scholarly journals A Novel Single-Loop Mechanism and the Associated Cylindrical Deployable Mechanisms

Symmetry ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1255
Author(s):  
Long Huang ◽  
Bei Liu ◽  
Lairong Yin ◽  
Jinhang Wang
Keyword(s):  
Parameter Optimization ◽  
Screw Theory ◽  
Motion Pattern ◽  
Geometrical Analysis ◽  
Interference Condition ◽  
Single Loop ◽  
Linear Pattern ◽  
Circular Pattern ◽  
New Type

This paper presents a new type of 2-DOF single-loop mechanism inspired by the Sarrus mechanism, and it utilizes this mechanism to construct 2-DOF cylindrical deployable mechanisms. First, the motion pattern of the single-loop mechanism is analyzed utilizing screw theory. According to the structural symmetries, the cylindrical deployable mechanisms are constructed through the linear pattern combination and circular pattern combination of the single-loop mechanisms. After the geometrical analysis and interference condition analysis, the axial, circumferential and area magnification ratios are defined and, furthermore, applied to the parameter optimization of the deployable mechanisms, forming an example surface. Finally, a simplified 1-DOF single-loop mechanism is derived from the proposed 2-DOF mechanism, which is used to construct 1-DOF cylindrical deployable mechanisms with singular free workspaces.

Type synthesis of 2R2T parallel mechanisms based on motion equivalent chain method

2014 ◽  
Vol 228 (17) ◽  
pp. 3209-3217 ◽  
Author(s):  
Wei Ye ◽  
Yuefa Fang ◽  
Sheng Guo ◽  
Haibo Qu
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Parallel Mechanisms ◽  
Motion Pattern ◽  
Type Synthesis ◽  
Constraint Force ◽  
Single Loop ◽  
Loop Chain ◽  
Serial Chains

In this paper, the motion equivalent chain method is proposed and then applied to the type synthesis of a class of 2R2T parallel mechanism. The equivalent serial chains are synthesized for a specific 2R2T motion pattern based on screw theory. Feasible limb structures that provide a constraint couple and a constraint force are enumerated according to the reciprocity of the twist and wrench systems. Several motion equivalent single loop chains are constructed with the equivalent serial chains. Using motion equivalent single loop chains to replace the equivalent serial chains, a class of 2R2T parallel mechanisms is obtained based on the foundation of motion equivalent single loop chain structures.

scholarly journals Kinematics analysis of a new parallel robotics

2020 ◽  
Vol 17 (2) ◽  
pp. 172988142091995
Author(s):  
Shi Baoyu ◽  
Wu Hongtao
Keyword(s):  
Degrees Of Freedom ◽  
Screw Theory ◽  
Parallel Robot ◽  
Virtual Prototype ◽  
Motion Platform ◽  
Closed Form Solutions ◽  
New Type ◽  
Virtual Prototype Technology ◽  
Parallel Robotics ◽  
D Model

A new type of parallel robot ROBO_003 is presented. Its mechanisms, kinematics, and virtual prototype technology are introduced. The research of degrees of freedom (DOF) is based on screw theory, a set of screw is separated as a branch, which named as constrain screw. The type of three DOF gained by counting constrain screw, the moving platform’s frame, and base platform’s frame is set, respectively, a complete kinematic research including closed-form solutions for direct kinematic problem. The 3-D model of ROBO_003 is established using SOLIDWORKS; position and orientation of motion platform can be gained using ADMAS, which is a type of virtual prototype technology. The resultant shows that the structure of ROBO_003 is reasonable, three DOF of motion platform can be operated in a reasonable range, the solutions to the direct kinematics are right, and robot ROBO_003 can be used in many industrial fields. The research of this article provides a basis for the practical application of parallel robotics ROBO_003.

scholarly journals Constraint and Singularity Analysis of the Exechon

2012 ◽  
Vol 162 ◽  
pp. 141-150 ◽  
Author(s):  
Semaan Amine ◽  
Stéphane Caro ◽  
Philippe Wenger
Keyword(s):  
Projective Space ◽  
Screw Theory ◽  
Singularity Analysis ◽  
Motion Pattern ◽  
Geometric Conditions ◽  
Moving Platform

