Design And Trafficability Analysis Of A Novel Articulated Chassis For Forestry

The terrain in China’s forest areas is mainly mountainous and hilly,with rugged roads and complex site conditions.Affected by the terrain environment,it is difficult for agricultural and forestry mechanization equipment to enter the operating environment without suitable power chassis.Therefore,high requirements are put forward for the terrain adaptability of mechanical power chassis.To achieve the goal of mechanization,automation,and intelligence of forestry equipment,it is necessary to take the lead in solving the problem of "entering and operating in mountainous areas" of equipment,that is,the issue of equipment chassis.When the power chassis of general forest machinery is working on uneven terrains,the power is often insufficient because of the poor traction between the wheels and the road surface,which affects the driving operation of the entire vehicle.This article designs a novel articulated chassis for forestry,which has good road surface profiling.The specific research content of this article are as follows:(1)Design of a chassis for forestry.Based on the principle of multi degree of freedom pavement profiling,a three degree of freedom articulated structure with active pitch function is designed by analyzing and combining the working principles of traditional three degree of freedom articulated structure and inclined crank rocker mechanism.Applying this articulated structure to a 4-wheel forest chassis,the articulated structure can innovatively achieve active pitch,active deflection,and passive torsion functions of the front and rear frames;At the same time,the driving force of the novel articulated chassis for forestry is calculated to provide a reference for the selection of motors.(2)Modeling analysis of a three degree of freedom articulated structure with active pitch function.Expounding the working principle of the articulated structure with three degrees of freedom,simplifying the articulated structure model and carrying out parametric modeling,establishing its kinematics and dynamics models,and solving the mathematical model of the relationship between the rotation angle of the rotary rod and the pitch angle of the front and rear frames;Quantitative relationship between output torque of the servo motor and angular acceleration and angle of the end pitching plate is obtained;The profile index parameters of the novel articulated chassis for forestry driving on uneven road surface are proposed and calculated.(3)Profile analysis and simulation experiment of slope obstacle modeling for the novel articulated chassis for forestry.Conduct obstacle crossing analysis on the extreme working conditions encountered by the chassis in the forest environment,and simplify the complex terrain environment in the forest area into three types of slope obstacle working conditions(slope,steep convex,and unilateral obstacle),analyzing the profiling principle of the chassis when crossing slope,steep convex,and unilateral obstacle,and the corresponding obstacle crossing strategy is proposed;Simultaneously establish three conditions in ADAMS and conduct simulation experiments.By analyzing the changes in parameters such as the height of the center of mass and the contact force between the wheels and the road surface,the climbing and obstacle crossing performance of the novel articulated chassis for forestry and the ordinary4-wheel chassis are compared.The results indicate that the novel articulated chassis for forestry has better road surface profiling ability than the ordinary chassis,and can smoothly pass through obstacles.(4)Based on the LQR algorithm,control strategy and simulation experiment of profile passing through convex(concave)road surface of the chassis.Unlike the extreme working conditions of slope obstacles,roads in forest areas mainly have convex(concave)undulating surfaces,Based on the variation of curvature radius of convex(concave)road surface,the novel articulated chassis for forestry profile control strategy for convex(concave)road surface is proposed,and a joint simulation experiment is established under given curvature conditions to verify the effectiveness of the profile control strategy.Firstly,profiling analysis is conducted on the chassis through convex(concave)road surfaces,and corresponding profiling control strategies are proposed;Secondly,a controller model based on angle tracking error is constructed according to the principle of LQR algorithm,so that the tracking error of the entire control system tends to zero and reaches a stable equilibrium state;Then,a convex(concave)road surface with known curvature radius is established in ADAMS,and a control strategy of building a joint simulation model is adopted to ensure that the chassis can smoothly climb over obstacles;Finally,analyze the simulation experimental results to verify the effectiveness of the proposed profiling control strategy and LQR controller.