CN101509816B - Force sensor and air measurement method thereof - Google Patents

Abstract

The invention discloses a force sensor and a wind speed measuring method thereof. The force sensor includes a wind-engaging body, an elastic beam, a first strain gauge group and a second strain gauge group. The measuring method adopts the strain gauges to measure the wind load of the elastic beam and obtains wind speed and direction through measurement. Without moving elements, the invention has quick response, simple and reliable structure and strong environment applicability.

Description

Force transducer and wind measurement method thereof

Technical field

The present invention relates to a kind of sensor and measuring method thereof, relate in particular to a kind of force transducer and wind measurement method thereof.

Background technology

At numerous areas such as meteorology, environmental protection, industrial and agricultural production, building, military affairs, air velocity all is an important detected parameters.Particularly development in recent years faster automatic weather station the measuring wind speed instrument is had higher requirement, development can adapt to bad weather condition, realizes that heterogeneous, the instantaneous accurate measuring wind speed instrument of multiple spot has more the meaning of particular importance.

At present, the employed instrument and equipment of measuring wind is various in style, usually based on following several principles: dynamic pressure type, mechanical type, hot type, ultrasonic type, digital etc.The pitot tube anemoscope is typical dynamic pressure type measuring wind speed instrument, and this device structure is simple, and is better to the adaptability of environment, and degree of accuracy and resolution are not measured but be suitable for low velocity wind all than higher; The mechanical type wind gage is simple in structure, utilize rotating vane probe perception simultaneously wind speed and direction, but make, installation requirement is higher, and inevitably has wearing and tearing and problem of aging in long-term use, influence measuring accuracy, also be not suitable under the harsh climate condition, working; The wind gage of thermal different type, the cooling velocity of utilizing the wind speed influence to add heat-sensitive element is come measuring wind, because it is easy of integration, it is a kind of wind speed method of the popular research in present measuring wind speed field, this quasi-instrument amount journey is less at present, can't be used to measure high speed winds, be subjected to humidity effect very big simultaneously, can not large tracts of land practicability; Influence hyperacoustic velocity of propagation based on wind speed in recent years, the ultrasonic wind speed measuring instrument has been proposed, but the velocity of sound is subjected to such environmental effects very obvious, and atmospheric humidity, temperature and wherein contained factors such as impurity concentration all can influence to some extent to the measuring accuracy of ultrasonic sensor.

Present measuring wind speed instrument is restricted by factors such as structure, principle, range, has the relatively poor problem of versatility, particularly is not suitable for open-air long-term unattended automatic weather station.

Summary of the invention

The present invention seeks to propose a kind of force transducer and wind measurement method thereof at the defective that prior art exists.

The present invention adopts following technical scheme for achieving the above object:

Force transducer of the present invention, it is characterized in that comprising wind-engaging body, elastic beam, the first foil gauge group and the second foil gauge group, wherein elastic beam is fixed in the inside of wind-engaging body, the first foil gauge group is arranged at the front side, top of elastic beam, the second foil gauge group is arranged at the bottom rear side of elastic beam, the first foil gauge group is identical with the second foil gauge group structure, each foil gauge group comprises four foil gauges, each foil gauge constitutes a brachium pontis of Hui Sitong full-bridge circuit, the input termination power of described favour stone full-bridge circuit.

The wind measurement method of described force transducer is characterized in that comprising the steps:

The first step: adopt force transducer to detect actual wind speed and obtain voltage change signal Δ U _o

Second step: adopt the described voltage change signal Δ of first step U _oCalculate two-dimentional power:

$\left\{\begin{array}{c}{F}_x=\mathrm{\Δ}{U}_{\mathrm{ox}}{W}_{x}E/\left({\mathrm{KUL}}_A\right)\\ F_y=\mathrm{\Δ}{U}_{\mathrm{oy}}{W}_{y}E/\left({\mathrm{KUL}}_B\right)\end{array}\right.,$

Δ U wherein _Ox, Δ U _OyBe respectively the described voltage change signal Δ of first step U _oAt the component of x axle and y axle, E is an elasticity modulus of materials, W _xAnd W _yBe respectively the bending sections coefficient of sensor section at x axle and y axle, U is the supply voltage of Hui Sitong full-bridge circuit, L _AAnd L _BBe respectively the arm of force of the first foil gauge group and the second foil gauge group, K is a gage factor, F _xAnd F _yBeing respectively the wind load F that force transducer is subjected to is two-dimentional power at the component of x axle and y axle;

