A Pen-based Human-computer Interaction Device Based On Double Targets Three-dimensional Ultrasound Positioning

The pen-based human-computer interaction has better immersion and usability. It iswidely used in education, medical, military and other fields, and it is a hotspot ofhuman-computer interaction in recent years. Ultrasound positioning technology is animportant means to realize the pen-based human-computer interaction, which has theadvantages of high accuracy, low cost, simple structure. The interaction electronicwhiteboard is its typical application. However, the existing products are mainly based ontwo-dimensional positioning technology. With the development of digital multimediatechnology, the needs of pen-based human-computer interaction products, which are basedon multi targets three-dimensional positioning technology, is an inevitable trend. Researchon multi targets ultrasound positioning key technology is the development of the pen-basedhuman-computer interaction base on the existing ultrasound positioning technology. It alsocan bring great economic benefits.This paper analysised TOA and TDOA positioning methods, and researched on themethods of extracting ultrasound signal delay time, differentiating the infrared signal andultrasound signal from double targets, and air mouse controlling based on gyroscopes oraccelerometers. Design the overall scheme of a pen-based human-computer interactiondevice based on double targets three-dimensional ultrasound positioning. Apply thethree-dimensional ultrasound positioning technology to the pen-based human-computerinteraction. Expand the scope of interaction with air mouse. Complete the design,development and test of the prototype. The main contributions and innovations are asfollows:(1) Propose a method of double targets three-dimensional ultrasound positioning. Thismethod takes the improved normalized threshold detection method to improve the accuracyof extracting the ultrasonic delay time, realize the frequency division multiplexing of38kHz and56kHz infrared signal by hardware circuit, realize the frequency division multiplexingof25kHz and40kHz ultrasound signal by digital filter, which has been optimized, andcompute the position of target by TOA positioning method. It has the advantages of smallpositioning error, high positioning speed and positioning double targets.(2) Propose a dynamic reference value air mouse controlling method, which combinesaccelerometer and gyroscope to position. This method computes the reference angle byaccelerometer sampling value and the offset angle by the gyroscope sampling value. Itupdates the reference value of the gyroscope and angle dynamically. Expand the using angleof air mouse and improve the stability of air mouse.(3) Develop the prototype of the pen-based human-computer interaction device basedon double targets three-dimensional ultrasound positioning. This paper designed two kindsof target based on PIC12F508and STC89C52, and a kind of receiving signal processingboard based on TMS320VC5502, and completed the program of target, signal receivingprocessing board and PC software.The test results show that the prototype worked stabilitywith good performance and meet the application requirements. It can position double targets.Its scope is larger than1.5m hemisphere. Its positioning error is less than5mm and itspositioning frequency is14Hz. The trajectories of positioning are same with the trajectoriesof targets moving. The refresh frequency of air mouse is31Hz. The trajectory of mousemoving is smooth.Compared with two-dimensional ultrasound interaction electronic whiteboard, thepen-based type human-computer interaction device based on double targetsthree-dimensional ultrasound positioning can position double targets, and it expand thescope of the pen-based human-computer interaction from two-dimensional to threedimensional. What’s more, it futher expands the three-dimensional scope with air mouse. Itprovides a certain reference value for the research and development of ultrasoundpositioning, air mouse, human-computer interaction, and related products.