Research On The Motion Control Algorithm Based On The6-DOF Stewart Platform

The6-DOF (degree-of-freedom) platform adopts the typical style of the Stewart parallelmechanism, and it has already been a major simulation equipment to simulate the ship sailing,the airplane flying and so forth. Based on the established inertial coordinate system and siamesedcoordinate system, the pose motion is changed into the matrix operation of coordinates. Thediscourse centers on the motion algorithms of the6-DOF Stewart platform, and the researchcontents are as follows:Firstly, the kinematics characteristics and the dynamics characteristics of the6-DOF Stewartplatform are studied and analyzed. The inverse kinematics is the basis for the below deducedmotion control algorithms, which is the motion planning control section of the motion controlsystem. The Elman recursive network is applied to approximate and solve the forwardkinematics, and the simulation result is shown that the well-trained network has the goodapproximation effect. Analyzing and deducing the dynamics characteristics, the relationshipbetween the hydraulic driving forces and the motion pose is obtained, which provides an indexfor the integral design of the6-DOF Stewart platform.Then, the model of the asymmetrical valve controlling asymmetrical hydraulic cylinder isbuilt and analyzed, and the nonlinear state equations and the linear transfer function is deduced,and a feed-forward disturbance compensator is designed to eliminate the effect of the externalload disturbing force to the system output., which provide the mathematical model of thecontrolled object to deduce the below motion control algorithms.Furthermore, aimed at the characteristics of the6-DOF Stewart platform, the PID controllaw based on the synchronous control principle, the control law based on the augmented linearquadratic regulator (ALQR) and the control law based on Backstepping are deduced respectively,which one of them is the operation control section of the motion control system.Finally, the simulation models are built to verify the control effect of three adopted motioncontrol algorithms of the6-DOF Stewart platform, and the simulation results are compared andanalyzed as well. The results are shown that the adopted motion control algorithms arereasonable and achievable. In addition, the control law based on Backstepping is suitable for thecondition that the pose motion is the sine signal, and the control law based on ALQR is suitablefor the condition that the pose motion is the step signal, the square-wave signal or the signalincluding the random disturbance, while the PID control law based on the synchronous controlprinciple is suitable for engineering applications for the reasons, such as simple to implement, easy to understand and so forth.