Papers by Keyword: Posture Error

Abstract: For an industrial robots with unknown parameters, on the basis of preliminary measurement and data of the Cartesian and joints coordinates which are shown on the FlexPendant, the kinematic parameters is identified by using genetic algorithms and accurate kinematics modeling of the robot is established. Experimental data could prove the validity of this method.

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: This paper takes a kind of 3-UPS Parallel Machine Tool (PMT) as the objective of research. First, the kinematic analysis is carried out to the machine and the kinematics equation is obtained. Then, the mathematical model on tool posture error of this machine is established in considering the joint gap based on the kinematics equation. According to the mathematical model expression, the posture error of tool tip point can be calculated when the specific values to the length error of the driving rod and the position error of the joint point are known. The establishment of error model has important theoretical significance to the design as well as the error analysis and compensation of this Parallel Machine Tool.

Abstract: This paper takes one kind of 3-TPT Hybrid Machine Tools (HMT) as the object to study. It mainly analyzes the influence of the parallelogram mechanism as the restraining chain of machine on the posture error of movable platform. Firstly, on the basis of introducing the structure of HMT, the kinematics of the restraining chain of this machine is analyzed, and the kinematics equation of the restraining chain is established. Secondly, the influence of two kinds of factors including the shape error of parallelogram mechanism and the micro-rotation of Hooker joint around the axis of connecting rod is analyzed respectively, and the theoretical relationship expression is acquired between various errors influencing factor and the posture error of movable platform, thus the foundation for the theoretical error analysis of the HMT is laid.