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 s ignals are not true sinusoidal waves and their distortion makes the positio ning accuracy worsen. In this paper, the authors propose non-sinusoidal two -phase type PLL (Phase-Locked Loop) to increase positioning accuracy of ser vomechanisms. To obtain high-precision detection of angular position, an it erative 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 r eserved.