Configuration synthesis and structural design of lower-mobility parallel external fixators based on corrective degree-of-freedom classification

2022 ◽  
Vol 168 ◽  
pp. 104593
Author(s):  
Shiping Zuo ◽  
Mingjie Dong ◽  
Chunjing Tao ◽  
Ran Jiao ◽  
Guotong Li ◽  
...  
Keyword(s):  
Structural Design ◽  
Degree Of Freedom ◽  
External Fixators ◽  
Lower Mobility ◽  
Configuration Synthesis

Topological Structural Design of Umbrella-Shaped Deployable Mechanisms Based on New Spatial Closed-Loop Linkage Units

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Wen-ao Cao ◽  
Donghao Yang ◽  
Huafeng Ding
Keyword(s):  
Structural Design ◽  
Closed Loop ◽  
Space Exploration ◽  
Degree Of Freedom ◽  
Structural Symmetry ◽  
Potential Applications ◽  
Good Potential

The umbrella linkage is one of the most classical deployable mechanisms. This paper concentrates on topological structural design of a family of umbrella-shaped deployable mechanisms based on new two-layer and two-loop spatial linkage units. First, deployable units are developed systematically from two-layer and two-loop linkage with four revolute pair (4R) coupling chains. Then, mobile connection modes of the deployable units are established based on the conditions of one degree-of-freedom (DOF) and structural symmetry. Finally, umbrella-shaped deployable mechanisms are constructed based on the developed deployable units and the established mobile connection modes. Like umbrellas, the designed deployable mechanisms can be actuated in a simple and reliable way, and those mechanisms have good potential applications in the fields of architecture, manufacturing, space exploration, and recreation.

Forward/Reverse Velocity and Acceleration Analysis for a Class of Lower-Mobility Parallel Mechanisms

2006 ◽  
Vol 129 (4) ◽  
pp. 390-396 ◽  
Author(s):  
Si J. Zhu ◽  
Zhen Huang ◽  
Hua F. Ding
Keyword(s):  
Kinematic Analysis ◽  
Jacobian Matrix ◽  
Hessian Matrix ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Analysis Method ◽  
Rear Part ◽  
Lower Mobility ◽  
Acceleration Analysis

This paper proposes a novel kinematic analysis method for a class of lower-mobility mechanisms whose degree-of-freedom (DoF) equal the number of single-DoF kinematic pairs in each kinematic limb if all multi-DoF kinematic pairs are substituted by the single one. For such an N-DoF (N<6) mechanism, this method can build a square (N×N) Jacobian matrix and cubic (N×N×N) Hessian matrix. The formulas in this method for different parallel mechanisms have unified forms and consequently the method is convenient for programming. The more complicated the mechanism is (for instance, the mechanism has more kinematic limbs or pairs), the more effective the method is. In the rear part of the paper, mechanisms 5-DoF 3-R(CRR) and 5-DoF 3-(RRR)(RR) are analyzed as examples.

scholarly journals Configuration synthesis of electric-drive transmissions for tracked vehicles

2018 ◽  
Vol 10 (1) ◽  
pp. 168781401774966
Author(s):  
Ming-Fei Gao ◽  
Ji-Bin Hu ◽  
Zeng-Xiong Peng
Keyword(s):  
Graph Theory ◽  
Electric Drive ◽  
Synthesis Method ◽  
Theory Model ◽  
Degree Of Freedom ◽  
Transmission Mechanism ◽  
Necessary Condition ◽  
Tracked Vehicles ◽  
Configuration Synthesis ◽  
Complex Transmission

This article focus on the configuration synthesis of electric-drive transmissions for tracked vehicles. First, a new graph theory model is proposed to represent the transmission mechanism, which makes the complex transmission system easier to understand. Second, a configuration synthesis method is proposed based on kinematics and statics, in which the speed degree of freedom and torque degree of freedom are considered as the constraints of configuration synthesis. Also, the expressions for speed degree of freedom and torque degree of freedom are derived. Third, based on the graph theory model, the necessary condition to achieve skid steering in the transmission of tracked vehicles is obtained. The results of this article can provides a theoretical basis for the design and analysis of transmission mechanism of tracked vehicles.

