Multi-degree-of-freedom precise assembling and adjusting method for high-precision star sensor image detector

Abstract

The invention relates to a multi-degree-of-freedom precise assembling and adjusting method for a high-precision star sensor image detector, which is characterized in that a non-contact three-coordinate measuring instrument is applied to control the position and the inclination angle of the image detector in a chip assembling and adjusting process, and meanwhile, the characteristic of non-contact measurement can protect a chip from being damaged; for the inclination angle of the image detector, two times of adjustment control are carried out on the three-coordinate measuring instrument and the focusing table in sequence, and the precision requirement of the whole machine is met. And the detector is reinforced by using eight jackscrews on the side surface and the top surface, so that the mechanical stability of the installation and adjustment precision is ensured. According to the method, five-degree-of-freedom assembling and adjusting can be achieved, assembling stress is avoided while the assembling and adjusting precision is improved, and the precision stability after assembling and adjusting can be well kept.

Description

Technical Field

[0001] The invention belongs to the technical field of star sensor installation and adjustment, and relates to an installation and adjustment method for an image detector in a high-precision star sensor. Background Art

[0002] As an important attitude determination device for satellite platforms, the star sensor works by imaging stars in space, obtaining star observation vectors, using star map matching to determine the directions of the three axes of the star sensor in inertial space, and using the conversion relationship between the star sensor's body coordinate system and the satellite's body coordinate system to determine the satellite's attitude in inertial space.

[0003] The imaging component of the star sensor is the core component, such as Figure 1 As shown, it is usually composed of an optical lens, a main structure, a chip flange, an image detector and other connecting structures. The optical lens is installed on the upper side of the main structure, and the tilting ring and the chip flange are installed on the lower side in sequence. The image detector is installed on the chip flange. Four side top screws and four top top screws are installed on the side and top surface of the chip flange to ensure accuracy and stability. Four bosses are provided on the tilting ring to adjust the coaxiality of the optical lens axis and the normal of the image detector chip.

[0004] The installation and adjustment requirements of the image detector are:

[0005] ①The normal line of the detector image plane is coaxial with the optical axis of the optical lens.

[0006] ②The detector image plane coincides with the focal plane of the optical lens.

[0007] ③The position and angle of the two axes in the detector image plane.

[0008] ④ After achieving five degrees of freedom, ensure the stability of the adjustment accuracy.

[0009] Patent "A focal plane assembly of a star sensor and its assembly and adjustment method" CN117135432A, through grinding columns or parallelism adjustment mechanism for assembly and adjustment, the parallelism adjustment mechanism can adjust the distance between each support point and the circuit board, grinding columns can adjust the parallelism between the lens image plane and COMS by grinding the height of each grinding column. This method uses 4 grinding columns to adjust the parallelism between the lens image plane and COMS. The 4 grinding columns are easy to bring assembly stress for posture adjustment, which is not conducive to maintaining precision stability; this method adjusts 3 degrees of freedom.

[0010] Patent "An automatic calibration device and method for the focal plane of a star sensor" CN111707291 B uses a three-coordinate measuring instrument to position the mechanical components in the star sensor detection assembly, and uses a visual detection system to position the optical components in the star sensor detection assembly. The controller calculates the position difference between the optical components and the mechanical components in the star sensor detection assembly to achieve adjustment. This method uses two instruments, a contact three-coordinate measuring instrument and a visual measurement system, to measure, only controlling the relative position of the mechanical components and the optical components, adjusting three degrees of freedom, and does not explain how to maintain the accuracy stability.

[0011] Patent "A system and method for realizing high-precision orthogonality adjustment of star sensor image plane" CN109870828B describes the posture adjustment process of the star sensor image plane and realizes the adjustment of the image plane with three degrees of freedom, but does not explain how to maintain the accuracy stability after adjustment. Summary of the invention

[0012] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art and provide a high-precision star sensor image detector multi-degree-of-freedom precision assembly method, which can achieve 5-degree-of-freedom assembly, avoid assembly stress while improving the assembly accuracy, and can well maintain the accuracy stability after assembly.

