Adaptive robust tracking control of a proportional pressure-reducing valve with dead zone and hysteresis

Abstract

Proportional pressure-reducing valves (PPRVs) are typical proportional valves widely used in the hydraulic industry because they are inexpensive, not prone to malfunction, easy to handle and service. However, they suffer from performance degradations due to the existence of dead zone and hysteresis. An effective control method should be developed to improve the performance of PPRVs, as their characteristics significantly affect the entire hydraulic system. This article focuses on high-performance pressure-tracking control of a PPRV with dead zone and hysteresis. A non-linear phenomenological model is put forward to describe the characteristics of dead zone and hysteresis, as well as dynamic behaviour of the PPRV. The proposed phenomenological model is described using an ideal third-order linear model preceded by a dead zone term and a hysteresis term. To handle parameter uncertainties and uncertain non-linearities in the phenomenological model, an adaptive robust controller is synthesized without constructing a dead zone inverse or hysteresis inverse. The developed controller guarantees bounded pressure-tracking error and precise steady-state tracking accuracy. Comparative simulations and experiments with different pressure trajectories are carried out to verify the effectiveness of the proposed method. Both simulation and experimental results show that with the proposed adaptive robust control (ARC) approach, the non-linear dead zone and hysteresis may be well compensated and improved pressure-tracking performance achieved.