Research On The Forward Kinematics Solution Of 6-DOF Platform

In 1965, Stewart invented the six-DOF motion platform. Relative to the serial robot,parallel robot has several advantages, such as good precision, high rigidity, simple structure and strong carrying capacity. It was widely used in tire testing machines, sports simulators,parallel machine tools, precision positioning, operator and some recreational facilities and so on. Domestic and foreign scholars have done much research work on six degrees of freedom parallel robot. Mainly concentrated in the kinematics analysis, dynamic analysis, drive and control strategy to improve its optimization.The kinematics of six-DOF platform includes two aspects, forward solution and inverse solution. The forward kinematics solution is more complex which is used to calculate the exercise space, to avoid the singularity position, proofreading zero position and also it's the basis of precise position control. Study of kinematics has certain theoretical and practical value.There are many methods to solve the forward solution equation; the commonly used ones are numerical iterative method, analytical method and homotopy algorithm. The numerical iterative algorithm has the disadvantage of dependence on the initial value; the neural network algorithm was used to optimize it. The problem of solve the parallel platform's inverse kinematics equation is simple; so many groups of training samples can be got within the workspace to train the BP neural network. The length value of the rod was put into the neural network, to get the initial result approaching the real value, and then as initial value the of the Newton-Raphson algorithm, programmed in Matlab in operation. We can get the satisfied location of the upper platform.The numerical iterative method can not work out all the positions of the upper platform,that's not easy for other analysis. In this paper, the structure of six-DOF motion platform was simplified using elimination method and Wu's method. Through eliminate the variables of its mathematical functions; its all solutions can easily be worked out.