CN101067555B - Force balancing resonance micro-mechanical gyro - Google Patents

Abstract

The invention relates to an equilibrium type resonance micro mechanical top, which includes static comb tooth driver, mass block, double end tuning fork resonator and static comb tooth strength balancer. When adds the driving voltage to the static comb tooth driver, the mass block does along x axis direction oscillation motion, and circles the z axis in exterior under the rate of angular motion function to produce along y direction coriolis force. The static comb tooth strength balancer used to balance the mass block in y direction Coriolis force and keep the mass block in the equilibrium position of the y direction. The invention structural style enhanced the micro mechanical top sensitivity, the resolution and the dynamic range and realized Coriolis force change, which had the top sensitive angular speed to transform the resonator resonance frequency change, and then through the feedback return route adjustment achieved the new balanced equilibrium type feedback system, and effectively suppressed the non-linear influence.

Description

Force Balanced Resonant Micromachined Gyroscope

technical field

The invention belongs to the field of micro-mechanical sensors in micro-electro-mechanical systems (MEMS), and is widely used in the fields of automotive electronics, aerospace, weaponry and the like as a micro-inertial device.

Background technique

The classic frame-type mechanical rotor gyroscope based on the principle of angular momentum is assembled from hundreds of (about 300) parts. It has a complex structure, large volume, and short service life, which cannot meet the requirements of technological development and many new applications. Therefore, solid-state gyroscopes without mechanical rotors have been developed one after another, such as laser gyroscopes, hemispherical resonant gyroscopes, and fiber optic gyroscopes. The performance of the first two gyroscopes can reach the drift accuracy of inertial navigation (0.01°/h); but the price is high and the volume is large, which is still not suitable for the needs of the developing miniature inertial measurement unit and low-cost commercial market. However, MEMS is in the development period, and its technology and market are not yet mature, but its broad development prospects and huge social and economic benefits are well known to the world. Therefore, the development of a new generation of micromachined gyroscopes (MMGs) has received widespread attention worldwide, and driven by the needs of the automotive industry, it has become the subject of extensive research and development since the mid-1980s.

In terms of testing principles, currently silicon micromachined gyroscopes generally adopt capacitive detection methods. Capacitance detection has the advantages of small temperature drift, high sensitivity, good reliability and stability. However, with the continuous shrinking of the structure size of micro-inertial devices, their sensitivity and resolution are greatly reduced, reaching the limit state of detection. The signal-to-noise ratio of the detection output signal is very low, and the signal detection circuit and processing circuit are very complicated, which is unfavorable for miniaturization and integration. In 2002, A.A. Seshia and others from Berkeley in the United States proposed a realization structure of the silicon resonant micro-machined gyroscope, which effectively combined the previous silicon micro-machined gyroscope and the micro-machined resonator, thereby effectively avoiding the capacitive detection. Effects of noise disturbance. However, the vibration dynamic equation of the micromechanical resonator is very complicated. When only considering the steady state, the output displacement signal is both an amplitude modulation signal and a frequency modulation signal, and the demodulation process is affected by nonlinear factors. Most of the current micro-mechanical gyroscope products are of medium and low precision, which seriously restricts their application scope. They are mostly used in commercial fields that do not require high precision. To improve the performance of existing micro-mechanical gyroscopes is to achieve high sensitivity and high resolution. , low noise, low drift and large dynamic range.

Contents of the invention

The technical problem of the present invention is: to overcome the deficiencies of the prior art, to provide a force-balanced resonant micro-machined gyroscope, to solve the existing micro-machined gyroscope sensitivity, resolution is not high enough, and the problems existing in capacitance detection, suppress non- linear effect.

