Research On Tactile Rendering System Based On Friction Control

Intelligence and multi-channel are the development trends of human-computer interactiontechnology. It will greatly improve the quality and efficiency of human-computer interaction by usingseveral human sensing channels in a parallel approach, such as auditory, visual, smell and touch, etc.Among them, tactile has been widely used in the field of human-computer interaction as an importantchannel for human perceiving the real world. In virtual reality system and tele-operation system,tactile rendering can enhance the reality and quality of the system. Among several tactile renderingmethods, friction control based methods can realize continuous and fine tactile perception, and hasbecome a hot research in tactile rendering field. Therefore, designing a tactile rendering system,which based on the friction control, is particularly important. In this thesis, we use the squeeze filmeffect to design and realize a friction control based tactile rendering system.First, through the analysis of the air squeeze film effect, we obtain the relationship between thefriction coefficients of tactile panel and its vibration amplitude. Then, we analyzed the influence ofseveral factors, i.e. the size of tactile panel and the position of piezoelectric ceramic, on the vibrationamplitude of tactile panel, by using the finite element analysis method with ANSYS software.Secondly, the hardware design of tactile rendering system is presented. The system consists oftactile rendering module, piezoelectric ceramic driver module, finger position detection module,machine vision processing module, system central control module and power supply module. Tactilerendering module, which is made of a passive touch plate and a piezoelectric ceramic array, acts as aninterface of interaction between human operators and the system. Piezoelectric ceramic driver moduleis used to provide the driving signal to the piezoelectric ceramic array. Finger position detectionmodule is employed to collect the variable information of finger position, and then converts thisinformation into digital information in order to transmit it to the system central control module.Machine vision processing module is used to collect and display the image. System central controlmodule, which based on BF609microcontroller, is used to coordinate each module in order to makethe whole system realize the friction based tactile rendering. Power supply module provides therequired voltage for each module to ensure that the system work properly.Thirdly, based on this tactile rendering system, a series experiments have been conducted toverify the effectiveness of the system. These experiments include the vibration characteristics oftactile plate, the sensory threshold of human finger to the friction coefficient, the perception of difference of friction coefficients, the perception experiments of simple geometry and Chinesecharacters. Experiments results show that the minimum voltage amplitude, which the finger can sensethe friction decrease on plate surface, is24.2V. And the minimum difference of driving voltage forhuman identifying the difference of two friction coefficients is about14.8V. These experimentsdemonstrate that tactile rendering system presented in this thesis can successfully render different thetactile information, and also can be applied to the perception of simple graphics and surface texture.After the summary of the research works in this paper, the challenges and future researchdirections of friction control-based tactile rendering system are presented.