Research On Visuo-haptic Rendering Key Methods In Magnetic Levitation Visuo-haptic Interaction

The visual channel and haptic channel are important sensory channel for human to explore the world.The immersion of the virtual reality application will be greatly enhanced by the introduction of visuo-haptic interaction.Nowadays,there are many methods to provide visuo-haptic feedback during the interaction process.Among all the methods,the contactless magnetic levitation visuo-haptic interaction overcomes the inherent friction in mechanical interaction and has promising prospects.However,there are still many problems in the magnetic levitation visuo-haptic interaction such as the unrealistic penetrations between the virtual tool and other virtual objects,the unrealistic artifacts in visuo-haptic feedback,and the running velocity conflict between haptic rendering and visual rendering.To solve the problems above,improve the credibility of the magnetic levitation visuo-haptic interaction,achieve stable coordination between visual rendering and haptic rendering,and provide a realistic operating environment of “ what you see is what you touch” for the user,this paper conducts many researching works about the key visuo-haptic rendering technologies in magnetic levitation visuo-haptic interaction.The main contributions of this paper lie in the following:1)Aiming at the specific requirements of magnetic levitation visuo-haptic interaction for visual credibility,by adjusting and improving about the original position-based dynamic simulation method,this paper proposed a new physical simulation model which is suitable for magnetic levitation visuo-haptic interactions.In addition,for mapping the visual positioning data to the pose data of virtual haptic tools,a filtering mapping algorithm for positioning data is proposed which realizes a stable mapping of user input to changes of poses of virtual tools,and satisfies users' demands for free manipulation of virtual tools.2)Aiming at the specific requirements of magnetic levitation visuo-haptic interaction for haptic credibility,a multi-ray haptic rendering method is proposed which models the virtual haptic tools by multiple rays.By making full use of the collision information and symbolic distance function defined in this paper,the fast penetration detection for virtual haptic tools and the fast calculation for the non-penetrating pose of graphical tools can be easily realized.In addition,based on the principle of force system equivalence,the spherical hinges are used to model the magnetic levitation visuo-haptic interaction process which can complete the calculation about six degree-of-freedom haptic feedback in real-time.3)Aiming at the velocity conflict between haptic rendering and visual rendering in magnetic levitation visuo-haptic interaction,a multi-rate systematic simulation framework is proposed by this paper.The whole system is divided into some parallel modules,and respective data communication strategy between the parallel modules is constructed.Based on the above framework,a multi-rate collaborative method based on double-buffer is proposed.Moreover,by further improvement of the double-buffer method,a multi-rate collaborative method based on delayed rendering is proposed,which effectively reduces the discontinuity in the calculation results of haptic rendering by setting up double buffers in parallel modules,combined with delayed rendering and linear incremental increments,thereby making the haptic feedback output more smoother.