ObjectiveThe obstacle crossing performance and adaptability to different terrain are most important factors for the technical characteristics of the chassis that is the key part of forestry equipment, also they are the key reasons to decide whether the forestry equipment could work in the forest. Since the typical plantations in our country have many short obstacles and gullies, the obstacle crossing performance and adaptability of traditional chassis are not good enough to work in the complex terrain.

MethodFor improving the obstacle crossing performance, a method based on D-H theory was used to establish a kinematics model for a new type of six-wheeled-leg forestry chassis with levelling initiative gait. By space geometry coordinates transformation method, single-cylinder wheeled-legs mechanism was compared with double-cylinder wheeled-legs mechanism in obstacle crossing ability.

ResultIt was concluded that the obstacle crossing ability of double-cylinder wheeled-legs mechanism was always greater than single-cylinder wheeled-legs mechanism. The optimum arrangement of double-cylinder position was achieved with the D-H kinematics solution method. In contrast to prototype test, the highest obstacle crossing numerical similarities of theory analysis and simulation were 99.7% and 97.8%, respectively. The obstacle crossing height of wheeled-legs of chassis was much better than before, and could reach 285.9mm. So it is completely suitable for the application in the field of forestry and a typical unknown terrain. The correctness of the theoretical research method was validated.

ConclusionThis paper provides theory basis for the research on the double-cylinder wheeled-legs mechanism motion characteristics, the obstacle crossing ability of chassis, and the large-scale development and application of intelligent forestry mechanical chassis.