High-linear digital hydraulic valve control by an equal coded valve system and novel switching schemes

This study proposes a novel digital hydraulic valve system using multiple equal size on/off valves and a circulating switching control, with an aim to increase the resolution and the linearity of the digital hydraulic valve systems. The solution is founded on the equal coded valve system concept which represents a recent development in the digital hydraulic valve technology. The circulating switching control algorithm is used to overcome nonlinearities occurring in the typical non-circulating switching control and to decrease the operating frequency of single on/off valves. As a result, a substantial improvement in tracking control performance is demonstrated with 8 + 8 parallel connected valves. The results verify that compact, robust, and high-performance valve control can be realized.