scholarly journals Design, Fabrication, and Testing of a Novel 3D 3-Fingered Electrothermal Microgripper with Multiple Degrees of Freedom

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 444
Author(s):  
Guoning Si ◽  
Liangying Sun ◽  
Zhuo Zhang ◽  
Xuping Zhang
Keyword(s):  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Polyimide Film ◽  
Zebrafish Embryos ◽  
Multiple Degrees Of Freedom ◽  
Electrothermal Actuator ◽  
3D Space ◽  
Pick And Place

This paper presents the design, fabrication, and testing of a novel three-dimensional (3D) three-fingered electrothermal microgripper with multiple degrees of freedom (multi DOFs). Each finger of the microgripper is composed of a V-shaped electrothermal actuator providing one DOF, and a 3D U-shaped electrothermal actuator offering two DOFs in the plane perpendicular to the movement of the V-shaped actuator. As a result, each finger possesses 3D mobilities with three DOFs. Each beam of the actuators is heated externally with the polyimide film. The durability of the polyimide film is tested under different voltages. The static and dynamic properties of the finger are also tested. Experiments show that not only can the microgripper pick and place microobjects, such as micro balls and even highly deformable zebrafish embryos, but can also rotate them in 3D space.

Time-varying mesh stiffness calculation for gear pairs with misalignment errors in multiple degrees of freedom based on an analytical method

2021 ◽  
pp. 095440622110392
Author(s):  
Qi Wen ◽  
Qi Chen ◽  
Qungui Du ◽  
Yong Yang
Keyword(s):  
Analytical Model ◽  
Contact Line ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Single Pair ◽  
Time Varying ◽  
Mesh Stiffness ◽  
Position Change ◽  
Multiple Degrees Of Freedom ◽  
Effective Contact

Misalignment errors (MEs) in multiple degrees of freedom (multi-DOFs) at the mesh position will lead to a change in the time-varying mesh stiffness (TVMS) and then affect the dynamic behaviour of gear pairs. Therefore, a new, more rapid, three-dimensional analytical model for TVMS calculation for gear pairs with three rotational and three translational MEs is established in this paper, and a new solution method based on potential energy theory is presented. In addition, the correctness of the new model is verified by the finite element method (FEM). Moreover, the effective contact line, uneven distribution of mesh force on the contact line, and mesh position change are taken into account. Finally, the TVMS under different ME conditions is calculated with the new analytical model. The results showed that the different MEs have dissimilar effects on the TVMS, and the relationship between the ME and TVMS is nonlinear. In addition, the region of single-pair and double-pair teeth in contact would also change with ME.

Prediction of Blade Flutter in a Tuned Rotor

1985 ◽  
Author(s):  
Jianmin Xu ◽  
Zhaohong Song
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Rotating Blades ◽  
Multiple Degrees Of Freedom ◽  
Strip Theory ◽  
Blade Flutter ◽  
Good Agreement

This paper is about blade flutter in a tuned rotor. With the aid of the combination of three dimensional structural finite element method, two dimensional aerodynamical finite difference method and strip theory, the quasi-steady models in which two degrees of freedom for a single wing were considered have been extended to multiple degrees of freedom for the whole blade in a tuned rotor. The eigenvalues solved from the blade motion equation have been used to judge whether the system is stable or not. The calculating procedure has been formed and using it the first stage rotating blades of a compressor where flutter had occurred, have been predicted. The numerical flutter boundaries have good agreement with the experimental ones.

scholarly journals From cineradiography to biorobots: an approach for designing robots to emulate and study animal locomotion

2016 ◽  
Vol 13 (119) ◽  
pp. 20151089 ◽  
Author(s):  
K. Karakasiliotis ◽  
R. Thandiackal ◽  
K. Melo ◽  
T. Horvat ◽  
N. K. Mahabadi ◽  
...  
Keyword(s):  
Design Process ◽  
Motor Skills ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Dynamic Properties ◽  
Three Dimensional ◽  
Dynamic Scaling ◽  
Descending Pathways ◽  
Animal Locomotion ◽  
Lateral Displacements

