CN100405067C - Micromechanical angle acceleration sensor - Google Patents

Abstract

The present invention relates to a micromechanical angular acceleration transducer which mainly comprises a suspended quality block, two beams for connecting the suspended quality block with a fixed end and two detecting polar plates relative to the detection of angular acceleration, wherein the detecting polar plates are fixed with the fixed end, and the quality block and the detecting polar plates are two poles of a capacitor. When rotating angular acceleration is applied to the beams connecting the quality block, the quality block can deflect, which causes distances among the quality block and the detecting polar plates to change and finally leads capacitance values among the detecting polar plates and the quality block to change; the value of the measured angular acceleration can be judged by testing the amount of change in capacitance of the detecting polar plates. The present invention has the advantages of simple structure, strong overload resisting capacity and high sensitivity and measuring precision.

Description

Micromechanical angle acceleration sensor

Technical field

The invention belongs to microelectronics technology, particularly a kind of angular acceleration transducer that is used to measure the attitude of movable body.

Background technology

At present, for the attitude of measuring movable body, employing be traditional rate gyroscope, the principle of work of rate gyroscope is to come responsive angle rate signal by coriolis force.It is exactly design and manufacturing microsensor that MEMS uses the most widely.Use the dynamo-electric part of sensor to produce sensitive information, electronic section is then handled the information that electromechanics partly produces.The MEMS gyro is exactly the MEMS sensor that is used for measured angular speed.

At present, the state-of-the-art technology of MEMS gyro, as " 1998 the 17th the 1st phases of volume of sensing technology (Journal of TransducerTechnology) " " relation of silicon micro mechanical tuning fork gyroscope detection sensitivity and natural frequency " literary composition, and U.S. Patent number is described in the US6837108B disclosed " a kind of microelectron-mechanical gyroscope that increases dynamic range " (INCREASING THE DYNAMIC RANGE OF AMEMS GYROSCOPE), the gyrostatic structure of MEMS is that the square monocrystalline silicon flat boards of two block lengths (mass) that have comb electrode link to each other by flexible support arm and with the monocrystalline silicon base, and being suspended from the base top, base is provided with the pair of planar electrode of electrically driven (operated) comb electrode and capacitance detecting.

In the MEMS gyroscope, act on angular velocity on the oscillating mass piece by the size measurement that detects Ge Shili.When mass when x axle (driving shaft) vibrates, just can detect size around the angular velocity of z axle input.When the angular velocity input is arranged around the z direction of principal axis, will produce brother's formula acceleration at the y direction of principal axis, under the effect of brother's formula acceleration, can force mass in the y direction according to certain frequency vibration, the amplitude of this vibration and the size of input angular velocity are certain proportionate relationship.Therefore, can determine the value of input angular velocity according to the size of vibration amplitude.

The MEMS gyro is also bringing corresponding deficiency and shortcoming greatly and when improving detection sensitivity, measuring accuracy for enlarging dynamic range, its pectination is comparatively complicated, make anti-overload ability relatively poor, thereby influence serviceable life, and be difficult to adapt under the rugged surroundings such as angular acceleration change is very big and measure.

Summary of the invention

The present invention is different from the principle of work of above MEMS gyro.Utilize the principle of work of angular acceleration and acceleration, designed can the perception angular acceleration signal sensor and relevant angular acceleration signal modulation and demodulation handle detection system, and having simple in structurely, anti-overload ability is strong, the micromechanical angle acceleration sensor that sensitivity and measuring accuracy are high.

Micromechanical angle acceleration sensor provided by the invention comprises a suspended matter gauge block, the beam of two quality of connection pieces and stiff end, characteristics be also comprise two with detect the relevant detection pole plate of angular acceleration; Detect pole plate and stiff end and fix, mass is two utmost points of electric capacity with detecting pole plate; When on quality of connection piece beam, applying the angular acceleration of a rotation, mass will deflect, the distance that causes mass and detect between the pole plate changes, the capacitance that finally causes detecting between pole plate and the mass changes, and just can judge the size of measured angle acceleration by the capacitance change of test detection pole plate.