[0013] The technical solution of the present invention is: a high-precision star sensor image detector multi-degree-of-freedom precision adjustment method, comprising the following steps:

[0014] (1) Fix the chip flange on the working table of the non-contact three-dimensional coordinate measuring machine with a vise, so that the chip bonding surface on the chip flange is in a horizontal state, and the edge of the chip flange is visually flush with the Y axis of the non-contact three-dimensional coordinate measuring machine, and tighten the chip flange; wherein the probe axis of the non-contact three-dimensional coordinate measuring machine is the Z axis downward, and the Y axis is selected in a plane perpendicular to the Z axis;

[0015] (2) Use a non-contact three-dimensional coordinate measuring machine to measure the four edges on the chip flange, use the two parallel edges to construct a rectangle, and use the coordinates of the intersection of the diagonals of the rectangle as the coordinates of the structural center; use a non-contact three-dimensional coordinate measuring machine to find three points on the four structural tilt reference bosses on the chip flange, respectively, and use the three points to establish one mounting surface. The four structural tilt reference bosses establish a total of four mounting surfaces, and use these four mounting surfaces to construct a plane as the structural reference surface;

[0016] (3) Apply silicone rubber to the chip bonding surface of the chip flange, except for the three bosses on the bonding surface; bond the image detector to the chip bonding surface of the chip flange, measure the four corner points of the rectangular bright frame of the image detector, construct the intersection of the diagonal lines of the four corner points as the coordinates of the center position of the image detector, and manually fine-tune the position of the image detector until the deviation between the coordinates of the center position of the image detector and the coordinates of the center of the structure is less than the required value;

[0017] A straight line is constructed using the long side of the rectangular bright frame of the image detector, and the angle between the constructed straight line and the straight line where the edge of the chip flange substantially parallel to the Y axis is located is calculated, and the angle of the image detector is manually adjusted until the angle between the constructed straight line and the straight line where the edge of the chip flange substantially parallel to the Y axis is located is less than the required value;

[0018] Take one point at each of the four corners of the rectangular bright frame of the image detector, construct a plane as the image detector image plane, calculate the angle between the normal line of the image detector image plane and the normal line of the structural reference plane, and manually adjust the image detector body to change its angle until the deviation of the angle between the image detector image plane and the structural reference plane is less than the required value;

[0019] (4) After curing at room temperature, re-measure the three deviations in step (3) to see whether they are all less than their corresponding required values. If so, proceed to the next step. If not, disassemble the image detector and return to step (3);

[0020] (5) Screw in the top screw and the side screw, apply silicone rubber between the soft pressing end of the screw and the image detector, and apply silicone rubber on the thread of the screw; observe the position of the front end of the screw and the image detector, stop screwing in when the soft pressing end of the screw just touches the image detector, and clean up the overflowed glue after completion;

[0021] (6) Re-measure the three deviations in step (3) to see whether they are all less than their corresponding required values. If they are satisfied, proceed to the next step. If not, loosen the top screw and the side screw and return to step (5);

[0022] (7) Install the tilt ring between the chip flange and the main structure, and tighten the mounting screws; install the optical lens on the upper side of the main structure; adjust the star point position of the star simulator to fall on the four corners of the image detector image plane, respectively, and compare the imaging areas of the four star points. If the difference between the maximum and minimum values ​​exceeds the required value, grind the boss at the punching position of the tilt ring, and reinstall the tilt ring after grinding until the difference between the maximum and minimum values ​​of the imaging areas of the four star points on the image detector image plane does not exceed the required value;

[0023] (8) Apply epoxy glue to the contact surface gaps of the main structure, chip flange, and tilt ring.

[0024] Furthermore, in the step (3), when applying the silicone rubber, the thickness of the adhesive layer is determined by the height of the three bosses, and the amount of adhesive applied is determined by whether there is overflow at the edge of the image detector.

[0025] Preferably, in step (4), the curing time at room temperature is 24 hours.

[0026] Preferably, the required value of the deviation between the center position coordinates of the image detector and the center coordinates of the structure is 10 to 20 μm.

[0027] Preferably, the required value of the angle between the constructed straight line and the straight line where the edge of the chip flange substantially parallel to the Y-axis is located is 2″.

[0028] Preferably, the required value of the angle deviation between the image detector image plane and the structural reference plane is 2".

[0029] Preferably, the required value of the difference between the maximum and minimum imaging areas of the four star points on the image plane of the image detector is 2 pixels.

[0030] Preferably, the Y-axis is specifically the direction of the linear guide rail in the left and right directions when the front is facing the non-contact three-dimensional coordinate measuring machine operating table, and the positive direction is from right to left.

