The Research On Dynamic Performance Of Comb Micro Gyroscope

Compared to conventional gyroscopes,the micro machined gyroscopes have the advantages of small size,light weight,low cost,good dynamic performance,low energy consumption,easy to intelligentize and digitization,high reliability,and integration.So the micro gyroscopes widely used in aerospace,medical devices,automotive technology,weapons and equipment and other fields.In many studies of micro gyroscopes,the improvement of micro gyroscopes sensitivity and accuracy are always main pursuit of goals.At present,the study of micro gyroscopes dynamic performance is based on the ideal processing of micro gyroscope.The quantitative analysis of influence on the performance is quite rare when considering all kinds of manufacturing error in dynamic performance of micro gyroscope.What's more,manufacturing error will change the inherent frequency,bandwidth,sensitivity of the micro gyroscopes,which affect the micro gyroscope output precision and stability of the system.So this article conducts the study of micro gyro dynamic performance,considering a wide variety of manufacturing error through the quantitative analysis,the theoretical analysis,the finite element modal analysis and harmonic response analysis to study influence of manufacturing error on the inherent frequency,mode and mode coupling of micro gyroscope.The results of the study provide theory basis for improving the processing technology and performance of micro machined gyroscope.Establish and analyze comb micro mechanical gyroscope's dynamics equation,we found that in order to achieve the highest sensitivity,the excitation frequency should be equal to the micro gyroscope drive mode's inherent frequency,and the driving mode frequency is close to or equal to the detection mode frequency,which is also one of the theoretical basis of the structure design of micro gyroscope.The influence of etching error on the performance parameters of micro gyroscope is studied by finite element numerical simulation.The results show that the natural frequency of the gyroscope can deviate from the theoretical design value.The micro beam stiffness and the inherent frequency of micro gyroscope increase with over etching angle.If the maximum over etching angle is ±2°,rates of change of the inherent frequencies of the driving mode and sensitive mode are more than 14%.Etching error can cause work mode of micro gyroscope order reduction and make interferential mode betweendriving mode and sensitive mode.And the frequency of interferential mode and driving mode are nearly equal,it will affect the output precision of micro gyroscope.Finally,on the whole,bandwidth decreases with the increase of over etching angle.Due to the sensitivity is affected by many factors,so it has no obvious change rule.When etching Angle between 0° and 1.5°,the sensitivity of micro gyroscope will be higher than without etching error case.The effects of three kinds of bandwidth errors on the inherent frequencies and modes of micro gyroscope are studied.When the two driving micro beam bandwidth on the same diagonal is identical in size and the bandwidth on the two pairs of diagonal beams is different,the bandwidth error will cause the coupling between the driving mode and the detection mode of the micro gyroscope,and the coupling degree increases with the increase of bandwidth error.The ratio of the detection direction displacement of the sense mass to the driving direction displacement of the sense mass is called the modal coupling ratio.When the bandwidth error is 0.1 microns,the modal coupling ratio reaches 0.88.When the same side of the micro beam bandwidth equal and the two sides of the micro beam bandwidth unequal or only one micro beam exist error and the other three micro beam does not exist error,the mode coupling phenomenon caused by the bandwidth error can be ignored basically.The shape of U micro beam is optimized by finite element method and found that the modal coupling is the most serious when the length of one side of the U beam is half of the other side.When the U beam is degenerated into crab foot beam or equal U beam on both sides,the mode coupling of micro gyroscope driven mode by bandwidth error can be avoided basically.Through the simulation analysis of harmonic response,it is verified that the mode coupling phenomenon will cause serious interference to the micro gyroscope measurement signal,so the mode coupling phenomenon is one of the important factors affecting the performance of micro gyroscope.The results of the study of the structure design of micro gyroscope has a certain guiding significance.The results have some guiding significance for the structural design of micro gyroscope.