Learning And Cognitive System Based On Virtual Texture Tactile Rendering

With the development of virtual reality technology, tactile rendering technology has attractedmore and more attention. Tactile rendering based on friction control simulates tactile information bythe lateral force field on the interface, which is the most potential method and can be applied toperform more sophisticated virtual tactile textures. Experiment has shown that the squeeze film effectcan significantly reduce the friction coefficient of the contacted flat surface. In order to implement thepromising learning and cognition system of graphs and text for the blind and school-age children,research on friction based tactile rendering through the principle of squeeze film effect is carried outin this thesis.After reviewing various tactile rendering technologies as well as tactile haptic devices anddiscussing their respective advantages and disadvantages, the research of virtual texture tactilerendering is carried out and applied to develop a learning and cognitive system. The system consistsof camera module, tactile rendering surface module, piezoelectric ceramic driver module, fingerposition detection module, central control module and power supply module. The camera module isused to collect external text or graphic information. The tactile rendering surface module acts as ainterface of interaction between the operator and the system for expressing virutual tactile information.The piezoelectric ceramic driver module is used to provide the drive signal for piezoelectric ceramicplate. The finger position detection module is used to detect the position of the operator’s finger andcontrol the friction coefficient field. As the core of the system, the central control module DM3730isused for coordinating each module. The power supply module provides the required voltage for eachmodule to ensure that the system work properly.Finally, experiments of the tactile and perception characteristics of the human finger areconducted based on the developed learning and cognitive system. The effectiveness and practicabilityof tactile rendering based on friction control have been verified. These experiments include thesensory threshold of human finger to the coefficient of friction, the sensory threshold of human fingerin different texture background, experiment of learning and recognizing simple geometric shapes andChinese characters. Experimental results show that the minimum average width of smooth texture inrough context that human finger can perceive is1.11mm. Moreover, the minimum average width ofthe rough texture in smooth context that human finger can perceive is1.26mm. From the datamentioned previously we can calculate the difference is13.5%. Tactile rendering based on squeeze film effect can fulfill the requirements of human perceive textand picture messages, so it is of great significance for promoting the development of haptictechnology.