[0031] The advantages of the present invention compared with the prior art are:

[0032] (1) The present invention can realize the adjustment of the image detector's two-axis position in the image plane, rotation in the image plane, and the coaxiality of the detector's image plane normal and optical axis, with a total of 5 degrees of freedom, by using a non-contact three-dimensional coordinate measuring instrument, replacing a focus ring with a suitable thickness, and grinding a tilt ring;

[0033] (2) The non-contact three-dimensional coordinate measuring machine has limited measurement accuracy in the direction of the optical axis. In order to make up for this deficiency, the present invention can improve the alignment accuracy of the image detector image plane normal and the optical axis by grinding the height of the four bosses of the tilting ring. At the same time, the simultaneous grinding of the four bosses of the grinding ring can ensure that the four grinding rings are in the same plane, avoiding assembly stress;

[0034] (3) The present invention controls the amount of glue applied to the detector chip and the chip flange by the height of the three bosses on the mounting surface of the chip flange, thereby improving the reliability and precision stability of the product;

[0035] (4) The present invention can ensure the stability of installation and adjustment accuracy by fixing the side top screws and the top surface top screws, and the relative position and angle will not change under mechanical conditions such as vibration and impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the star sensor image detector and its structure of the present invention;

[0037] Figure 2 It is a flow chart of the installation and adjustment method of the present invention;

[0038] Figure 3 It is a schematic diagram of the structure of the side top screw and the top top screw of the present invention;

[0039] Figure 4 This is a schematic diagram of the chip flange assembly and adjustment reference of the present invention;

[0040] Figure 5 A schematic diagram for establishing a chip flange installation position reference of the present invention;

[0041] Figure 6 A schematic diagram of establishing a chip flange installation tilt reference of the present invention;

[0042] Figure 7 A schematic diagram for determining the coordinates of the center position of the image detector of the present invention;

[0043] Figure 8 It is a schematic diagram of the installation of the side top screw and the top top screw of the present invention;

[0044] Fig. 9 This is a schematic diagram of the installation of the tilting ring of the present invention;

[0045] Fig.10 It is a schematic diagram of the inclined ring of the present invention. DETAILED DESCRIPTION

[0046] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0047] like Figure 2 As shown, the specific installation and adjustment process of the method of the present invention is as follows:

[0048] Step one: Preparation for installation.

[0049] Parts that need to be prepared for installation and adjustment: image detector, chip flange, side screws, top screws, main structure, and optical lens.

[0050] The side top wire and the top top wire are as follows Figure 3 As shown, the two types of top screws have the same structure, consisting of a set screw and a soft clamping end, wherein the set screw is made of stainless steel, the outer cylindrical surface is a full-length thread, the soft clamping end is a non-metallic material (such as polyimide), and the set screw and the soft clamping end are bonded into one by silicone rubber.

[0051] Equipment and tooling required: non-contact three-dimensional coordinate measuring machine, precision vise, and torque screwdriver.

[0052] Auxiliary materials needed: silicone rubber; epoxy glue.

[0053] Step 2: Chip flange clamping

[0054] Fix the chip flange on the working table of the non-contact three-dimensional coordinate measuring machine with a precision vise, and adjust the precision vise to ensure that the chip bonding surface on the chip flange is in a horizontal state. Figure 4 As shown, the edge of the chip flange is visually flush with the Y axis of the three-coordinate device, and the chip flange is tightened. Among them, there are four straight edges around the upper end face of the chip flange. After the edges are extended, they can form a rectangle as a reference for the adjustment of two positions in the image detector image plane; the mounting ears on the upper end face of the chip flange have four protruding planes as a reference for the adjustment of the image detector image plane. The probe axis of the non-contact three-coordinate measuring device is the Z axis facing downward, and the plane formed by the X axis and the Y axis is perpendicular to the Z axis. In the present invention, when the front side is facing the non-contact three-coordinate measuring instrument operating table, the direction of the linear guide rails in the left and right directions is positive from right to left.

[0055] Step 3: Adjust the position and establish the tilt reference

[0056] like Figure 5 As shown, a non-contact three-dimensional coordinate measuring instrument is used to measure the four edges on the chip flange, and a rectangle is constructed with two parallel edges. The coordinates of the intersection of the diagonals of the constructed rectangle are used as the coordinates of the center of the structure.

[0057] like Figure 6 As shown, a non-contact three-dimensional coordinate measuring machine is used to find three points on the four structural tilt reference bosses on the chip flange, and a plane is established with the three points. A total of four mounting surfaces are established with the four structural tilt references. A plane is constructed with these four mounting planes as a structural reference plane, and the normal of the structural reference plane is used as the adjustment reference for the normal of the image detector image plane.

