CN112747892A - In-situ calibration device and method for measuring micro aerodynamic force air floatation platform - Google Patents
In-situ calibration device and method for measuring micro aerodynamic force air floatation platform Download PDFInfo
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Abstract
The invention relates to a device and a method for measuring the in-situ calibration of a micro aerodynamic air flotation platform, wherein the device bears a load model and at least four calibration pieces; the load bearing model is arranged on the air floating platform to be calibrated and is in a free state in the horizontal direction relative to the air floating plane; the four calibration pieces are arranged on the air floatation platform, can apply load forces in different directions to a load bearing model and are used for simulating the axial force, the lateral force and the yaw moment of the model subjected to pneumatic load; and a tension sensor is arranged between the load bearing model and the air floatation platform corresponding to the load force direction. According to the invention, the signal-moment relation is obtained in an in-situ calibration mode, no additional system error is introduced, and the accuracy of the force measuring platform is ensured.
Description
Technical Field
The invention relates to an in-situ calibration device for a force measuring platform in a low-speed wind tunnel test, in particular to an in-situ calibration device for measuring a micro aerodynamic force air-flotation force measuring platform.
Background
The gap in performance between high-level athletes in today's racing sports is sometimes only on the order of milliseconds. The air resistance experienced by sports equipment and athletes in many sports events, such as racing yachts, snowmobiles, and other sports events, is relatively small compared to other resistances, but still has a non-negligible effect on athletic performance. Besides applying related subject knowledge of nutriology, sports science and the like to improve physical quality and technical level of athletes, the resistance measured by a scientific test means can provide theoretical basis and data support for optimizing the appearance of an apparatus and guiding the training and competitive actions of the athletes, and air resistance can be reduced by optimization design according to a test result to improve the performance.
The micro air resistance can be measured by applying a high-precision air flotation force measuring test platform in a low-speed wind tunnel test, and other aerodynamic forces comprise lateral force, yawing moment and the like. The important step before the application of the force measuring platform is to calibrate the air floatation force measuring platform and obtain the accurate relation between the voltage value measured by the sensor and the actually loaded force and moment. However, in the ground debugging, it is found that the accuracy of the output of the force sensor is greatly influenced by factors such as ground flatness and the installation state of the platform when the platform after calibration is changed to other positions. The force measuring platform needs to be calibrated in situ in a test site before use to ensure the accuracy of the result.
Disclosure of Invention
The technical problem solved by the invention is as follows: aiming at the in-situ calibration requirement, the in-situ calibration device for the micro aerodynamic air floatation platform is provided.
The technical scheme of the invention is as follows: the utility model provides a measure little aerodynamic force air supporting platform normal position calibrating device, includes: a load-bearing model and at least four calibration pieces;
the load bearing model is arranged on the air floating platform to be calibrated and is in a free state in the horizontal direction relative to the air floating plane; the four calibration pieces are arranged on the air floatation platform, can apply load forces in different directions to a load bearing model and are used for simulating the axial force, the lateral force and the yaw moment of the model subjected to pneumatic load; a tension sensor is arranged between the load bearing model and the air floatation platform corresponding to the direction of the load force, senses the tension load and outputs axial force, lateral force and yaw moment signals; the calibration part comprises a pulley component, a steel wire rope, a weight tray and a standard weight; the pulley assembly comprises a pulley yoke and a fixed pulley supported by the pulley yoke, and the pulley yoke is arranged on the air floatation platform; one end of the steel wire rope is connected with the load bearing model and is connected with the top of the weight tray by crossing a fixed pulley in the pulley component; and the steel wire rope from the load bearing model to the fixed pulley part is required to be vertical to the surface of the load bearing model at the joint of the steel wire rope and the model, the standard weight is used for being placed on a weight tray to realize force loading, and the total gravity of the weight is recorded as the magnitude of the applied load force.
Preferably, the angle error of the wire rope crossing the fixed pulley part in both horizontal and vertical directions is not more than 3 minutes.
Preferably, the weight of the single standard weight is between 1/10 and 1/30 of the full range of the load cell in the corresponding direction.
