Adaptive online correction and interpolation of quadrature encoder signals using radial basis functions

This paper considers the development of an adaptive online approach for the correction and interpolation of quadrature encoder signals, suitable for application to precision motion control systems. It is based on the use of a two-stage double-layered radial basis function (RBF) neural network. The first RBF stage is used to adaptively correct for the imperfections in the encoder signals such as mean, phase offsets, amplitude deviation and waveform distortion. The second RBF stage serves as the inferencing machine to adaptively map the quadrature encoder signals to higher order sinusoids, thus, enabling intermediate positions to be derived. Experimental and simulation results are provided to verify the effectiveness of the RBF approach.

[1]  D. Broomhead,et al.  Radial Basis Functions, Multi-Variable Functional Interpolation and Adaptive Networks , 1988 .

[2]  Jacek M. Zurada,et al.  Introduction to artificial neural systems , 1992 .

[3]  A. M. Madni,et al.  An absolute high performance, self calibrating optical rotary positioning system , 2001, 2001 IEEE Aerospace Conference Proceedings (Cat. No.01TH8542).

[4]  Philip D. Wasserman,et al.  Neural computing - theory and practice , 1989 .

[5]  N. Cheung.  An innovative method to increase the resolution of optical encoders in motion servo systems , 1999, Proceedings of the IEEE 1999 International Conference on Power Electronics and Drive Systems. PEDS'99 (Cat. No.99TH8475).

[6]  D. Signorini,et al.  Neural networks , 1995, The Lancet.

[7]  Andrew R. Webb,et al.  Functional approximation by feed-forward networks: a least-squares approach to generalization , 1994, IEEE Trans. Neural Networks.

[8]  Simon Haykin,et al.  Neural Networks: A Comprehensive Foundation , 1998 .

[9]  Kok Kiong Tan,et al.  New interpolation method for quadrature encoder signals , 2002, IEEE Trans. Instrum. Meas..

[10]  Yoshihisa Suzuki,et al.  A method of improving the resolution and accuracy of rotary encoders using code compensation technique , 1991, [1991] Conference Record. IEEE Instrumentation and Measurement Technology Conference.

[11]  K. P. Birch,et al.  Optical fringe subdivision with nanometric accuracy , 1990 .

[12]  K. Watanabe,et al.  A hybrid digital and analog controller for DC and brushless servomotors , 1989, 6th IEEE Conference Record., Instrumentation and Measurement Technology Conference.

[13]  P L Heydemann,et al.  Determination and correction of quadrature fringe measurement errors in interferometers. , 1981, Applied optics.

[14]  J.R.R. Mayer,et al.  High-resolution of rotary encoder analog quadrature signals , 1994 .

[15]  K. Watanabe,et al.  A microstep controller of a DC servomotor , 1990, 7th IEEE Conference on Instrumentation and Measurement Technology.

[16]  Lennart Ljung,et al.  System Identification: Theory for the User , 1987 .

[17]  Hartmut Logemann,et al.  Multivariable feedback design : J. M. Maciejowski , 1991, Autom..

[18]  David S. Broomhead,et al.  Multivariable Functional Interpolation and Adaptive Networks , 1988, Complex Syst..