Deep water towing tank PIV system calibration target posture adjusting mechanism and use method

Abstract

The application discloses a calibration target posture adjusting mechanism of a deep water towing pool PIV system and a use method thereof. The posture adjusting mechanism is connected with the PIV system, and the structure of the posture adjusting mechanism is as follows: a flat base is provided, a lower adjusting plate is mounted on the flat base, an upper adjusting plate is mounted above the lower adjusting plate in a matched mode, a yaw angle adjusting module and a roll angle adjusting module are respectively mounted at two ends of the flat base, two vertical supports vertically downward are fixed to the bottom surface of the flat base, a horizontal support is mounted between the two vertical supports through fasteners, a calibration target frame is mounted between the two vertical supports below the horizontal support, a calibration target is fixedly mounted in the calibration target frame, grooves are formed in the two ends of the upper edge frame and the lower edge frame of the calibration target frame, cuboid aluminum rods are placed in the grooves, and a silicon reflecting mirror is mounted at the outer end of the calibration target frame. A reference block is further arranged on the top surface of the posture adjusting mechanism, two vertical lines are fixed to the reference block, and a counterweight is arranged at the bottom of each vertical line. The adjusting precision is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ship hydrodynamics test, in particular to a deep water towing tank PIV system calibration target posture adjustment mechanism and use method, which is mainly the working principle of a deep water towing tank vehicle-mounted Stereo-PIV (SPIV for short) system calibration target posture adjustment mechanism, and particularly relates to accurate adjustment of three degrees of freedom positions of the calibration target and PIV system laser sheet light alignment. BACKGROUND

[0002] The deep water towing tank vehicle-mounted SPIV system belongs to a 2D3C type PIV system, and the system has the following characteristics: the observed flow field area is large (generally up to 300mm*200mm); it is a non-contact measurement method, and has small disturbance to the surrounding flow field; the laser illuminates the test area in the form of a sheet of light; two cameras are configured, and two two-dimensional vector fields are combined into one three-dimensional vector field through a calibration process.

[0003] Calibration has always been the basis for the accuracy and reliability of PIV measurement. The accuracy of the calibration process of a PIV system directly reflects the required accuracy level of the measurement, just like all other measurement systems. In PIV testing, what can be directly obtained is the displacement of particles in the image plane, which is only a scaled value of the true displacement of the particles, and the PIV calibration process is to obtain the mapping function of the image plane mapping to the object plane in the real physical space. Although any object of known size can be used as a reference for determining the mapping function, it is still recommended to use a calibration target for the conversion calibration of the physical space and the image plane. The calibration target surface is covered with grid points, including two-dimensional calibration targets (target disc flat, grid points uniformly distributed on the disc) and three-dimensional calibration targets (generally double-sided and double-layer, with grid points uniformly distributed on each face and each layer). If a two-dimensional calibration target is used, a precise positioning displacement system needs to be used to move multiple positions in the direction perpendicular to the grid point plane, so as to realize spatial calibration. The deep water towing tank has a complex field environment and limited space, and therefore a three-dimensional calibration target is used to calibrate the system in the deep water towing tank.

[0004] Moreover, the orientation reference can be easily found when using SPIV in air and circulating water tank, and there is enough space to arrange the infrared cross line sheet light alignment tool near the reference, the attitude of the laser sheet light can be adjusted by using the infrared cross line, to ensure that the parallelism of the laser sheet light and the measured area surface is very high, then the calibration target grid point surface is placed in the center surface of the laser sheet light and parallel to the sheet light, although there is an error between the position of the calibration target and the center surface of the sheet light in actual operation, but the position of the laser sheet light is accurate, and the position can be repaired by Self-calibration technology later; However, in the deep water towing tank, the space around the orientation reference (given a reference orientation and a reference surface, the reference orientation is perpendicular to the area surface to be tested, that is, the calibration target grid surface should be perpendicular to the reference orientation, and the reference surface is perpendicular to the reference orientation) is limited due to the constraints of the site environment, and the infrared cross line sheet light alignment tool cannot be used, only the attitude of the calibration target can be adjusted by using the orientation reference and the related attitude adjustment mechanism, and then the position of the laser sheet light is adjusted by using the calibration target, therefore, the calibration process of the deep water towing tank is complex, and the precision is difficult to control, which restricts the research level of the fine test of underwater flow field. SUMMARY

[0005] The applicant provides a deep water towing tank PIV system calibration target attitude adjustment mechanism and use method with reasonable structure aiming at the defects in the above existing production technology, so that the problems of quickly and accurately adjusting the attitude (yaw angle, roll angle and pitch angle) of the calibration target of the deep water towing tank SPIV system and accurately adjusting the laser sheet light can be effectively solved, and comprehensive adjustment means and high adjustment precision can be realized.

[0006] The technical scheme adopted by the application is as follows:

[0007] The utility model provides a kind of deep water towed pool PIV system calibration target posture adjustment mechanism, including with PIV system connection's posture adjustment mechanism, the structure of the posture adjustment mechanism is as follows: including flat base, the upper surface of the flat base is equipped with lower adjusting plate by fastener, the upper adjusting plate is cooperatively installed above the lower adjusting plate, the both ends of the flat base are equipped with yaw angle adjustment module and roll angle adjustment module respectively, one end of the upper adjusting plate is provided with roll angle module connecting seat, the roll angle module connecting seat is connected with roll angle adjustment module, the lower adjusting plate is provided with yaw angle module connecting seat, and the yaw angle module connecting seat is connected with yaw angle adjustment module;It is equipped with mounting frame outside the flat base, and the mounting frame is above the upper adjusting plate, the top surface of the mounting frame is equipped with a plurality of mounting holes, for being connected with reference object of calibration site;Two vertical supports that are vertically downwards are fixed on the bottom surface of the flat base, and horizontal support is installed between the two vertical supports by fastener, and calibration target frame is installed between the two vertical supports below the horizontal support, the calibration target frame is fixedly installed calibration target inside, and the both ends of the upper frame and the lower frame of calibration target frame are provided with groove, and cuboid aluminum bar is placed in the groove, and silicon reflector lens is installed outside the calibration target frame;Reference block is further provided on the top surface of the posture adjustment mechanism, two plumb lines are fixed on the reference block, and the bottom of the plumb line is counterweight;Digital laser level is fixed on the top surface of calibration target frame.

