가상(假想) 히치점의 위치(位置)가 트랙터의 조향(操向) 안정성(安定性)에 미치는 영향(影響)(I) -가상(假想) 히치점의 안전(安全) 영역(領域)에 대한 이론적(理論的) 고찰(考察)-

Effects of VHP Positions on the Steering Stability of Agricultural Tractors(I) -Derivation of Safe Region for VHP Locations-

This study was conducted to investigate the influences of virtual hitch point (VHP) positions of a three-point hitch on the steering stability of agricultural tractors. The VHP locations were determined analytically from the linkage geometry and implement posture during the normal tillage operations. The maximum force applicable to the VHP was also determined under the given soil and power constraints. From these possible ranges of the VHP locations, a safe region for steering control was determined theoretically by using maximum applicable forces for the given tractor and implement combinations. With VHP positions within the safe region, tractor can maintain the minimum soil reaction forces, assumed 20% of the total tractor weight in this study, at the front wheels which is required for the steering control under the maximum traction conditions. This paper mainly concerns with mathematical developments for the determination of VHP locations and maximum forces applicable to the VHP for steering control. Experimental validation of the theory developed here follows as the second part of this study.