Technical solution of the present invention: the force-balanced resonant micromechanical gyroscope includes four parts: a double-ended tuning fork resonator, an electrostatic comb driver, a mass block, and an electrostatic comb force balancer. The entire structure is an axisymmetric figure, and the mass block is in the middle. Position, with two degrees of freedom in the x and y directions, two electrostatic comb drivers fixed on the base are placed symmetrically in the x direction, and two electrostatic comb force balancers fixed on the base are symmetrically placed in the y direction and two double-ended tuning fork resonators DETF, the mass block is driven by the electrostatic force of the electrostatic comb driver, and oscillates along the x direction. force effect. The electrostatic comb force balancer is used to balance the Coriolis force, so that the mass block is in a balanced position in the y direction. When the input angular velocity changes, a periodic Coriolis force appears on the mass block in the y direction and is transmitted to the connected two On a double-ended tuning fork resonator, and the size is equal and the direction is opposite, so that the natural resonant frequency changes. Measuring its differential output can feed back and adjust the drive voltage of the electrostatic comb force balancer, so that the mass returns in the y direction. The balance position realizes the dynamic closed-loop detection of the input angular velocity.

The working principle of the present invention: the force balance resonant micro-mechanical gyroscope belongs to the vibrating gyroscope (VG), and it works based on the principle that there is a modal coupling effect when the excited vibration has Coriolis acceleration, which is essentially due to the existence of Coriolis acceleration An energy transfer between the two modes is induced. Its basic principle is shown in Figure 2, in which the mass block 3P is fixed on the xoy plane of the rotating coordinate system, and the mass block P will move along the x-axis direction at the speed of the relative rotating coordinate system after being driven by the electrostatic force of the electrostatic comb driver. υ motion, the rotating coordinate system rotates around the negative z-axis with an angular velocity ω. The formula of the Coriolis force due to the Coriolis effect is F _cor =-2m _P [ω×υ], that is, the mass P is subjected to the Coriolis force F _cor along the positive y-axis in the rotating coordinate system, where m _P is the mass of the plate The mass of block P. It can be seen that the Coriolis force F _cor is directly proportional to the input angular velocity ω acting on the mass P, and obtaining the information of the Coriolis force F _cor means obtaining the information of the input angular velocity ω.

只与梳齿的厚度h和梳齿间隙d有关，与梳齿宽度b无关。在

的情况下，则施加在质量块上的静电力为 $F_x=2\frac{\&PartialD;C}{\&PartialD;x}{V}_d{V}_i\sin {\mathrm{\&omega;}}_{p}t.$ 通过改变驱动电压V(t)＝V_d+V_isinω_pt大小来使静电力F_x平衡科氏力F_cor，即有F_x＝F_cor。The Coriolis force F _cor is balanced by an electrostatic comb force balancer, so that the mass is in a balanced position in the direction of the Coriolis force F _cor . The structural diagram of the comb teeth is shown in Figure 3, and the driving voltage V(t)=V _d +V _i sinω _p t is applied to the electrostatic comb force balancer, and the electrostatic force generated in the x-axis direction is: $f_e=\frac{1\&PartialD;\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="S071A0327620070717E000011.png,S071A0327620070717E000022.png"\; state="\{\{state\}\}">C</figure-callout>}}{2\&PartialD;x}V{\left(t\right)}^2$ $f_e=\frac{1\&PartialD;\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="S071A0327620070717E000011.png,S071A0327620070717E000022.png"\; state="\{\{state\}\}">C</figure-callout>}}{2\&PartialD;x}V{\left(t\right)}^2=\frac{1}{2}\frac{\&PartialD;C}{\&PartialD;x}(V_{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="S071A0327620070717E000011.png,S071A0327620070717E000022.png"\; state="\{\{state\}\}">d</figure-callout>}}^2+\frac{1}{2}{V}_i^2+2V_d{V}_i\sin {\mathrm{\&omega;}}_{p}t-\frac{1}{2}{V}_i^2\mathrm{<figure-callout\; id="2"\; label="cos"\; filenames="S071A0327620070717E000011.png,S071A0327620070717E000022.png"\; state="\{\{state\}\}">cos</figure-callout>}2{\mathrm{\&omega;}}_{p}t).$ in, $\frac{\&PartialD;C}{\&PartialD;x}=2\mathrm{no}{\mathrm{\&epsiv;}}_r{\mathrm{\&epsiv;}}_0\frac{h}{d},$ Right now

It is only related to the thickness h of the comb teeth and the gap d of the comb teeth, and has nothing to do with the width b of the comb teeth. exist

In the case of , the electrostatic force exerted on the mass block is $f_x=2\frac{\&PartialD;C}{\&PartialD;x}{V}_d{V}_i\sin {\mathrm{\&omega;}}_{p}t.$ By changing the magnitude of the driving voltage V(t)=V _d +V _i sinω _p t, the electrostatic force F _x can balance the Coriolis force F _cor , that is, F _x =F _cor .

