The Study Of PVDF Ultrasonic Transducer With Wide Beam Angle And Its Application In 3D Positioning

With the development of human-computer interaction technology,ultrasonic transmitters are widely used in three-dimensional spatial positioning systems.In a three-dimensional ultrasonic positioning system,the transmission angle of the ultrasonic transmitter determines the coverage area of the three-dimensional positioning.In related applications of three-dimensional ultrasound positioning,in order to achieve a wide range of coverage,the sensor needs to have a relatively wide transmitting and receiving range.Ultrasonic transmitters with large radiation angles are a better choice in applications.Few ultrasonic transmitters can be used to cover three-dimensional space.At the same time,the size of the transmission equipment is reduced,and the complexity of the structure of the transmission equipment is reduced.Aiming at the problem of the small beam angle of existing PVDF ultrasonic transmitters,this paper studies the characteristics of PVDF piezoelectric materials and PVDF ultrasonic sensors,and completes the structural design,simulation analysis and experimental testing of two types of PVDF ultrasonic transmitters.Large-angle emission and its application in three-dimensional positioning.The main research contents are as follows:(1)Based on the research of PVDF piezoelectric materials and PVDF ultrasonic sensors,in order to realize the large-angle emission of ultrasonic waves in the vertical direction and make its shape and structure suitable for electronic pens,a PVDF ultrasonic transmitter with a truncated conical structure was designed.The truncated conical PVDF ultrasonic transmitter is composed of two identical PVDF piezoelectric films with partial ring structure,so that the molecular length of each film is as large as possible.The simulation uses COMSOL multiphysics simulation software.A three-dimensional model of a truncated conical PVDF ultrasonic transmitter was constructed,and truncated conical structures with different base angles were selected for simulation.The vertical beam angle was compared,and the transmitter corresponding to the large vertical beam angle was selected as the design size.The vertical beam angle,horizontal beam angle,and vibration mode of the round-shaped PVDF transmitter of this size at different frequencies are calculated by simulation and researched and verified(2)In order to further expand the beam angle of the PVDF ultrasonic transmitter and realize the spherical emission of ultrasonic waves,a PVDF ultrasonic transmitter with a double cylindrical structure is designed.The quasi-spherical PVDF ultrasonic transmitter consists of two identical strip-shaped PVDF piezoelectric films enclosed in two vertically crossing grooves on a spherical substrate,and is fixed by an adhesive method to form two cylindrical vertical crossing structures in space..The simulation uses COMSOL multiphysics simulation software.A three-dimensional model of a quasi-spherical PVDF ultrasonic transmitter was constructed,and the vertical and horizontal beam angles of the transmitter at different frequencies were simulated to calculate the three-dimensional sound pressure distribution.The ultrasonic emission performance was studied and verified(3)Measure and compare the two designed ultrasonic transmitters.Measure the frequency response,impulse response,vertical beam angle,and horizontal beam angle of the truncated conical PVDF ultrasonic transmitter.Comparative analysis of the characteristics of truncated conical PVDF ultrasonic transmitter,cylindrical PVDF ultrasonic transmitter and piezoelectric ceramic sensor.It is verified that the truncated conical PVDF ultrasonic transmitter has a wider bandwidth and a larger ultrasonic radiation angle.The frequency response,impulse response,vertical beam angle,and horizontal beam angle of the quasi-spherical PVDF ultrasonic transmitter were measured and researched to verify that it realizes the spherical emission of ultrasonic waves.Based on the quasi-spherical PVDF ultrasonic transmitter has the characteristics of spherical emission and a large angle of ultrasonic radiation.The quasi-spherical PVDF ultrasonic transmitter is mounted on an electronic pen and applied in a three-dimensional ultrasonic positioning systemThe main contributions and innovations of this article include(1)A PVDF ultrasonic transmitter with a truncated conical structure is designed The transmitter consists of two identical partial ring structures,the bottom angle of the circular table ?=37°,the radius of the top surface of the table r=2mm,and the radius of the bottom of the table R=10mm,height of round table h=6mm.The thickness of the PVDF piezoelectric film is 30?m,and the gap width at the junction of the two films is 1.0mm.From the simulation results,it can be seen from the simulation results that as the frequency increases,the maximum displacement(DMX)moves from the bottom of the circular table(the surface corresponding to the maximum radius)to the top(the surface corresponding to the minimum radius).The experimental measurement results show that the truncated conical PVDF ultrasonic transmitter has a bandwidth of 11kHz,a vertical beam angle of 140°,and a horizontal beam angle of 360°.(2)A quasi-spherical PVDF ultrasonic transmitter is designed.The transmitter consists of two identical strip-shaped PVDF piezoelectric films enclosed in two vertically crossing grooves on a spherical substrate and fixed by gluing,forming a structure of two cylindrical vertical crosses in space.The radius of the plastic spherical substrate isr1=9mm,the radius of the cylindrical PVDF piezoelectric film is r2=7mm,the width of the groove on which the piezoelectric film is placed on the spherical substrate is w=6mm,and the thickness of the PVDF piezoelectric film is 30?m.The measurement results show that the quasi-spherical PVDF ultrasonic transmitter has a bandwidth of 9kHz,a vertical beam angle of 240°,and a horizontal beam angle of 360°.The quasi-spherical transmitter was applied to the electronic pen and applied in a three-dimensional ultrasonic positioning systemThe two structures of the PVDF ultrasonic transmitter designed in this paper realize the transmission of ultrasonic waves with a large radiation angle.When applied to a three-dimensional positioning system,it can achieve equipment miniaturization,reduce the density of positioning nodes,and reduce system complexity and cost.