편경사 도로에서 6WD 미끄럼 조향 차량의 직선 주행제어 알고리즘에 관한 연구

Abstract

Many studies have been conducted on the vehicle driving control at supeelevated turning roads. Superelevated roads were built to ensure the stability of vehicles turning at a high speed. While there have been many studies that focused on manual steering vehicles, more studies on skid-steering vehicles are needed. As a skid-steering vehicle is unable to generate enough steering force on its front wheels, its steering stability becomes inferior at a super-elevated road to that of a manual-steering vehicle. The manual-steering vehicle is advantageous in counterbalancing the lateral force generated at a super-elevated road with its front wheels’ rotating force. The skid steering vehicle, however, turns on the road according to the difference between the inside and outside driving forces. Therefore, slips can occur while turning. More slips can occur to the vehicle because its body should be steered depending on the number of wheels slipping; therefore, the vehicle needs a stronger steering system. Depending on the angles of super-elevated roads, the lateral force that a vehicle receives acts to direct the disturbance, with which the vehicle is traveling straight. If a vehicle experiences a side slip due to some disturbance without input steering, there is a problem in the stability in steering the vehicle. In this study, the lateral force generated due to the superelevation of the road was determined using the vehicle dynamics at a steady state. The vehicle speed was then calculated using the obtained lateral force. The lateral acceleration was measured using a sensor, with which the speed was estimated. The estimated speed was further used to modify the formula of the vehicle dynamic model at a steady state; thus, the errors in the lateral direction were calculated. The aim of this approach was to reduce the difference between the path along which the reference model actually travelled and that along which the vehicle planned to travel. Basically, the vehicle was steered using the difference between the left and right torques, and the driving force was controlled by distributing the force equally to the tires. The desired moment and lateral speed were substituted to the equation for calculating the torque control, by which the vehicle could overcome the influence of the lateral force at a superelevated road, and could be stably driven.