Research On Harvesting Performance And Harvesting Behavior Simulation Of Harvester In Virtual Environment

With the deepening of the degree of agricultural mechanization in China,the performance requirements of agricultural harvesters or agricultural tractors were getting higher and higher.In order to promote the standardization and digitization of agricultural machinery development in China,the combination of agricultural machinery technology and virtual reality simulation technology is a big trend.When harvesting crops,it would be affected by harvest time,weather and other factors;when climbing the agricultural vehicle,it would be limited by the slope site;the gearbox oil would also be difficult to observe the oil in real time.Those extended the development cycle.Therefore,this paper took large agricultural harvesters and agricultural tractors as the object,and combined with the efficiency of the physics engine of Unity3 D virtual engine software,and deeply studied the simulation modeling technology of agricultural natural virtual environment,the climbing performance of harvesters and the display of harvesting behavior.Simulation,as well as lubrication simulation of standard cylindrical spur gears,was designed to advance the research process of agricultural machinery for digital simulation.Based on the Unity3 D virtual reality engine,this paper used virtual reality technology to deeply study the rigid body collision,vehicle driving,gravity and other force effects in the 3D virtual environment.The vehicle control,crop harvesting simulation and smooth particle fluid in the virtual environment.The kinetic method simulated the lubricant in the gearbox.The details are as follows:(1)For the problem of harvesting the crops in the virtual scene,the corn mining crops were taken as an example to show the mechanical interaction process between the harvester and the crop corn based on virtual reality technology.The method simulated the sky in the virtual environment by using the skybox and particle system in Unity3 D,and used the CAD/CAM system software to complete the modeling of the agricultural harvester and uses 3ds Max and Unity3 D software to model the trees,grass and other plants.In order to further simulate the virtual agricultural natural environment and meet the requirements of virtual reality immersion,this paper build a perspective control rule based on Unity3 D virtual environment,and mapped the environment model with Shader Lab language,and controlled the camera to virtual roaming realize in the agricultural virtual environment,and controlled the harvester to complete the harvest simulation.(2)In order to simulate the climbing behavior of agricultural tractors in virtual environment,analyze the process of climbing the agricultural tractor under driving force,design the Phys X physics engine embedded in the vehicle control based on Unity3 D software,and use the motor of the Wheel Collider component.The torque provided the vehicle driving force,and the large-scale agricultural tractor was used as an example to carry out the climbing simulation.Firstly,the tractor simulation model was constructed,and the rear axle transmission was analyzed.The corresponding motor torque was added to the drive wheel to meet the actual motion simulation requirements.Then,the factors and parameters of different road surface impact climbing were collected and integrated into the virtual environment.In the ramp,a slope with adjustable slope was constructed.Finally,the vehicle slope verification test and vehicle stability performance test were designed to obtain a data line chart for data analysis.In this paper,after the drive,the body mass was 3000 kg,the wheel drive torque was 10000N/m,and the ground friction factor was 0.54,the climbing simulation was shown.It is concluded that the agricultural tractor can only climb a steep slope with a gradient of 10 degrees.(3)In order to promote the gear squeezing simulation of the gearbox in agricultural vehicles,the smooth particle hydrodynamics method was used to simulate the motion law of liquid by using the process of interaction of a large number of fluid particles in the virtual environment.Select the appropriate smooth kernel function,obtain the real-time acceleration of each fluid particle simulated in the virtual scene by the NS equation,and then use the Metaball technology to realize the liquid rendering effect in Unity3 D software,add the rotating gear to simulate the lubrication effect,and obtain the gear and fluid.The physical calculation of each frame before the particle collides was approximately 76 ms per frame.Once the gear participates in the collision,the CPU consumption was greatly increased,roughly 647 ms per frame.