IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0835450
(2007-08-08)
|
등록번호 |
US-7461548
(2008-12-09)
|
우선권정보 |
FR-06 07239(2006-08-09) |
발명자
/ 주소 |
|
출원인 / 주소 |
|
대리인 / 주소 |
|
인용정보 |
피인용 횟수 :
2 인용 특허 :
6 |
초록
A method and a device for obtaining the three components (u,v,w) of the air speed (TA) of an aircraft along its flight path, the device including an arm (2) provided with two pressure probes disposed at each of its ends, each probe having two pressure intakes.
대표청구항
▼
What is claimed is: 1. A method of obtaining the three components u, v, and w of the air speed along a trajectory TA of an aircraft in a non-rotary rectangular frame of reference (x,y,z) , characterized by the following steps: a) measuring air pressures via at least four pressure intakes P1, Q1, P2
What is claimed is: 1. A method of obtaining the three components u, v, and w of the air speed along a trajectory TA of an aircraft in a non-rotary rectangular frame of reference (x,y,z) , characterized by the following steps: a) measuring air pressures via at least four pressure intakes P1, Q1, P2, and Q2, a first group of air intakes P1 and Q1, and a second group of air intakes P2 and Q2 being disposed respectively on first and second pressure probes S1 and S2 interconnected by an arm (2) rotating at a constant speed of rotation Ω about its center C and orthogonally about a drive shaft (3) such that the pressure intakes P1and Q1 of the first pressure probe S1 and the pressure intakes P2 and Q2 of the second pressure probe S2 are at equal distances R from the center of rotation C of the rotary arm, and furthermore the pressure intakes P1 and P2 are respectively symmetrical with the pressure intakes Q1 and Q2 relative to the plane of rotation PR of said arm (2); b) converting the four pressure measurements into four electric signals; c) establishing a first magnitude S by adding the electric signals obtained from the two pressure intakes P1 and P2 disposed above the plane of rotation PR and subtracting the electric signals obtained from the two pressure intakes Q1 and Q2 disposed below said plane of rotation; d) establishing a second magnitude D by adding the electric signals obtained from one of the two pressure probes and by subtracting the electric signals obtained from the other pressure probe; e) using a Taylor/MacLaurin series development of the theoretical expression for the tangential speed TB of the air in register with each pressure intake and retaining only the first order terms so as to obtain firstly a first expression representative of the first magnitude S and secondly a second expression representative of the second magnitude D having the following forms respectively: description="In-line Formulae" end="lead"S=-4ρf0Ufz'wdescription="In-line Formulae" end="tail" description="In-line Formulae" end="lead"D=-4ρU[(1-f02)vt-fr 'vr]description="In-line Formulae" end="tail" where: ρ=density of air; U=the driven speed of the probes in the rotary movement of the arm (2) =-ΩR ; vs=U +vt; vr=the component of TA along an axis r passing through the probes and the center C; vt=the component of TA along an axis t orthogonal to the axis r and in the plane PR f0=the first term of the Taylor/MacLaurin series development of the function f; f'r=the partial derivative of f relative to r; f'z=the partial derivative of f relative to z; f) since the first expression S is proportional to w, and since the other terms are known, deducing w therefrom by identifying said first expression S with the first magnitude S, said operation being performed by harmonic analysis synchronized on the speed of rotation of the arm (2) from a synchronization signal T such that the mean component M of the first magnitude S provides w on the basis of knowledge of the one-to-one relationship between said mean component M and w as obtained by prior calibration; and g) since the second expression D is a periodic function of time due to the constant speed of rotation Ω of the arm and depends on two periodic components vt and Vr of the air speed along the trajectory in two orthogonal axes, respectively t and r linked with a probe, contained in said plane of rotation and respectively normal and radial relative to said arm (2), producing, by said harmonic analysis synchronized on the speed of rotation of the arm, the first order harmonic components DC and DS of the second magnitude D, and consequently the components u and v as a function of previously established corresponding calibration. 