| The free-form surface optical component has the advantages of improving theperformance of optical system, reducing its bulk and weight. With the development ofscience and technology, its application has gradually expanded, whatever aerospace,national defense military and other cutting-edge technology development, or ordinaryoffice and the civilian products, the precise optical technology plays an important role in it.In medical optical camera, scanner, infrared night vision and other fields, it also has abroad application. The researchers at home and abroad generally believed that the diamondturning based on fast tool servo (FTS) is one of the most promising methods for theconstruction of free-form surface optical component.FTS has developed from the single-DOF stage to the process of multi-DOF stage. Inview of the processing limitations of the single-DOF FTS, it can only move in onedirection and can only meet the constant feed toolpath for the error compensation.Therefore, on the basis of the single-DOF FTS, it needs to develop the multi-DOF FTS tomeet the machining for complex surface component. Multi-DOF FTS can achieve activelycutting and multi-direction error compensation, and can solve the cutting force disturbance.Also it can realize the synchronization and coordination between the machine tool spindleand FTS device. Therefore, it is necessary to research on the Multi-DOF FTS device for itsprocessing capacity.This paper developed a new type of large stroke3-DOF linear FTS device forfree-form surface optical component.The device can realize its fast servo processing in thethree linear directions. The main content is summarized as below:Through completing the structure layout, and the selection of the driving and detectingelement for the FTS, it expounds its mechanism composition and working principle.Following the research and analysis for the size parameters of the flexible hinges of theguiding and decoupling mechanism, this paper completed the size design for the FTSdevice. A set of tool position adjusting mechanism is designed, and the whole assemblyinstructions is explained.Through the statics, coupling and dynamics analysis for FTS device, the analysisresults suggested that the FTS device can meet the design requirement and the couplingeffect is small. Basing on the analysis, this paper optimized the flexible hinge mechanism parameters of FTS device. Through the comparison and analysis, it greatly improved themechanical characteristic of the FTS device. The displacements in directions of Xã€Y and Zare0.50119mm,0.51092mm and0.53196mm. And the first natural frequency is morethan86HZ.This paper carried the experiment for the system identification of the3-DOF FTSdevice by using the System Identification Toolbox of MATLAB. By this method, we getthe control model of the FTS device. The identification accuracies in three directions aremore than95%, which have met the performance requirements. From the perspective ofrelative gain model, it is proved that the coupling effect is very small and the FTS can beseen as three independent movement systems. Basing on the study of the step response andstability analysis, this paper has designed three controllers for the FTS control model,including PID controller, feedforward+PID feedback controller and MRAC+PID controller.Finally using the step signal, the sine signal and the frequency sweep signal, this paper hastested and analyzed the three controllers and the results shows that the feedforward+PIDfeedback controller is more applicable to the FTS system. The research result on the fasttool servo has a certain significance of guidance in the actual production for free-formsurface optical component. |