scholarly journals Effect of Mechanical Loading and Increased Gap on the Dynamic Response of Multiple Degree of Freedom Electrostatic Actuator

Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 18
Author(s):  
Hussam Kloub
Keyword(s):  
Dynamic Response ◽  
Mechanical Loading ◽  
Structural Design ◽  
Switching Time ◽  
Mechanical Load ◽  
Electrostatic Force ◽  
Degree Of Freedom ◽  
Electrostatic Actuator ◽  
State Response ◽  
Collision Force

A novel monolithic structural design of an electrostatic actuator with a multiple degree of freedom is presented as an approach for a system that is capable of performing scalable stroke and large electrostatic force beyond mN range. An electromechanical system model based on Simulink software was developed for a proposed design of the electrostatic actuator. The dynamic response of the actuator was simulated and the mechanical bouncing response due to effect of realizing extra mechanical stoppers or passivation layer was investigated. Additionally, the mechanical bouncing as well as steady state response of the actuator was investigated under various mechanical loading values. The results showed that the switching time increased as the mechanical load was increased. In addition, bouncing maximum peak increased as the collision force was increased.

A Family of Novel Lower-Mobility Decoupled Parallel Mechanisms

2007 ◽  
Author(s):  
Daxing Zeng ◽  
Sijun Zhu ◽  
Zhen Huang
Keyword(s):  
Real Time ◽  
Basic Feature ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Real Time Control ◽  
Motion Feature ◽  
Time Control ◽  
Fixed Base ◽  
Lower Mobility ◽  
Moving Platform

This paper presents a family of novel lower-mobility decoupled parallel mechanisms (DPMs), which consists of one 5-DOF (degree of freedom) DPM, two 4-DOF DPMs, three 3-DOF DPMs, and three 2-DOF DPMs. The basic feature of this family is that the moving platform and the fixed base of the DPMs are connected by two limbs and the motion of the moving platform is fully decoupled. Then the constraint screw method is used to analyze the motion feature of all DPMs presented in this paper. The mobility of these DPMs has also been calculated by the Modified Grubler-Kutzbach criterion. All the DPMs in this paper are simple and no computation is required for real-time control.

Design and Development of a Novel 2-Degree-of-Freedom Parallel Robot

Robotica ◽  
2019 ◽  
Vol 38 (1) ◽  
pp. 1-14
Author(s):  
Changxi Cheng ◽  
Wenkai Huang ◽  
Chunliang Zhang
Keyword(s):  
Structural Design ◽  
Medical Science ◽  
Parallel Robot ◽  
Parallel Robots ◽  
Degree Of Freedom ◽  
Static Stiffness ◽  
Reachable Workspace ◽  
Workspace Analysis ◽  
Potential Applications ◽  
Speed Performance

SummaryParallel robots are widely used in the fields of manufacturing, medical science, education, scientific research, etc. Many studies have been conducted on the topic already. However, shortcomings still exist, especially in certain situations. To meet the demand of good speed and load performances at the same time, this work presents a novel 2-degree-of-freedom parallel robot. The structural design, static, stiffness, and reachable workspace analysis of the robot are given in the manuscript. Experiment regarding the accuracy and speed performance is conducted, and the results are provided. In the end, potential applications of the proposed robot are suggested.

scholarly journals A New Metamorphic Parallel Leg Mechanism with Reconfigurable Moving Platform

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yong Xu ◽  
Zheng Liang ◽  
Jiali Liu
Keyword(s):  
Parallel Mechanism ◽  
Degrees Of Freedom ◽  
Closed Loop ◽  
Screw Theory ◽  
Degree Of Freedom ◽  
Walking Robots ◽  
Metamorphic Mechanism ◽  
Parallel Leg Mechanism ◽  
Moving Platform ◽  
Configuration Synthesis