[0058] Step 4: Gluing and adjustment test

[0059] Apply silicone rubber to the chip bonding surface on the chip flange. Do not apply adhesive to the three bosses on the bonding surface. The boss positions are as follows: Figure 5 As shown, the three bosses are used to control the thickness of the glue layer. The boss height is the thickness of the glue layer of the silicone rubber. The amount of glue applied is based on whether there is overflow at the edge of the image detector.

[0060] Bond the image detector to the chip flange, measure the four corner points of the rectangular bright frame of the image detector, and construct the intersection point using the diagonal lines of the four corner points, such as Figure 7 As shown, the intersection coordinates are the coordinates of the detector center position. Manually fine-tune the image detector position and measure the center position again until the deviation between the detector center position coordinates and the structure center coordinates is less than the required value. The required value varies with the requirements of products with different precisions, and can generally be 10 to 20 μm. In the embodiment of the present invention, 15 μm is selected.

[0061] At the same time, a straight line is constructed with the long side of the rectangular bright frame of the image detector, and the angle between the constructed straight line and the straight line where the edge of the chip flange is roughly parallel to the Y axis is calculated. If it is greater than the required value, the image detector angle is manually adjusted until the deviation is less than the required value. The required value varies with the requirements of products with different precisions. In the embodiment of the present invention, 2" is selected.

[0062] At the same time, take one point at each of the four corners of the rectangular bright frame of the image detector, construct a plane as the image detector image plane, calculate the angle between the normal line of the image detector image plane and the normal line of the structural reference plane, if it is greater than the required value, then use a toothpick to gently push the image detector body to change its angle until the deviation of the angle between the image detector image plane and the structural reference plane is less than the required value. The required value varies with the requirements of products with different precisions, and 2" is selected in the embodiment of the present invention.

[0063] The above two angles and positions will change during each adjustment process. After each adjustment, these deviations need to be measured until the three deviations meet the required values ​​at the same time.

[0064] After curing at room temperature for 24 hours, retest the above accuracy. If it meets the requirements, this step is completed; if it does not meet the requirements, the image detector needs to be disassembled and reassembled until it meets the requirements.

[0065] Step 5: Install the top screw

[0066] like Figure 8 As shown, screw in the top screw and the side screw, apply silicone rubber protection between the soft pressing end of the screw and the image detector, and apply silicone rubber on the screw thread. Observe the front end of the screw and the position of the image detector, stop screwing when the soft pressing end of the screw just touches the image detector, and clean up the overflowed glue after completion.

[0067] Re-measure the accuracy described in the fourth step above. If the requirements are met, this step is completed; if not, loosen the top screw, re-tighten it and re-measure the position and angle values ​​until the requirements are met.

[0068] Step 6: Tilt ring grinding adjustment and testing

[0069] like Fig. 9 As shown, install the tilt ring between the chip flange and the main structure, and tighten the mounting screws; install the optical lens on the upper side of the main structure; and perform precision focusing on the installed components. Adjust the star point position of the star simulator to fall on the four corners of the image detector image plane, and compare the imaging areas of the four star points. If the difference between the maximum and minimum values ​​exceeds the required value, grind the boss at the punching position of the tilt ring, as shown in Figure 1. Fig.10As shown, after grinding, the imaging areas of the four star points are installed and measured respectively until the difference between the maximum and minimum imaging areas of the star points does not exceed the required value. The required value varies with the requirements of products with different precisions. In the embodiment of the present invention, 2 pixels are selected.

[0070] After completion, apply epoxy glue to the contact surface gaps of the main structure, chip flange, and tilting ring to enhance the stability of the assembly and adjustment accuracy.

[0071] At this point, all the adjustment steps are completed. Among them, for the adjustment of the optical axis of the optical lens and the image plane of the image detector coaxially (that is, the image plane of the detector is tilted), the third and fourth steps are fine adjustment, and the sixth step is fine adjustment. If the completion accuracy of the third step is good, the sixth step only needs to be tested and confirmed, and no grinding adjustment is required.