The 3rd step: adopt described two-dimentional power of second step to calculate the component of the described actual wind speed v of the first step at x axle and y axle: $\left\{\begin{array}{c}{v}_x=\sqrt{1630F_x/S}=\sqrt{1630\mathrm{\Δ}{U}_{\mathrm{ox}}{W}_{x}E/\left({\mathrm{KUL}}_{A}S\right)}\\ v_y=\sqrt{1630F_y/S}=\sqrt{1630\mathrm{\Δ}{U}_{\mathrm{oy}}{W}_{y}E/\left({\mathrm{KUL}}_{B}S\right)}\end{array}\right.,$ Wherein S is the cross-sectional area of force transducer, v _xAnd v _yBe respectively the component of actual wind speed v at x axle and y axle;

The 4th step: adopt the component v of described actual wind speed of the 3rd step at x axle and y axle _xAnd v _yObtain actual wind speed v and actual wind speed angle α: $\left\{\begin{array}{c}v=\sqrt{{v_x}^2+{{\mathrm{<figure-callout\; id="2"\; label="v\; y"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">v</figure-callout>}}_y}^2}\\ \tan \mathrm{\&alpha;}={\tan }^{-1}(v_y/v_x)\end{array}\right..$

Beneficial effect of the present invention: the present invention is based on the wind load principle, it is made up of the elastic strain beam of two quadratures, adopts foil gauge to measure the wind load of elastic beam, reaches the purpose of wind speed, wind direction measurement.Compare with the mechanical anemometer that generally uses, it does not have moving component, and it is fast, simple and reliable for structure to have a response, and the environment characteristic of strong applicability is a kind of extremely promising measuring wind speed instrument.

The principle of the invention is simple, novel structure, this force transducer structure is special, the characteristic that himself has effective responsive unidirectional force, to export bridge circuit independent fully in addition, make that the degree of coupling reduces as much as possible between the dimension of this 2 dimension sensor, solved coupled problem between the dimension that puzzlement multi-dimension force sensor precision improves substantially.Is a kind of new trial with this multi-dimension force sensor utilization with the measuring wind speed field, by further experiment with the environmental parameter that records (as air pressure P, absolute humidity e, temperature t etc.) in order to air severe is demarcated, just can effectively overcome traditional wind measurement method and be subjected to the bigger problem of external environment factor affecting, and simple in structure, can realize heterogeneous accurate measurement, use as the engineering of this novel multi-vitamin force transducer and have very that wide development is worth.

Description of drawings

Fig. 1 (a) is a force transducer directions X sectional view of the present invention,

(b) be force transducer Y direction sectional view of the present invention;

Fig. 2 is force transducer strain beam of the present invention cross section;

Fig. 3 is Hui Sitong full-bridge circuit figure of the present invention.

Embodiment

Be elaborated below in conjunction with the technical scheme of accompanying drawing to invention:

As shown in Figure 1,1 is the wind-engaging body of a round section, blast is converted to the load of 2 D force sensor by it.2 is elastic beam, and it comes down to the combination of the elastic strain beam of two quadratures, and elastic beam is opened two groove A, B up and down respectively, in order to increase the sensitivity of sensor.The both sides of elastic beam are pasted one group of foil gauge 3,4 respectively, constitute the differential full bridge measurement circuit of Hui Sitong, can measure the X of elastic beam, the strain of Y both direction respectively, thereby measure the wind load F of elastic beam.Wherein, the top sensors A is used for measured X directive effect power Fx, and below sensor B is used to measure the directed force F y of Y direction.

As shown in Figure 2, the strain transducer beam only has the surface of a pair of side to post foil gauge, the beam body deformability (is the strain of directions X as figure foil gauge A perception) that is used for the perception specific direction, beam body hollow in addition, strengthened the beam body deformability of perceived direction (directions X as shown in FIG.), greatly reduce of the influence of the power of other directions (as Y direction among the figure), almost can ignore foil gauge.