Preferably, the number of the calibration pieces is 4, and one calibration piece is arranged at the tail end of the air floatation platform and used for simulating the axial force; arranging one calibration piece on the overlooking right side of the air floatation platform, wherein the calibration piece is positioned on the transverse symmetrical line of the air floatation platform and used for simulating lateral force; two calibration pieces are arranged on the overlooking left side of the force measuring platform, are symmetrical relative to a transverse symmetrical line of the air floatation platform and are used for simulating a yawing moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction.
Preferably, the number of the calibration pieces is 5, one calibration piece is arranged at the front end and the tail end of the air floatation platform, and the two calibration pieces are superposed to simulate axial force; arranging one calibration piece on the overlooking right side of the air floatation platform, wherein the calibration piece is positioned on the transverse symmetrical line of the air floatation platform and used for simulating lateral force; two calibration pieces are arranged on the overlooking left side of the force measuring platform, are symmetrical relative to a transverse symmetrical line of the air floatation platform and are used for simulating a yawing moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction.
Preferably, the number of the calibration pieces is 6, one calibration piece is arranged at the front end and the tail end of the air floatation platform, and the two calibration pieces are superposed to simulate axial force; two calibration pieces are arranged on the overlooking left side of the force measuring platform, and the two calibration pieces are symmetrical relative to the transverse symmetrical line of the air floating platform; two calibration pieces symmetrical to the left side are arranged on the right pitching side of the force measuring platform, and the four calibration pieces on the left side and the right side are superposed to simulate lateral force or yaw moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction.
Preferably, the distance between two calibration pieces disposed on the left or right side of the air bearing platform should be no less than 1/2 of the total length of the air bearing platform.
An in-situ calibration method implemented according to the in-situ calibration device comprises the following steps:
s1, preloading each calibration piece, adding 3 kg-4 kg standard weights on the weight tray of each calibration piece, keeping the state for more than 30 minutes, and fully releasing the stress of the steel wire rope on the calibration piece;
s2, adding a standard weight pre-tightening steel wire rope on the weight tray of each calibration piece;
s3, calibrating three components of axial force, lateral force and pitching moment through multiple times of loading, wherein the initial value of the signal of the tension sensor needs to be acquired before each time of loading and is used as a zero point needing to be deducted; wherein the content of the first and second substances,
calibrating the axial force: adjusting the loading load for simulating the axial force calibration piece, and loading the standard weights one by one within the range of the tension sensor to obtain 6-8 loading points; then unloading one by one to obtain 5-7 loading points; repeating the loading and unloading process for two to three times;
calibrating the lateral force: adjusting the loading load for simulating the lateral force calibration piece, and loading standard weights one by one within the range of the measuring range of the tension sensor to obtain 10-15 loading points; then unloading one by one to obtain 9-14 loading points; repeating the loading and unloading process for two to three times;
calibrating the yaw moment: setting an initial state within the measuring range of the tension sensor, namely marking any one of the two sides of the air floatation platform with one side of two calibration pieces as a standard piece A and adding 5-15 standard weights, and directly adding a balance weight with the same weight on the other side; during calibration, 1 standard weight is unloaded on the standard part A, and simultaneously, 1 standard weight with the same mass is loaded on the other calibration part on the same side, which is recorded as the standard part B, so as to obtain a loading point, and the like, until the unloading of the standard weight on the standard part A is finished, and then 1 standard weight is sequentially unloaded from the standard part B and recorded on the standard part A until the unloading of the standard part B is finished;
and S4, performing data fitting according to the loading amount of the loading points and the data of each loading point tension sensor to obtain calibration coefficients of axial force, lateral force and yaw moment, and realizing in-situ calibration of the air-floating platform by using the calibration coefficients.
Preferably, the calibration coefficient is expressed by the following formula:
in the formula, b1Is the calibration coefficient of axial force, lateral force, or yaw moment, yi、tiRespectively the load force and the output signal of the tension sensor at the ith loading point when the axial force, the lateral force or the yawing moment is calibrated, n is the total number of loading points loaded when the axial force, the lateral force or the yawing moment is calibrated,
are arithmetic averages.