[0008] As further improvement of the above technical solution:

[0009] The mounting frame is in the shape of "┏┓".

[0010] The upper adjusting plate comprises an upper adjusting plate body, and a first supporting arm is arranged on each side of the upper adjusting plate body, a second supporting arm is arranged on each side of the lower adjusting plate, the corresponding first supporting arm and second supporting arm are connected by a split pin and a pin shaft, and the upper adjusting plate body rotates around the pin shaft.

[0011] The lower adjusting plate comprises a lower adjusting plate body, the lower adjusting plate body is placed on the flat base, a hexagonal head bolt passes through the through hole of the lower adjusting plate body and the through hole of the flat base from top to bottom, and the hexagonal head bolt is screwed tightly with the hexagonal nut on the lower surface of the flat base, so that the lower adjusting plate can rotate around the hexagonal head bolt.

[0012] The single vertical support is in the shape of T.

[0013] The horizontal support is in the shape of I.

[0014] The installation structure of the yaw angle adjustment module is as follows: A No. 1 hinge bolt is installed on the yaw angle module connecting seat through a No. 1 hexagonal head reamer hole using a bolt; a No. 1 adjusting nut is inserted between the No. 1 adjusting nut pressure plate and the No. 1 adjusting nut base plate; a No. 1 internal hexagonal head screw aligns and tightens the No. 1 adjusting nut pressure plate and the No. 1 adjusting nut base plate; the No. 1 adjusting nut pressure plate, the No. 1 adjusting nut, and the No. 1 adjusting nut base plate are installed as a whole into the opening slot of the yaw angle adjustment module base; the No. 1 hinge bolt passes through the No. 1 adjusting nut pressure plate, assembles with the No. 1 adjusting nut, and passes through the No. 1 adjusting nut base plate and the yaw angle adjustment module base; a bolt through the No. 1 hexagonal head reamer hole passes through the perforated ring at the tail end of the No. 1 hinge bolt, fixing the perforated ring to the yaw angle module connecting seat; a No. 1 clamping bolt is screwed into the threaded hole on the yaw angle adjustment module base; the bottom of the yaw angle adjustment module base is fixed to the flat base by welding.

[0015] The installation structure of the roll angle adjustment module is as follows: A No. 2 adjusting nut is installed between the No. 2 adjusting nut pressure plate and the No. 2 adjusting nut base plate; a No. 2 hexagon socket head cap screw aligns and presses the No. 2 adjusting nut pressure plate and the No. 2 adjusting nut base plate together; the No. 2 adjusting nut pressure plate, the No. 2 adjusting nut, and the No. 2 adjusting nut base plate are installed as a whole into the opening groove of the roll angle adjustment module base and slide freely within the groove; a No. 2 hinge bolt passes through the No. 2 adjusting nut pressure plate, assembles with the No. 2 adjusting nut, and passes through the No. 2 adjusting nut base plate and the roll angle adjustment module base; a No. 2 hexagon head reamer bolt passes through the opening ring at the tail end of the No. 2 hinge bolt, fixing the opening ring to the roll angle module connecting seat; a No. 2 clamping bolt is screwed into the threaded hole (606) on the roll angle adjustment module base to lock the adjusting nut.

[0016] The calibration target frame.

[0017] A method for using a calibration target attitude adjustment mechanism in a deep-water towed pool PIV system includes the following operating steps:

[0018] S1: Preparation work. First, fix the three-dimensional calibration target in the calibration target frame. The precision-machined calibration target frame ensures that the four sides of the frame are parallel to the four sides of the corresponding calibration target. The calibration target frame is hung on the adjustment base by two vertical brackets.

[0019] S2: Adjust the connection between the base and the reference object, and give a reference direction perpendicular to the calibration target grid surface;

[0020] S3: Place the digital laser level on the upper frame of the calibration target frame, measure the roll angle of the calibration target frame, and use the roll angle adjustment module to adjust the roll angle of the calibration target frame to zero degrees.

[0021] S4: Place the digital laser level horizontally on the upper edge of the calibration target frame, measure the pitch angle of the calibration target frame, and adjust the pitch angle of the calibration target frame to zero degrees by using the pitch angle adjusting screw;

[0022] S5: A groove with the same specification is opened at both ends of the upper and lower edges of the calibration target frame, and optionally three grooves are opened, and a rectangular aluminum rod is installed in the groove, then two plumb lines are suspended according to the reference block provided by the azimuth reference, and are respectively close to the left and right aluminum rods, and the distances from the three intersection points formed by the plumb lines and the aluminum rods to the calibration target grid surface are measured by using a steel ruler, the distances from the three intersection points to the calibration target grid surface are consistent, and the yaw angle of the calibration target frame is adjusted to zero degrees by adjusting the yaw angle adjusting module on the base;

[0023] S6: Turn on the laser of the PIV system, adjust the position of the entire PIV laser body through the attitude adjusting mechanism until the two plumb lines fall in the laser sheet light area, combine the two plumb lines and the laser light on the aluminum rod to form a strong reflection point, adjust the laser light path setting so that the two plumb lines fall in the sheet light area and the laser light on the aluminum rod forms a strong reflection point, and the reflection point is at least three, and the distance from each reflection point to the calibration target grid surface is consistent;

[0024] S7: Move the PIV system in a direction perpendicular to the calibration target grid surface so that the two plumb lines fall in the sheet light area or the sheet light falls on the silicon mirror sheet on the side edge of the calibration target frame, and observe whether the light traces formed by the laser reflected by the silicon mirror sheet on the PIV laser body coincide with the sheet light traces of the PIV light outlet, and the result is used to check the alignment quality of the laser sheet light, and if the deviation is large, S6 needs to be repeated.

