| Summary: | 碩士 === 中原大學 === 光機電及資電控產業研發碩士專班 === 98 === Abstract
As the electronic products are gotten smaller and the quantity of output is to be requested, the trend of the needs for speed and accuracy is more precise. Therefore, upgrading the speed and the accuracy of contour error on tracking control has become an important point. However, the process method of traditional CNC machines only can support line and circular interpolations but cannot accept motion along curve and circular paths. Therefore, the traditional CNC machines have to rely on CAM, a method to generate the NC code called G-code by approximating many tiny linear or circular segments, to plan the cutter paths. But this approximating method requires higher transmission speed; it also occupies huge memory capacity and makes the velocity of machine tool discontinuous, in order to difficultly meet the requirement of high speed and better precision.
In the thesis, the main purpose is to track the path, the nonlinear characteristic in a servomechanical system may pose performance limitations. Friction is an important factor which affect the precision of positioning. A mathematical model of a 3-Axis Engraving Machine with IP controller has been established with consideration of friction effects, and consider the reference trajectory for the NURBS (Non-uniform rational b-splines) path. Contour error refers to the lack of coordination on multi-axis motion and errors generation between motion path and pre-set path. In order to solve the contour error using cross-coupled control of the compensation operation, and increase the coordination of the axis to reduce the contour error. Combinations in such a controller to replace the traditional calculating the controller parameters way of try and error. Focus on path tracking in three-dimensional space. Moreover, through 3-Axis Engraving Machine actually make the finished product and contour error is about 0.2mm with coordinate measuring machine.
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