Preferably, a isiThe input is the load force, t, of each loading point for calibrating the lateral forceiThe input is the output signal of the tension sensor when the axial force is calibrated, and the output signal is obtained by utilizing a calibration coefficient calculation formulab1Is the interference coefficient of the lateral force and the axial force.
Compared with the prior art, the invention has the beneficial effects that:
(1) the signal-moment relation is obtained through an in-situ calibration mode, extra system errors are not introduced, and the accuracy of the force measuring platform is guaranteed.
(2) The mass error of the standard weight is 0.001%, and the application of the standard weight to loading can ensure higher loading accuracy.
(3) And the loading scheme is reasonably designed, so that the reliability of the calibration result of the force measuring platform is ensured.
Drawings
FIG. 1 is a schematic overall layout of the present invention;
FIGS. 2a-2c are diagrams of calibrators according to the present invention;
FIG. 3 is a schematic view of a loaded coordinate system of the present invention;
FIG. 4 is a calibration result of the present invention;
fig. 5 is a schematic diagram of a sensor layout.
Detailed Description
The invention is further illustrated by the following examples.
Before the test, the air-floating force-measuring platform (also called air-floating platform/force-measuring platform) can be calibrated in situ after the working position in the wind tunnel is debugged. The relation between the output signal of the force measuring platform and the actual load is obtained by an in-situ calibration method. And a calibration piece is arranged at a proper position selected by the force measuring platform and connected with the model to provide a standard load for the model bearing the load in the force measuring platform. During calibration, the load sizes of the calibration pieces at different positions are adjusted, and a proper loading scheme is designed. The load that the calibration piece provides for the model is a tensile load.
The utility model provides a measure little aerodynamic force air supporting platform normal position calibrating device, includes: a load bearing model and a calibration piece; the load bearing model is arranged on the air floating platform to be calibrated and is in a free state in the horizontal direction relative to the air floating plane; the four calibration pieces are arranged on the air floatation platform, can apply load forces in different directions to a load bearing model and are used for simulating the axial force, the lateral force and the yaw moment of the model subjected to pneumatic load; a tension sensor is arranged between the load bearing model and the air floatation platform corresponding to the load force direction; the tension sensor senses tension load and outputs axial force, lateral force and yaw moment signals.
In a preferred embodiment of the invention, 5 tension sensors are arranged on the force-measuring platform, as shown in fig. 5. All the tension sensors are fixed on the force measuring platform and are connected with the load bearing model. Wherein 1 tension sensor is located the longitudinal axis of force-measuring platform front end for measure the axial force that the model received and output axial force signal. The other 4 tension sensors are respectively arranged at the left front, the left rear, the right front and the right rear of the force measuring platform and are symmetrical relative to the longitudinal axis and the transverse axis of the force measuring platform, and the output signals of the tension sensors can be added, subtracted and combined to measure the lateral force and the yaw moment borne by the model and output signals. Subtracting the sum of the signals of the right front sensor and the right rear sensor from the sum of the signals of the left front sensor and the left rear sensor to obtain a lateral force signal; and subtracting the sum of the signals of the left front sensor and the left rear sensor to obtain a yaw moment signal. The number of the calibration pieces is 4-6 generally, and when the number of the calibration pieces is 4, one calibration piece is arranged at the tail end of the air floating platform and used for simulating axial force; arranging one calibration piece on the overlooking right side of the air floatation platform, wherein the calibration piece is positioned on the transverse symmetrical line of the air floatation platform and used for simulating lateral force; two calibration pieces are arranged on the overlooking left side of the force measuring platform, are symmetrical relative to a transverse symmetrical line of the air floatation platform and are used for simulating a yawing moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction. The positions of the four calibration pieces are designed in such a way that the in-situ calibration of the platform can be carried out under a proper loading scheme, and the relation between the output signal and the resistance, the lateral force and the yaw moment which are subjected to the pneumatic load is obtained.