[0025] The beneficial effects of the present application are as follows:

[0026] The present application has the advantages that the structure is compact and reasonable, the operation is convenient, in the extremely limited operation space and the background of the reference direction, the installation platform with poor horizontal degree, parallelism and the like is comprehensively considered, the mechanism with three-dimensional corner adjustment is designed, and the operation is simple and convenient; the present application can effectively solve the difficulty of accurately quantitatively adjusting the three corners of the calibration target in the deep water towing pool, simultaneously realize the accurate adjustment of the laser sheet light direction by using the calibration target attitude adjusting mechanism, and the laser sheet light direction directly determines the real flow field test surface, the importance of which has far exceeded the category of measurement accuracy, so that the calibration accuracy and the PIV test accuracy can be extremely effectively improved by the calibration target attitude adjusting mechanism.

[0027] Meanwhile, the present application also has the following advantages:

[0028] (1) Under the premise of limited reference objects and operating space in deep water towing pool, a three-degree-of-freedom (multi-dimensional) adjustment mechanism for the attitude of the calibration target was designed. The calibration target frame can be finely adjusted and has a position locking function through mechanical parts such as screws / nuts.

[0029] (2) The auxiliary tool used to adjust the yaw angle of the calibration target can be used to adjust the laser beam direction. The auxiliary tool has a high utilization rate and reduces the need for environmental space.

[0030] (3) Multiple tools are used to align and verify the laser sheet light direction, resulting in high adjustment accuracy. Attached Figure Description

[0031] Figure 1 This is a front view of the calibration target of the present invention.

[0032] Figure 2 for Figure 1 Side view.

[0033] Figure 3 This is a schematic diagram of the installation of the PIV system and positioning mechanism of the present invention.

[0034] Figure 4 This is a diagram showing the external relationship between the laser sheet and the calibration target in this invention.

[0035] Figure 5 This is a schematic diagram of the posture adjustment mechanism of the present invention.

[0036] Figure 6 This is a schematic diagram of the posture adjustment mechanism of the present invention from another perspective.

[0037] Figure 7 This is a partial exploded view of the attitude adjustment mechanism of the present invention.

[0038] Figure 8 This is a top view of the attitude adjustment mechanism of the present invention.

[0039] Figure 9 This is a front view of the attitude adjustment mechanism of the present invention.

[0040] Figure 10 This is a cross-sectional view of the yaw angle adjustment module of the present invention.

[0041] Figure 11 This is a cross-sectional view of the roll angle adjustment module of the present invention.

[0042] Figure 12 This is a schematic diagram of the structure of the present invention in its working state.

[0043] The components include: 1. Mounting bracket; 2. Upper adjustment plate; 3. Lower adjustment plate; 4. Flat plate base; 5. Yaw angle adjustment module; 6. Roll angle adjustment module; 7. No. 1 screw; 8. No. 2 screw; 9. Horizontal bracket; 10. Vertical bracket; 11. Digital display laser level; 12. No. 3 screw; 13. No. 4 screw; 14. Calibration target frame; 15. No. 5 screw; 16. Silicon reflector; 17. No. 6 screw; 18. Hex nut; 19. Hex head bolt; 20. Calibration target; 21. Groove; 22. PIV system; 23. Attitude adjustment mechanism; 24. Vertical line; 25. Counterweight; 26. Reference block;

[0044] 201. Cotter pin; 202. Pin shaft; 203. Upper adjusting plate body; 204. Support arm No. 1; 205. Roll angle module connector;

[0045] 301. Second support arm; 302. Lower adjustment plate main body; 303. Yaw angle module connector; 304. Roll angle module support;

[0046] 501. No. 1 clamping bolt; 502. No. 1 adjusting nut pressure plate; 503. No. 1 hinge bolt; 504. No. 1 adjusting nut; 505. No. 1 adjusting nut base plate; 506. Yaw angle adjustment module base; 507. No. 1 hexagonal head reamer bolt; 508. No. 1 internal hexagonal head screw;

[0047] 601. No. 2 clamping bolt; 602. No. 2 adjusting nut pressure plate; 603. No. 2 hinge bolt; 604. No. 2 adjusting nut; 605. No. 2 adjusting nut base plate; 606. Roll angle adjustment module base; 607. No. 2 hexagonal head reamer bolt; 608. No. 2 internal hexagonal head screw. Detailed Implementation

[0048] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0049] like Figures 1-12As shown, the posture adjustment mechanism of the deep water towing tank PIV system calibration target of the embodiment comprises a posture adjustment mechanism 23 connected with the PIV system 22, and the structure of the posture adjustment mechanism 23 is as follows: a flat base 4 is provided, a lower adjustment plate 3 is installed on the upper surface of the flat base 4 through fasteners, an upper adjustment plate 2 is installed above the lower adjustment plate 3 in a matched manner, a yaw angle adjustment module 5 and a roll angle adjustment module 6 are respectively installed at the two ends of the flat base 4, a roll angle module connecting seat 205 is arranged at one end of the upper adjustment plate 2, the roll angle module connecting seat 205 is connected with the roll angle adjustment module 6, a yaw angle module connecting seat 303 is arranged on the lower adjustment plate 3, and the yaw angle module connecting seat 303 is connected with the yaw angle adjustment module 5; an installation frame 1 is arranged outside the flat base 4 and is located above the upper adjustment plate 2, a plurality of mounting holes are arranged on the top surface of the installation frame 1 and are used for being connected with reference objects in a calibration site; two vertical supports 10 downward and vertically fixed are arranged on the bottom surface of the flat base 4, a horizontal support 9 is arranged between the two vertical supports 10 through fasteners, a calibration target frame 14 is arranged between the two vertical supports 10 below the horizontal support 9, a calibration target 20 is fixedly arranged in the calibration target frame 14, grooves 21 are formed at the two ends of the upper and lower edges of the calibration target frame 14, and cuboid aluminum rods are placed in the grooves 21, and a silicon reflecting mirror 16 is arranged at the outer end of the calibration target frame 14; a reference block 26 is further arranged on the top surface of the posture adjustment mechanism 23, two plumb lines 24 are fixed on the reference block 26, and a counterweight 25 is arranged at the bottom of the plumb line 24; and a digital laser level 11 is fixed on the top surface of the calibration target frame 14.