Robots are increasingly used as scientific tools to investigate animal locomotion. However, designing a robot that properly emulates the kinematic and dynamic properties of an animal is difficult because of the complexity of musculoskeletal systems and the limitations of current robotics technology. Here, we propose a design process that combines high-speed cineradiography, optimization, dynamic scaling, three-dimensional printing, high-end servomotors and a tailored dry-suit to construct Pleurobot: a salamander-like robot that closely mimics its biological counterpart, Pleurodeles waltl . Our previous robots helped us test and confirm hypotheses on the interaction between the locomotor neuronal networks of the limbs and the spine to generate basic swimming and walking gaits. With Pleurobot, we demonstrate a design process that will enable studies of richer motor skills in salamanders. In particular, we are interested in how these richer motor skills can be obtained by extending our spinal cord models with the addition of more descending pathways and more detailed limb central pattern generator networks. Pleurobot is a dynamically scaled amphibious salamander robot with a large number of actuated degrees of freedom (DOFs: 27 in total). Because of our design process, the robot can capture most of the animal's DOFs and range of motion, especially at the limbs. We demonstrate the robot's abilities by imposing raw kinematic data, extracted from X-ray videos, to the robot's joints for basic locomotor behaviours in water and on land. The robot closely matches the behaviour of the animal in terms of relative forward speeds and lateral displacements. Ground reaction forces during walking also resemble those of the animal. Based on our results, we anticipate that future studies on richer motor skills in salamanders will highly benefit from Pleurobot's design.

Flow-induced patterns in directional solidification: localized morphologies in three-dimensional flows

2000 ◽  
Vol 421 ◽  
pp. 369-380 ◽  
Author(s):  
Y.-J. CHEN ◽  
S. H. DAVIS
Keyword(s):  
Directional Solidification ◽  
Degrees Of Freedom ◽  
Eigenvalue Problems ◽  
Three Dimensional ◽  
Localized States ◽  
Marginal Stability ◽  
Multiple Degrees Of Freedom ◽  
Flow Stagnation ◽  
Moving Front ◽  
Morphological Patterns

We consider the effect of steady, three-dimensional cellular convective fields impressed upon the moving front of a dilute binary alloy in directional solidification. The flows have length scales longer than the characteristic lengths of the morphological instability. A Floquet problem with multiple degrees of freedom in space governs the interfacial dynamics and determines the morphological patterns and marginal stability boundaries. In the cases of weak flows the induced patterns are superpositions of rolls modulated by the forced flows. When the flows are strong, the instability becomes spatially localized and confined at inward flow-stagnation regions on the front. Numerical computations and the WKB method are used to solve the eigenvalue problems, showing various localized states depending on the structures of the imposed flows.

scholarly journals A pathway to desired functionalities in vertically aligned nanocomposites and related architectures

MRS Bulletin ◽  
2021 ◽  
Author(s):  
Aiping Chen ◽  
Quanxi Jia
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Interface Microstructure ◽  
Two Dimensional ◽  
Superconducting Properties ◽  
Multiple Degrees Of Freedom ◽  
Challenges And Opportunities ◽  
Vertically Aligned

AbstractEpitaxial vertically aligned nanocomposites (VANs) and their related architectures have shown many intriguing features that are not available from conventional two-dimensional planar multilayers and heterostructures. The ability to control constituent, interface, microstructure, strain, and defects based on VANs has enabled the multiple degrees of freedom to manipulate the optical, magnetic, electrochemical, electronic, ionic, and superconducting properties for specific applications. This field has rapidly expanded from the interest in oxide:oxide to oxide:metal, metal:nitride and nitride:nitride systems. To achieve unparalleled properties of the materials, three-dimensional super-nanocomposites based on a hybrid of VAN and multilayer architectures have been recently explored as well. The challenges and opportunities of VAN films are also discussed in this article.

