Research On Control System Of Fast Tool Servo Based On Maxwell Normal Force

Optical freeform surfaces can not only improve the imaging quality of optical systems and offer new opportunities to optical designers,but also can simplify system configuration with fewer surfaces and lower mass.However,freeform surfaces are defined as surfaces with no axis of rotational invariance which may appear to have regular or irregular surface structures.It accordingly brings motion of more complexity and high frequency to the tool path when machining the surface and makes machining optical freeform surfaces more difficult.Fast tool servo(FTS)systems have high frequency response,flexible movement which can be used in machining optical surfaces to obtain high cutting qualities.Development of FTS with higher frequency,longer stroke and larger capacity make it easier to process complex freeform surfaces.The main works of the paper can be summarized as follows,1.FPGA+DSP control structure design was proposed based on the analysis of processing requirements.Peripheral device control and data read-write were implemented by FPGA while DSP worked on control algorithm and other data options.Designing of hardware and debugging of the control system along with data acquisition and lathe coordinates reading module were completed.The design bandwidth of hardware is at least 3KHz while the resolution is 5nm.2.The structure of Active Disturbance Rejection Control(ADRC)was designed and simulated by Simulink module.And parameters were set by Matlab and empirical formulas.Results showed that settling time is shortened from 46.0ms to 3.1ms by ADRC algorithm.3.The performances of FTS system working in closed-loop were tested by using the self-developed precision displacement platform.Results showed that the system has a resolution of 5nm with the closed-loop bandwidth 4KHz.Single-sine surface machining experiments verified that this system can satisfy the demanding of such machining tasks.