The micromechanical angle acceleration sensor also has the differential ference spiral signal detection system.The mass of micromechanical angle acceleration sensor and two detection pole plates constitute two capacitor C ₁, C ₂, the electric capacity both sides add a HF voltage V _ACAs modulation signal, be high-frequency voltage signal with the angular acceleration mechanical oscillation signal of low frequency variations by amplitude modulation(PAM), and become voltage signal V after two discharge circuits that detected high-frequency voltage signal passes through respectively to be connected are amplified ₁, V ₂, this voltage signal V ₁, V ₂Behind differential amplifier by connecting, full wave rectifier, the low-pass filter, the demodulation from the high frequency carrier of low frequency angular acceleration signal can be come out, by amplifier signal be amplified and exports the voltage signal of the angular acceleration that is detected again once more.The mechanical angle acceleration transducer also has the self-oscillation signal detection system.The mass of micromechanical angle acceleration sensor is formed two electrodes with the detection pole plate; One of them electrode is as detecting electrode, be used for testing the capacitance variations signal that causes by angular acceleration, with this signal through connect electric capacity/voltage C/V converter and be converted to voltage signal, after the rectification and filtering of institute's connection full wave rectifier, low-pass filter, signal is amplified and exports the voltage signal of the angular acceleration that is detected once more by amplifier again; Another electrode is as drive electrode, by acting on voltage on this electrode as static driven power, allow mass center on middle axle swing, the voltage that acts on this electrode comprises driving DC voltage and driving alternating voltage, drives DC voltage by fixing participation voltage V _BEFProvide, the driving alternating voltage is by producing behind the phase shift of C/V conversion back connection and process phase-shifter and amplitude limiter circuit and the amplitude limit.Constituted the closed loop oscillatory system from the detecting electrode to the drive electrode, free-running frequency is as the carrier frequency of angle signal for faster.

Micromechanical angle acceleration sensor provided by the invention has outstanding advantage and obvious improvement is:

1, micromechanical angle acceleration sensor is different with traditional angular rate sensor principle of work.Traditional angular rate sensor is to come responsive angle rate signal by coriolis force, micromechanical angle acceleration sensor then is responsive angular acceleration signal, angular acceleration signal can obtain angle rate signal after by integration, has solved traditional angular rate sensor and has been subject to the difficult problem that acceleration disturbs.

2, micromechanical angle acceleration sensor has stronger anti-overload ability, the high and measuring accuracy height of detection sensitivity.

3, the micromechanical angle acceleration sensor volume is little, and is simple in structure, and dynamic range is big, long service life.Be particularly suitable for the attitude measurement under the rugged surroundings such as angular acceleration change is very big.

Description of drawings

Fig. 1 is the front view of micromechanical angle acceleration sensor slab construction;

Fig. 2 is the side view of micromechanical angle acceleration sensor slab construction;

Fig. 3 is the vertical view of micromechanical angle acceleration sensor slab construction;

Fig. 4 is when applying an angular acceleration to beam, mass and the structural representation that detects the polar plate spacing variation;

Fig. 5 is the front view of micromechanical angle acceleration sensor prong structure;

Fig. 6 is the A-A cut-open view of micromechanical angle acceleration sensor prong structure;

Fig. 7 is the differential ference spiral signal detection system schematic diagram of micromechanical angle acceleration sensor;

Fig. 8 is the self-oscillation signal detection system schematic diagram of micromechanical angle acceleration sensor.

Embodiment

Describe the specific embodiment of the present invention in detail below in conjunction with accompanying drawing.

Fig. 1, Fig. 2, Fig. 3 and shown in Figure 4, the basic structure of micromechanical angle acceleration sensor, comprise a suspended matter gauge block 1, two beams 2 that connect suspended matter gauge block and stiff end, and two with detect the relevant detection pole plate 3 of angular acceleration, detection pole plate and stiff end 4 are fixing, and mass is two electrodes of electric capacity with detecting pole plate; When on the beam of quality of connection piece, applying the angular acceleration of a rotation, mass will deflect, the distance that causes mass and detect between the pole plate changes, the capacitance that finally causes detecting pole plate changes, and just can judge the size of measured angle acceleration by the capacitance change of test detection pole plate.The principle of work of micromechanical angle acceleration sensor is as follows:

Mass is symmetrically with respect to beam, and beam has the torsionspring characteristic, applies an angular acceleration ε on to beam, wherein $\mathrm{\ϵ}=\frac{\mathrm{d\ω}}{\mathrm{dt}}\·r$ , mass is owing to be subjected to equal and opposite in direction, two power F that direction is opposite ₁And F ₂, and deflect, deflection angle is θ.

