The Research On Key Technology Of Tactile Feedback Based On Airborne Ultrasound

With the development of human-computer interaction,a variety of efficient and natural human-computer interaction methods have emerged.At the same time,simple visual and auditory feedback can no longer meet the needs of human-computer interaction.As one of the most important ways of human perception,tactile has attracted more and more attention of researchers.As a kind of tactile feedback,ultrasound tactile feedback technology can get rid of the shackles of devices,increase the naturalness of interaction,and provide users with a more natural and intuitive interaction.It can be widely used in education,medical treatment,entertainment and other fields.This paper mainly studies the ultrasound tactile feedback technology.Based on the physical principle of acoustic radiation pressure and phased array technology,we optimize the system structure,design the hardware system based FPGA,study the high-precision ultrasound focusing method,complete the design software system,and exploit the ultrasound tactile feedback system.On this basis,the influence of multi-array synthetic aperture on the focusing accuracy and focal intensity is studied,and the local array focusing method based on the effective emission angle of transducer is explored,and the hardware and software design is completed.Then,the influence of driving signal duty cycle,modulation frequency and rendering waveform on the system performance is studied to explore the best rendering method,which can provide a reference for the subsequent 3D aerial tactile rendering.The main work of this paper is as follows:(1)Based on the physical principle of acoustic radiation pressure and phased array technology,the overall framework of ultrasound tactile feedback system was designed,and the hardware system based on FPGA was designed,built and debugged.Multichannel ultrasound focusing delay control method based on a variable-length shift register for airborne ultrasound tactile feedback is proposed,and the software design of ultrasound tactile feedback system are completed based on this method.After that,the focusing accuracy of the ultrasound tactile feedback system is tested through experiments.(2)A local ultrasound array focusing method based on multi-array synthetic aperture is proposed,and the hardware system construction and software system design of four array ultrasound tactile feedback system are completed based on this method.After that,we test the difference between single-array system and four-array system in focal intensity,focusing accuracy and power consumption,and the influence of local array focusing method on focusing accuracy and power consumption.(3)The effects of driving signal duty cycle,modulation frequency,rendering waveform on the system focal intensity,focusing accuracy,power consumption and human subjective feeling were studied,so as to explore the best rendering method of ultrasound tactile feedback system,and provide reference for the next 3D aerial tactile rendering.The main contributions and innovations of this paper include:(1)Multichannel ultrasound focusing delay control method based on a variable-length shift register for airborne ultrasound tactile feedback is proposed.This method according to the delay time of muti-channel signal to set the length of the shift register to realize delay control of multi-channel signal.Compared with the method of using the timer and delay circuit,this method has the advantages of simple structure,flexible control,less occupation of resources,easy control of synchronization between muti-channel,and easy realization of multi-channel control.Moreover,the focusing accuracy of the system can be adjusted by changing the frequency of control clock(2)A local ultrasound array focusing method based on multi-array synthetic aperture is proposed.According to the maximum radiation angle of the tranducer,this method controls the working state of the transducer and realizes the local focusing of single-array or multi-arrays.On the premise of ensuring the final tactile effect,this method can reduce the the system power consumption and noise by reducing the number of transducer working at the same time.This method is flexible to expand.This method can increase focusing aperture by increasing the number of transducer arrays to improve the focal intensity and focusing accuracy of the system.Moreover,multiple arrays are controlled uniformly,and the synchronization between each array is high.