Electro-Hydraulic Feedforward Control Power Steering System for Trucks and Buses

Vehicle responsiveness to the driver's steering maneuvers and external turbulences caused by irregularities in the road surface and wind gusts are two opposing factors to be studied for better stability and controllability of vehicles. The cruising speeds of vehicles on freeways have been becoming higher, and wider physiological differences in the driving ability of drivers are appearing with the increase in elderly drivers. Therefore, to meet the requirements of higher cruising speeds and the expanding physiological differences between drivers, an electro-hydraulic feedforward control power steering system has been developed for trucks and buses. This is a parallel operating system consisting of a mechanical route and an electronic route, and improves vehicle responsiveness so as to absorb the physiological differences of drivers. The new system reduces the lateral acceleration, yawing and rolling angle during high-speed driving to the equivalent of a 40 km/h lower speed level than the actual vehicle speed. The improvement of vehicle response to external turbulences remains as the next subject to be studied.