Research On Kinematics Of6Dof Parallel Robot Based On Improved Differential Evolution

6-DOF parallel platform has a strong bearing capacity, high rigidity, high precision, the system dynamic response characteristics of fast and small cumulative error, and it has been applied widely in the field of flight simulators, new types of machine tools, aviation spacecraft docking. Parallel robot has been extensively investigated by virtue of its high force-to-weight, high stiffness and precision, low inertia, and its widespread applications in various fields such as flight simulators, space docking motion system, spherical radio telescopes, and virtual lathe. However forward kinematics solution is foundation of parallel robot mechanism application, there has been no satisfactory solution. The essence of forward kinematics is to solve a set of nonlinear equations with multiple strong coupling but it is very complicated. As a result this problem has always attracted many researchers due to its intricacy and quite a few approaches have been proposed over the last decade. These methods can be classified into the following three classes included analytical approaches, numerical methods and artificial intelligence based methods.The analytical approaches transform the nonlinear equation into a high-order polynomial through the elimination, then using the geometric algebra for solving. Lee has successfully solved the forward kinematics problem using this approach. But it is difficult to really implement because the calculation is large and complex. The numerical methods get the calculation results by an iterative routine has presented to solve a macro-micro parallel manipulator. The proposed algorithm was originally given by T. Dekker wherein a combination of bisection, secant, and inverse quadratic interpolation methods is used. However, the main challenge of this method is that the results depend on the choice of initial value and there exist convergence problem. In order to overcome the complexity using traditional method to solve the nonlinear equations, Neural networks (NN) and genetic algorithms (GA) also have been raised to solve the forward kinematics problem for a variety of parallel robots. Neural network need to have enough samples to train the network, but these samples is not easy to obtain before we have known the forward kinematics. The genetic algorithm is easy to fall into local minimum, and it seek out the forward kinematics of the shortcomings is not necessarily the optimal solution. The differential evolution algorithm is co-sponsored by Rainer Storn and Kenneth Price in1996. It is a simple yet powerful population-based stochastic search algorithm and it is also an efficient and effective global optimizer in the continuous search domain. In this paper, a differential evolution with adaptive control parameters is proposed for solving the forward kinematics problem of six degrees of freedom parallel robot.First, the object of this paper study is a middle size parallel robot that produced by Suzhou Boshi Robot technology limited corporation, introduced the structural parameters and the works of six degrees of freedom parallel robot, laid the foundation for the further study of its kinematics.Homogeneous, established according to the characteristics of the six degrees of freedom parallel robot dynamic, static two coordinate systems, inverse kinematics analysis model to get the6-DOF parallel robot inverse kinematics, and finally got its inverse kinematics6-DOF parallel robot motion planning trajectory.Then, with six degrees of freedom parallel robot inverse kinematics solution is relatively easy to solve the characteristics, the establishment of the Forward Kinematics of approximation by the inverse kinematics model, and improved differential evolution algorithm variability factor and crossover factor selected, so that every time adaptive adjustment of the current individual fitness before the evolution of operating control parameters, and finally improved differential evolution algorithm to calculate the Forward Kinematics of6-DOF parallel robot.Then, in order to be more intuitive kinematics experiments and subsequent dynamics, robot control theory, this paper develop and design of the six degrees of freedom kinematics simulation platform using VC++.Finally, this section is summarizes, and prospect for further research direction.