Research Of Gantry Crane Digital-analog Hybrid Hydraulic Steering System Based On High-speed On-off Valve

900T rubber-tyred gantry crane is the key equipment for concrete box-beammanufacturing and installation in the high-speed railway construction, and it has largelifting capacity, strong function, high mechanization and reliability. Compared with thetraditional gantry crane, it turned more flexibly and can finish straight, transverse,oblique, around the center and the "eight" type steering mode. Steering mechanism isthe important part of gantry crane and the key part which is distinguished from the railgantry crane.The previous gantry crane hydraulic steering control system adopts electro-hydraulic proportional control technology, and this mode can independently andaccurately adjust the speed and position of each wheel-group, then guarantee thewheel-group’s steering Synchronization. The digital-analog hybrid control hydraulicsteering system based on high-speed on-off valve of the gantry crane is improved onthe basis of the original system, which use one valve and two or more high-speed on-off valve to control two or more steering driving cylinders. In the new control scheme,the digital valve can be directly control by the digital quantity of computer interface,and the production process of digital valve is relatively simple, the price advantage isobvious, and it works stabley and reliably.Through the theoretical calculation, obtain the steering wheel-group’ssynchronous curve in ideal “eight" shape steering mode, then use AMESim software tomake model and simulation on the hydraulic steering control system, in the digital-analog hybrid control method, synchronous steering curves are obtained in simulationunder different on-off valve frequencies, then compare the emulational curve with thetheoretical curve. Through the CATIA make finite element analysis of steeringmechanism to check the strength and verify the feasibility of the digital-analog hybrid control scheme, finally design the electric control system and make experimentalplatform for debugging test. The application research on digital-analog hybrid controlscheme is of high significance for the similar control system, and has a very hightheoretical and practical value for multi-wheel synchronous steering system as well aschina’s railway traffic modernization.