Saw Inertial Sensing Technique

The quality of inertial guidance apparatus is an important factor connected withperformance figure of independent and self-determinate navigator. As surface acousticwave (SAW) inertial guidance apparatus is a kind of high sensitive sensor, it is worthstudying its transducer principle and measuring technique not only in theory but alsoin engineering application. The task of this paper is on SAW inertial guidance sensor,which contains SAW accelerometer with cantilever beam and SAW gyro in detail.On SAW accelerometerThe disadvantage on SAW accelerometer with cantilever beam is analyzed andsome engineer improvement plans are discussed after introducing the elementaryprinciple of SAW theory and technology in brief. The achievements on the SAWaccelerometer is showed below in detail:1. A new system design about SAW accelerometer with quartz cantilever beam isfulfilled. It not only heightens the SAW accelerometer sensitivity and veracity, butalso improves its performance figure.2. A new SAW accelerometer frame based on floating zero principle is put forwardtheoretically, because elementary method of reducing temperature influence is to setup the floating zero SAWR, which has same temperature frequency characteristic asthe measuring SAWR. Another advantage of the new machinery of the SAWaccelerometer with quartz cantilever beam is reducing technological requirement toSAWRs.3. The dynamics characteristic of the SAW accelerometer differential frequencyoutput response to step function acceleration impulse is discussed. This work changesthe situation to be lack of theoretical research about SAW accelerometer dynamicscharacteristic, and enriches the theory of SAW accelerometer with cantilever beam.4. The function of judging the direction of acceleration is added to traditional SAWaccelerometer by use of the band pass characteristic of surface acoustic wave filter(SAWF). Furthermore, this new SAW accelerometer system gets the ability to adjustmeasuring range and sensitivity in time according to measured acceleration, as a result of utilizing electronic force in parallel-plate capacitor and the acceleration directionjudgment SAWF.This achievement not only enlarges traditional SAW accelerometer's applicationscope, but also prevent quartz cantilever beam from destruction and fag owing toacceleration inertial force over-impact.5. The step function acceleration measuring technique and project is studied. Thedynamic characteristic and performance of the acceleration measuring system isimproved. A new measuring method to acceleration in time is put forward, which canadjust measuring range according to measured acceleration automatically, get theacceleration measuring result as soon as possible and heighten measuring accuracy.On SAW gyroscopic effect acoustooptical measuring technologyThere is gyroscopic effect in surface acoustic wave according to the theoreticalanalysis to the acoustic wave equation. However, it is difficult to detect and measureSAW gyroscopic effect. According to the study experience from developed country,the high precision characteristic of optical measuring technique and the acoustoopticalphysics achievement, a new SAW gyroscopic effect detection and measuring plan isput forward. The core of the method is to get out SAW gyroscopic effect informationthrough Bragg diffraction effect from rotating piezoelectric-acoustooptical mediumfirstly, and then measure it by use of precision optical measuring technique.The research on SAW gyroscopic effect detection and measuring technique is givenbelow in detail, after introducing gyroscopic effect and acoustooptical Braggdiffraction effect briefly.1. The existence of SAW gyroscopic effect and engineering feasibility of itsacoustooptical detection and measuring plan is discussed. The elementary principleand the measure equation of SAW gyroscopic effect acoustooptical measurement areanalyzed. The system design principle is studied.2. The SAW gyroscopic effect and piezoelectric-acoustooptical characteristic ofLiNbO₃ crystal is researched.3. A new tiny angle measuring plan with CCD about the SAW gyroscopic effect isprompted. The core of SAW gyroscopic effect measurement is to measure tiny Braggdiffraction angle, therefore, the key technology of tiny angle measurement includingCCD distinguishability and system distinguishability are discussed, after the basic measuring system with CCD is put forward.4. The main direction and way forward for further research on SAW inertialguidance theory and technology is pointed out in the conclusion of the paper.