| IntroductionDynamic movie (Dynamic Motion Simulator), which came from the Flight Simulator to cultivate pilots,is a high-tech entertainment project gradually rised throughout the world since Nineties 20th century. The main mystery of dynamic movie, in addition to wide screen and stereo, the audience seating will make synchronous activity following the evolution of the plot on the screen, so that the audience have a more realistic immersive feel. Therefore, the research and development of this seat which has six-DOF is practical and significant, while the essence structure of the six-DOF motion simulator is six-DOF Parallel Mechanism.Research SignificanceAs a new development direction, the six-DOF Parallel Mechanism has a wide range of applications in all areas of social life. it is significant and valuable to research and development this mechanism. Compared with Western developed countries, our country's six-DOF motion simulator's design and manufacturing level have a larger gap, we have much to study on the the key issue of parallel mechanism technological. Therefore, it is very significant to make further experiment study and theoretical analysis on the key component of the six-DOF Parallel Mechanism.Although the spatial structure of parallel mechanism seems relatively simple, but it has a larger workload and complex calculation to set up and analysis the kinematics model, the workspace model, dynamic model, control model and error analysis model etc. Therefore, it is very important using computer simulation during the research of parallel mechanism, through the use of computers powerful calculation and analysis function, we can greatly improve the efficiency and accuracy of research. And during the research and development process, through the computer simulation,we can make a reasonable evaluation of a part of the parallel system, and we can also evaluate the impact between the various parts, as well as their impact on the overall system. More importantly, we can shorten product development design cycle and reduce the risk of R & D investment, that is we can produce the best products with the least time. In addition, the parallel mechanism's "hardware" is easy, and it's "software" is complex, but this does not mean that the operation of control software is complex, this complex should be hidden at the back interface. Therefore, the development of integration of various forms of parallel mechanism kinematics, dynamics, simulation and control of three-dimensional visualization system, is very important to the development of the six-DOF motion platform.According to "the key technology and equipment research of dynamic movie" which is one of an important project of science and technology development progrom of Jilin Province, this paper analyse the kinematics and dynamics of 6-SPS parallel mechanism, design and development of the Prototype of six DOF motion platform and visualization system for the dynamic movie. Theoretical AnalysisStarting with the structure of the 6-SPS parallel mechanism, this article derived direct and inverse kinematics solutions of the mechanism. Because it is easy to analyze the inverse kinematics solution and hard to analyze the direct kinematics solution, and it is necessary to realize the real-time calculation of the inverse solution while controlling the Dynamic Motion Simulator. So this paper, gaved a detailed inverse position solution, and did not make further study on the direct position solutions, only gave a Newton iteration method. Based on the Influence Coefficient Method, derived the velocity and acceleration of the mechanism, as the kinematics control equations of the platform.In order to verify the Technical Index of the platform, the workspace of 6-SPS parallel mechanism is also studied briefly. A search idea of the boundary radius was put forward, and we can get the workspace of the platform quickly. According to the structure parameters of the platform, the workspace can be calculated(Fig 1.1). Visualization System DesignThe visualization system of the 6-SPS parallel mechanism can provide an intuitive visualization of the movement information, realize the function of online animation, simulate the actual work of parallel mechanism, observe the interference between the various components effectively, and output curves of kinematics and dynamics, solve the problem of kinematics and dynamics curve visualization. Therefore, the development of the system is helpful to understand and master the kinematics and dynamics character of the mechanism completely and can provide software support for the development of the platform prototype.According to the structural characteristics of the parallel mechanism, using MATLAB language,developed the visualization system to provide software support for the development of the platform prototype. This system includes kinematics, dynamics simulation system, and simplified workspace model, with a good user-friendly interface, this software can be used as a design or analysis software. The flowchart of the whole system as shown by Fig 1.2.Prototype DevelopmentFrom the design point, the six DOF motion platform is the same as parallel machine tool, parallel robots and flight simulators in the kinematics, dynamics and other mechanism theory. But from structural features, control accuracy and response speed, etc., they have much difference. Parallel Machine Tool and Parallel robot focused on the position and velocity accuracy, while the motion simulator concerne more about the control accuracy of the acceleration and sudden acceleration. In addition, the requirements for the carrying capacity and workspace of the sports simulator are relatively high.The technical index of the Dynamic Motion Simulator is shown in table 1.1. The flowchart of the prototype development is shown in Fig 1.3. According to the technical index, the selected the prototype's parameters are shown in the table 1.2, the workspace of the prototype is obtained by calculation(figure1.1), which is like mushroom shape, and the axis of rotation can reach 25°, consistent with the requirements of technical index. Prototype three-dimensional model is shown in Fig 1.4. ConclusionAccording to "the key technology and equipment research of dynamic movie" which is one of an important project of science and technology development progrom of Jilin Province, this paper analyse the kinematics and dynamics of 6-SPS parallel mechanism, design and development of the Prototype of six DOF motion platform and visualization system for the dynamic movie. Through computer simulation, the Prototype meet the requirement of the technical index. |
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