-base rigid body in Denavit-Hartenberg representation. The interactions between humans and box are modeled as a set of grasping forces which are treated as unknowns (design variables) in the optimization formulation. An inverse-dynamics-based optimization method is used to simulate the team lifting motion where the dynamic effort of two humans is minimized subjected to physical and task-based constraints. The design variables are control points of cubic B-splines of joint angle profiles of two humans and the box, and the grasping forces between humans and the box. Two numerical examples are successfully simulated with different box weights (20 Kg and 30 Kg, respectively). The humans’ joint angle, torque, ground reaction force, and grasping force profiles are reported. The joint angle profiles are validated with the experimental data.

scholarly journals An investigation of various actuation mechanisms in robot arm

2019 ◽  
Vol 52 (9-10) ◽  
pp. 1299-1307 ◽  
Author(s):  
J Prakash ◽  
M Ilangkumaran
Keyword(s):  
Analytical Approach ◽  
Robot Arm ◽  
Force Analysis ◽  
Linkage Mechanism ◽  
Actuation Mechanism ◽  
Research Activities ◽  
Grasping Force ◽  
Object Shapes ◽  
End Effectors ◽  
Four Bar Linkage

Many research activities have been carried out to develop a simple mechanism for grasping irregular object shapes using two- or three-fingered robot end effectors. The idea behind this work is to develop three-fingered intelligent grippers that are capable of sensing different factors like weight, effort required, compactness, robustness, and stability of the object held during the manipulations. In this paper, five different actuation mechanisms, namely, edge-cam-operated actuation mechanism, toggle-linkage-based actuation mechanism, wedge-cam-operated gripper, sliding slotted pin–ball joint arrangement, and rack-and-pinion-operated four-bar linkage mechanism, are introduced. The actuation and grasping force of the gripper are to be determined using the analytical approach (static force analysis). Finally, the effective intelligent gripper mechanism is identified based on grasping force for grasping 1 kg weight of a prespecified object.

Hybrid Force-Position Humanoid Hand Control in 3D Virtual Environment

2015 ◽  
Vol 762 ◽  
pp. 91-97 ◽  
Author(s):  
Danut A. Bucur ◽  
Luige Vladareanu ◽  
Hong Nian Yu ◽  
Xian Chao Zhao ◽  
Stefan Dumitru
Keyword(s):  
Virtual Environment ◽  
3D Modeling ◽  
Position Control ◽  
Control Method ◽  
Robotic Hand ◽  
Simulation Environment ◽  
Software Packages ◽  
Hand Control ◽  
3D Virtual Environment ◽  
Humanoid Hand

This paper presents the workflow to create a robotic humanoid hand simulation environment using two top software packages and also the implementation of an intelligent hybrid force - position control method using neural networks for force closing operation of a humanoid robotic hand modeled in the 3D virtual environment. The benefits that the 3D modeling provides are described and then the results of the proposed method are presented. This approach allows studying the motion of the robotic system under different circumstances without any greater costs.

scholarly journals Kineto-Elasto-Static Design of Underactuated Chopstick-Type Gripper Mechanism for Meal-Assistance Robot

Robotics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 50
Author(s):  
Tomohiro Oka ◽  
Jorge Solis ◽  
Ann-Louise Lindborg ◽  
Daisuke Matsuura ◽  
Yusuke Sugahara ◽  
...  
Keyword(s):  
Contact Force ◽  
Position Control ◽  
Vision System ◽  
Three Dimensional ◽  
Target Object ◽  
Grasp Planning ◽  
Torsion Spring ◽  
3D Printed ◽  
Gripping Force ◽  
Contact Position

Our research aims at developing a meal-assistance robot with vision system and multi-gripper that enables frail elderly to live more independently. This paper presents a development of a chopstick-type gripper for a meal-assistance robot, which is capable of adapting its shape and contact force with the target food according to the size and the stiffness. By solely using position control of the driving motor, the above feature is enabled without relying on force sensors. The gripper was designed based on the concept of planar 2-DOF under-actuated mechanism composed of a pair of four-bar chains having a torsion spring at one of the passive joints. To clarify the gripping motion and relationship among the contact force, food’s size and stiffness, and gripping position, kineto-elasto-static analysis of the mechanism was carried out. It was found from the result of the analysis that the mechanism was able to change its gripping force according to the contact position with the target object, and this mechanical characteristic was utilized in its grasp planning in which the position for the gripping the object was determined to realize a simple control system, and sensitivity of the contact force due to the error of the stiffness value was revealed. Using a three-dimensional (3D) printed prototype, an experiment to measure the gripping force by changing the contact position was conducted to validate the mechanism feature that can change its gripping force according to the size and the stiffness and the contact force from the analysis results. Finally, the gripper prototype was implemented to a 6-DOF robotic arm and an experiment to grasp real food was carried out to demonstrate the feasibility of the proposed grasp planning.

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