Abstract
As industrial automation becomes widely used nowadays, prices of machine tools are natural to be decreasing for higher competitiveness. That is, for one thing, demands of higher accuracy and lower cost parts as feedback system in a machine are rising rapidly in following years. Without some key techniques, domestic suppliers still fall behind in offering such kind of products that are able to improve precision of feedback systems and additionally help suppliers stretch profit margins. In respect of magnetic encoder manufacturing, it has been proved that some domestic encoder-supplier has an ability to minimize the pole pitch deviation and unbalance magnetic field like other foreign manufacturers. Even though the qualities of locally made encoders are almost identical to those products other brands offer, it still exists a huge difference between the local made and the other brand-trusted measuring system in performance of resolution, measuring accuracy and tolerance so that it is limited to let market strategies go further with extended industrial applications. This research focused on the development of real-time signal correcting applied on quadrature signals system such as magnetic and optical encoders. Considering the imperfection of signals in quadrature, amplitude deviation, phase shifts and random noises, which could cause inaccurate interpolation on fine, scale positioning, this approach of signal correction based on phase-lock-loop are designed to extract phases of a pair of input signals and regenerate the corresponding signals to alleviate uncertainty of position analyzing. In a first place, regardless of real-time calculation error, a prototype of signal correction was constructed in Simulink to simulate the transient response of parameters modulation with real phase A and B data sampled from oscilloscope. In this process, optimal parameter self-adjustment mechanism was built to make a trade-off between time lag and noise reduction. Next, the verified construction was implemented in LabVIEW FPGA to test the performance of real-time compensation, system repeatability and noises reduction with different sensors applied. Experimental data indicated that the aim of increasing resolution and keeping nice repeatability as other brands’ products was reached through the proposed method.