${\mathrm{<figure-callout\; id="1"\; label="F"\; filenames="C20051001288400092.png,C20051001288400102.png"\; state="\{\{state\}\}">F</figure-callout>}}_1=m\&CenterDot;\mathrm{\&epsiv;}=m\&CenterDot;\left(\frac{\mathrm{d\&omega;}}{\mathrm{dt}}\right)\&CenterDot;r$

${\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="C20051001288400092.png"\; state="\{\{state\}\}">F</figure-callout>}}_2=-m\&CenterDot;\mathrm{\&epsiv;}=m\&CenterDot;\left(\frac{\mathrm{d\&omega;}}{\mathrm{dt}}\right)\&CenterDot;r$

So, the mass size that is subjected to making a concerted effort is:

$F=F_1-{\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="C20051001288400092.png"\; state="\{\{state\}\}">F</figure-callout>}}_2=2m\&CenterDot;\left(\frac{\mathrm{d\&omega;}}{\mathrm{dt}}\right)\&CenterDot;r$

Because the deflection of mass causes that mass and the distance that detects between the pole plate change, and makes that detecting capacitance changes.

Before not deflecting, mass and the capacitance that detects between the pole plate are:

${\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="C20051001288400092.png,C20051001288400102.png"\; state="\{\{state\}\}">C</figure-callout>}}_1={\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="C20051001288400092.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=C_0={\mathrm{\&epsiv;}}_r\&CenterDot;{\mathrm{\&epsiv;}}_0\&CenterDot;\frac{A}{d}$

Wherein, A is the area of mass; D is the distance between mass and the detection pole plate.

Behind mass deflection θ angle, the capacitance C between mass and the detection pole plate ₁, C ₂An increase, one reduces.

Fig. 5 and shown in Figure 6 is the prong structure of micromechanical angle acceleration sensor.The mass of micromechanical angle acceleration sensor is provided with plurality of square holes 101, corresponding to square hole set on the mass, detect pole plate and be provided with several prongs 201, in the middle of the square hole on the prong insertion mass, the capacitance and the capacitance change Δ C that detect between pole plate and the mass have been increased, the sensitivity that has improved sensor.This structure is the improvement of carrying out on the basis of slab construction, and its principle of work is identical with the principle of work of slab construction angular acceleration transducer.

Shown in Figure 7, be the signal detection system of micromechanical angle acceleration sensor.The mass of micromechanical angle acceleration sensor and two detection pole plates constitute two capacitor C ₁, C ₂, the electric capacity both sides add a HF voltage V _ACAs modulation signal, be high-frequency voltage signal with the angular acceleration mechanical oscillation signal of low frequency variations by amplitude modulation(PAM), and become voltage signal V after two discharge circuits that detected high-frequency voltage signal passes through respectively to be connected are amplified ₁, V ₂, this voltage signal V ₁, V ₂Behind differential amplifier by connecting, full wave rectifier, the low-pass filter, the demodulation from the high frequency carrier of low frequency angular acceleration signal can be come out.

Work as C ₁, C ₂After the signal that detects passes through amplifier, voltage V ₁, V ₂Be respectively:

$V_1=V_{\mathrm{AC}}\&CenterDot;\frac{C_1}{C_F}$

${\mathrm{<figure-callout\; id="2"\; label="V"\; filenames="C20051001288400092.png"\; state="\{\{state\}\}">V</figure-callout>}}_2=V_{\mathrm{AC}}\&CenterDot;\frac{C_2}{C_F}$

Work as V ₁, V ₂After the difference amplification, can get:

$V=V_{\mathrm{AC}}\&CenterDot;(\frac{C_2}{C_F}-\frac{C_1}{C_F})=V_{\mathrm{AC}}\&CenterDot;\frac{C_2-C_1}{C_F}=V_{4C}\&CenterDot;\frac{\mathrm{\&Delta;C}}{C_F}$

By amplifier signal is amplified and exports the voltage signal of the angular acceleration that is detected again once more.

