The Analysis Of The Lower-Mobility And Overconstrained Parallel Mechanism

This paper presents a novel 2-RPU/SPR 2R1 T parallel mechanism, which has one translational degree of freedom(DOF) and two rotational DOFs. The properties of the rotational axes of the mechanism are analyzed by using screw theory, and the results show that the 2-RPU/SPR mechanism has two rotational continuous axes. Using rotating transform formula, the rotational angle that the two continuous rotational axes of the moving platform take, receives the position of the moving platform. According to the length constraint conditions of the parallel mechanism, solve length of the rod, which is related with the position of moving platform. The dynamics model is established on the basis of the principle of virtual work, the simulation of mechanism dynamics is implemented by using Adams Software. The position analysis of the 2-RPU/SPR mechanism is also carried out. The proposed 2R1 T mechanism has very simple kinematic model. The parameter is very convenient, and the parallel mechanism has good prospect.Using analysis of the inverse position solves the forward position, the analytic formula of the forward position is found out, and the simulation verification is made by the Adams software. Based on the 6-SPS parallel mechanism, the multiple sets of real solutions are worked out by using the Matlab software and the Adams software. The different Spline curves make the six lengths achieve the same pose of the moving platform, the reason that leads to multiplicity of forward solutions is obtained. The parallel mechanism has the characteristics of the kinematics analysis.By using the screw theory, the statics models of the four kinds of mechanism are carried out, and the driving forces and the equivalent constraining forces are solved. It knows that the 2-RPU/SPR PM is more superior to others by the data of the driving forces and equivalent constraining forces. By using the principle of virtual work theory, the dynamic models of the four kinds of mechanisms are constructed, the driving forces and equivalent constraining forces are solved. The simple mathematical models of the dynamic and static mechanics spend relatively less operation-time. For the results of the simulation verification institutions, it places a 6-d force on the moving platform. The equivalent constraining forces and the driving forces can be obtained after programming; Due to the driving forces of the agency 2-RPU/SPR is relatively small, a six dimensional force of changing over time could be placed on the moving platform, the equivalent constraining forces and the driving forces can be obtained, then equivalent constraining forces and driving forces of the kinematic pair of 2-RPU/SPR change less. In Adams software to build the line model of the four institutions, emulating the binding force/torque and the driving force of the beginning of the certification body. It is verifying about the consistency and correctness between the mathematical model and simulation model. Finally, it is concluded that 2-RPU/SPR parallel mechanism is more superior to other three institutions.