A high-precision positioning servo-controller using non-sinusoidal two-phase type PLL
Most servomechanisms use encoders whose output signals are 90 degrees phase-shifted sinusoidal waves for detecting angular position. These two-phase signals are not true sinusoidal waves and their distortion makes the positioning accuracy worsen. In this paper, the authors propose non-sinusoidal two-phase type PLL (Phase-Locked Loop) to increase positioning accuracy of servomechanisms. To obtain high-precision detection of angular position, an iterative learning method to compensate the wave distortion was tried, and a high-resolution and high-precision positioning controller that can use low-resolution encoders was obtained. This paper discusses the proposed method and gives experimental results. (C) 1999 Elsevier Science Ltd. All rights reserved.
positioning servomechanism pll (phase-locked loop) rotary encoder