Study On Climbing Performance Analysis And Yaw Moment Control Of Articulated Tracked Vehicles

Articulated tracked vehicles have good passability in swamps,forests,and wading roads.They are also called all-terrain vehicles and have excellent climbing and obstacle crossing capabilities.In addition,compared with traditional forest fire trucks,the large load capacity of articulated tracked vehicles can carry more water and rescue materials during operation,improving continuous combat capabilities,and have great significance for forest fire prevention and control.This paper conducts a theoretical analysis of the climbing performance of the 30 t articulated tracked vehicle,and then conducts experimental verification through multi-body dynamics simulation software Recurdyn,and finally studies the yaw moment control of the vehicle.First of all,the virtual prototype model of the whole vehicle is built based on Pro/E,and the crucial system of the articulated fire truck is introduced followingly.Based on the research of track ground mechanics,the classical mechanics theory is applied to the dynamic analysis of the climbing process of the articulated tracked vehicles,and the maximum climbing degree of the vehicle when the vehicle is running on the slope laterally and longitudinally when fully loaded is calculated;Taking into account the fire truck’s special nature,the change of the liquid volume when the following vehicle is not fully loaded will cause its cross-sectional shape to change,which will affect the position of the center of mass and thus affect the climbing performance of the vehicle.Therefore,the cross-sectional shape is divided into triangles,parallelograms,and trapezoids to be discussed separately,and the maximum climbing degree of the vehicle is calculated when driving sideways on a slope;The working condition of climbing A-shaped ramp is selected to simulate the vehicle passing through the soil slope between the forests,due to the hinge mechanism when passing the highest point of the A-shaped slope,only a pair of front and rear wheels touch the ground.At this time,the hinge mechanism receives the greatest force and may lose stability.Therefore,the most dangerous vehicle posture is selected,calculating the centroid coordinates of the front and rear vehicles,and then the force of the articulated mechanism is calculated through the dynamic model.The result shows that the vehicle can pass the sharp point of the A-shaped ramp with a gradient angle of 20 deg stably.In order to verify the results of the theoretical analysis of the climbing performance in the third chapter,simulates the climbing process through the software Recurdyn.First,construct the slope pavement files with the same slope angle and different soil conditions,select the vehicle roll angle as the stability evaluation index to analyze the simulation results,and compare the impact of different soils on the vehicle climbing performance.Second,construct pavement files with the same soil conditions but different slope angles to study the impact of slope angles on vehicle climbing performance.Aiming at the problem of vehicle rollover caused by driving deviation when the slope angle increases in the simulation results,a PID controller is used for differential control and a rollover prevention control scheme is proposed.Finally,a dynamic simulation of the process of the vehicle passing the A-shaped slope with a gradient angle of 20 degrees as an example verifies the accuracy of the theoretical model.In order to study the yaw stability,establish a two-degree-of-freedom steering dynamics model,design a "feedforward + feedback" controller based on LQR,perform direct yaw moment control through Matlab,and select angle step input conditions for simulation Experiments verify the effect of the controller,and the results show that after the yaw moment is controlled,the vehicle can quickly stabilize with a smaller overshoot,which effectively improves the safety and stability of driving.