Design and Experimental Study of a 3-DOF Parallel Swivel Head

2013 ◽  
Vol 418 ◽  
pp. 132-140
Author(s):  
Dan Wang ◽  
Jiang Zhen Guo ◽  
Rui Fan ◽  
Wu Yi Chen

Traditional parallel mechanisms (PMs) are usually characterized by small tilting capability. To overcome this problem, a 3-DOF parallel swivel head (PSH) with large tilting capacity is proposed in this paper. The proposed PSH, which is structurally developed from a conventional 3-PRS parallel mechanism (PM), can achieve a large tilting capability by means of structural improvements. Firstly, a modified spherical joint with a maximum tilting angle of ±120o is devised to diminish the physical restrictions on the orientation workspace. Secondly, a UPS typed leg is introduced for the sake of singularity elimination. The superiority of the proposed PSH 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 PSH 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.

Author(s):  
Jiangzhen Guo ◽  
Dan Wang ◽  
Rui Fan ◽  
Wuyi Chen

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.


2011 ◽  
Vol 127 ◽  
pp. 277-282
Author(s):  
Peng Fei Dang ◽  
Li Jin Fang

This paper establishes position error model based on parallel robot kinematics theory, and analyses position error of the 3-TPS hybrid machine tool. Firstly, to calculate position error of the movable plate caused by the parallel mechanism links, through error model of the parallel mechanism which is established through inverse kinematics of the hybrid machine tool. Then, according to the error model of constraint mechanism established by transformation matrix method, the position error has been simulated and calculated. Finally, this paper compares the effects of both mechanisms. The analysis indicates the link error of constraint mechanism has more influence on movable plate posture than parallel mechanism, and provides help with motion error compensation and kinematic calibration.


2011 ◽  
Vol 204-210 ◽  
pp. 1651-1654
Author(s):  
Yan Fei Zhang ◽  
Jin Liang Gong ◽  
Xiu Ting Wei

On one hand, parallel machine tool enjoys many advantages over conventional serial counterpart, on the other hand, it also suffers from the disadvantages of coupled position and orientation, difficulty in kinematic modeling, strict requirements for components and difficulty in manufacturing of the spherical joint adopted in some limbs. Hybrid mechanism, however, will serve the turn in some cases. By using a three degree-of-freedoms parallel mechanism and a slide worktable which will fulfill one movement, a novel four degree-of-freedoms hybrid machine tool is put forward. The kinematic solutions are analyzed and closed-form kinematic solutions are given. The methods and theories adopted here can be used for design of other types of hybrid machine tools.


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