[0050] The cross section of the installation frame 1 is in a “┏┓” structure.

[0051] The upper adjustment plate 2 comprises an upper adjustment plate body 203, one first support arm 204 is arranged at each side of the upper adjustment plate body 203, one second support arm 301 is arranged at each side of the lower adjustment plate 3, the corresponding first support arm 204 and the second support arm 301 are connected through an open pin 201 and a pin shaft 202, and the upper adjustment plate body 203 rotates around the pin shaft 202.

[0052] The lower adjustment plate 3 comprises a lower adjustment plate body 302, the lower adjustment plate body 302 is placed on the flat base 4, a hexagonal head bolt 19 passes through the through hole on the lower adjustment plate body 302 and the through hole on the flat base 4 from top to bottom, is matched with a hexagonal nut 18 on the lower surface of the flat base 4 and is tightened, and the lower adjustment plate 3 can rotate around the hexagonal head bolt 19.

[0053] The single vertical support 10 is in a T-shaped structure.

[0054] The horizontal support 9 is in an I-shaped structure.

[0055] The mounting structure of the yaw angle adjustment module 5 is that a first knuckle bolt 503 is mounted on the yaw angle module connecting seat 303 by a first hex head hinge hole bolt 507, a first adjusting nut 504 is arranged between a first adjusting nut pressing plate 502 and a first adjusting nut bottom plate 505, and a first internal hexagonal cylindrical head screw 508 is used to align and press the first adjusting nut pressing plate 502 and the first adjusting nut bottom plate 505. The first adjusting nut pressing plate 502, the first adjusting nut 504 and the first adjusting nut bottom plate 505 are arranged in the opening groove of the yaw angle adjustment module base 506 as a whole, the first knuckle bolt 503 passes through the first adjusting nut pressing plate 502, is assembled with the first adjusting nut 504 and passes through the first adjusting nut bottom plate 505 and the yaw angle adjustment module base 506, the first hex head hinge hole bolt 507 passes through the opening ring at the tail end of the first knuckle bolt 503 to fix the opening ring on the yaw angle module connecting seat 303, and the first pressing bolt 501 is screwed into the threaded hole on the yaw angle adjustment module base 506. The bottom of the yaw angle adjustment module base 506 is fixed on the flat base 4 by welding.

[0056] The mounting structure of the roll angle adjustment module 6 is that a second adjusting nut 604 is arranged between a second adjusting nut pressing plate 602 and a second adjusting nut bottom plate 605, a second internal hexagonal cylindrical head screw 608 is used to align and press the second adjusting nut pressing plate 602 and the second adjusting nut bottom plate 605, the second adjusting nut pressing plate 602, the second adjusting nut 604 and the second adjusting nut bottom plate 605 are arranged in the opening groove of the roll angle adjustment module base 606 as a whole and can slide freely in the groove, a second knuckle bolt 603 passes through the second adjusting nut pressing plate 602, is assembled with the second adjusting nut 604 and passes through the second adjusting nut bottom plate 605 and the roll angle adjustment module base 606, a second hex head hinge hole bolt 607 passes through the opening ring at the tail end of the second knuckle bolt 603 to fix the opening ring on the roll angle module connecting seat 205, and a second pressing bolt 601 is screwed into the threaded hole on the roll angle adjustment module base 606 to lock the adjusting nut 604.

[0057] The calibration target frame 14.

[0058] The use method of the calibration target posture adjustment mechanism of the deep water towing tank PIV system in the embodiment includes the following operation steps:

[0059] S1: preparation work, first, fix the three-dimensional calibration target 20 in the calibration target frame 14, the precisely processed calibration target frame 14 ensures that the four edges of the frame are parallel to the four edges of the calibration target 20, and the calibration target frame 14 is hung on the adjustment base through two vertical supports 10;

[0060] S2: connect the adjustment base with the reference object, and give the reference direction perpendicular to the calibration target grid surface;

[0061] S3: Place the digital laser level 11 on the upper edge of the calibration target frame 14, measure the roll angle of the calibration target frame 14, and adjust the roll angle of the calibration target frame 14 to zero degrees using the roll angle adjustment module 6.

[0062] S4: Place the digital laser level 11 on the upper edge of the calibration target frame 14, measure the pitch angle of the calibration target frame 14, and adjust the pitch angle of the calibration target frame 14 to zero degrees using the pitch angle adjustment screw.

[0063] S5: A groove 21 of the same size is opened at both ends of the upper and lower edges of the calibration target frame 14, and optionally three grooves 21 are opened, and then a rectangular aluminum rod is installed in the groove 21, and then two plumb lines 24 are suspended according to the reference block 26 provided by the azimuth reference, and are respectively close to the left and right aluminum rods, and the distance from the three intersection points formed by the plumb lines 24 and the aluminum rods to the calibration target grid surface is measured respectively using a steel ruler, the distance from the three intersection points to the calibration target grid surface is consistent, and the yaw angle of the calibration target frame 14 is adjusted to zero degrees by adjusting the yaw angle adjustment module 5 on the base.

[0064] S6: Turn on the laser of the PIV system 22, adjust the position of the entire PIV laser body through the attitude adjustment mechanism 23 until the two plumb lines 24 fall within the laser sheet light area, and combine the two plumb lines 24 and the intense reflection points formed by the laser on the aluminum rod to adjust the laser light path setting so that the two plumb lines 24 fall within the sheet light area and the laser forms intense reflection points on the aluminum rod, and the reflection points are at least three, and the distance from each reflection point to the calibration target grid surface is consistent.

[0065] S7: Move the PIV system 22 in a direction perpendicular to the calibration target grid surface so that the two plumb lines 24 fall within the sheet light area or so that the sheet light falls on the silicon mirror sheet 16 on the side edge of the calibration target frame 14, and observe whether the light traces formed by the laser reflected by the silicon mirror sheet 16 on the PIV laser body coincide with the sheet light traces of the PIV light outlet, and this result is used to check the alignment quality of the laser sheet light, and if the deviation is large, S6 needs to be repeated.

