Precision and Dimensional Analysis about Parallel Mechanism Having Less Degree of Freedom Based on Differential Geometry

2014 ◽  
Vol 940 ◽  
pp. 509-512 ◽  
Author(s):  
De Xing Zheng ◽  
Bin Wang
Keyword(s):  
Differential Geometry ◽  
Dimensional Analysis ◽  
Parallel Mechanism ◽  
Structural Parameters ◽  
Maximum Error ◽  
Error Model ◽  
Degree Of Freedom ◽  
Vector Model ◽  
Parallel Mechanisms ◽  
Output Error

A 3-PUU parallel mechanism was studied, which can perform one-dimensional translation about z-axis and two-dimensional rotations about y-axis and x-axis. This paper shows the study about the precision analysis, the dimensional analysis and the synthesis problem of the parallel mechanism having less degree of freedom. First, the closed-loop vector model was built based on analyzing the branched-chains of 3-PUU, the pose error model was built through the differential geometry, and the error model of positive solutions was obtained which contains all the structural parameters errors. For the error of structural parameters given, the pose output error can be solved out by application of this model, the area of maximum error is found out. And the influence of pose output error was analyzed with postures changed. The dimensional analysis of 3-PUU was also done by this error model, and the reasonable selection of mechanism parameters was discussed. And then the rationality of structure dimensional design was discussed in this paper. Finally, this method also may be used in the dimensional analysis of other less freedom parallel mechanisms.

A 3-ṞPR Parallel Mechanism With Singularities That are Self-Motions

2010 ◽  
Vol 2 (3) ◽  
Author(s):  
Novona Rakotomanga ◽  
Ilian A. Bonev
Keyword(s):  
Parallel Mechanism ◽  
Control Strategies ◽  
Joint Space ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Active Joint ◽  
Cartesian Space ◽  
Three Degree Of Freedom

The Cartesian workspace of most three-degree-of-freedom parallel mechanisms is divided by Type 2 (also called parallel) singularity surfaces into several regions. Accessing more than one such region requires crossing a Type 2 singularity, which is risky and calls for sophisticated control strategies. Some mechanisms can still cross these Type 2 singularity surfaces through “holes” that represent Type 1 (also called serial) singularities only. However, what is even more desirable is if these Type 2 singularity surfaces were curves instead. Indeed, there exists at least one such parallel mechanism (the agile eye) and all of its singularities are self-motions. This paper presents another parallel mechanism, a planar one, whose singularities are self-motions. The singularities of this novel mechanism are studied in detail. While the Type 2 singularities in the Cartesian space still constitute a surface, they degenerate into lines in the active-joint space, which is the main result of this paper.

Design of Statically Balanced Six-Degree-of-Freedom Parallel Mechanisms Based on Tensegrity System

2009 ◽  
Author(s):  
S. M. Mehdi Shekarforoush ◽  
Mohammad Eghtesad ◽  
Mehrdad Farid
Keyword(s):  
Parallel Mechanism ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Engineering Systems ◽  
Suitable Alternative ◽  
Tensegrity Systems ◽  
Six Degree Of Freedom

A parallel mechanism that is based on tensegrity system is studied in this article. Tensegrity systems are a suitable alternative for conventional engineering systems like mechanisms for some application. In this article, tensegrity mechanisms are classified into tensegrity mechanism with passive and active compliant components. Based on this classification, two types of six-degree-of-freedom parallel mechanism are proposed and kinematics and static of them are solved. The first type is the 6–6 tensegrity mechanism with passive compliant components and the second type is the 6-3 tensegrity mechanism with active compliant components.

Design and workspace analysis of a 3-degree-of-freedom parallel swivel head with large tilting capacity

2015 ◽  
Vol 231 (10) ◽  
pp. 1838-1849 ◽  
Author(s):  
Jiangzhen Guo ◽  
Dan Wang ◽  
Rui Fan ◽  
Wuyi Chen
Keyword(s):  
Machine Tool ◽  
Parallel Mechanism ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Spherical Joint ◽  
Hybrid Machine Tool ◽  
Tilting Angle ◽  
Workspace Analysis ◽  
Hybrid Machine ◽  
Orientation Workspace

Traditional parallel mechanisms are usually characterized by small tilting capability. To overcome this problem, a 3-degree-of-freedom parallel swivel head with large tilting capacity is proposed in this article. The proposed parallel swivel head, which is structurally developed from a conventional 3-PRS parallel mechanism, can achieve a large tilting capability by means of structural improvements. First, a modified spherical joint with a maximum tilting angle of ±120° is devised to diminish the physical restrictions on the orientation workspace. Second, a UPS typed leg is introduced for the sake of singularity elimination. The superiority of the proposed parallel swivel head is theoretically proved by investigations of singularity-free orientation workspace and then is experimentally validated using a prototype fabricated. The theoretical and experimental results illustrate that the proposed parallel swivel head has a large tilting capacity and thus can be used as swivel head for a hybrid machine tool which is designed to be capable of realizing both horizontal and vertical machining.

