Title: Zero magnitude error tracking control for servo system with extremely low-resolution digital encoder
Authors: Zhenyu Zhang; Nejat Olgac
Addresses: Servo Department, Western Digital Corporation, Irvine, CA, 92614, USA ' Department of Mechanical Engineering, University of Connecticut, Storrs, CT, 06269-3139, USA
Abstract: Harmonic magnitude control presents no particular difficulty when it uses appropriate sensors. The size, costs and accessibility of technology of these hardware may, however, severely constrain the capabilities in particular applications. Very commonly used extremely low-resolution encoders, for instance, present two complications: 1) large quantisation errors at and between two successive measurements; 2) stochasticity of actual amplitude given the desired discrete encoder readings. This paper proposes a method which enables accurate peak-to-peak stroke control when extremely low-resolution encoder is utilised. Essentially, it treats a stochastic stroke control problem by converting it into a deterministic one. The proposed control strategy consists of a two-stage tuning: 1) coarse tuning which results in desired encoder readings in peak-to-peak swings; 2) fine tuning which adapts the control gains to achieve the actual peak-to-peak stroke based on the derived deterministic relationships between the amplitude and encoder readings. Simulations and experiments are provided to validate the proposed method.
Keywords: extremely low-resolution digital encoder; zero magnitude error tracking; servo control; intra-cytoplasmic sperm injection; ICSI.
International Journal of Mechatronics and Manufacturing Systems, 2017 Vol.10 No.4, pp.355 - 373
Received: 01 Apr 2017
Accepted: 02 Oct 2017
Published online: 22 Dec 2017 *