以等幅反向的形式作用在两端对称的两个双端音叉谐振器上，使其弹性系数K_l受到调制发生周期性的变化。其弹性系数k_l与科氏力成正比，可表示为 $k_l=C_{\mathrm{mode}}\frac{\left|F_{\mathrm{cor}}^{\&prime;}\right|}{2L_r},$ 其中C_mode为双端音叉谐振器的振型常数。如图4所示，双端音叉谐振器在轴向时变科氏力

作用下的动力学方程为： $m_r{\stackrel{..}{x}}_r+b_r{\stackrel{.}{x}}_r+(k_r+k_l\sin \left({\mathrm{\&omega;}}_{p}t\right))x_r=F_d,$ 其中，F_d为加在谐振器上的驱动电压产生的驱动力，K_r为谐振器在未受科氏力作用时系统的弹性系数，k_l sin(ω_pt)为谐振器在驱动频率为f_p＝ω_p/2π的科氏力

的调制作用下附加的弹性系数，在零点附近，此附加项可线性化为k_lω_pt。单个双端音叉谐振器的谐振频率变化为 ${\mathrm{\&omega;}}_r=\sqrt{\frac{k_r+k_l{\mathrm{\&omega;}}_{p}t}{m_r}}\&ap;{\mathrm{\&omega;}}_{r0}+\frac{{\mathrm{\&omega;}}_{r0}}{2}\frac{k_l{\mathrm{\&omega;}}_{p}t}{k_r},$ 对称的两个双端音叉谐振器的谐振频率变化量的差动输出为 $\mathrm{\&Delta;f}=\frac{1}{2\mathrm{\&pi;}}(\mathrm{\&Delta;}{\mathrm{\&omega;}}_1-\mathrm{\&Delta;}{\mathrm{\&omega;}}_2)=\frac{1}{2\mathrm{\&pi;}}2\mathrm{\&Delta;\&omega;}=\frac{{\mathrm{\&omega;}}_{r0}}{2\mathrm{\&pi;}}\frac{k_l{\mathrm{\&omega;}}_{p}t}{k_r}.$ 以之为控制信号，通过力平衡控制回路调节静电梳齿力平衡器的驱动电压使质量块在科氏力

作用下达到新的平衡状态，从而实现对输入角速度ω的检测。At the moment when the input angular velocity changes, the Coriolis force $f_{\mathrm{cor}}^{\&prime;}\&NotEqual;f_x,$ Since the designed structure is an axisymmetric figure, the Coriolis force

It acts on two symmetrical double-ended tuning fork resonators in the form of equal amplitude and reverse, so that the elastic coefficient K _l is modulated and changes periodically. Its elastic coefficient k _l is proportional to the Coriolis force, which can be expressed as $k_l=C_{\mathrm{mode}}\frac{\left|f_{\mathrm{cor}}^{\&prime;}\right|}{2L_r},$ Among them, C _mode is the mode constant of the double-ended tuning fork resonator. As shown in Figure 4, the double-ended tuning fork resonator has a time-varying Coriolis force in the axial direction

The kinetic equation under action is: $m_r{\stackrel{..}{x}}_r+b_r{\stackrel{.}{x}}_r+(k_r+k_l\sin \left({\mathrm{\&omega;}}_{p}t\right))x_r=f_d,$ Among them, F _d is the driving force generated by the driving voltage applied to the resonator, K _r is the elastic coefficient of the system when the resonator is not affected by the Coriolis force, k _l sin(ω _p t) is the resonator at the driving frequency The Coriolis force of f _p = ω _p /2π