scholarly journals Three-Dimensional Imaging With Multiple Degrees of Freedom Using Data Fusion

2015 ◽  
Vol 103 (9) ◽  
pp. 1654-1671 ◽  
Author(s):  
Pedro Latorre-Carmona ◽  
Filiberto Pla ◽  
Adrian Stern ◽  
Inkyu Moon ◽  
Bahram Javidi
Keyword(s):  
Data Fusion ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Three Dimensional Imaging ◽  
Multiple Degrees Of Freedom ◽  
Using Data

Denavit-Hartenberg Parameterization of Euler Angles

2012 ◽  
Vol 7 (2) ◽  
Author(s):  
S. V. Shah ◽  
S. K. Saha ◽  
J. K. Dutt
Keyword(s):  
Multibody Systems ◽  
Degrees Of Freedom ◽  
Systematic Approach ◽  
Three Dimensional ◽  
Euler Angle ◽  
Euler Angles ◽  
Spherical Joint ◽  
Multiple Degrees Of Freedom ◽  
Cartesian Space ◽  
Revolute Joints

Euler angles describe rotations of a rigid body in three-dimensional Cartesian space, as can be obtained by, say, a spherical joint. The rotation carried out by a spherical joint can also be expressed by using three intersecting revolute joints that can be described using the popular Denavit-Hartenberg (DH) parameters. However, the motions of these revolute joints do not necessarily correspond to any set of the Euler angles. This paper attempts to correlate the Euler angles and DH parameters by introducing a concept of DH parameterization of Euler angels. A systematic approach is presented in order to obtain the DH parameters for any Euler angles set. This gives rise to the concept of Euler-angle-joints (EAJs), which provide rotations equivalent to a particular set of Euler angles. Such EAJs can be conveniently used for the modeling of multibody systems having multiple-degrees-of-freedom joints.

scholarly journals A three-dimensional actuated origami-inspired transformable metamaterial with multiple degrees of freedom

2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Johannes T.B. Overvelde ◽  
Twan A. de Jong ◽  
Yanina Shevchenko ◽  
Sergio A. Becerra ◽  
George M. Whitesides ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Multiple Degrees Of Freedom

scholarly journals Computational Motor Control: Redundancy and Invariance

2007 ◽  
Vol 97 (1) ◽  
pp. 331-347 ◽  
Author(s):  
Emmanuel Guigon ◽  
Pierre Baraduc ◽  
Michel Desmurget
Keyword(s):  
Nervous System ◽  
Motor Control ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Optimal Feedback Control ◽  
Kinematic Chains ◽  
3D Space ◽  
Antagonist Muscles ◽  
Characteristic Features ◽  
System 1

The nervous system controls the behavior of complex kinematically redundant biomechanical systems. How it computes appropriate commands to generate movements is unknown. Here we propose a model based on the assumption that the nervous system: 1) processes static (e.g., gravitational) and dynamic (e.g., inertial) forces separately; 2) calculates appropriate dynamic controls to master the dynamic forces and progress toward the goal according to principles of optimal feedback control; 3) uses the size of the dynamic commands (effort) as an optimality criterion; and 4) can specify movement duration from a given level of effort. The model was used to control kinematic chains with 2, 4, and 7 degrees of freedom [planar shoulder/elbow, three-dimensional (3D) shoulder/elbow, 3D shoulder/elbow/wrist] actuated by pairs of antagonist muscles. The muscles were modeled as second-order nonlinear filters and received the dynamics commands as inputs. Simulations showed that the model can quantitatively reproduce characteristic features of pointing and grasping movements in 3D space, i.e., trajectory, velocity profile, and final posture. Furthermore, it accounted for amplitude/duration scaling and kinematic invariance for distance and load. These results suggest that motor control could be explained in terms of a limited set of computational principles.

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