The number of the calibration pieces is 5, one calibration piece is arranged at the front end and the tail end of the air floatation platform, and the axial force is simulated by superposing the calibration pieces and the tail end; arranging one calibration piece on the overlooking right side of the air floatation platform, wherein the calibration piece is positioned on the transverse symmetrical line of the air floatation platform and used for simulating lateral force; two calibration pieces are arranged on the overlooking left side of the force measuring platform, are symmetrical relative to a transverse symmetrical line of the air floatation platform and are used for simulating a yawing moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction.
The number of the calibration pieces is 6, one calibration piece is arranged at the front end and the tail end of the air floatation platform, and the axial force is simulated by superposing the calibration pieces and the tail end; two calibration pieces are arranged on the overlooking left side of the force measuring platform, and the two calibration pieces are symmetrical relative to the transverse symmetrical line of the air floating platform; two calibration pieces symmetrical to the left side are arranged on the right pitching side of the force measuring platform, and the four calibration pieces on the left side and the right side are superposed to simulate lateral force or yaw moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction.
The calibration member is composed of a standard member 1 as an example, as shown in fig. 2c, and includes a pulley assembly 11, a wire rope 12, a weight tray 13 and a standard weight 14. The pulley assembly 11 includes a pulley frame 111 and a fixed pulley 112 supported by the pulley frame. One end of the steel cable 12 is connected with the load bearing model and connected with the top of the weight tray 13 by crossing the fixed pulley 112. The steel wire rope 12 from the load bearing model to the fixed pulley part needs to be ensured to be vertical to the model surface at the joint of the steel wire rope 12 and the load bearing model, and in order to ensure the calibration precision, the angle error of the steel wire rope is not more than 3 minutes when measured in the horizontal direction and the vertical direction. The weight tray 13 is naturally drooped after being connected with the steel wire rope 12, and the whole posture of the weight tray 13 needs to be kept vertical. Different numbers of standard weights 14 can be placed on the tray at the bottom of the weight tray 13. The total weight of all the standard weights 14 is the magnitude of the applied load force.
The standard weights 14 are selected according to the measuring range of the sensor in the force measuring platform, the weight of a single weight is generally between 1/10 and 1/30 of the full measuring range of the force measuring sensor corresponding to the calibrating piece where the weight is located, and the number of loading points is guaranteed in a certain component load design loading scheme, so that the smoothness and the accuracy of a signal-load curve obtained by loading can be guaranteed.
In the following, 4 calibration pieces shown in fig. 1 are taken as an example, and as shown in fig. 2a, a calibration piece 1 is arranged at the end of the force-measuring platform; the calibration piece 2 (comprising pulley assemblies, steel cables 22, weight plates 23 and standard weights 24) is arranged on the right side (top view) of the force measuring platform as shown in fig. 2b, and is positioned on the transverse symmetry line of the platform; on the left side (in plan view) of the force-measuring platform, there are arranged a calibration piece 3 (comprising a pulley assembly, a cable 32, a weight pan 33 and a standard weight 34.) and a calibration piece 4 (comprising a pulley assembly, a cable 42, a weight pan 43 and a standard weight 44.), both of which are symmetrical with respect to the lateral symmetry line of the platform. Four calibration pieces apply tensile loads to the load-bearing model.
In the present embodiment, the application of a load to the calibration piece 1 mainly causes a change in the force platform resistance signal; the application of a load to the calibration element 2 alone or a symmetrical load to both the calibration element 3 and the calibration element 4 mainly causes a change in the lateral force signal of the force-measuring platform; applying a cross load to the calibration piece 3 and the calibration piece 4 mainly causes a change in the force platform yaw moment signal.
The coordinate system in this embodiment is defined as shown in fig. 3. Looking down the force measuring platform, wherein the X axis represents the axial force direction, and the positive direction points forwards; the Z axis represents the direction of lateral force, and the positive direction points to the right; the Y axis points to the inside of the paper according to the right-hand rule.