[0066] The specific structure and function of the deep water towing pool PIV system calibration target attitude adjustment mechanism of the present application are as follows:

[0067] There are two threaded holes on the convex boss on both sides of the flat base 4, and the mounting bracket 1 is precisely fixed with the flat base 4 through a No. 1 screw 7, and there are eight threaded holes on the upper surface of the mounting bracket 1 for connecting and fixing with the reference object in the calibration site.

[0068] As Figure 8As shown, there is a No. 1 support arm 204 (with through hole) on each side of the upper adjustment plate 2. The No. 1 support arm 204 can be stably connected to the No. 2 support arm 301 (with through hole) of the lower adjustment plate 3 through the cooperation of the cotter pin 201 and the pin shaft 202, and the upper adjustment plate body 203 is allowed to rotate around the pin shaft 202; the roll angle module connecting seat 205 is connected to the roll angle adjustment module 6.

[0069] The lower adjustment plate 3 is placed on the flat plate base 4. The hexagonal head bolt 19 passes through the through hole on the lower adjustment plate body 302 and the through hole on the flat plate base 4 from top to bottom, and is tightened with the hexagonal nut 18 on the lower surface of the flat plate base 4. The lower adjustment plate 3 can rotate around the hexagonal head bolt 19. The yaw angle module connector 303 is connected to the yaw angle adjustment module 5.

[0070] Two T-shaped vertical supports 10 pass through the flat plate base 4 and the lower adjustment plate body 302 from bottom to top, and are fixed to the lower surface of the upper adjustment plate body 203 with No. 6 screws 17. The openings of the vertical supports 10 and the upper adjustment plate body 203 that mate with the No. 6 screws 17 are all threaded through holes. The two ends of the I-shaped horizontal supports 9 of No. 2 screws 8 are respectively connected to the two vertical supports 10. The openings of the horizontal supports 9 and the vertical supports 10 that mate with the No. 2 screws 8 are all threaded through holes. The two horizontal supports 9 can improve the parallelism between the two vertical supports 10.

[0071] like Figure 1 As shown, the calibration target 20 has four threaded blind holes around its perimeter. The calibration target frame 14 has a through hole and a threaded through hole on each of its two side frames, and a threaded through hole on its bottom frame. The position and diameter of the three threaded through holes on the calibration target frame 14 match the specifications of the threaded blind holes on the calibration target 20. The No. 4 screw 13 fixes the calibration target 20 to the calibration target frame 14 through the aforementioned threaded through holes. Furthermore, precision machining ensures that the four sides of the calibration target 20 are parallel to the corresponding frames on the calibration target frame 14. In this way, the yaw angle, pitch angle, and roll angle of the calibration target 20 can be characterized by the yaw angle, pitch angle, and roll angle of the upper frame of the calibration target frame 14. The No. 3 screw 12 is specially treated with smooth end polishing. Its size matches the through hole specifications on both sides of the calibration target frame 14. The two No. 3 screws 12 suspend the calibration target frame 14 at the lower end of the vertical bracket 10. The calibration target frame 14 can rotate around the No. 3 screw 12. The opening of the vertical bracket 10 that mates with the No. 3 screw 12 is a threaded through hole.

[0072] like Figure 6 and Figure 8As shown, a first adjusting nut 504 is arranged between the first adjusting nut pressing plate 502 and the first adjusting nut bottom plate 505, and a first internal hexagonal cylindrical head screw 508 is used to align and press the first adjusting nut pressing plate 502 and the first adjusting nut bottom plate 505 (with a slight excess for the rotation of the first adjusting nut 504); the first adjusting nut pressing plate 502, the first adjusting nut 504 and the first adjusting nut bottom plate 505 are arranged as a whole in the open slot of the yaw angle adjustment module base 506 and can freely slide in the slot; the first articulated bolt 503 passes through the first adjusting nut pressing plate 502, is assembled with the first adjusting nut 504 and passes through the first adjusting nut bottom plate 505 and the yaw angle adjustment module base 506, a first hexagonal head hinge hole bolt 507 passes through the open hole ring at the tail end of the first articulated bolt 503 to fix the open hole ring on the yaw angle module connecting seat 303; the first pressing bolt 501 is screwed into the threaded hole on the yaw angle adjustment module base 506 to lock the first adjusting nut 504; the bottom of the yaw angle adjustment module base 506 is fixed on the flat base 4 by welding.

[0073] As shown, Figure 9 a second adjusting nut 604 is arranged between the second adjusting nut pressing plate 602 and the second adjusting nut bottom plate 605, and a second internal hexagonal cylindrical head screw 608 is used to align and press the second adjusting nut pressing plate 602 and the second adjusting nut bottom plate 605 (with a slight excess for the rotation of the second adjusting nut 604); the second adjusting nut pressing plate 602, the second adjusting nut 604 and the second adjusting nut bottom plate 605 are arranged as a whole in the open slot of the roll angle adjustment module base 606 and can freely slide in the slot; the second articulated bolt 603 passes through the second adjusting nut pressing plate 602, is assembled with the second adjusting nut 604 and passes through the second adjusting nut bottom plate 605 and the roll angle adjustment module base 606, a second hexagonal head hinge hole bolt 607 passes through the open hole ring at the tail end of the second articulated bolt 603 to fix the open hole ring on the roll angle module connecting seat 205; the second pressing bolt 601 is screwed into the threaded hole on the roll angle adjustment module base 606 to lock the second adjusting nut 604; the bottom of the roll angle adjustment module base 606 is fixed on the roll angle module support seat 304 by welding.

[0074] The adjustment sequence is: roll angle adjustment, pitch angle adjustment, yaw angle adjustment, iterative fine adjustment of the above three angles, laser sheet light alignment and laser sheet light alignment verification.

[0075] Roll angle adjustment:

[0076] The second adjusting nut 604 in the roll angle adjusting module 6 is screwed to change the relative position of the second adjusting nut 604 and the second universal bolt 603, and the second adjusting nut pressing plate 602, the second adjusting nut 604 and the second adjusting nut bottom plate 605 slide as a whole in the opening slot of the roll angle adjusting module base 606, so that the upper adjusting plate body 203 is rotated around the pin shaft 202 through the second universal bolt 603 and the roll angle module connecting seat 205, so that the roll angle of the calibration target 20 can be changed. The digital laser level 11 is placed on the upper frame of the calibration target frame 14 to measure the roll angle, and the roll angle adjusting module 6 is adjusted so that the digital laser level 11 shows 0 or close to 0.