This paper deals with the constraint and the singularity analysis of the Exechon. Using the screw theory, the constraint and actuation wrenches acting on the moving platform are analyzed. The motion pattern of the Exechon is characterized based on a representation of the constraint wrenches in the projective space. A wrench graph representing the constraint and actuation wrench systems in the projective space is obtained. Based on this wrench graph, a superbracket of the Exechon is formulated. Finally, this superbracket is explored to provide the geometric conditions for the parallel singularities of the Exechon.

scholarly journals A Character Frequency based Approach to Search for Substrings of a Circular Pattern and its Conjugates in an Online Text

2021 ◽  
Vol 22 (2) ◽  
Author(s):  
Vinod Prasad
Keyword(s):  
Computational Biology ◽  
Data Structures ◽  
Fundamental Problem ◽  
Text Processing ◽  
Suffix Trees ◽  
Linear Pattern ◽  
Circular Pattern ◽  
String Processing ◽  
Novel Method ◽  
Processing Algorithms

A fundamental problem in computational biology is to deal with circular patterns. The problem consists of finding the least certain length substrings of a pattern and its rotations in the database. In this paper, a novel method is presented to deal with circular patterns. The problem is solved using two incremental steps. First, an algorithm is provided that reports all substrings of a given linear pattern in an online text. Next, without losing efficiency, the algorithm is extended to process all circular rotations of the pattern. For a given pattern P of size M, and a text T of size N, the algorithm reports all locations in the text where a substring of Pc is found, where Pc is one of the rotations of P. For an alphabet size σ, using O(M) space, desired goals are achieved in an average O(MN/σ) time, which is O(N) for all patterns of length M ≤ σ. Traditional string processing algorithms make use of advanced data structures such as suffix trees and automaton. We show that basic data structures such as arrays can be used in the text processing algorithms without compromising the efficiency.

Optimum Design and Trafficability Analysis for an Articulated Wheel-legged Forestry Chassis

2021 ◽  
pp. 1-17
Author(s):  
Zhibo Sun ◽  
Dan Zhang ◽  
Zhilong Li ◽  
Shi Yan ◽  
Na Wang
Keyword(s):  
Parameter Optimization ◽  
Kinematic Analysis ◽  
Screw Theory ◽  
Kinematic Model ◽  
Surface Profile ◽  
Error Rates ◽  
Wheel Slip ◽  
Working Environments ◽  
Rigid Model ◽  
Four Bar Linkage

Abstract High trafficability and stability are the most two significant features of the forestry chassis. In this study, in order to improve surface trafficability, a novel articulated wheel-legged forestry chassis(AWLFC) is presented. To balance the trafficability and stability, a serial suspension system which is a combination with the active four-bar linkage articulated suspension (AFLAS) and passive V shape rocker-bogie is proposed. Then, parameter optimization with a comprehensive object function is implemented not only to enhance the trafficability and stability benefit of the structure but also to reduce the wheel slip. After that, through the flexible kinematic model based on screw theory, characteristics such as leveling ability and surface profile accessibility of the chassis are analyzed. The minimum accessible radius is obtained as 3088mm, and the longitudinal and lateral leveling angle reaches to 22° and 28.7° separately. The new chassis performs better on leveling ability and surface profile accessibility than the forestry chassis in the current literature. Finally, compared with the simulation and prototype experiment, error rates of the flexible kinematic analysis are reduced by 12.2% and 8.6% related to the rigid model. Previously inaccessible forestry working environments can be available with the development of AWLFC.

Dynamics Analysis and Parameter Optimization of New Vibration Platform

2014 ◽  
Vol 1061-1062 ◽  
pp. 771-775
Author(s):  
Yan Bin Liu ◽  
Chen Xu Yin ◽  
Jia Jia Ma
Keyword(s):  
Frequency Response ◽  
Parameter Optimization ◽  
Prototype Model ◽  
Flexible Body ◽  
Dynamics Analysis ◽  
Frequency Model ◽  
Body Model ◽  
New Type ◽  
Simulation Results ◽  
The Stability

A new type of vibration platform was presented and its dynamic characteristics was studied in this paper, A virtual prototype model of vibration platform was built by using software Soldworks and ADAMS.The flexible body model of spring was built based on ADAMS flexible module,rigid-flexible coupled dynamic of vibration platform were analyzed by using simulation, the natural frequency, model of vibration and frequency response were further analyzed. The stiffness of spring and flexible cable were optimized according to the analysis results, The post-optimality simulation results show that the stability and frequency response of vibration platform have improved.

