The Research Of A Novel Four DOF Parallel Platform

Virtual axis machine tool is the combinative result of the parallel robot technology, modern machine tool design and the control technology. Usually, it contains two platforms, which connected by certain poles. These poles are fixed-length or expandable, and there are spherical joint and Hook joint in their two extremities. These joints are used to connect the platforms. Then the parallel platform could achieve a movement of three to six degrees freedom. The four degrees freedom parallel platform is one kind of the parallel kinematics machine. Be compared to the normal numerical control machine tool, it has some advantages such as:simple structure,lighter quality,the speed of response is quick,less investment of hardware. All of these show its high additional technical valve.In order to avoid some disadvantages such as high manufacturing costs, the ratio of the working space and the dimension are unreasonable etc, then raised a new kind of four degrees parallel platform. And there carry on an analysis of some questions about its structural,workspace,kinematics analysis,rigidity ect.First of all, carry on a research on the working space and the kinematics. A motion modeling was carried on the parallel platform, and establishes a coordinate system in the model. Then the rotation matrix was used to identify the relationship between the platform and the rock. So the coordinates of four platforms hinges which relative to the rack are deduced. Based on the relationship between these coordinates and the length of bars, we can get some kinematics equations of the workplace. Eventually the direct kinematics solutions of the parallel platform can be obtained.Secondly, carry on a research on the rigidity of the platform. Research about the load capacity,kinetics,strange configuration of the few degrees of freedom parallel machine has a big relation with rigidity of the platform. And it has a vital significance to research the machinery rigidity. This paper will establish a matrix equation of platform's rigidity, which could analyze the rigidity of the platform and the construction parameter's influence to rigidity.Finally, this paper will make a simulation of the entity to the platform. The movement of the parallel platform is a space motion. Calculate its kinematics is complicated and its workspace is difficult to imagine. So, it is necessary to establish a suitable model to simulation. That can make the machinery's movement visualized. Through the simulation we can see the model characteristic and movement characteristic of the machinery or whether there is interference about the machinery before the platform was made. Then the error could be checked in the designed, this can cut down the cost of research and produce. This paper will through PRO/E establish the part model of platform, and assemble the machinery and definition the restriction condition in ADAMS. Then use the data which achieved form kinematics analyzes to drive the machinery. And then complete the simulation of the platform.