[0077] Pitch angle adjustment:

[0078] The vertical support 10 is provided with two fifth screws 15 on both sides of the upper frame of the calibration target frame 14, and the fifth screws 15 can touch the upper frame of the calibration target frame 14. The fifth screws 15 can push the calibration target frame 14 to rotate around the third screw 12, so as to change the pitch angle of the calibration target 20. The digital laser level 11 is placed on the upper frame of the calibration target frame 14 to measure the pitch angle, and the fifth screw 15 is screwed so that the digital laser level 11 shows 0 or close to 0.

[0079] Yaw angle adjustment:

[0080] The first adjusting nut 504 in the yaw angle adjusting module 5 is screwed to change the relative position of the first adjusting nut 504 and the first universal bolt 503, and the first adjusting nut pressing plate 502, the first adjusting nut 504 and the first adjusting nut bottom plate 505 slide as a whole in the opening slot of the yaw angle adjusting module base 506, so that the lower adjusting plate body 302 is rotated around the hexagonal head bolt 19 through the first universal bolt 503 and the yaw angle module connecting seat 303. In the present application, the upper adjusting plate 2 and the lower adjusting plate 3 do not have relative displacement in the yaw attitude, so the upper adjusting plate 2 also rotates around the hexagonal head bolt 19, and the vertical support 10, the calibration target frame 14 and the calibration target 20 related thereto also rotate around the hexagonal head bolt 19, so that the yaw angle of the calibration target 20 can be changed. The upper frame and the lower frame of the calibration target frame 14 are provided with a groove 21 with the same specification at both ends (the distance of each groove 21 from the side frame near it is the same), and a groove 21 with the same specification as the upper and lower frames is also opened on one side frame of the calibration target frame 14. The position of the groove 21 is below the fourth screw 13. As shown in the figure, Figure 7As shown, a cuboid aluminum rod is installed in any three grooves 21 selected from the upper and lower borders of the calibration target frame 14. The cuboid aluminum rod can move within the grooves 21 and is then fixed with hexagonal head screws. This invention ensures that the cuboid aluminum rod is perpendicular to the grid surface of the calibration target 20 and can adjust the distance of the cuboid aluminum rod extending beyond the upper / lower border of the calibration target frame 14 as needed. Next, two vertical lines 24 are suspended according to the reference surface provided by the orientation reference object. A counterweight 25 is attached to the end of the vertical line 24 and points towards the center of the earth. The vertical lines 24 are close to the left and right cuboid aluminum rods respectively. The distances from the three intersection points formed by the vertical lines 24 and the cuboid aluminum rods to the grid surface of the calibration target 20 are measured with measuring tools such as steel rulers. The yaw angle adjustment module 5 is adjusted so that the distances from the three intersection points to the grid surface of the calibration target 20 are consistent or have small deviations.

[0081] Iterative fine-tuning:

[0082] After initially adjusting the roll, pitch, and yaw angles, repeat the above steps to finely adjust the three degrees of freedom of the calibration target 20 until the calibration requirements are met. Finally, use the first clamping bolt 501 to lock the first adjusting nut 504 to prevent changes in the yaw angle of the calibration target 20, use the second clamping bolt 601 to lock the second adjusting nut 604 to prevent changes in the roll angle of the calibration target 20, and use two No. 5 screws 15 to hold the upper frame of the calibration target frame 14 to prevent changes in the pitch angle of the calibration target 20.

[0083] Laser sheet alignment:

[0084] like Figure 3 As shown, the laser of the PIV system 22 is turned on, and the position of the PIV system 22 is adjusted by the attitude adjustment mechanism 23 (Note: the attitude adjustment mechanism 23 is based on the reference orientation provided by the orientation reference object and can move the PIV system 22 in at least two dimensions) so that the two vertical lines 24 roughly fall within the laser sheet light area; as Figure 10 As shown, three cuboid aluminum rods are installed on the grooves of the upper, lower, and side frames of the calibration target frame 14. The laser beam leaves intense irradiation points on these three cuboid aluminum rods. The distances from the irradiation points on the three cuboid aluminum rods to the grid surface of the calibration target 20 are measured with a ruler as L1, L2, and L3, respectively. The laser beam path of the PIV system is adjusted so that L1 = L2 = L3. The attitude adjustment mechanism 23 controls the PIV system 22 to move towards the calibration target 20 along a direction perpendicular to the grid surface of the calibration target 20, with a moving distance of L1. This allows the grid surface of the calibration target 20 to fall on the center of the laser beam. At this point, the laser beam alignment is considered to be complete.

[0085] Laser sheet optical alignment verification:

[0086] The position of the PIV system 22 is finely adjusted by the attitude adjustment mechanism 23 so that the two plumb lines 24 fall within the laser sheet light area, which is used to check the alignment quality of the laser sheet light; in addition, a plurality of silicon mirror pieces 16 are mounted on one side frame of the calibration target frame 14, which is also used to verify the alignment quality of the laser sheet light. The specific operation process is as follows: first, the position of the PIV system 22 is adjusted by the attitude adjustment mechanism 23 until the laser sheet light is basically irradiated on the center line of the silicon mirror piece 16, then the reflected light trace left by the laser sheet light reflected by the silicon mirror piece 16 on the PIV system 22 is found, and finally it is judged whether the reflected light trace coincides with the exit light trace generated by the laser sheet light on the laser exit module of the PIV system 22. If the deviation is large, the laser sheet light alignment process needs to be further refined.