Shaft Drive CVT: A New Type CVT Applying Crossed Axle Traction Drive

2003 ◽  
Author(s):  
Masashi Yamanaka ◽  
Katsumi Inoue ◽  
Genso Igari ◽  
Yukihito Narita
Keyword(s):  
Power Transmission ◽  
Contact Point ◽  
Design Procedure ◽  
Transmission Efficiency ◽  
Input Output ◽  
Geometrical Analysis ◽  
Traction Drive ◽  
Input Shaft ◽  
New Type ◽  
Input Torque

The crossed axle traction drive developed by the authors is applied to a new mechanism of CVT, the Shaft Drive CVT. The input and output shafts with conical disks are parallel and a idler shaft having conical rollers at both ends is placed perpendicular to the input/output shafts. This idler shaft transmits a torque from the input shaft to the output shaft and its movement produces the speed variation by changing the contact point between the input/output disks and the idler rollers. The purposes of this study are 1) to propose the new CVT mechanism, 2) to design a curved shape of disk to decrease an amount of spin caused by the movement of contact point, 3) to develop a prototype to confirm the CVT to work and to evaluate the effect of curved disk by means of a power transmission efficiency. The design procedure of shapes of disk and roller are shown by geometrical analysis. The amount of spin is reduced 80% using the proposed concave disk. The range of speed changing ratio of the prototype is 0.5 to 2. The efficiency of 80% was obtained in case of input torque 10 Nm at uniform rate by using the conical disks. The effectiveness of concave disk is evaluated by comparing the experimental results using the conical and concave disks, respectively.

Design and Analysis of a New Type Forging Manipulator

2017 ◽  
Author(s):  
Yanwen Li ◽  
Xiaofei Shi ◽  
Pengfei Mao ◽  
Yubo Cai ◽  
Maoling Wang
Keyword(s):  
Parallel Mechanism ◽  
Large Scale ◽  
Screw Theory ◽  
Synthesis Method ◽  
Degree Of Freedom ◽  
Lateral Movement ◽  
Kinematic Position ◽  
New Type ◽  
Forging Manipulator ◽  
Increasing Demand

Large-scale forging manipulator is the indispensable equipment in the operations of automated forging. Because of the increasing demand of forging manipulator, large and medium-sized enterprises pay more and more attention to the forging operation in production. Lower freedom parallel mechanism is obtained by using the constraint-synthesis method based on the screw theory, then a mechanism of forging manipulator is designed including raising and lowering, pitching, lateral swing, lateral movement, forth or back and clamp rotation. The new type forging manipulator is a hybrid serial-parallel mechanism. The degree of freedom of the parallel mechanism is calculated by using the modified Grübler-Kutzbach criterion, and then the degree of freedom of the machine is determined. Through closed geometric method, the kinematic position analysis is performed, and the correctness of the theoretical analysis results is verified.

Multi-Objective Technologic Parameter Optimization of Face Milling Based on GRA-PSO Algorithm

2013 ◽  
Vol 364 ◽  
pp. 504-508 ◽  
Author(s):  
Dong Hong Tang ◽  
Yue Han
Keyword(s):  
Parameter Optimization ◽  
Preferential Flow ◽  
Pso Algorithm ◽  
Steering System ◽  
Face Milling ◽  
Corner Detection ◽  
Steering Angle ◽  
Wheel Loader ◽  
Steer By Wire ◽  
New Type

The development and characteristics of Steer-By-Wire is introduced and the design of Steer-By-Wire in articulated wheel loader is fully discussed in this paper. The whole system takes advantage of proportional decompression valve to control the motion of preferential flow amplifier valve, and further to achieve steering by controlling steering cylinder. Whats more, this paper has also elaborated on a design of new-type steering angle detection devices of vehicle frame, which aims at more accurate corner detection and is also a breakthrough in steering system of wheel loader.

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