The additional elastic coefficient under the modulation of , in the vicinity of zero, this additional item can be linearized as k _l ω _p t. The resonant frequency of a single double-ended tuning fork resonator changes as ${\mathrm{\&omega;}}_r=\sqrt{\frac{k_r+k_l{\mathrm{\&omega;}}_{p}t}{m_r}}\&ap;{\mathrm{\&omega;}}_{r0}+\frac{{\mathrm{\&omega;}}_{r0}}{2}\frac{k_l{\mathrm{\&omega;}}_{p}t}{k_r},$ The differential output of the resonant frequency variation of two symmetrical double-ended tuning fork resonators is $\mathrm{\&Delta;\; f}=\frac{1}{2\mathrm{\&pi;}}(\mathrm{\&Delta;}{\mathrm{\&omega;}}_1-\mathrm{\&Delta;}{\mathrm{\&omega;}}_2)=\frac{1}{2\mathrm{\&pi;}}2\mathrm{\&Delta;\&omega;}=\frac{{\mathrm{\&omega;}}_{r0}}{2\mathrm{\&pi;}}\frac{k_l{\mathrm{\&omega;}}_{p}t}{k_r}.$ Using it as a control signal, the driving voltage of the electrostatic comb force balancer is adjusted through the force balance control loop to make the mass block under the Coriolis force

A new equilibrium state is reached under the action, so as to realize the detection of the input angular velocity ω.

Advantage of the present invention compared with prior art:

(1) The double-ended tuning fork resonator adopted in the present invention can convert the change of the Coriolis force generated by the sensitive angular velocity of the micromechanical gyroscope into the change of the resonant frequency of the resonator, thereby feedback-adjusting the driving voltage of the electrostatic comb force balancer, It effectively avoids the influence of noise interference in capacitance detection, and is easy to process digital signals.

(2) The electrostatic comb force balancer adopted in the present invention can balance the Coriolis force effect produced by the sensitive angular velocity of the micro-mechanical gyroscope, so that the micro-mechanical gyroscope is in a static equilibrium state in this direction, effectively suppressing the influence of nonlinearity, It also solves the complex vibration dynamic equation in the detection process of using the micromechanical resonator alone, only considers the steady state situation, and the output displacement signal is both an amplitude modulation signal and a frequency modulation signal and other factors.

Description of drawings

Fig. 1 is the schematic diagram of the force balance type resonant micromachined gyroscope of the present invention;

Fig. 2 is a schematic diagram of the basic principle of the Coriolis effect of the present invention;

Fig. 3 is a comb structure diagram of the present invention;

Fig. 4 is the structural diagram of double-ended tuning fork resonator of the present invention;

5 is a structural diagram of Embodiment 1 of the force-balanced resonant micromachined gyroscope of the present invention;

Fig. 6 is a structural diagram of Embodiment 2 of a force-balanced resonant micromachined gyroscope.

Detailed ways

As shown in Fig. 1, the present invention consists of four parts: a double-ended tuning fork resonator 1, an electrostatic comb driver 2, a mass block 3, and an electrostatic comb force balancer 4, and the entire structure is an axisymmetric figure. The mass block 3 is in the middle position and has two degrees of freedom in x and y directions. Two electrostatic comb drives 2 fixed on the base are symmetrically placed in the x direction, and two electrostatic comb drives 2 fixed on the base are symmetrically placed in the y direction. Electrostatic comb force balancer 4 and two double-ended tuning fork resonators DETF1.

As shown in Figure 4, the double-ended tuning fork resonator 1 includes a driving static tooth 6, a measuring static tooth 7, a beam 11 and a movable tooth 5, wherein two symmetrical tuning fork beams perform simple harmonic vibration, and the driving static teeth 6 and The movable tooth 5 constitutes a pair of dynamic and static comb teeth, and the double-ended tuning fork resonator 1 works in a resonant state through electrostatic force, and by measuring the pair of dynamic and static comb teeth formed by the fixed teeth 7 and movable teeth 5, the vibration of the tuning fork beam on the axis is sensitive. The change of resonance frequency under the action of axial force realizes the measurement of axial force. After the drive signal with frequency equal to the resonant frequency of the double-ended tuning fork resonator 1 is applied to the driving stationary tooth 6, the mass block 3 performs a resonant motion in the y direction, and the measuring stationary tooth 7 outputs a resonant frequency signal.

The electrostatic comb driver 2 and the electrostatic comb force balancer 4 have the same uniformly distributed static teeth, which form a dynamic and static comb pair structure with the movable teeth distributed on the mass block, and generate electrostatic force under the driving voltage. The former is used to generate the electrostatic force of the mass block for simple harmonic vibration, and the latter is used to balance the Coriolis force generated by the sensitive angular velocity of the gyro, so that the gyro is in a balanced position in the direction of the Coriolis force.

