Application research of electro-hydraulic servo steering system based on independent metering system

Electro-hydraulic servo steering system (EHSSS) is a key technology for heavy vehicles. The traditional EHSSS has high control accuracy but low energy efficiency. Therefore, this paper proposes a novel EHSSS based on independent metering system, which can combine high steering accuracy with high energy efficiency. Firstly, two servo-proportional valves are used to reduce the throttling loss at the meter-out orifice. The servo motor pump is used to keep the pump supply pressure at a low value. Then, to ensure high steering accuracy, a position-velocity-pressure combined control strategy is proposed for easy engineering practice. And a smooth switching strategy is proposed to achieve smooth mode switching at high frequency. Finally, the effectiveness of the proposed method is verified by experiments. The experimental comparison results show that the proposed method can achieve the same accuracy as the valve-controlled steering system with less energy, and can realize smooth mode switching.