2. A method according to claim 1, wherein steps b), c) , and d) are performed as follows: an electric signal Ep1 generated by a pressure sensor Cp1associated with the pressure intake P1 is transmitted to two combiner members OC1 and OC2 and is given a positive sign; an electric signal Ep2 generated by a pressure sensor Cp2associated with the pressure sensor P2 is transmitted firstly to the combiner member OC1 and associated with a positive sign, and secondly to the combiner member OC2 and associated with a negative sign; an electric signal EQ1 generated by a pressure sensor CQ1associated with the pressure intake Q1 is transmitted firstly to the combiner member OC1 and is associated with a negative sign, and secondly to the combiner member OC2 and is associated with a positive sign; the electric signal EQ2 generated by the pressure sensor CQ2 associated with the pressure intake Q2 is transmitted to both combiner members OC1 and OC2 and is associated with a negative sign; the first magnitude S is established by the first combiner OC1 summing the electric signals; and the second magnitude D is established by the second combiner member OC2 by summing the electric signals. 3. A method according to claim 1 wherein the steps b), c), and d), are performed as follows: the pressures of the pressure intakes P1 and P2 are transmitted to a pressure sensor cP1P2 that measures a differential pressure equal to the pressure measured by the pressure intake P1 minus the pressure measured by the pressure intake P2 and converted into an electric signal EP1P2 the pressures of the pressure intakes P1 and Q1 are transmitted to a pressure sensor CP1Q1 that measures a differential pressure equal to the pressure measured by the pressure intake P1 minus the pressure measured by the pressure intake Q1 and converted into an electric signal EP1Q1 the pressures of the pressure intakes P2 and Q2 are transmitted to a pressure sensor CP2Q2 that measures a differential pressure equal to the pressure measured by the pressure intake P2 minus the pressure measured by the pressure intake Q2, and converted into an electric signal EP2Q2; and the pressures of the pressure intakes Q1 and Q2 are transmitted to a pressure sensor CQ1Q2 that measures a differential pressure equal to the pressure measured by the pressure intake Q1 minus the pressure measured by the pressure intake Q2 and converted into an electric signal EQ1Q2 the signal for the first magnitude S is obtained by a first summing circuit SO1 adding the signals EP1Q1 and EP2Q2 ; and the signal for the second magnitude D is obtained by a second summing circuit SO2 adding the signals EP1P2 and EQ1Q2. 4. A method according to claim 1 , wherein the electric signals are analog signals. 5. A method according to claim 1, wherein the electric signals are digital signals. 6. A method according to claim 1, wherein the synchronization signal T is generated by a phonic wheel. 7. A method according to claim 1, wherein the synchronization signal T is generated by an angle encoder. 8. A method according to claim 1, wherein a phase shift between the maximum value of the signal for the second magnitude and a probe facing the speed direction, as determined during calibration of a probe, is compensated by shifting the phase of the synchronization signal T. 9. A method according to claim 1, wherein a phase shift between the maximum value of the signal for the second magnitude and a probe facing the speed direction, as determined during calibration of a probe, is compensated by using a rotation matrix applied to the components provided by the harmonic analysis. 10. A device (1) for implementing the method specified by claim 1, the device comprising: an arm (2) orthogonal at its center C to a drive shaft (3) directed along the z axis, rotating at a constant speed of rotation Ω in a plane of rotation PR; two pressure probes S1 and S2 disposed, one at one end of the arm (2) and the other at the opposite end of said arm (2); four pressure intakes Pi and Qi such that two pressure intakes P1 and Q1 are disposed on the pressure probe S1 and two pressure intakes P2 and Q2 are disposed on the pressure probe S2.the pressure probes Pi and Qi of any one probe being symmetrical about the plane of rotation PR, being respectively above and below said plane of rotation PR; four pressure sensors [(CP1, CP2, CQ1, CQ2) , (CP1P2CP1Q1CP2Q2,CQ1Q2)], each pressure sensor being associated with at least one pressure intake, converting pressure measurements into electric signals; processor means (5,6) for processing the electric signals generated by the four pressure sensors to establish a first magnitude S and a second magnitude D; a harmonic analyzer AH coupled to a synchronizer SY delivering a synchronization signal T, firstly so that the processing of the