[0087] In actual work process, the following steps are completed:

[0088] First step: the three-dimensional calibration target is fixed in the calibration target frame 14, and the precisely processed calibration target frame 14 ensures that the four edges of the frame are strictly parallel to the four edges of the calibration target. The calibration target frame 14 is hung on the adjustment base through two supports, and the adjustment base is connected with the reference (a given reference direction perpendicular to the grid surface of the calibration target);

[0089] Second step: the digital laser level 11 is reasonably placed on the upper frame of the calibration target frame 14 to measure the roll angle of the calibration target frame 14, and the roll angle adjustment module 6 on the adjustment base can adjust the roll angle of the calibration target frame 14 to be close to zero degree;

[0090] Third step: the digital laser level 11 is reasonably placed on the upper frame of the calibration target frame 14 to measure the pitch angle of the calibration target frame 14, and the pitch angle adjusting screw on the adjustment base can adjust the pitch angle of the calibration target frame 14 to be close to zero degree;

[0091] Fourth step: the upper frame and the lower frame of the calibration target frame 14 are both provided with a groove 21 of the same specification (the distance from each groove 21 to the side frame near it is the same), three grooves 21 are selected, a rectangular aluminum rod is installed in the groove, and then two plumb lines 24 are hung down according to the reference surface provided by the azimuth reference, and are close to the left and right aluminum rods respectively. The distance from the three intersection points formed by the plumb lines 24 and the aluminum rods to the calibration target grid surface is measured by a steel ruler and other measuring tools respectively, and the yaw angle adjustment module 5 on the adjustment base can adjust the yaw angle of the calibration target frame 14 to be close to zero degree (the distances from the three intersection points to the calibration target grid surface are consistent);

[0092] Fifth step: the yaw angle, roll angle and pitch angle are gradually fine-tuned to zero degree by repeating the second, third and fourth steps;

[0093] Sixth step: open the PIV laser, adjust the position of the whole PIV thunder body through the attitude adjustment mechanism 23, until the two plumb lines 24 fall in the laser sheet light area, combined with the two plumb lines 24 and the laser on the aluminum rod form a strong reflection point, adjust the laser light path setting, so that the two plumb lines 24 fall in the sheet light area, and the laser on the aluminum rod form a strong reflection point (at least three) to the distance of the calibration target grid surface is consistent;

[0094] Seventh step: move the PIV system 22 along the direction perpendicular to the calibration target grid surface, so that the two plumb lines 24 fall in the sheet light area or the sheet light falls on the silicon mirror sheet 16 on the side of the calibration target frame 14, observe whether the light trace formed by the silicon mirror sheet 16 reflected by the laser irradiated on the PIV thunder body coincides with the sheet light trace of the PIV light outlet, and the result is used to check the alignment quality of the laser sheet light, if the deviation is large, the sixth step needs to be repeated.

[0095] The present application only needs to use nuts, bolts and screws and other simple mechanical components to realize the three-degree-of-freedom attitude adjustment of the calibration target of the deep water towing tank vehicle-mounted PIV system, which realizes the fine adjustment (including position locking) of the attitude of the calibration target, optimizes the size space of the attitude adjustment mechanism 23 as much as possible, and reduces the requirement for the limited operation space around; the whole mechanism of the present application is simple and convenient to operate, improves the use efficiency, and can use conventional measuring tools to quantitatively inspect the attitude of the calibration target, so that the calibration target attitude adjustment mechanism 23 has wide applicability in the deep water towing tank.

[0096] The present application highlights the multifunctionality of the calibration target attitude adjustment mechanism 23, which can be used to accurately align the direction of the laser sheet light, and provides various methods to verify the alignment quality of the sheet light direction.

[0097] The above description is an explanation of the present application, not a limitation of the invention, the scope of the present application is limited to the claims, within the protection scope of the present application, any form of modification can be made.

Claims

1. A calibration target attitude adjustment mechanism for a deep-water towed pool PIV system, characterized in that: The system includes an attitude adjustment mechanism (23) connected to the PIV system (22). The attitude adjustment mechanism (23) has the following structure: a flat base (4), a lower adjustment plate (3) is mounted on the upper surface of the flat base (4) by fasteners, an upper adjustment plate (2) is mounted above the lower adjustment plate (3), a yaw angle adjustment module (5) and a roll angle adjustment module (6) are respectively mounted on both ends of the flat base (4), a roll angle module connector (205) is provided at one end of the upper adjustment plate (2), the roll angle module connector (205) is connected to the roll angle adjustment module (6), a yaw angle module connector (303) is provided on the lower adjustment plate (3), the yaw angle module connector (303) is connected to the yaw angle adjustment module (5); a mounting frame (1) is provided outside the flat base (4), the mounting frame (1) is positioned above the upper adjustment plate (2), and the mounting frame (1) is positioned above the upper adjustment plate (2). 1) The top surface is provided with multiple mounting holes for connecting with reference objects at the calibration site; two vertical supports (10) are fixed on the bottom surface of the flat plate base (4), and a horizontal support (9) is installed between the two vertical supports (10) by fasteners. A calibration target frame (14) is installed between the two vertical supports (10) below the horizontal support (9). A calibration target (20) is fixedly installed inside the calibration target frame (14). The upper part of the calibration target frame (14) Grooves (21) are opened at both ends of the frame and the bottom frame. A cuboid aluminum rod is placed in the groove (21). A silicon reflective lens (16) is installed at the outer end of the calibration target frame (14). A reference block (26) is also set on the top surface of the attitude adjustment mechanism (23). Two vertical lines (24) are fixed on the reference block (26). The bottom of the vertical lines (24) is a counterweight (25). A digital display laser level (11) is fixed on the top surface of the calibration target frame (14).

2. The target attitude adjustment mechanism for the deep-water towed pool PIV system as described in claim 1, characterized in that: The cross-section of the mounting bracket (1) is in the shape of "┏┓".

3. The target attitude adjustment mechanism for the deep-water towed pool PIV system as described in claim 1, characterized in that: The upper adjustment plate (2) includes an upper adjustment plate body (203), with a first support arm (204) on each side of the upper adjustment plate body (203) and a second support arm (301) on each side of the lower adjustment plate (3). The corresponding first support arm (204) and second support arm (301) are connected by a cotter pin (201) and a pin shaft (202), and the upper adjustment plate body (203) rotates around the pin shaft (202).

