Tactile Feedback Modeling And Rendering Of Virtual Keys

The appearance of touch screen has changed the interaction mode of electronic products.Compared with the combination of keyboard and mouse,the full touch screen operation interface promotes the interaction space further,but at the expense of the real feeling feedback during the interaction,it affects the user's interaction efficiency,interactive immersion and reality,and weakens the possibility of visually impaired people using electronic products.And providing tactile feedback for virtual keys can solve the above problems to a great extent.There are two parts to realize the tactile feedback of virtual keys,namely,the establishment of feedback model and the design of rendering method.The former is the basis and premise of virtual keys realistic feedback,including the structure analysis of physical keys,the extraction of feedback feature and feedback parameter in the process of pressing,and the construction of tactile feedback system.The latter is the key and guarantee of virtual keys realistic feedback,including the design,loading,and mapping relationship with the feedback model.The main difficulty of the above work is to ensure the lightweight,miniaturization and low delay of the tactile feedback system,while requiring the virtual key tactile rendering effect to be more similar to the real key.At present,the research of virtual keystroke tactile feedback is divided into rendering method design and feedback device design,which mainly depends on different types of motor,ultrasonic vibrator,electrostatic force,and unique mechanical structure.Most of the tactile feedback rendering methods ignore the complex state changes in the process of pressing,only pay attention to the outstanding effect of the state conversion moment,the reality needs to be improved,or the simple content-based data-driven tactile feedback rendering method.Lack of complex modeling process,mostly for a single feedback factor play a leading role in the application scene.The realistic effect of tactile feedback device is relatively good,but most of them have complex mechanical structure and large volume,which are mostly used in wearable devices.Aiming at the above problems,this paper puts forward the modeling and rendering method of virtual keystroke tactile feedback based on force-displacement curve,builds the pen virtual keystroke device and verifies its performance.The main contributions and innovations are as follows:(1)A two-model virtual key tactile feedback modeling and rendering method based on force-displacement curve is proposed.By analyzing the structure and feedback characteristics of physical keys,the force-displacement curve is divided into three feedback intervals: smoothing,jumping and bottoming By measuring the contact velocity of the hand and the acceleration data of the key,the parameters of the tactile feedback model of each interval are selected,and the parameters of the tactile feedback model are optimized by the user experiment,the force-displacement curve,the feedback model and the mapping relationship between the driving signals are established,the loading mode of the driving signal is designed according to the change of the pressure applied by the user during the interaction,the corresponding driving signal is generated,and the pen tool is used to obtain the pressure in real time,the contact area is larger,and the tactile feedback is easy to be sensed,The pressure pen with vibration motor is used as an interactive tool to realize real-time tactile feedback at any position in the interactive interface.(2)A set of pen virtual key tactile feedback system platform is built.The user interaction interface is designed by Unity3 D,and the specific function is realized C#programming language.The system can obtain the change of pressure when the user presses the virtual key in real time,and generate the driving signal according to the change of pressure and the force-displacement curve,and drive the vibration motor to produce the corresponding tactile feedback effect.Provide real-time tactile feedback rendering for virtual keys.(3)The effectiveness of the impact response model of the single degree of freedom spring-mass damper system for simulating the force mutation effect during the mechanical keystroke interaction and the flexibility tactile illusion model for simulating the elastic effect during the mechanical keystroke interaction are verified.The user experiment is designed and the feedback parameters of the model are optimized according to the experimental results.This paper puts forward the basic solution and parameter guidance for the realization method of real feeling feedback in the process of virtual keystroke pressing,and verifies the effectiveness of the modeling and rendering method proposed in this paper.The virtual keystroke tactile feedback effect of single model and double model is compared with that of real keystroke.