Development Of A Multidimensional Vibration Table For On-board Equipment

In the process of vehicle running, the car embedded devices will suffer from complex and composite pitching in multiple dimensions, such as vertical vibration, transversal vibration, longitudinal vibration, rolling, pitch, yaw, etc. In order to reproduce this bumpy motion furthest, offering the devices in study an effective vibration test environment, this paper developed a new multidimensional vibration table with deficient DOF. The new vibration table is an economical and practical vibration test equipment, for it can realize two kinds of excitation through mechanism’s reconstruction.Firstly, this paper synthesizes several less-degree-of-freedom parallel mechanisms, and choose one named 3-P(4S) parallel mechanism as the final configuration scheme through comparative analysis. The greatest strength of the selected mechanism is that it can realize not only three-dimensional accurate translational movement, but also six-dimensional coupled random movement. After having a detailed analysis of the freedom of 3-P(4S) parallel mechanism with screw theory, the properties of the freedom of the mechanism are obtained when the closed-loop in each limb is in different arrangement such as trapezoid, triangle and parallelogram.Secondly, this article makes a kinematic analysis of the 3-P(4S) mechanism under two different configurations. The reverse position are solved by Newton Method, and the forward position are solved by Quasi-Newton Method. The explicit representation of reverse position and the velocity Jacobian matrix are also obtained. Besides that, using search method based on reverse position when the closed-loop is arranged as a triangle, and using search method based on forward position instead when the closed-loop is arranged as a trapezoid, the reachable workplace and the gesture distribution of the mechanism under different configurations are obtained.Thirdly, this article designs the mechanical structure of the multidimensional vibration table. At the same time, we set up a control cabinet, which exposes a lot of functionality including controlling, data collecting and processing, PC operation, etc. After introducing magnetic spring into the structure of the actuator innovatively, it is found that the workload of the actuator is reduced greatly. The experiment of using a laser interferometer to measure the positioning accuracy of the actuator has been done, and the result shows that the actuator can reach 10-micron location accuracy.Finally, the analytical expressions of forward and reverse position are obtained by using geometric method, with which the error mapping model of the mechanism is built. After analyzing the error sources, separating uncontrollable error and controllable error, the error parameters to be compensated are determined. This article describes the error measurement principle based on the laser tracker, and builds the error identification model. The kinematic calibration experiment has been contacted, and its result demonstrates the effectiveness of the foregoing methods.