Type Synthesis of 3-DOF Rotational Parallel Mechanisms With No Intersecting Axes

2012 ◽  
Author(s):  
Ziming Chen ◽  
Wen-ao Cao ◽  
Zhen Huang
Keyword(s):  
Parallel Mechanism ◽  
Screw Theory ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Constraint Force ◽  
New Approach ◽  
Spherical Parallel Mechanism ◽  
Rotational Motions

Parallel mechanisms which can realize three rotational motions are very important in the parallel mechanism family. Not the same with the traditional spherical parallel mechanism, a new kind of 3-DOF (degree of freedom) rotational parallel mechanism with no intersecting axes (RPMNIA) are proposed in this paper. This kind of rotational parallel mechanisms have the advantages of easy manufacturing. A new approach using the screw theory and the subchain theory is proposed to design the branches with only one constraint force and some new one-force-branches are found. Using these new branches, a group of 3-DOF rotational parallel mechanisms without intersecting axes are synthesized.

scholarly journals Control Method for Realistic Motion in a Construction Tele-robotic System with a 3-DOF Parallel Mechanism

2003 ◽  
Vol 15 (4) ◽  
pp. 361-368 ◽  
Author(s):  
Dingxuan Zhao ◽  
◽  
Yupeng Xia ◽  
Hironao Yamada ◽  
Takayoshi Muto
Keyword(s):  
Parallel Mechanism ◽  
Control Method ◽  
Robotic System ◽  
Degree Of Freedom ◽  
Experimental Result ◽  
Parallel Mechanisms ◽  
High Quality ◽  
Link Mechanism ◽  
Acceleration Sensors ◽  
Parallel Link

In this study, we developed a construction tele-robotic system, which can be widely used, for example, for restoration works in damaged areas. The system consists of a servo-controlled construction robot, two joysticks for operations of the robot from a remote place and a 3-degree-of-freedom (DOF) parallel mechanism. An important problem to be solved in such a system is how to convey adequate presence of working area in a high quality to the operator. In this paper, we propose a control method of a 3-DOF parallel link mechanism to simulate the motion of the construction robot by using three acceleration sensors. The validity of this method has been confirmed experimentally. According to the experimental result, each motion of roll, pitch and heave of the construction robot can be simulated accurately by the 3-DOF parallel mechanisms.

Kinematic Analysis of a Novel Three Degree of Freedom Parallel Mechanism

2011 ◽  
Vol 320 ◽  
pp. 228-231 ◽  
Author(s):  
Xiu Qin Huang ◽  
Hui Ping Shen ◽  
Xiu Mei Xin
Keyword(s):  
Industrial Application ◽  
Parallel Mechanism ◽  
Degree Of Freedom ◽  
Structural Parameter ◽  
Parallel Mechanisms ◽  
Input And Output ◽  
Solid Foundation ◽  
Input Variables ◽  
Three Degree Of Freedom ◽  
Kinematics Parameters

A novel 3 degree of freedom(1-Translation and 2-Rotation) parallel mechanisms is investigated. The forward and inverse position of the mechanism are studied. The influences by the three input variables on the three output variables are analyzed carefully and the valid working ranges of input and output variables are given by discussing structural parameter. These provide a solid foundation for selecting structural designs and kinematics parameters accurately and for realizing the control and industrial application of the mechanism.

scholarly journals Type Synthesis of 1T2R Parallel Mechanisms Using Structure Coupling-Reducing Method

2019 ◽  
Vol 32 (1) ◽  
Author(s):  
Haitao Liu ◽  
Ke Xu ◽  
Huiping Shen ◽  
Xianlei Shan ◽  
Tingli Yang
Keyword(s):  
Explicit Form ◽  
Parallel Mechanism ◽  
Analytic Solutions ◽  
Forward Kinematics ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Real Time Control ◽  
Time Control ◽  
Topological Characteristics ◽  
Zero Coupling