Measuring process is as follows:

1, the wind-engaging body is subjected to wind load F effect, obtains X shown in Figure 1 after the decomposition, the component Fx on the Y direction, Fy.Corresponding foil gauge A, the moment My that B is suffered, Mx are determined in position according to sensor

$A\&RightArrow;\left\{\begin{array}{c}{M}_{\mathrm{Ay}}=F_x\&CenterDot;L_A\\ M_{\mathrm{Ax}}=F_y\&CenterDot;L_A\end{array}\right.$ $B\&RightArrow;\left\{\begin{array}{c}{M}_{\mathrm{By}}=F_x\&CenterDot;L_B\\ M_{\mathrm{Bx}}=F_y\&CenterDot;L_B\end{array}\right.---\left(1\right)$

2, there is the moment of flexure on the both direction to do the time spent when effect simultaneously on the sensor cross-section,, can utilizes superposition principle to obtain that the most dangerous place normal stress is on the xsect because material is obeyed Hooke's law and distortion is very little

$\left\{\begin{array}{c}{\stackrel{\&RightArrow;}{\mathrm{\&sigma;}}}_A={\stackrel{\&RightArrow;}{M}}_{\mathrm{Ay}}/W_y+{\stackrel{\&RightArrow;}{M}}_{\mathrm{Ax}}/W_x\\ {\stackrel{\&RightArrow;}{\mathrm{\&sigma;}}}_B={\stackrel{\&RightArrow;}{M}}_{\mathrm{By}}/W_x+{\stackrel{\&RightArrow;}{M}}_{\mathrm{Bx}}/W_y\end{array}\right.---\left(2\right)$

Wherein Wx and Wy are the bending sections coefficient of sensor section.

Ignore between dimension and disturb, (2) formula can be made into

$\left\{\begin{array}{c}{\mathrm{\&sigma;}}_A=M_{\mathrm{Ay}}/W_y=F_x\&CenterDot;L_A/W_y={\mathrm{\&sigma;}}_x\\ {\mathrm{\&sigma;}}_B=M_{\mathrm{Bx}}/W_y=F_y\&CenterDot;L_B/W_y={\mathrm{\&sigma;}}_y\end{array}\right.---\left(3\right)$

According to Fig. 2, be easy to get:

Wy＝2(b ³h/4)/(12b/2)＝b ²h/48 (4)

3, by Hooke's law the pass of strain and stress be as can be known: ε=σ/E further obtains:

$\left\{\begin{array}{c}{\mathrm{\&epsiv;}}_x={\mathrm{\&sigma;}}_x/E=F_x\&CenterDot;L_A/\left(W_{y}E\right)\\ {\mathrm{\&epsiv;}}_y={\mathrm{\&sigma;}}_y/E=F_y\&CenterDot;L_B/\left(W_{y}E\right)\end{array}\right.---\left(5\right)$

E is the elastic constant relevant with material character.

4, utilize Hui Sitong full-bridge mode, promptly all insert in four brachium pontis positions of electric bridge foil gauge resistance (as Fig. 3, R ₁, R ₂, R ₃, R ₄Be arm resistance) measure the suffered stress situation of foil gauge, insert relative arm strainometer tension (the Δ R of electric bridge ₁/ R ₁, Δ R ₄/ R ₄), alternate arm strainometer pressurized (Δ R ₂/ R ₂,-Δ R ₃/ R ₃), (R under congruent arm condition ₁=R ₂=R ₃=R ₄) obtain:

$\mathrm{\&Delta;}{U}_o=\frac{0.25U(\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1/{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1+\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_2/R_2+\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3/R_3+\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_4/R_4)}{1+0.5(\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_1/R_1-\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_2/R_2+\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="3"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3/R_3-\mathrm{\&Delta;}{\mathrm{<figure-callout\; id="4"\; label="R"\; filenames="H2009100299703E00011.png"\; state="\{\{state\}\}">R</figure-callout>}}_4/R_4)}=U\frac{\mathrm{\&Delta;}{R}_1}{R_1}---\left(6\right)$

Δ R wherein ₁/ R ₁=K ε ₁, promptly

ε ₁＝ΔUo/(KU) (7)

5, by the measurement of change in voltage being obtained the strain of foil gauge, (6) substitution (7) is got:

$\left\{\begin{array}{c}{F}_x=\mathrm{\&Delta;}{U}_{\mathrm{ox}}{W}_{x}E/\left({\mathrm{KUL}}_A\right)\\ F_y=\mathrm{\&Delta;}{U}_{\mathrm{oy}}{W}_{y}E/\left({\mathrm{KUL}}_B\right)\end{array}\right.---\left(8\right)$

6, because wind acts on particular cross section and can produce pressure (ω, every square metre of ox), be called blast.Blast and respective relationships

$\mathrm{\&omega;}=\frac{\mathrm{\&gamma;}}{2g}{v}^2---\left(9\right)$

Wherein, v is tested wind speed (m/s), and γ is air severe (N/m ³), it is directly proportional with atmospheric density ρ, and γ=ρ g, g are acceleration of gravity (9.8m/s ²).