As shown in the schematic diagram of the coordinate system shown in fig. 3, when the force measuring platform is in use, the axial force borne by the model is usually the resistance of the air flow in the wind tunnel to the model, and the axial force borne by the model is positive when pointing to the negative X direction because the axial force is usually backward; the lateral force is positive when pointing to the positive direction of Z, and the yawing moment is positive when pointing to the positive direction of y.
In the embodiment, each calibration piece is preloaded, 3-4 weights with the mass of 1000g are added on the weight plates 13-43 of the calibration pieces 1-4, the state is kept for more than 30 minutes, and the stress of the steel wire ropes 12-42 on the calibration pieces is fully released for formal loading.
In the present embodiment, during normal loading, the weights 14 to 44 are first added to the weight disks 13 to 43 of the calibration pieces 1 to 4 to pre-tighten the wire ropes. A1000 g weight is added to each of the calibration piece 1 and the calibration piece 4, and 2 500g weights are loaded on each of the calibration piece 3 and the calibration piece 4, so that the whole loading system is balanced while pre-tightening. Then, the calibration work of the three components of the axial force (resistance), the lateral force and the pitching moment is performed according to the following method.
In this embodiment, before each loading, an initial value of the force platform sensor signal needs to be acquired as a zero point that needs to be deducted.
(i) Calibration axial force (resistance): adjusting the loading load of the calibration piece 1, and loading one by adopting a single weight with the mass of 500g to obtain 6-8 loading points; and then unloading one by one to obtain 5-7 loading points. This was repeated three times.
(ii) Calibrating the lateral force: the loading load of the calibration piece 3 and the calibration piece 4 is adjusted, according to the specification of the coordinate system in fig. 3, when the loading lateral force is positive. Loading 10-15 points one by adopting a single weight with the mass of 200 g; and then unloading one by one to obtain 9-14 loading points. This was repeated three times.
(iii) Calibrating the yaw moment: when calibrating the yaw moment, the weight of the calibration piece 2 is changed to 2000g, and 10 weights of 200g are added to the calibration piece 3 as an initial state.
Subtracting 1 weight of 200g from the calibration piece 3, adding 1 weight of 200g to the calibration piece 4, and so on; after the calibration piece 3 is unloaded to the last time, the calibration piece 3 is loaded again one by one and the calibration piece 4 starts to be unloaded one by one, so that 22 loading points are obtained. This was repeated three times.
In this embodiment, the distance between the calibration piece 3 and the calibration piece 4 is 3.505 meters, and the distance is used to calculate the yaw moment, specifically, the weight of the weight on the calibration piece 3 is subtracted by the weight of the weight on the calibration piece 4, and the obtained difference is multiplied by half of the distance (i.e. the moment arm). If in the initial state, there is a weight of 2kg on the calibration piece 3, there is no weight on the calibration piece 4, that is, 0kg, the magnitude of the yaw moment borne by the model is:
(2(kg)-0(kg))×3.505(m)/2＝3.505kg·m；
under the first load point, there is 1.8kg weight on the calibration piece 3, has 0.2kg weight on the calibration piece 4, and the yaw moment size that the model bore is:
(1.8(kg)-0.2(kg))×3.505/2＝2.804kg·m。
and so on.
(iv) During the calibration process, it is found that loading the lateral force can generate a disturbance amount on the axial force, so the influence of the lateral force loading on the axial force coefficient needs to be calibrated. And simultaneously acquiring data of the resistance component of the force measuring platform according to the step of calibrating the lateral force to obtain the interference coefficient. In the present embodiment, a data processing manner and a result are given by taking data of 22 load points of one of the loads of the yaw moment as an example.
