FORECASTING COMPENSATORY CONTROL IN MACHINING FLATNESS (TOOL, ACCURACY, MICROCOMPUTER, TIME SERIES)

A new approach parallel to adaptive control called FCC (Forecasting Compensatory Control), which can facilitate in principle the compensation of deterministic as well as stochastic error components and ultimately has the potential of greatly increasing accuracy of metal cutting machines, has been recently developed. The basic logic of this method is based on in-process error measurement, stochastic modeling, and forecasting compensatory control.;Through the application of the proposed FCC system to on-line cutting experiments, the workpiece flatness error can be reduced up to 80% during machining, which demonstrates the feasibility of the proposed method.;In this research, FCC scheme was implemented to improve machining flatness error in the case of three dimensional prismatic workpieces in an end-milling operation. The proposed FCC system for the flatness control consists of an in-process flatness error measurement system, a precision hydraulic positioning servo system, and a digital microcomputer system. A solid basis for stochastic modeling and control for flatness accuracy was established through review studies on the mathematical foundations of the FCC control algorithm. A laser-based in-process flatness error measurement system was developed for active error sensing during a real machining operation. An in-process flatness error evaluation method was proposed by defining an unique in-process reference plane for on-line application. Preliminary off-line controller simulations were performed to study the effectiveness of the developed FCC system.