On The 2-DOF Spherical Parallel Mechanism For Stabilization And Vibration Isolation

As an important research branch of vibration control, active vibration isolation technology has been paid more and more attention, and has been successfully applied in many fields. As the mechanism noumenon of a multi degree of freedom active vibration isolation, there are two main types of stabilization platform in the configuration, which are the frame structure and the multi-point support parallel structure. But, compared with the traditional frame structure and multi-point support structure, parallel mechanism has the advantages of higher bearing capacity, higher rigidity, higher precision, easier to realize high speed, easier in inverse solution solving and so on. Aiming at the demand for the two rotational freedom degree of airborne stable vibration isolation, the paper presents a new type of parallel vibration isolation device with two rotational degrees of freedom, which is based on the theory of spherical parallel mechanism. The design concept is presented, which not only enriches the configuration of the two degree of freedom stability platform, but also inherits the advantages of parallel mechanism and spherical mechanism. The main research contents of this paper include the following aspects:Firstly, this thesis analyzes the development of stable platform at home and abroad, and the structure of the stable platform is analyzed and evaluated. Then, based on the research of parallel mechanism and spherical parallel mechanism, the idea of applying the spherical parallel mechanism to the vibration isolation platform is presented.Secondly, a two degree of freedom spherical parallel mechanism(2-RRR/U) is designed to meet the requirements of two rotational degrees of freedom by analyzing and studying the mechanism of three degrees of freedom parallel mechanism(3-RRR) and parallel robot mechanism. Then, the freedom of the mechanism is analyzed and verified by using the modified Kutzbach-Grubler freedom formula and the screw theory.Thirdly, according to the design requirements and mechanism design theory, a series of analysis of the mechanism are carried on. Analyses include:(1) The kinematic analysis of the mechanism is carried out: with D-H representation method of robot mechanism, the analytic expression of the inverse solution of the mechanism is given by the rotation transformation of the coordinate system. Combined with the mechanism velocity Jacobian matrix and the inverse solution, the position numerical solving method of positive solutions of mechanism is given by the numerical iteration method based on the steepest descent method. Finally, the mechanism velocity and acceleration analysis are given.(2) Performance analysis of mechanism motion is carried out: The singularity analysis of the mechanism is carried out by using Jacobian algebra theory; After that, a method of analyzing the workspace of given a position or a position range is used to analyze the workspace of the mechanism, and with the aid of MATLAB programming, the flexible working space is given; Finally, by analyzing the performance of the stabilized platform, a set of design parameters of stabilized platform prototype are determined.Finally, the design of the stable platform principle prototype is carried out: In the Solid Works and ANSYS software platform, the design and analysis of the parts and the coordination of the parts are presented, and the key technologies and solutions are given. In the end, the virtual prototype model of the stable platform is established, and the simulation is verified, which lays the foundation for the construction of the prototype.