Air severe γ is air pressure P (millimeter of mercury), absolute humidity e (millimeter of mercury), temperature t (℃) function, its computing formula is:

γ＝1.293(P-0.378)/(760(1+0.00387t)) (10)

At air pressure is under 101.325kPa, 15 ℃ of normal temperature and the absolutely dry situation, γ=0.012018kN/m ³, to locate for 45 ° at latitude, the acceleration of gravity on the sea level is g=9.8m/s ², substitution (9) formula gets

ω＝γv ²/(2g)＝0.012018v ²/(2×9.8)≈v ²/1630kN/m ² (11)

And air pressure P, absolute humidity e, temperature t is all relevant with height above sea level, in the measuring wind speed process of reality, can in order to γ air severe be revised by experiment with environmental parameter substitution (2) formula.

Because of F=ω S, S is an area of section again, so

$v_{x/y}=\sqrt{1630F/S}---\left(12\right)$

7, (Fx, (12) formula that Fy), carries it into just obtains wind speed (v to utilize multi-dimension force sensor structure described in the step e and Wheatstone bridge part to go out two-dimentional power with regard to energy measurement _x, v _y):

$\left\{\begin{array}{c}{v}_x=\sqrt{1630\mathrm{\&Delta;}{U}_{\mathrm{ox}}{W}_{x}E/\left({\mathrm{KUL}}_{A}S\right)}\\ v_y=\sqrt{1630\mathrm{\&Delta;}{U}_{\mathrm{oy}}{W}_{y}E/\left({\mathrm{KUL}}_{B}S\right)}\end{array}\right.---\left(13\right)$

8, carry out according to parallelogram law at last and become to obtain:

$v=\sqrt{{v_x}^2+{v_y}^2}$ (14)

tanα＝tan ^-1(v _y/v _x)

Obtain the required wind speed size and Orientation that records thus.

9, again the lifting surface area of force cell is estimated.Multi-dimension force sensor maximum range of the present invention is 200g, and promptly 0.2kg is 2N.Getting maximum range is that the corresponding wind speed of 2N becomes 30m/s, and required area is: S=F/ ω=2/ (900 * 1000/1630)=0.0036m ²=36cm ², promptly area is 6 * 6 centimetres.When wind speed was 1m/s, the power of generation was F=ω S=0.0036 * 1000/1630=0.002N, promptly is equivalent to 0.0002kg=0.2g, was 1/100 precision.

Claims (2)

1. force transducer, it is characterized in that comprising wind-engaging body (1), elastic beam (2), the first foil gauge group (3) and the second foil gauge group (4), wherein elastic beam (2) is fixed in the inside of wind-engaging body (1), the first foil gauge group (3) is arranged at the front side, top of elastic beam (2), the second foil gauge group (4) is arranged at the bottom rear side of elastic beam (2), the first foil gauge group (3) is identical with second foil gauge group (4) structure, each foil gauge group comprises four foil gauges, each foil gauge constitutes a brachium pontis of Hui Sitong full-bridge circuit, the input termination power of described favour stone full-bridge circuit.

2. the wind measurement method based on the described force transducer of claim 1 is characterized in that comprising the steps:

The first step: adopt force transducer to detect actual wind speed and obtain voltage change signal Δ U _o

Second step: adopt the described voltage change signal Δ of first step U _oCalculate two-dimentional power:

Δ U wherein _Ox, Δ U _OyBe respectively the described voltage change signal Δ of first step U _oAt the component of x axle and y axle, E is an elasticity modulus of materials, W _xAnd W _yBe respectively the bending sections coefficient of sensor section at x axle and y axle, U is the supply voltage of Hui Sitong full-bridge circuit, L _AAnd L _BBe respectively the arm of force of the first foil gauge group (3) and the second foil gauge group (4), K is a gage factor, F _xAnd F _yBeing respectively the wind load F that force transducer is subjected to is two-dimentional power at the component of x axle and y axle;

The 3rd step: adopt described two-dimentional power of second step to calculate the component of the described actual wind speed v of the first step at x axle and y axle:

Wherein S is the cross-sectional area of force transducer, v _xAnd v _yBe respectively the component of actual wind speed v at x axle and y axle;

The 4th step: adopt the component v of described actual wind speed of the 3rd step at x axle and y axle _xAnd v _yObtain actual wind speed v and actual wind speed angle α:

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