Recently, soft grippers have garnered considerable interest in various fields, such as medical rehabilitation, due to their high compliance. However, the traditional PneuNet only reliably grasps medium and largeobjects...Recently, soft grippers have garnered considerable interest in various fields, such as medical rehabilitation, due to their high compliance. However, the traditional PneuNet only reliably grasps medium and largeobjects via enveloping grasping (EG), and cannot realize pinching grasping (PG) to stably grasp small and thinobjects as EG requires a large bending angle whereas PG requires a much smaller one. Therefore, we proposeda multi-structure soft gripper (MSSG) with only one vent per finger which combines the PneuNet in the proximal segment with the normal soft pneumatic actuator (NSPA) in the distal segment, allowing PG to be realizedwithout a loss in EG and enhancing the robustness of PG due to the height difference between the distal andproximal segments. Grasping was characterized on the basis of the stability (finger bending angle describes) androbustness (pull-out force describes), and the bending angle and pull-out force of MSSG were analyzed using thefinite element method. Furthermore, the grasping performance was validated using experiments, and the resultsdemonstrated that the MSSG with one vent per finger was able to realize PG without a loss in EG and effectivelyenhance the PG robustness.展开更多
The aim of this paper is to study the static problem about a general elastic multi-structure composed of an arbitrary number of elastic bodies, plates and rods. The mathematical model is derived by the variational pri...The aim of this paper is to study the static problem about a general elastic multi-structure composed of an arbitrary number of elastic bodies, plates and rods. The mathematical model is derived by the variational principle and the principle of virtual work in a vector way. The unique solvability of the resulting problem is proved by the Lax-Milgram lemma after the presentation of a generalized Korn's inequality on general elastic multi-structures. The equilibrium equations are obtained rigorously by only assuming some reasonable regularity of the solution. An important identity is also given which is essential in the finite element analysis for the problem.展开更多
A finite element method is introduced to solve the general elastic multi-structure problem, in which the displacements on bodies, the longitudinal displacements on plates and the longitudinal displacements on beams ar...A finite element method is introduced to solve the general elastic multi-structure problem, in which the displacements on bodies, the longitudinal displacements on plates and the longitudinal displacements on beams are discretized using conforming linear elements, the rotational angles on beams are discretized using conforming elements of second order, the transverse displacements on plates and beams are discretized by the Morley elements and the Hermite elements of third order, respectively. The generalized Korn's inequality is established on related nonconforming element spaces, which implies the unique solvability of the finite element method. Finally, the optimal error estimate in the energy norm is derived for the method.展开更多
Based on the creative and groundbreaking work done by Feng and Shi, some further work has been carried out comprehensively by the first author on the formulation of elastic multi-structures. The main contribution of t...Based on the creative and groundbreaking work done by Feng and Shi, some further work has been carried out comprehensively by the first author on the formulation of elastic multi-structures. The main contribution of this paper can be summarized as follows: The work of Feng and Shi has been extended to an elastic multi-structures with nonlinear structural element: shell in both linear and nonlinear case. Three general combinations of multi-structures have been formulated, that is, Case 1: linear elements of 3-D body, 1-D bar/beam, 2-D plates and 2-D shell; Case 2: nonlinear elements of 3-D body, 1-D bar/beam, 2-D plates and 2-D shell; and Case 3: the linear-nonlinear mix problem of 3-D body (nonlinear), 1-D bar/beam (linear), 2-D plates (linear) and 2-D shell (linear). From the investigation, it has proved that the higher dimensional element will have a strong influence on the lower one with the inner linkage boundaries, and also proved that solution uniqueness of elastic multi-structures is different from a single 3-D body.展开更多
基金the National Key Research and Development Program of China(No.2020YFB1313100)。
文摘Recently, soft grippers have garnered considerable interest in various fields, such as medical rehabilitation, due to their high compliance. However, the traditional PneuNet only reliably grasps medium and largeobjects via enveloping grasping (EG), and cannot realize pinching grasping (PG) to stably grasp small and thinobjects as EG requires a large bending angle whereas PG requires a much smaller one. Therefore, we proposeda multi-structure soft gripper (MSSG) with only one vent per finger which combines the PneuNet in the proximal segment with the normal soft pneumatic actuator (NSPA) in the distal segment, allowing PG to be realizedwithout a loss in EG and enhancing the robustness of PG due to the height difference between the distal andproximal segments. Grasping was characterized on the basis of the stability (finger bending angle describes) androbustness (pull-out force describes), and the bending angle and pull-out force of MSSG were analyzed using thefinite element method. Furthermore, the grasping performance was validated using experiments, and the resultsdemonstrated that the MSSG with one vent per finger was able to realize PG without a loss in EG and effectivelyenhance the PG robustness.
基金This work was partly supported by the 973 projectthe National Natural Science Foundation of China(Grant No.10371076)+1 种基金E-Institutes of Shanghai Municipal Education Commission(Grant No.E03004)The Science Foundation of Shanghai(Grant No.04JC14062).
文摘The aim of this paper is to study the static problem about a general elastic multi-structure composed of an arbitrary number of elastic bodies, plates and rods. The mathematical model is derived by the variational principle and the principle of virtual work in a vector way. The unique solvability of the resulting problem is proved by the Lax-Milgram lemma after the presentation of a generalized Korn's inequality on general elastic multi-structures. The equilibrium equations are obtained rigorously by only assuming some reasonable regularity of the solution. An important identity is also given which is essential in the finite element analysis for the problem.
基金supported by the National Natural Science Foundation(Grant No.10371076)E-Institutes of Shanghai Municipal Education Commission(Grant No.E03004)The Science Foundation of Shanghai(Grant No.04JC14062).
文摘A finite element method is introduced to solve the general elastic multi-structure problem, in which the displacements on bodies, the longitudinal displacements on plates and the longitudinal displacements on beams are discretized using conforming linear elements, the rotational angles on beams are discretized using conforming elements of second order, the transverse displacements on plates and beams are discretized by the Morley elements and the Hermite elements of third order, respectively. The generalized Korn's inequality is established on related nonconforming element spaces, which implies the unique solvability of the finite element method. Finally, the optimal error estimate in the energy norm is derived for the method.
文摘Based on the creative and groundbreaking work done by Feng and Shi, some further work has been carried out comprehensively by the first author on the formulation of elastic multi-structures. The main contribution of this paper can be summarized as follows: The work of Feng and Shi has been extended to an elastic multi-structures with nonlinear structural element: shell in both linear and nonlinear case. Three general combinations of multi-structures have been formulated, that is, Case 1: linear elements of 3-D body, 1-D bar/beam, 2-D plates and 2-D shell; Case 2: nonlinear elements of 3-D body, 1-D bar/beam, 2-D plates and 2-D shell; and Case 3: the linear-nonlinear mix problem of 3-D body (nonlinear), 1-D bar/beam (linear), 2-D plates (linear) and 2-D shell (linear). From the investigation, it has proved that the higher dimensional element will have a strong influence on the lower one with the inner linkage boundaries, and also proved that solution uniqueness of elastic multi-structures is different from a single 3-D body.
