Papers by Keyword: Parallel Machine Tool (PMT)

Abstract: This paper took a 3-UPS Parallel Machine Tool (PMT) as the object of research; it mainly introduced the process of establishing the compensation strategy for this PMT. Firstly the kinematics equations on driving chain and constraint chain was established on the basis of kinematics analysis. Then according to the structural characteristics and the results of kinematics analysis, the error compensation strategy of feedback correction type with the semi-closed loop control mode was used in the error compensation for this PMT by the method of installing respectively the encoders on the each joint of parallelogram mechanism, namely the compensation way of “parallel driving and series feedback” was adopted. Finally this paper has also deduced the theoretical model of error compensation. The research results in this paper provided a theoretical basis for realizing error compensation of this PMT, and had important practical significance for improving machining precision of PMT

Abstract: This paper took one kind of 3-TPT Parallel Machine Tool (PMT) as the object of research. It mainly analyzed the influences of the position error of joint points in the fixed platform to the position error of tool of this PMT. Firstly, on the basis of introducing the structure of PMT, the kinematics of this machine was analyzed, and the inverse kinematics equation of this PMT was obtained. Then the influence situation of the position error of joint points in the fixed platform to the position error of tool was studied based on the kinematics analysis results and the error independent function principle, and the corresponding mathematical expression of error influence was established. Thus the theoretical foundation was laid for the comprehensive establishment of error model and the error compensation of this PMT

Abstract: This paper took a kind of 3-TPT Parallel Machine Tool (PMT) as the object of research, and it mainly researched the measurement method to position coordinates of movable platform in PMT. First the paper introduced the structure of 3-TPT PMT. Then illustrated the device structure and the basic measurement principle for measuring the position coordinates of movable platform. Finally carried on the theoretical analysis to the specific measurement method and established the corresponding mathematics relationship. The measurement method that was presented in this paper had characteristics of simple structure, convenient and flexible operation, economical and so on, and simultaneously the research results of this paper laid a theoretical foundation for improving the movement precision of this PMT and had important practical significance

Abstract: This paper took a kind of 3-TPT Parallel Machine Tool (PMT) as the object of research, and it mainly researched the measurement method to position coordinates of movable platform in PMT. First the paper introduced the structure of 3-TPT PMT. Then illustrated the device structure and the basic measurement principle for measuring the position coordinates of movable platform. Finally carried on the theoretical analysis to the specific measurement method and established the corresponding mathematics relationship. The measuring device that was presented in this paper had characteristics of direct-viewing measurement relationship, simple structure and low cost etc., and simultaneously the research results of this paper laid a theoretical foundation for improving the movement precision of this PMT and had important practical significance.

Abstract: This paper takes a new-type 3-TPT 3-DOF parallel machine tool as the object of study, established the positive and negative solution of kinematic equations of the machine, and derived the Jacobian matrix and Jacobian inverse matrix of the machine tool. On this basis, the singularity and stationarity of the machine tool were researched by using Matlab and got the expression of the absolute value of Jacobian matrix determinant of the machine tool. The velocity distribution curves of telescopic driving rods of the machine tool were simulated, too. The results show that the machine tool has advantages such as good stationarity and no singularity and so on. The study provides certain theoretical basis for the structural optimum design and performance analysis of parallel machine tool.

Abstract: Firstly, structure component of the 6PUS-UPS PMT (Parallel Machine Tool) was introduced. Secondly, errors during the machine tool debugging were analyzed and measured, and those determined by the 6PUS-UPS PMT structure character were focused on, including the clearance error between the slider and the guide way, the vibration error and the verticality error and so on. Lastly, the verticality error was measured using the digital display micrometer and the frame level, which has great influence on the 6PUS-UPS PMT precision

Abstract: In order to solve the problems that traditional kinematics model built by the method of D-H parameters can only reflect relative movements between adjacent components and can't express directly the spatial poses of every component relative to static platform, Lie-algebras is used this paper to establish the product of exponential formula of forward direct kinematics of every branch chains. The elimination method and Paden - kahan sub-problems are used to calculate joint variables. Then the quick and intuitive inverse algorithm of cross rods parallel machine tools is acquired. The algorithm provides reliable proofs for the analysis of error compensation, kinematics interference and singularity. Finally we prove our theory with an example of an actual parallel machine tool.

Abstract: This paper took a kind of 3-TPT Parallel Machine Tool (PMT) as the object of research; it mainly introduced the process of establishing the compensation strategy for this PMT. Firstly the kinematics equation of this PMT was established on the basis of kinematics analysis, the results showed that the kinematics equation of this PMT have characteristics that are simple calculation, explicit expression and unique solution. Then according to the structural characteristics and the results of kinematics analysis, the error compensation strategy of feedback correction type with the semi-closed loop control mode was used in the error compensation for this PMT by the method of assembling the gratings on the driving rods, namely the compensation way of “parallel driving and parallel feedback” was adopted. The research results in this paper provided a theoretical basis for realizing error compensation of this PMT, and had important practical significance for improving machining precision of PMT.

Abstract: The hardware control system of the 5-UPS/PRPU PMT (parallel machine tool) with redundant actuation was reconstructed to realize its hybrid force/position control, which was based on the primary “IPC+PMAC motion controller” system mode. Meanwhile, more perfect open type PMT control platform was constructed. Visual Basic language was used to realize the force servo control of the redundant limb and the relevant experiment was completed in the primary CNC system, combining with the PAMC motion controller library function. The results show that the force servo control strategy is exact and the newly designed hardware control system is effective, these results also provide feasible hardware basis and control method to realize the hybrid force/position control.

Abstract: The dynamic characteristics of parallel 3-TPT machine tool are researched by simulation and experiment in this paper. Firstly, modal analysis principle of machine tool was analyzed in theory, and the parameters of dynamic characteristic were identified by theoretical analysis. Then vibration model of parallel machine tool was built in ADAMS and formed vibration system of rigid and flexible coupling for simulation analysis, and from the simulation results got the value of parameters for vibration characteristic of parallel machine tool. The simulation results showed that the simulation method and result dates are validated, which provides reference for dynamic optimal design.