Deadzone compensation control based on detection of micro flow rate in pilot stage of proportional directional valve

Zhengyu Lu; Junhui Zhang; Bing Xu; Di Wang; Qi Su; Jinyuan Qian; Geng Yang; Min Pan

doi:10.1016/j.isatra.2019.03.030

Deadzone compensation control based on detection of micro flow rate in pilot stage of proportional directional valve

ISA Trans. 2019 Nov:94:234-245. doi: 10.1016/j.isatra.2019.03.030. Epub 2019 Apr 2.

Authors

Zhengyu Lu¹, Junhui Zhang², Bing Xu³, Di Wang⁴, Qi Su⁵, Jinyuan Qian⁶, Geng Yang⁷, Min Pan⁸

Affiliations

¹ The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, No.38 Zheda Road, Hangzhou, 310027, China. Electronic address: luzhenyu@zju.edu.cn.
² The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, No.38 Zheda Road, Hangzhou, 310027, China. Electronic address: benzjh@zju.edu.cn.
³ The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, No.38 Zheda Road, Hangzhou, 310027, China. Electronic address: bxu@zju.edu.cn.
⁴ The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, No.38 Zheda Road, Hangzhou, 310027, China. Electronic address: di_wang@zju.edu.cn.
⁵ The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, No.38 Zheda Road, Hangzhou, 310027, China. Electronic address: 06jxlsq@zju.edu.cn.
⁶ Institute of Process Equipment, College of Energy Engineering, Zhejiang University, No.38 Zheda Road, Hangzhou, 310027, China. Electronic address: qianjy@zju.edu.cn.
⁷ The State Key Laboratory of Fluid Power and Mechatronic Systems, Zhejiang University, No.38 Zheda Road, Hangzhou, 310027, China. Electronic address: yanggeng@zju.edu.cn.
⁸ The Centre for Power Transmission and Motion Control, University of Bath, Claverton Down, Bath, North East Somerset BA2 7AY, United Kingdom. Electronic address: M.Pan@bath.ac.uk.

PMID: 30975457
DOI: 10.1016/j.isatra.2019.03.030

Abstract

The pilot operated proportional directional valves (POPDVs) with a flow rate ranging from 100 to 1000 L/min are widely used in electro-hydraulic systems (EHSs). The deadzone of the pilot stage valve and its control compensation could significantly affect the position control performance for the main stage valve that could directly affect dynamics of EHSs In this paper, it is concluded that micro flow rates exist at the intermediate position of the valve based on the analysis of the continuity equation of the flow in the control chamber of the pilot stage. The micro flow rate is helpful to eliminate the discontinuity and unsmooth domain in the previous inverse deadzone compensation function. An improved deadzone detection method is proposed to calibrate the pilot valve flow characteristics which include the micro flow rate. This new method avoids the threshold selection of the main valve spool displacement which affects the detected deadzone values. Its detection processes are realized based on the pilot flow rate characterized by the speed of the main valve spool and the pilot valve displacement characterized by the solenoid current. The deadzone compensation control strategy based on the improved deadzone detection method is also designed. The experimental results using the steady-state position tracking and sinusoidal position tracking methods are verified. It is concluded that the tracking accuracy of the main valve spool position is effectively improved with this control strategy.

Keywords: Deadzone compensation; Deadzone detection; Micro flow rate; Pilot operated; Position control; Proportional directional valve.