Multi-axle vehicle as well as electro-hydraulic servo steering system and steering control method thereof

The invention discloses an electro-hydraulic servo steering system and a steering control method of a multi-axle vehicle and the multi-axle vehicle with the steering system. The electro-hydraulic servo steering system comprises a hydraulic steering system and an electric control system, wherein the hydraulic steering system comprises a variable pump, power-assisted steering oil cylinders and a servo proportional valve; the power-assisted steering oil cylinders are at least arranged on various rear steering axles; the servo proportional valve is used for controlling the trend of an oil path and the flow adjustment; the electronic control system comprises a lower controller and an upper controller; the lower controller is in signal connection with the servo proportional valve on each steering axle and forms closed loop control; and the upper controller is used for calculating a target corner of each steering axle according to a first axle corner and a steering mode. According to the invention, the electronic control systems of a two-stage controller is optimized, so that the servo proportional valve and the lower controller form a small closed loop; the lower controller with high frequency response is matched with the servo proportional valve to ensure the precision; and a programmable logic controller is used for main calculation work and transmitting a corner instruction to the each lower controller. The invention has the advantages of simple structural arrangement, safety, reliability and favorable control stability.