DOF and kinematics analysis of a 3-UPU parallel mechanism for telescope secondary mirror support

2021 ◽  
Author(s):  
Shuai Wang ◽  
Kunyao Zheng ◽  
Yi Chen ◽  
Mingming Xu ◽  
Dazhi Wang
Author(s):  
Dongming Gan ◽  
Jian S. Dai ◽  
Lakmal D. Seneviratne

This paper introduced a new metamorphic parallel mechanism consisting of four reconfigurable rTPS limbs. Based on the reconfigurability of the reconfigurable Hooke (rT) joint, the rTPS limb has two phases while in one phase the limb has no constraint to the platform, in the other it constrains the spherical joint center to lie on a plane. This results in the mechanism to have ability of reconfiguration between different topologies with variable mobility. Geometric constraint equations of the platform rotation matrix and translation vector are set up based on the point-plane constraint, which reveals the bifurcated motion property in the topology with mobility 2 and the geometric condition with mobility change in altering to other mechanism topologies. Following this, a unified kinematics limb modeling is proposed considering the difference between the two phases of the reconfigurable rTPS limb. This is further applied for the mechanism modeling and both the inverse and forward kinematics is analytically solved by combining phases of the four limbs covering all the mechanism topologies.


2010 ◽  
Vol 450 ◽  
pp. 283-287 ◽  
Author(s):  
Rui Wang ◽  
Gang Ding ◽  
Shi Sheng Zhong

A 5-axis parallel-serial machine tool is proposed, which consists of a 3-DOF parallel mechanism and a 2-DOF serial mechanism, and the kinematics analysis is discussed in detail based on the vector method. The size of the velocity transformation matrix is decreased. The problem of parameter coupling is resolved by adopting identity matrix and four-element vector. The relationship between the velocity and acceleration of the movable platform and the input parameters of the parallel mechanism is established. These algorithms are verified correct through ADAMS (Automatic Dynamic Analysis of Mechanical System) and can be referenced by kinematics analysis, dynamics analysis of parallel or parallel-serial machine tools, which have coupling kinematics parameters.


2012 ◽  
Vol 591-593 ◽  
pp. 754-757
Author(s):  
Hong Li Yun ◽  
Xiao Na Song

The kinematics analysis is carried out on a kind of 3-urps parallel mechanism (pm) with 6-dof. The positional inverse solution and Jacobean matrixes which is used to analyze the dexterity of mechanism are derived. Condition number is used as evaluating indicator of dexterity in this article, and its’ three-dimensional graphs are drawn when this mechanism in different attitudes. It is indicated that dexterity of moving is excelled than the rotary movement’s for this pm. The optimum dexterity can be obtained in the center of mechanism’s workroom, which can be applied to further characteristic analysis and kinematic design of mechanisms.


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