signal S relating to the first magnitude by an element CM provides an output signal M, and secondly the processing of the signal relating to the second magnitude D by elements CDC and CDS provides respectively two output signals DC and DS, the signals M, DC, and DS corresponding to the harmonic components respectively of the mean component of the first magnitude S, and the first order components in phase and in phase quadrature of the second magnitude D; and a calibration unit UE enabling the components u, v, and w of TA to be obtained in a non-rotary rectangular frame of reference (x,y,z), the value M providing w from knowledge of the one-to-one relationship between M and w as obtained by prior calibration, and the values DC and D respectively providing the components u and v on the basis of knowledge of one-to-one relationships obtained by prior calibration between DC and u, and between DS and v. 11. A device (1) according to claim 10, wherein each pressure probe S1 and S2 is symmetrical about the plane of rotation PR of said arm (2) with a streamlined anterior end portion situated on the advance side of the arm (2). 12. A device (1) according to claim 11, wherein each probe S1 and S2 is substantially cylindrical. 13. A device (1) according to claim 12, wherein each pressure probe S1 and S2 presents anterior and posterior end portions PA and PP that are substantially hemispherical and interconnected by a substantially cylindrical central shell CQ having its axis of symmetry orthogonal to said arm (2) and contained in the plane of rotation PR, and having a section that is substantially circular. 14. A device (1) according to claim 12, wherein each pressure probe S1 and S2 presents inner and outer end portions PT and PE that are substantially hemispherical and interconnected by a shell CQ that is substantially cylindrical, having its axis of symmetry directed along the arm (2), with the inner and outer end portions PT and PE being disposed respectively towards the center C and the outside of the arm (2) relative to the central shell CQ. 15. A device (1) according to claim 11, wherein each pressure probe S1 and S2 is substantially spherical. 16. A device (1) according to claim 15, wherein the pressure intakes Pi and Qi are oriented along a direction making an angle a lying in the range 25°to 35°relative to the plane of rotation PR. 17. A device (1) according to claim 15, wherein the pressure intakes Pi and Qi are oriented along a direction making an angle a lying in the range 55°to 70°relative to the plane of rotation PR. 18. A device (1) according to claim 10, wherein each pressure sensor CP1, CP2, CQ1CQ2, is disposed directly at a respective pressure intake P1, P2, Q1,Q2, measures an absolute pressure, and delivers a respective electric signal EP1,EP2,EQ1, EQ2,that is an analog signal or a digital signal. 19. A device (1) according to claim 18, wherein the processor means ( 5) comprise a first combiner member OC1 that calculates the first magnitude S (electric signal S) such that: S=EP1+EP2-EQ1-EQ2. 20. A device (1) according to claim 10, wherein each pressure sensor CP1, CP2,CQ1,CQ2, is pneumatically connected to a respective pressure intake P1,P2Q1Q2, measures absolute pressure, and delivers a respective electric signal EP1EP2EQ1 EQ2 that may be an analog signal or a digital signal. 21. A device (1) according to claim 10, wherein each pressure sensor CP1P2CP1Q1CP2Q2CQ1Q2 is connected to two pressure intakes, respectively P1 & P2,P1 & Q2,P2 & Q1,Q1 & Q2, measures a differential pressure, and delivers a respective electric signal EP1P2EP1Q1EP2Q2EQ1Q2. and a second combiner member OC2 that calculates the second magnitude D (electric signal D) such that: D=EP1+EQ1-EP2-EQ2. 22. A device (1) according to claim 21, wherein the processor means (5) comprise a first summing circuit SO1 that calculates the first magnitude S (electric signal S) such that: description="In-line Formulae" end="lead"S=EP1Q1+EP2Q2 description="In-line Formulae" end="tail" and a second summing circuit SO2 that calculates the second magnitude D (electric signal D) such that: description="In-line Formulae" end="lead"D=EP1P2+EQ1Q2.description="In-line Formulae" end="tail" 23. A device (1) according to claim 10, wherein the length 2R of the arm (2) is preferably shorter than 0.2 m. 24. A device (1) according to claim 10, wherein the synchronization signal T is generated by a phonic wheel. 25. A device (1) according to claim 10, wherein the synchronization signal T is generated by an angle encoder. 26. An aircraft, being fitted with the device (1) of claim 10.
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