In the loading process, every time a loading point is carried out, the output signals of all the tension sensors on the force measuring platform are collected. And subtracting the sum of the signals of the left front sensor and the right rear sensor from the sum of the signals of the right front tension sensor and the left rear tension sensor which are arranged on the force measuring platform to obtain a yaw moment signal. Yaw moment signal values obtained by calculation of 22 loading points form a one-dimensional yaw moment vector tmy(ii) a Calculating the yaw moment by the 22 loading points according to the method in the step (iii) to obtain a vector y of the yaw moment borne by the modelmy。
Vector y of yaw moment borne by modelmyComprises the following steps:
ymy＝[0,3.505,2.804,2.103,1.402,0.701,0,-0701,-1.402,-2.804,-3.505,-2.804,-2.103,-1.402,-0.701,0,0.701,1.402,2.103,2.804,3.505,0]T；
force platform sensor output signal vector tmyComprises the following steps:
tmy＝[0,5.348,4.279,3.204,2.126,1.049,-0.028,-1.104,-2.197,-4.333,-5.409,-4.345,-3.280,-2.199,-1.128,-0.065,1.023,2.120,3.183,4.269,5.343,0.002]T；
the least squares method is applied for linear fitting, as follows:
ymy＝b1tmy
in the formula b1Are coefficients obtained by calibration. Written in matrix form as follows:
can be solved to obtain:
wherein the content of the first and second substances,
is an arithmetic mean value; n is the total number of load points for a load.
To obtain b10.651. Thus ymy＝0.651×tmy. The curve is plotted as in fig. 4.
And repeating all points and the process of the loading for other two times, averaging the coefficients b1, b2 and b3 obtained by repeating the loading for three times, finally obtaining a coefficient b which is used as the coefficient finally obtained by the force measuring platform, and obtaining the actual load according to the output signal and the coefficient of the sensor in the formal test process.
It should be noted that y and t correspond when calibrating drag, lateral force and yaw moment. I.e. when y is the resistance calibration piece load at the end of the force platform, t is the resistance output signal, lateral force and yaw moment for the same reason.
And when the interference coefficient of the lateral force to the resistance is calibrated, y is the load of two lateral force calibration pieces on the left side of the force measuring platform, and t is a resistance output signal.
The invention has not been described in detail in part in the common general knowledge of a person skilled in the art.
Claims (10)
1. The utility model provides a measure little aerodynamic force air supporting platform normal position calibrating device which characterized in that includes: a load-bearing model and at least four calibration pieces;
the load bearing model is arranged on the air floating platform to be calibrated and is in a free state in the horizontal direction relative to the air floating plane; the four calibration pieces are arranged on the air floatation platform, can apply load forces in different directions to a load bearing model and are used for simulating the axial force, the lateral force and the yaw moment of the model subjected to pneumatic load; a tension sensor is arranged between the load bearing model and the air floatation platform corresponding to the direction of the load force, senses the tension load and outputs axial force, lateral force and yaw moment signals; the calibration part comprises a pulley component, a steel wire rope, a weight tray and a standard weight; the pulley assembly comprises a pulley yoke and a fixed pulley supported by the pulley yoke, and the pulley yoke is arranged on the air floatation platform; one end of the steel wire rope is connected with the load bearing model and is connected with the top of the weight tray by crossing a fixed pulley in the pulley component; and the steel wire rope from the load bearing model to the fixed pulley part is required to be vertical to the surface of the load bearing model at the joint of the steel wire rope and the model, the standard weight is used for being placed on a weight tray to realize force loading, and the total gravity of the weight is recorded as the magnitude of the applied load force.
2. The in-situ calibration device of claim 1, wherein: the angle error of the steel wire rope across the fixed pulley part in the horizontal and vertical directions is not more than 3 minutes.
3. The in-situ calibration device of claim 1, wherein: the weight of the single standard weight is between 1/10 and 1/30 of the full range of the load cell in the corresponding direction.
4. The in-situ calibration device of claim 1, wherein: the number of the calibration pieces is 4, and one calibration piece is arranged at the tail end of the air floatation platform and used for simulating axial force; arranging one calibration piece on the overlooking right side of the air floatation platform, wherein the calibration piece is positioned on the transverse symmetrical line of the air floatation platform and used for simulating lateral force; two calibration pieces are arranged on the overlooking left side of the force measuring platform, are symmetrical relative to a transverse symmetrical line of the air floatation platform and are used for simulating a yawing moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction.
