Research On Virtualassembly Method And System Implementation Of Pneumatic Gun Based On Virtual Reality

Pneumatic guns have long been a national security concern.It doesn’t use gunpowder to propel the warhead,but it can be powerful enough to be excited by the air pressure generated by the cylinder.The specific kinetic energy of the air gun muzzle is up to 300J/cm~2,200 times the standard for firearms in China.In recent years,there have been frequent smuggling cases of pneumatic air guns into China,and frequent reports of air gun crimes and injuries have seriously threatened people’s lives.Every year,Chinese customs officers seize a large number of air-powered guns smuggled into the country.To evade regulators,criminals began disassembling pneumatic guns into parts.Illegal elements use batch,break whole into parts of the gimmick smuggled into the country,the situation is extremely complex.In order to determine the nature of a gas-powered gun smuggling case,customs officers need to assemble the seized parts into a whole gun and test the specific kinetic energy of the gun.However,there are many kinds of pneumatic guns,which are difficult to identify,and the complex assembly process of guns requires a lot of labor cost and time cost for customs anti-smuggling personnel to learn,all of which bring challenges to the inspection,identification and control of pneumatic guns.In view of the wide variety of pneumatic guns,different kinds of pneumatic guns have different assembly processes.In order to improve the work efficiency and quality of customs personnel in assembly,this project developed a virtual assembly training system of pneumatic guns with strong immersion,natural interaction and easy access.Specific work includes:(1)High precision 3D reconstruction of pneumatic gun parts:according to the appearance characteristics and complexity of pneumatic gun parts,they can be divided into standard parts,regular parts and complex parts.The standard parts were modeled by Solid Works mechanical modeling software,the regular parts were reconstructed by plane structured light scanning technology,and the complex parts were reconstructed by line laser scanning technology.3D scanning reverse reconstruction is an important part of the construction of immersive virtual environment.The accuracy of the above three 3D component modeling methods decreases successively.Therefore,parts are divided into complex parts only if standard modeling is not possible.In this thesis,after evaluating and classifying different types of parts,different 3D reconstruction methods are used for reverse modeling,which not only ensures the modeling accuracy but also improves the modeling speed.(2)Human-computer interaction method research based on Leap Motion and Unity3D:In order to further improve the sense of immersion in the virtual assembly training system of aerodynamic guns,the development of virtual reality hardware technology is fully investigated.Several virtual reality headsets and human-computer interaction devices on the market are compared.After comparing the pros and cons of interactive devices like virtual gloves,Kinect and Leap Motion,as well as their compatibility with head-mounted displays like Pimax and Htc Vive,Finally,the Pimax Vision8KX head-mounted display and the Leap Motion controller’s Ultraleap Stereo IR 170 sensor are selected for virtual reality assembly hardware equipment.Human-computer interaction focuses on how to use the Leap Motion controller to carry out the immersive grasping and assembly experience.Some improvements are made on the basis of the traditional interactive methods,and the sequence of the virtual assembly of the pneumatic gun is planned,and the steps of the real assembly are completely copied into the virtual assembly.(3)Design and implementation of VR assembly system:a virtual assembly system with low coupling degree and strong expansibility is designed and developed according to users’requirements and existing equipment.The system consists of immersive virtual environment,model database,teaching module and training evaluation module.The main function of the virtual assembly system is to import high-precision 3D aerodynamic gun model and help the staff to complete the teaching operation of virtual assembly and the training and evaluation after the virtual assembly.Finally,the feasibility of the interactive virtual assembly training system for pneumatic gun is verified.