Simulations were conducted adopting planar motion analysis to clarify the mechanism of Jack-knifing, which is a behavior to articulated vehicles. An articulated vehicle was modeled with a Three-wheel vehicle model, the dynamic characteristics of the hitch angle with respect to the steering angle of the front wheels were derived in numerical analysis, and the stability was investigated for changes in the front-wheel steering angle, initial vehicle speed, traction coefficient, and trailer mass. Pole-zero maps and frequency responses were obtained for analysis of the stability of the articulated vehicle. An increase in the trailer mass causes the poles of the system to approach the origin, which deteriorates stability. And an increase in vehicle speed also deteriorates stability, but the vibration decreases.

As the first step in realizing autonomous hitching of agricultural implements, a hitch coupler prototype was developed to allow quick implement hitching and to eliminate manual operations such as coupling of hydraulic/electric connectors. Hitching tests conducted on concrete and grassland surfaces revealed that the position and angular tolerance of the hitch coupler at the final tractor-implement alignment were approximately 3-5 cm and 5 °, respectively. When the hitch coupler was optimally positioned between the tractor and implement, it could attach different implements with implement movement of less than 2.3 cm and 2.1 °. This also considerably reduced the hitching/unhitching time by up to 85.7 % compared with that of the conventional methods.