5. The in-situ calibration device of claim 1, wherein: the number of the calibration pieces is 5, one calibration piece is arranged at the front end and the tail end of the air floatation platform, and the axial force is simulated by superposing the calibration pieces and the tail end; arranging one calibration piece on the overlooking right side of the air floatation platform, wherein the calibration piece is positioned on the transverse symmetrical line of the air floatation platform and used for simulating lateral force; two calibration pieces are arranged on the overlooking left side of the force measuring platform, are symmetrical relative to a transverse symmetrical line of the air floatation platform and are used for simulating a yawing moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction.
6. The in-situ calibration device of claim 1, wherein: the number of the calibration pieces is 6, one calibration piece is arranged at the front end and the tail end of the air floatation platform, and the axial force is simulated by superposing the calibration pieces and the tail end; two calibration pieces are arranged on the overlooking left side of the force measuring platform, and the two calibration pieces are symmetrical relative to the transverse symmetrical line of the air floating platform; two calibration pieces symmetrical to the left side are arranged on the right pitching side of the force measuring platform, and the four calibration pieces on the left side and the right side are superposed to simulate lateral force or yaw moment; the tail end of the air floating platform is consistent with the tail end of the load bearing model arranged on the air floating platform in direction.
7. The in-situ calibration device of claim 4, 5 or 6, wherein: the distance between two calibration members disposed on the left or right side of the air bearing platform should be no less than 1/2 of the total length of the air bearing platform.
8. An in-situ calibration method implemented by the in-situ calibration apparatus according to claim 1, comprising the steps of:
s1, preloading each calibration piece, adding 3 kg-4 kg standard weights on the weight tray of each calibration piece, keeping the state for more than 30 minutes, and fully releasing the stress of the steel wire rope on the calibration piece;
s2, adding a standard weight pre-tightening steel wire rope on the weight tray of each calibration piece;
s3, calibrating three components of axial force, lateral force and pitching moment through multiple times of loading, wherein the initial value of the signal of the tension sensor needs to be acquired before each time of loading and is used as a zero point needing to be deducted; wherein the content of the first and second substances,
calibrating the axial force: adjusting the loading load for simulating the axial force calibration piece, and loading the standard weights one by one within the range of the tension sensor to obtain 6-8 loading points; then unloading one by one to obtain 5-7 loading points; repeating the loading and unloading process for two to three times;
calibrating the lateral force: adjusting the loading load for simulating the lateral force calibration piece, and loading standard weights one by one within the range of the measuring range of the tension sensor to obtain 10-15 loading points; then unloading one by one to obtain 9-14 loading points; repeating the loading and unloading process for two to three times;
calibrating the yaw moment: setting an initial state within the measuring range of the tension sensor, namely marking any one of the two sides of the air floatation platform with one side of two calibration pieces as a standard piece A and adding 5-15 standard weights, and directly adding a balance weight with the same weight on the other side; during calibration, 1 standard weight is unloaded on the standard part A, and simultaneously, 1 standard weight with the same mass is loaded on the other calibration part on the same side, which is recorded as the standard part B, so as to obtain a loading point, and the like, until the unloading of the standard weight on the standard part A is finished, and then 1 standard weight is sequentially unloaded from the standard part B and recorded on the standard part A until the unloading of the standard part B is finished;
and S4, performing data fitting according to the loading amount of the loading points and the data of each loading point tension sensor to obtain calibration coefficients of axial force, lateral force and yaw moment, and realizing in-situ calibration of the air-floating platform by using the calibration coefficients.
9. The method of claim 8, wherein: the calibration coefficient is expressed by the following formula:
in the formula, b1Is the calibration coefficient of axial force, lateral force, or yaw moment, yi、tiLoad force at the ith load point in axial force, lateral force, or yaw moment calibration, respectively, andthe tension sensor outputs signals, n is the total number of loading points loaded during the calibration of axial force, lateral force or yawing moment,
are arithmetic averages.
10. The method of claim 9, wherein: will yiThe input is the load force, t, of each loading point for calibrating the lateral forceiB is obtained by inputting the output signal of the tension sensor when the axial force is calibrated and utilizing a calibration coefficient calculation formula1Is the interference coefficient of the lateral force and the axial force.
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