The principle diagram of the force-balanced resonant micro-mechanical gyroscope shown in FIG. 1 can be realized with various structural diagrams. For example, the realization structure of the force-balanced resonant micro-mechanical gyroscope as shown in FIG. 5 and FIG. 6 can be used. As shown in Figure 5, the structure is an axisymmetric figure, and the mass block 3 includes an internal movable tooth frame and an external frame, and is fixed to the base through four support beams 9 and anchor points 8. Place four electrostatic comb drivers 2 fixed on the base in the x direction inside the inner movable tooth frame, place two electrostatic comb force balancers 4 fixed on the base symmetrically in the y direction outside the outer frame, and two Double-ended tuning fork resonator 1. As shown in FIG. 6 , the structure is an axisymmetric figure, and the mass block 3 is flat and in the middle position, and is fixed to the base by four support beams 9 and anchor points 8 . Two electrostatic comb drivers 2 fixed on the base are symmetrically placed in the x direction, and two electrostatic comb force balancers 4 fixed on the base are placed symmetrically in the y direction, and are passed through two levers fixed on the base The amplifying mechanism 10 is connected with the two outer double-ended tuning fork resonators 1 . Wherein, the lever amplification mechanism 10 utilizes a typical lever principle, uses the anchor 8 as a fulcrum, and achieves the effect of amplifying the Coriolis force by reducing the force arm.

In the structure of the present invention, the substrate material is glass, and the sensitive structure material is monocrystalline silicon, which is manufactured by standard bulk silicon technology, and has better mechanical properties than previous polycrystalline silicon micromechanical gyroscopes.

Claims (3)

1. The force-balanced resonant micromechanical gyroscope is characterized in that: it includes a double-ended tuning fork resonator (1), an electrostatic comb driver (2), a mass (3), and an electrostatic comb force balancer (4). The micromechanical gyro described above has a symmetrical structure as a whole, with a mass block (3) in the middle, and the mass block (3) has two degrees of freedom in x and y directions, and two electrostatic comb teeth fixed on the base are symmetrically arranged in the x direction The drive (2) has two electrostatic comb force balancers (4) fixed on the base and two double-ended tuning fork resonators (1) symmetrically arranged in the y direction, and the mass block (3) is driven by the electrostatic comb drive ( 2) Driven by the electrostatic force, it makes oscillating motion along the x direction. If there is an external input angular velocity signal along the z axis direction, the mass block will be affected by the Coriolis force along the y direction. The electrostatic comb force balancer (4) is used for Balance this Coriolis force so that the mass block is in a balanced position in the y direction. When the input angular velocity changes, the mass block (3) appears a periodically changing Coriolis force in the y direction, and transmits it to the two connected double-ended tuning forks On the resonator (1), and the size is equal and the direction is opposite, so that the natural resonant frequency changes. Measuring its differential output can feed back and adjust the drive voltage of the electrostatic comb force balancer (4), so that the mass (3) in Return to the equilibrium position in the y direction to realize the dynamic closed-loop detection of the input angular velocity. 2. The force balance type resonant micromachined gyroscope according to claim 1, characterized in that: the double-ended tuning fork resonator (1) can realize the resonant detection mode, and it adopts two working in the simple harmonic vibration state. The symmetrical tuning fork beam can measure the axial force through the change of the resonant frequency of the sensitive tuning fork beam under the action of axial force. The drive static tooth and the movable tooth are symmetrically placed on the outside of the two tuning fork beams to form a dynamic and static comb pair. 3. The force-balanced resonant micromachined gyroscope according to claim 1, characterized in that the electrostatic comb force balancer (4) has the same uniformly distributed static teeth as the electrostatic comb driver (2), and the mass The moving teeth distributed on the block (3) form a dynamic and static comb pair structure; the electrostatic comb force balancer (4) generates electrostatic force under the driving voltage to balance the Coriolis force generated by the sensitive angular velocity of the gyroscope, so that the gyroscope is in the equilibrium position in the force direction.

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