This paper proposes the concept of full configuration state of metamorphic mechanism. Based on the concept, the configuration synthesis principle of metamorphic parallel mechanism is put forward. Firstly, a metamorphic parallel mechanism in full configuration state is synthesized, and then full configuration state evolves into a specific configuration state by increasing constraints or decreasing degrees of freedom. A reconfigurable moving platform based on the triple symmetric Bricard spatial closed-loop mechanism with a single degree of freedom is proposed. Based on this, a new method for switching motion configuration states of the metamorphic parallel mechanism is constructed. According to the configuration synthesis principle presented above, a novel metamorphic parallel mechanism that can switch between three- and four-degree-of-freedom is synthesized, and then the triple symmetric Bricard spatial closed-loop mechanism is used as the reconfigurable moving platform (that is, the reconfigurable foot of a walking robot) of the metamorphic mechanism, and thus, a novel metamorphic parallel leg mechanism is created. The screw theory is used to verify the degrees of freedom of the new type of metamorphic parallel leg. The proposed metamorphic parallel leg mechanism is expected to improve flexibility and adaptability of walking robots in unstructured environment.

On the Estimate of the Two Dominant Axes of the Knee Using an Instrumented Spatial Linkage

2012 ◽  
Vol 28 (2) ◽  
pp. 200-209 ◽  
Author(s):  
Gianluca Gatti
Keyword(s):  
Rotation Axis ◽  
Knee Kinematics ◽  
Simulated Data ◽  
Knee Dislocation ◽  
Degree Of Freedom ◽  
External Fixators ◽  
Human Knee ◽  
Mechanical Joint ◽  
Flexion Extension ◽  
Extension Axis

This article presents the validation of a technique to assess the appropriateness of a 2 degree-of-freedom model for the human knee, and, in which case, the dominant axes of flexion/extension and internal/external longitudinal rotation are estimated. The technique relies on the use of an instrumented spatial linkage for the accurate detection of passive knee kinematics, and it is based on the assumption that points on the longitudinal rotation axis describe nearly circular and planar trajectories, whereas the flexion/extension axis is perpendicular to those trajectories through their centers of rotation. By manually enforcing a tibia rotation while bending the knee in flexion, a standard optimization algorithm is used to estimate the approximate axis of longitudinal rotation, and the axis of flexion is estimated consequently. The proposed technique is validated through simulated data and experimentally applied on a 2 degree-of-freedom mechanical joint. A procedure is proposed to verify the fixed axes assumption for the knee model. The suggested methodology could be possibly valuable in understanding knee kinematics, and in particular for the design and implant of customized hinged external fixators, which have shown to be effective in knee dislocation treatment and rehabilitation.

Configuration Synthesis of Micro/Nano-Positioning Stage Based on Graph Theory

2011 ◽  
Vol 323 ◽  
pp. 3-7
Author(s):  
Chao Lin ◽  
Xin Hui Cui ◽  
Kai Cheng ◽  
Song Song Yu
Keyword(s):  
Graph Theory ◽  
Structural Design ◽  
Spanning Tree ◽  
Design Method ◽  
Structural Characteristics ◽  
Tree Graph ◽  
Positioning Stage ◽  
Bridge Type ◽  
Configuration Synthesis

The purpose of this paper was to generate several possible configurations of micro/nano-positioning stage with bridge-type mechanism based on graph theory. The structural characteristics of stage were discussed first. Then, these modules made up of micro/nano-positioning stage were abstracted. Thus the stage could be described with a tree-graph. According to the spanning tree theory, several possible configurations of stage are enumerated correspondingly. Subsequently, the configuration synthesis of six bridge-type mechanisms was investigated and 720 results were obtained. Rules for generating structures with symmetry are established. On the basis of this, several innovative structures are presented. Furthermore, the result of this paper provides a practicable approach for the structural design of stage and the design method based on graph theory is effective.

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