Research Of Key Technologies In Immersion Virtual Assembly Process Simulation

Virtual assembly process simulation based on virtual reality technology is a technology with great application potential,but it still lacks mature human-computer interaction and constraint information feedback methods.In this paper,two key simulation technologies of virtual hand interaction and assembly placement in virtual assembly are studied,implemented and validated.Relevant research results have good theoretical significance and application value for improving the practicability of virtual assembly technology at this stage.The main research results and work contents of this paper are as follows:(1)A virtual hand interaction system is developed.The geometric model of virtual hand is established based on the physiological characteristics of human hand and the motion principle of finger joints.The method of data collation based on data glove is studied and the motion mapping from hand to virtual hand is realized.A method based on virtual spring and finger segment collider to prevent finger and object from penetrating each other is studied,and the physical model of virtual hand is established by the Unity.Based on the collision detection information of physical model,heuristic grabbing rules of single and double hands and control methods for the transformation of grabbed objects are formulated.(2)A virtual assembly placement method based on part transformation information is established.A description method of part transformation based on PI and the OI is defined,and parts are divided into custom type,symmetry type and thread type.Based on the observation of the conventional assembly operation process,a virtual assembly placement method consisting of three stages of navigation motion,i.e.PI constraint,OI constraint and position coincidence,is proposed,and corresponding navigation trigger rules and navigation motion calculation methods are formulated for each part type.The motion relationship between virtual hand system and parts to be assembled,the distinguishing method between normal interference and abnormal interference,and the processing method of interchangeable parts are studied.(3)A reusable virtual assembly plugin was developed.A virtual assembly plugin is developed by the Unity,which consists of virtual hand preset object and four basic components: assembly message center,assembly placement actuator,part assembly information and interchange message exchanger.Taking the driving wheel hub of an electric vehicle as the object,this paper illustrates the specific process of building immersive virtual assembly process simulation environment based on the virtual assembly plugin developed in Unity engine platform and its practical effect.