[0072] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A high-precision star sensor image detector multi-degree-of-freedom precision adjustment method, characterized by: The steps include: (1) Fix the chip flange on the working table of the non-contact three-dimensional coordinate measuring machine with a vise, so that the chip bonding surface on the chip flange is in a horizontal state, and the edge of the chip flange is visually flush with the Y-axis of the non-contact three-dimensional coordinate measuring machine, and tighten the chip flange; The probe axis of the non-contact three-dimensional coordinate measuring machine is the Z axis, and the Y axis is selected in a plane perpendicular to the Z axis; (2) Use a non-contact three-dimensional coordinate measuring machine to measure the four edges on the chip flange, use the two parallel edges to construct a rectangle, and use the coordinates of the intersection of the diagonals of the rectangle as the coordinates of the structural center; use a non-contact three-dimensional coordinate measuring machine to find three points on the four structural tilt reference bosses on the chip flange, respectively, and use the three points to establish one mounting surface. The four structural tilt reference bosses establish a total of four mounting surfaces, and use these four mounting surfaces to construct a plane as the structural reference surface; (3) Apply silicone rubber to the chip bonding surface of the chip flange, except for the three bosses on the bonding surface; bond the image detector to the chip bonding surface of the chip flange, measure the four corner points of the rectangular bright frame of the image detector, construct the intersection of the diagonal lines of the four corner points as the coordinates of the center position of the image detector, and manually fine-tune the position of the image detector until the deviation between the coordinates of the center position of the image detector and the coordinates of the center of the structure is less than the required value; A straight line is constructed using the long side of the rectangular bright frame of the image detector, and the angle between the constructed straight line and the straight line where the edge of the chip flange substantially parallel to the Y axis is located is calculated, and the angle of the image detector is manually adjusted until the angle between the constructed straight line and the straight line where the edge of the chip flange substantially parallel to the Y axis is located is less than the required value; Take one point at each of the four corners of the rectangular bright frame of the image detector, construct a plane as the image detector image plane, calculate the angle between the normal line of the image detector image plane and the normal line of the structural reference plane, and manually adjust the image detector body to change its angle until the deviation of the angle between the image detector image plane and the structural reference plane is less than the required value; (4) After curing at room temperature, re-measure the three deviations in step (3) to see whether they are all less than their corresponding required values. If so, proceed to the next step. If not, disassemble the image detector and return to step (3); (5) Screw in the top screw and the side screw, apply silicone rubber between the soft pressing end of the screw and the image detector, and apply silicone rubber on the thread of the screw; observe the position of the front end of the screw and the image detector, stop screwing in when the soft pressing end of the screw just touches the image detector, and clean up the overflowed glue after completion; (6) Re-measure the three deviations in step (3) to see whether they are all less than their corresponding required values. If they are satisfied, proceed to the next step. If not, loosen the top screw and the side screw and return to step (5); (7) Install the tilt ring between the chip flange and the main structure, and tighten the mounting screws; install the optical lens on the upper side of the main structure; adjust the star point position of the star simulator to fall on the four corners of the image detector image plane, respectively, and compare the imaging areas of the four star points. If the difference between the maximum and minimum values ​​exceeds the required value, grind the boss at the punching position of the tilt ring, and reinstall the tilt ring after grinding until the difference between the maximum and minimum values ​​of the imaging areas of the four star points on the image detector image plane does not exceed the required value; (8) Apply epoxy glue to the contact surface gaps of the main structure, chip flange, and tilt ring.

2. The multi-degree-of-freedom precision adjustment method for a high-precision star sensor image detector according to claim 1, characterized in that: In the step (3), when applying the silicone rubber, the thickness of the glue layer is determined by the height of the three bosses, and the amount of glue applied is based on whether there is overflow at the edge of the image detector.

3. A high-precision star sensor image detector multi-degree-of-freedom precision adjustment method according to claim 1 or 2, characterized in that: In the step (4), the curing time at room temperature is 24 hours.

4. A high-precision star sensor image detector multi-degree-of-freedom precision adjustment method according to claim 1 or 2, characterized in that: The required value of the deviation between the center position coordinate of the image detector and the center coordinate of the structure is 10 to 20 μm.

5. A high-precision star sensor image detector multi-degree-of-freedom precision adjustment method according to claim 1 or 2, characterized in that: The required value of the angle between the constructed straight line and the straight line where the edge of the chip flange substantially parallel to the Y axis is located is 2″.

6. A high-precision star sensor image detector multi-degree-of-freedom precision adjustment method according to claim 1 or 2, characterized in that: The required value of the angle deviation between the image detector image plane and the structural reference plane is 2".

7. A high-precision star sensor image detector multi-degree-of-freedom precision adjustment method according to claim 1 or 2, characterized in that: The required value of the difference between the maximum and minimum values ​​of the imaging areas of the four star points on the image plane of the image detector is 2 pixels.

8. The multi-degree-of-freedom precision adjustment method for a high-precision star sensor image detector according to claim 1, characterized in that: The Y-axis specifically refers to the direction of the linear guide rails in the left and right directions when the front side faces the operating table of the non-contact three-dimensional coordinate measuring machine, and the positive direction is from right to left.

Images