4. The target attitude adjustment mechanism for the deep-water towed pool PIV system as described in claim 1, characterized in that: The lower adjustment plate (3) includes a lower adjustment plate body (302). The lower adjustment plate body (302) is placed on the flat plate base (4). The hexagonal head bolt (19) passes through the through hole on the lower adjustment plate body (302) and the through hole on the flat plate base (4) from top to bottom, and is tightened in conjunction with the hexagonal nut (18) on the lower surface of the flat plate base (4). The lower adjustment plate (3) can rotate around the hexagonal head bolt (19).

5. The target attitude adjustment mechanism for the deep-water towed pool PIV system as described in claim 1, characterized in that: The single vertical support (10) has a T-shaped structure.

6. The target attitude adjustment mechanism for the deep-water towed pool PIV system as described in claim 1, characterized in that: The horizontal support (9) has an I-shaped structure.

7. The target attitude adjustment mechanism for the deep-water towed pool PIV system as described in claim 1, characterized in that: The installation structure of the yaw angle adjustment module (5) is as follows: a No. 1 hinge bolt (503) is installed on the yaw angle module connecting seat (303) through a No. 1 hexagonal head reamer hole using a bolt (507); a No. 1 adjusting nut (504) is inserted between the No. 1 adjusting nut pressure plate (502) and the No. 1 adjusting nut base plate (505); a No. 1 internal hexagonal head screw (508) aligns and presses the No. 1 adjusting nut pressure plate (502) and the No. 1 adjusting nut base plate (505) together; the No. 1 adjusting nut pressure plate (502), the No. 1 adjusting nut (504), and the No. 1 adjusting nut base plate (505) are installed as a whole in the yaw angle adjustment module. In the opening slot of the module base (506), the No. 1 hinge bolt (503) passes through the No. 1 adjusting nut pressure plate (502), assembles with the No. 1 adjusting nut (504), and passes through the No. 1 adjusting nut base plate (505) and the yaw angle adjustment module base (506). The No. 1 hexagonal head reamer bolt (507) passes through the opening ring at the tail end of the No. 1 hinge bolt (503) and fixes the opening ring on the yaw angle module connecting seat (303). The No. 1 clamping bolt (501) is screwed into the threaded hole on the yaw angle adjustment module base (506). The bottom of the yaw angle adjustment module base (506) is fixed to the flat plate base (4) by welding.

8. The target attitude adjustment mechanism for the deep-water towed pool PIV system as described in claim 1, characterized in that: The installation structure of the roll angle adjustment module (6) is as follows: a No. 2 adjusting nut (604) is installed between the No. 2 adjusting nut pressure plate (602) and the No. 2 adjusting nut base plate (605), and the No. 2 internal hexagonal head screw (608) aligns and presses the No. 2 adjusting nut pressure plate (602) and the No. 2 adjusting nut base plate (605) together; the No. 2 adjusting nut pressure plate (602), the No. 2 adjusting nut (604) and the No. 2 adjusting nut base plate (605) are installed as a whole into the opening groove of the roll angle adjustment module base (606), and self-aligning within the groove. The sliding bolt (603) passes through the pressure plate (602) of the second adjusting nut, assembles with the second adjusting nut (604), and passes through the base plate (605) of the second adjusting nut and the base (606) of the roll angle adjustment module. The bolt (607) with the second hexagonal head reamer passes through the opening ring at the tail end of the bolt (603) and fixes the opening ring on the roll angle module connecting seat (205). The bolt (601) with the second clamping bolt is screwed into the threaded hole on the roll angle adjustment module base (606) to lock the second adjusting nut (604).

9. A method of using the calibration target attitude adjustment mechanism of a deep-water towed pool PIV system as described in any one of claims 1-8, characterized in that: The following steps are included: S1: Preparation work. First, fix the three-dimensional calibration target (20) inside the calibration target frame (14). The precision-machined calibration target frame (14) ensures that the four sides of the frame are parallel to the four sides of the calibration target (20). The calibration target frame (14) is hung on the adjustment base through two vertical supports (10). S2: Adjust the connection between the base and the reference object, and give a reference direction perpendicular to the calibration target grid surface; S3: Place the digital laser level (11) on the upper frame of the calibration target frame (14), measure the roll angle of the calibration target frame (14), and use the roll angle adjustment module (6) to adjust the roll angle of the calibration target frame (14) to zero degrees. S4: Place the digital laser level (11) flat on the upper frame of the calibration target frame (14), measure the pitch angle of the calibration target frame (14), and adjust the pitch angle of the calibration target frame (14) to zero degrees using the pitch angle adjustment screw. S5: The upper and lower edges of the calibration target frame (14) are both grooved (21) with the same specifications. Three grooves (21) are selected. A cuboid aluminum rod is installed in the groove (21). Then, two vertical lines (24) are suspended according to the reference block (26) provided by the orientation reference object. They are close to the left and right aluminum rods respectively. The distances from the three intersection points formed by the vertical lines (24) and the aluminum rods to the calibration target grid surface are measured with a steel ruler. The distances from the three intersection points to the calibration target grid surface are consistent. By adjusting the yaw angle adjustment module (5) on the base, the yaw angle of the calibration target frame (14) is adjusted to zero degrees. S6: Turn on the laser of the PIV system (22), adjust the position of the entire PIV laser body through the attitude adjustment mechanism (23) until the two vertical lines (24) fall into the laser sheet light area. Combine the two vertical lines (24) and the intense reflection points formed by the laser on the aluminum rod, adjust the laser light path setting so that the two vertical lines (24) fall into the sheet light area and the intense reflection points formed by the laser on the aluminum rod. There are at least three reflection points, and the distance from each reflection point to the calibration target grid surface is consistent. S7: Move the PIV system (22) along the direction perpendicular to the calibration target grid surface so that both vertical lines (24) fall within the sheet light surface or the sheet light falls on the silicon reflector (16) on the side of the calibration target frame (14). Observe whether the light trace formed by the laser reflected by the silicon reflector (16) irradiating the PIV laser body coincides with the sheet light trace at the PIV light outlet. This result is used to check the laser sheet light alignment quality. If the deviation is large, S6 needs to be repeated.

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