Wherein, above-described two discharge circuits are made of amplification circuit, capacitor C and resistance R respectively, and respectively by direct supply V _T1, V _T2V is adjusted in power supply _T1, V _T2Magnitude of voltage can be used for regulating the biasing and the sensitivity of output angle acceleration.

Shown in Figure 8, be the self-oscillation signal detection system of micromechanical angle acceleration sensor.The mass of micromechanical angle acceleration sensor is formed two electrodes with the detection pole plate; One of them electrode is as detecting electrode, be used for testing the capacitance variations signal that causes by angular acceleration, with this signal through connect electric capacity/voltage (C/V) and be converted to voltage signal, after the rectification and filtering of institute's connection full wave rectifier, low-pass filter, signal is amplified and exports the voltage signal of the angular acceleration that is detected once more by amplifier again; Another electrode is as drive electrode, by acting on voltage on this electrode as static driven power, allow mass center on middle axle swing, the voltage that acts on this electrode comprises driving DC voltage and driving alternating voltage, drives DC voltage by fixing participation voltage V _REFProvide, the driving alternating voltage is by producing behind the phase shift of C/V conversion back connection and process phase-shifter and amplitude limiter circuit and the amplitude limit.Constituted the closed loop oscillatory system from the detecting electrode to the drive electrode, free-running frequency is as the carrier frequency of angle signal for faster.

Wherein, above-described amplifier C/V is made of amplification circuit, capacitor C and resistance R, and by direct supply V _T3V is adjusted in power supply _T3Magnitude of voltage can be used for regulating the biasing and the sensitivity of output angle acceleration.

Claims (2)

1. micromechanical angle acceleration sensor comprises a suspended matter gauge block, two beams that connect suspended matter gauge block and stiff end, two with the relevant detection pole plate of detection angular acceleration; Detect pole plate and stiff end and fix, mass is two utmost points of electric capacity with detecting pole plate; When on the beam of quality of connection piece, applying the angular acceleration of a rotation, mass will deflect, the distance that causes mass and detect between the pole plate changes, the capacitance that finally causes detecting pole plate and mass changes, by the capacitance change of test detection pole plate, judge the size of measured angle acceleration; It is characterized in that: a described mass is provided with plurality of square holes, corresponding to square hole set on the mass, detect pole plate and be provided with several prongs, in the middle of the square hole on the prong insertion mass, the capacitance and the capacitance change that detect between pole plate and the mass have been increased, the sensitivity that has improved sensor.

2. micromechanical angle acceleration sensor according to claim 1 is characterized in that: it has the self-oscillation signal detection system; The mass of micromechanical angle acceleration sensor is formed two electrodes with the detection pole plate; One of them electrode is as detecting electrode, be used for testing the capacitance variations signal that causes by angular acceleration, this signal through the electric capacity/voltage C/V converter that connection be converted to voltage signal, after the rectification and filtering of the full wave rectifier through being connected, low-pass filter, signal is amplified and exports the voltage signal of the angular acceleration that is detected once more by amplifier again; Another electrode is as drive electrode, produce static driven power by the voltage that acts on the drive electrode, allow mass center on middle axle swing, the voltage that acts on the drive electrode comprises driving DC voltage and driving alternating voltage, drives DC voltage by voltage V _REFProvide, drive alternating voltage and be electric capacity by the conversion of C/V converter after through producing behind the phase shift of phase-shifter and amplitude limiter circuit and the amplitude limit, from the detecting electrode to the drive electrode, constituted the closed loop oscillatory system, free-running frequency is as the carrier frequency of angular acceleration signal; Described amplifier is: after capacitor C and the resistance R parallel connection, an end connects the inverting input of amplification circuit, and the other end connects the positive output end of amplification circuit, and the feeder ear of amplification circuit connects direct supply V _T3, and by direct supply V _T3Power supply, and adjust V _T3Magnitude of voltage is regulated the biasing and the sensitivity of output angle acceleration with fourth.

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