Research Of6Dof Motion Platform Control System Based On VxWorks

The6DOF motion platform with high rigidity, high load capacity and smallercumulative error, has been widely used in the flight simulation, automobilemanufacturing, shipbuilding, aerospace and other fields. As the key to the movementof the6DOF motion platform, real-time control system has become a research focus inrecent years. For making6DOF motion platform can simulate various flight statustimely and accurately, we research the6DOF motion platform control system based onthe VxWorks real-time operating system in this paper.Firstly, we do a detailed study of the kinematics of the6DOF motion platform,involving the inverse solution focused on the position of the moving platform andposition analysis of positive solutions. First we established homogeneous coordinatetransformation matrix between the moving coordinate system and the static coordinatesystem, and then derive the analytical solution of the inverse position, and based onthis, we derive a solution algorithm based on Newton-Taylor numerical iteration. It isconfirmed that the convergence of this method is fast, and also easy to computerprogramming.Secondly, in the control strategy, we use composite PID controller based theinverse kinematics to control the single servo system of the6-DOF motion platform.The mathematical model of the first hydraulic cylinder is given firstly, and then basedon this model, we design the PID controller. And for the relatively low damping of thehydraulic control system, we design the feedback correction of the dynamic pressureon the links to increase the damping of the control system. For the controller outputresponse time longer shortcomings,we design dynamic feedforward compensation toimprove the control system performance. Through MATLAB simulation control, weget better control simulation results.Finally, we design the6DOF motion platform real-time control system based onVxWorks. First the entire VxWorks system framework is given, and we design thearrangements for each task, the timing mechanism and system time, inter-task datainteraction; Then we realize the AD/DA digital board driver based on PCI/ISA bus in VxWorks and verify its accuracy and real. Followed, we achieve the kinematicsposition positive/inverse algorithm in VxWorks, compared with the Simulinkalgorithm,and verify the real-time performance. At the last, we discrete and achieve thecontrol algorithm in VxWorks, and compared with the Simulink algorithm. Thecompare experiment and verification of each module indicate the correctness of thealgorithm and satisfy the real-time performance at the same time.