Cross-Coupled Fuzzy Logic Control for Biaxial Servomechanisms

[[abstract]]This paper presents a design and implementation case study that focuses on contour of a biaxial CNC machine tools. However, it is difficult to obtain an accurate nonlinear mathematical model of cross-coupled multi-axis machine tools. In this paper we investigate an alternative to conventional approaches where we employ cross-coupled fuzzy logic controllers for improving contouring accuracy of multi-axis CNC machine tools. A new fuzzy rule-generated method which is based on a performance index of the contour error obtained from an online estimation algorithm is proposed. Experimental results have shown that the desired contouring accuracy can be achieved, and the proposed approach outperforms over uncoupled approaches. In conventional control, increasing contour feedrate for productivity may result in larger contour errors. However, the experimental results have shown that the performance of the proposed approach is still quite good with the increasing contour feedrate.

Cross-coupled fuzzy logic control for multiaxis machine tools

[[abstract]]This paper presents a design and implementation case study that focuses on contour control of a biaxial CNC machine tools. Since, it is difficult to obtain an accurate nonlinear mathematical model of cross-coupled multiaxis machine tools, here we investigate an alternative to conventional approaches where we employ crosscoupled fuzzy logic controllers for improving the contouring accuracy of multiaxis CNC machine tools. A new fuzzy rule-generated method which is based on a performance index of the contour error obtained from an on-line estimation algorithm is proposed. An adapted output scale factor is adopted to improve the system performance. Experimental results have shown that the desired contouring accuracy can be achieved, and the proposed approach outperforms over uncoupled approaches. In conventional control, increasing contour feedrate for productivity may result in larger contour errors. However, the experimental results have shown that the performance of the proposed approach is still quite good with increasing contour feedrate.

A study of backlash on the motion accuracy of CNC lathes

[[abstract]]In this paper, an analytical solution is reported to explain the experimentally observed backlash behaviors on the motion accuracy of CNC lathes. It is found that backlash occurs when the feed direction is reversed. Due to the imperfect transient response of the driving mechanism, not only the static backlash error but also the dynamic backlash error is generated on the contouring profile. A simple control strategy is then developed to reduce the static and dynamic backlash errors. Computational simulations and experimental results are presented to illustrate the proposed method.