Abstract Direct kinematics with analytic solutions is critical to the real-time control of parallel mechanisms. Therefore, the type synthesis of a mechanism having explicit form of forward kinematics has become a topic of interest. Based on this purpose, this paper deals with the type synthesis of 1T2R parallel mechanisms by investigating the topological structure coupling-reducing of the 3UPS&UP parallel mechanism. With the aid of the theory of mechanism topology, the analysis of the topological characteristics of the 3UPS&UP parallel mechanism is presented, which shows that there are highly coupled motions and constraints amongst the limbs of the mechanism. Three methods for structure coupling-reducing of the 3UPS&UP parallel mechanism are proposed, resulting in eight new types of 1T2R parallel mechanisms with one or zero coupling degree. One obtained parallel mechanism is taken as an example to demonstrate that a mechanism with zero coupling degree has an explicit form for forward kinematics. The process of type synthesis is in the order of permutation and combination; therefore, there are no omissions. This method is also applicable to other configurations, and novel topological structures having simple forward kinematics can be obtained from an original mechanism via this method.

scholarly journals Design of Self-Reconfigurable Multiarm Robot Mechanism Based on Deployable Kinematic Chains

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Fu-Qun Zhao ◽  
Sheng Guo ◽  
Hai-Jun Su ◽  
Hai-Bo Qu ◽  
Ya-Qiong Chen
Keyword(s):  
Parallel Mechanism ◽  
Parallel Mechanisms ◽  
Kinematic Chains ◽  
Assembly Method ◽  
Operation Modes ◽  
Object Based ◽  
Switch Operation ◽  
Storage Area ◽  
Mechanism Theory

Abstract As the structures of multiarm robots are serially arranged, the packaging and transportation of these robots are often inconvenient. The ability of these robots to operate objects must also be improved. Addressing this issue, this paper presents a type of multiarm robot that can be adequately folded into a designed area. The robot can achieve different operation modes by combining different arms and objects. First, deployable kinematic chains (DKCs) are designed, which can be folded into a designated area and be used as an arm structure in the multiarm robot mechanism. The strategy of a platform for storing DKCs is proposed. Based on the restrictions in the storage area and the characteristics of parallel mechanisms, a class of DKCs, called base assembly library, is obtained. Subsequently, an assembly method for the synthesis of the multiarm robot mechanism is proposed, which can be formed by the connection of a multiarm robot mechanism with an operation object based on a parallel mechanism structure. The formed parallel mechanism can achieve a reconfigurable characteristic when different DKCs connect to the operation object. Using this method, two types of multiarm robot mechanisms with four DKCs that can switch operation modes to perform different tasks through autonomous combination and release operation is proposed. The obtained mechanisms have observable advantages when compared with the traditional mechanisms, including optimizing the occupied volume during transportation and using parallel mechanism theory to analyze the switching of operation modes.

scholarly journals A New Method for Type Synthesis of 2R1T and 2T1R 3-DOF Redundant Actuated Parallel Mechanisms with Closed Loop Units

2020 ◽  
Vol 33 (1) ◽  
Author(s):  
Yongquan Li ◽  
Yang Zhang ◽  
Lijie Zhang
Keyword(s):  
Closed Loop ◽  
Screw Theory ◽  
Line Graph ◽  
Degree Of Freedom ◽  
Parallel Mechanisms ◽  
Type Synthesis ◽  
Allocation Criteria ◽  
Grassmann Line Geometry ◽  
Moving Platform ◽  
Atlas Method

Abstract The current type synthesis of the redundant actuated parallel mechanisms is adding active-actuated kinematic branches on the basis of the traditional parallel mechanisms, or using screw theory to perform multiple getting intersection and union to complete type synthesis. The number of redundant parallel mechanisms obtained by these two methods is limited. In this paper, based on Grassmann line geometry and Atlas method, a novel and effective method for type synthesis of redundant actuated parallel mechanisms (PMs) with closed-loop units is proposed. Firstly, the degree of freedom (DOF) and constraint line graph of the moving platform are determined successively, and redundant lines are added in constraint line graph to obtain the redundant constraint line graph and their equivalent line graph, and a branch constraint allocation scheme is formulated based on the allocation criteria. Secondly, a scheme is selected and redundant lines are added in the branch chains DOF graph to construct the redundant actuated branch chains with closed-loop units. Finally, the branch chains that meet the requirements of branch chains configuration criteria and F&C (degree of freedom & constraint) line graph are assembled. In this paper, two types of 2 rotational and 1 translational (2R1T) redundant actuated parallel mechanisms and one type of 2 translational and 1 rotational (2T1R) redundant actuated parallel mechanisms with few branches and closed-loop units were taken as examples, and 238, 92 and 15 new configurations were synthesized. All the mechanisms contain closed-loop units, and the mechanisms and the actuators both have good symmetry. Therefore, all the mechanisms have excellent comprehensive performance, in which the two rotational DOFs of the moving platform of 2R1T redundant actuated parallel mechanism can be independently controlled. The instantaneous analysis shows that all mechanisms are not instantaneous, which proves the feasibility and practicability of the method.

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