Papers by Keyword: Parallel Machine Tool (PMT)

Abstract: A computational model for position and posture error of 6-DOF parallel machines is proposed based on D-H transformation matrix and the inverse kinematics. The model is used to construct a linear least-square identification model for geometric parameter errors. Error identification program and compensation method are also presented. Simulation results indicate that the effects on position and posture of machines are almost equivalent from calculated least-square solution and from real values. The pose error of moving platform can be decreased up to 90% if error compensation is performed by modifying the input kinematic parameters of driving joints.

Abstract: Based on the Lagrange equation, a dynamic equation of 2-PRR parallel machine tool has been established and the relation among displacement,velocity and acceleration of moving platform was given. By modeling and simulating on the simulink of Matlab, forword dynamics are solved. This paper also provide a reference for dynamics analysis and optimization of less freedom machine tool

Abstract: The machinery composition and working principle of 3-TPT parallel machine tool were analyzed. The three dimensional solid models of components of 3-TPT parallel machine tool were designed by using Pro/E. The virtual assembly and connection of the machine tool were accomplished in the assembly environment of Pro/E. Besides, the three-dimensional motion simulation of mechanism about the machine tool was researched in the mechanism module of Pro/E. The three-dimensional animation achieved by the simulation has the strong sense of reality. The working principle of the parallel machine tool was verified by the simulation. The simulation results show that the machine tool has advantages such as good stationarity, no interference and no singularity.

Abstract: The 3 DOF parallel machine tool CNC system based on DSP takes 3-HUU configuration of parallel machine tool as the control object, and adopts TMS320F2812 of TI DSP as control core of the CNC system. This paper mainly studies hardware design and software design of the lower control system of the 3 DOF parallel machine tool, and does practical test which shows that the CNC system can well control the parallel machine tool and finish machining movement.

Abstract: This paper proposes a novel three degrees of freedom parallel machine tool. The parallel machine tool consists of three serial chains and a fixed base and a moving platform which can be moved in a pose space corresponding to the three degrees of freedom. By using matrix methods, a error model of the parallel machine was developed. The explicit solution of the error of joint and the stroke error of telescopic link were solved for analysis of influence factors of error on the position of moving platform. It provided a theoretical foundation for error compensation of parallel machine tool.

Abstract: Traditional feedback linearization approach (TFL) requires a priori knowledge of plant, which is difficult and the computational efficiency of controller is low due to complex dynamics of plant. In order to improve the tracking performance of hydraulic parallel machine tool and limit the drawbacks of TFL, a novel approximate feedback linearization approach is proposed in this paper. The mathematical models of hydraulic parallel machine tool are established using Kane method and hydromechanics. The approximate feedback linearization control is designed for the parallel machine tool in joint space, with the position and the stored data in the previous time step are employed, as a learning tool to yield improved performance. Under Lyapunov theorems, the stability of the presented algorithm is confirmed in the presence of uncertainties. Simulation results show the proposed control is readily and effective to realize path tracking, it exhibits excellent performance and high efficiency without a precision dynamics of plant. Moreover, the presented algorithm is well suitable for most industrial applications.

Abstract: In this paper, a PUU parallel machine tool with three translational degrees of freedom (DOF) is designed which is usually used in the complex grain machining of the solid rocket engine.， and its numerical control system is described in detail. The so-called “PC+PMAC” is used as the hardware platform, and Windows as the software one, the parallel machine tool NC system is built. The features, such as multi-axis motion control and fast real time communication of PMAC, software resources and efficient data processing of PC are utilized such that Man Machine Interface, position servo control, real time measurement of cutter configuration and closed loop control of the parallel machine tool are realized.

Abstract: The static stiffness characteristic of parallel machine tool is an important factor and reference for machine design and optimization. The static stiffness characteristic of 3-TPT parallel machine tool is researched in this paper. The structural analytical model of machine tool is built by ANSYS software, which has two different work positions and three kinds of different workloads. The details of analytical process and method are provided, and the deformation conditions and the laws of stiffness variation are got. The main factors of static stiffness are obtained, so it provides an important reference for modifying structure of machine tool and relative research.

Abstract: This paper proposes an optimization method which makes the structural parameters are minimum and the workspace is maximum based on 3-DOF parallel machine tool. By analysis the conditions of boundary, parameters optimization model is built and gives out the explicit solution of dexterous workspace. Analysis the effect of structural parameters on workspace. The results show the workspace is a unsingularity space.

Abstract: In order to grasp the vibration characteristics of a novel High-Speed 4-HPS-HPH PMT(parallel machine tool), A vibration behaviors analysis method using virtual prototype simulation was put forward. By the united application of CAD, CAE and visual technologies, the rigid-flexible vibration model of 4-HPS-HPH PMT was constructed. Then the dynamic response of the tool tip, including vibration displacement, vibration velocity, vibration acceleration, and maximum dynamic stresses of driving limbs were realized. The simulation results show that the rigid-flexible vibration model proposed can indicate the vibration behaviors of parallel machine tool. This research provides necessary guidance for dynamic performance analysis, optimization design and control of this 4-HPS-HPH PMT.