Spacecraft buffer airbag inflation and time-sharing exhaust control method

Abstract

The invention discloses an inflation and time-sharing exhaust control method for a buffer airbag of a spacecraft. The method comprises the following steps: setting a synchronization signal waiting time parameter; when the spacecraft buffer airbag reaches the airbag inflation discrimination height, sending an airbag inflation instruction according to the synchronization signal waiting time parameter; when the overload information reaches a preset threshold value, it is judged that the reentry capsule lands; the posture of the return capsule is judged, and if the quadrant III faces forwards, an exhaust mode with the quadrant III facing forwards is started; if the quadrant I faces forwards, entering an I-quadrant forward exhaust mode; if the posture is not judged out after the preset time, all the air bags are controlled to be exhausted at the same time, and exhausting is finished. According to the invention, the problem of non-synchronization of air bag inflation instructions caused by inter-board difference of a redundancy control system can be solved.

Description

Technical Field

[0001] The invention relates to a method for controlling the inflation and time-sharing exhaust of a spacecraft cushion airbag, and belongs to the technical field of landing cushioning of a returning spacecraft. Background Art

[0002] The landing cushioning process is one of the most important links in the execution of the returning spacecraft mission. Usually, there are mechanical cushioning, horizontal rolling landing, reverse thrust active cushioning and airbag cushioning methods and means to solve the landing cushioning problem of spacecraft. The landing method using airbag cushioning has the advantages of small device mass, simple structure, small installation envelope and low cost, and has been widely used in spacecraft design.

[0003] The traditional exhaust airbag cushioning design will release the cushioning airbag during the descent of the spacecraft and allow air to fill the airbag. When the spacecraft lands, the airbag is compressed and the compressed air is passively discharged from the exhaust hole or exhaust valve, thereby absorbing the impact energy of the spacecraft during the landing process and achieving the purpose of cushioning. However, doing so will cause the overload curve to be triangulated, with a high overload peak value, which is easily affected by the external environment, causing the stability of the spacecraft to deteriorate at the moment of landing, causing the spacecraft to tip over. Using air pressure or mechanism to control the exhaust port area can effectively reduce the overload peak, but the design has shortcomings such as complex drive structure, high assembly precision requirements and low time control precision.

[0004] FPGA Design of Landing Cushioning Control System Based on Active Exhaust Airbag, Sun Xiyun et al., Space Return and Remote Sensing, Vol. 40, No. 8. The exhaust control method in the paper is a simplified engineering method. The active exhaust control method of the airbag is studied. The control system cannot independently control each airbag, and the differentiated control needs to be improved. At the end of the article, it is also proposed that "further research is needed on how the landing exhaust control strategy can adapt to the different ground environments of the landing site, and explore the implementation method of the optimal control law under the premise of high reliability."

[0005] Patent "A combined buffered active exhaust control system" by Li Bo et al., application number: CN202211528401.5. The patent records that the airbags are differentially exhausted according to the preset control strategy after comparing the landing point wind speed with the preset wind speed. In engineering implementation, the landing point wind speed of the spacecraft cannot be written into the return control program in advance.

[0006] The patent "An active exhaust control system and method for return capsule landing cushion airbags" by Sun Xiyun et al., application number: 202018016796.6, records real-time monitoring of the sensing data of the return capsule overload sensor, which is used as an incentive to transfer the function of the cushion airbag landing control model, and perform a weighted evaluation of the force conditions of each airbag control point. Based on the evaluation results, an exhaust control instruction sequence for the airbag is formed to exhaust the cushion airbag to ensure that the overload value meets the requirements. The control method does not introduce the motion characteristics of the cabin parachute system. Summary of the invention

[0007] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art and provide a spacecraft cushion airbag inflation and time-sharing exhaust control method, which can solve the problem of airbag inflation command asynchronism caused by differences between boards in a redundant control system.

[0008] The technical solution of the present invention is:

[0009] The present invention discloses a method for controlling the inflation and time-sharing exhaust of a spacecraft cushion airbag, comprising:

[0010] Set the waiting time parameters for synchronization signal;

[0011] When the spacecraft cushion airbag reaches the airbag inflation determination altitude, the airbag inflation command is sent according to the waiting synchronization signal time parameter;

[0012] When the overload information reaches the preset threshold, the return capsule is judged to have landed;

[0013] Determine the attitude of the return capsule. If quadrant III is facing forward, enter the quadrant III forward exhaust mode; if quadrant I is facing forward, enter the quadrant I forward exhaust mode; if the attitude is not determined within the predetermined time, control all airbags to exhaust at the same time, and the exhaust ends.

[0014] Furthermore, in the above method, the waiting synchronization signal time parameter is specifically:

[0015] T_wait=ΔRef / M

[0016] ΔRef=Max{|Ref1-Ref2|, |Ref1-Ref3|, |Ref2-Ref3|}

[0017] M=V2-V1

[0018] Wherein, T_wait is the maximum waiting time for inter-board synchronization; ΔRef is the maximum value of the voltage difference between boards; M is the change rate of the voltage at the height of the synchronization control point; Ref1, Ref2, and Ref3 are the reference voltages of the AD chips of the three boards respectively; V2 is the voltage value corresponding to the atmospheric pressure at the height 0.5 s backward from the control point, and V1 is the voltage value corresponding to the atmospheric pressure at the height 0.5 s forward from the control point.

[0019] Further, in the above method, the specific method for judging the attitude of the return capsule is as follows:

[0020] When AD1_G_FIT_X < YZ and AD2_G_FIT_X < YZ and AD3_G_FIT_Y > YZ, it is judged that the third quadrant is facing forward;

[0021] When AD1_G_FIT_X > YZ and AD2_G_FIT_X > YZ and AD3_G_FIT_Y < YZ, it is judged that the first quadrant is facing forward;

[0022] Wherein, AD1_G_FIT_X is the value after AD sampling and filtering of the overload in the X direction at the position of the overload sensor a; AD2_G_FIT_X is the value after AD sampling and filtering of the overload in the X direction at the position of the overload sensor b; AD3_G_FIT_Y is the value after AD sampling and filtering of the overload in the Y direction at the position of the overload sensor c; YZ is the minimum overload threshold for judging the movement direction.

[0023] Further, in the above method, the exhaust mode with the third quadrant facing forward is specifically as follows:

[0024] If min(PP1, PP2) > max(PP4, PP5), perform the control mode of facing forward in the third quadrant and raising the head;

[0025] If min(PP4, PP5) > max(PP1, PP2), perform the control mode of facing forward in the third quadrant and lowering the head;

[0026] If the attitude cannot be judged after exceeding the predetermined time, perform time-sharing exhaust, specifically: exhaust the airbags P1, P2, P3, and P6 first, and then exhaust the airbags P4 and P5 after a delay of 30 - 40 ms.

[0027] Further, in the above method, the control mode of facing forward in the third quadrant and raising the head is specifically as follows:

[0028] Sort the pressure values of the airbags P1, P2, P3, and P6, and select the airbag corresponding to the maximum value to exhaust first;

[0029] Delay for 10 - 15 ms, refresh the pressure values of the airbags P1, P2, P3, and P6 after sampling and filtering, assign the pressure value corresponding to the exhausted airbag to 0X 0, and then sort them;

[0030] When the same pressure value appears, the airbags are sorted in order of priority from high to low in order of P1, P2, P3, and P6, and the airbag with the highest priority is deflated first;

[0031] When all values ​​are 0, the airbags are sorted in order of priority from high to low in order of P1, P2, P3, and P6, and the airbags with high priority are deflated first;

[0032] Repeat this process at intervals of 10 to 15 ms until the P1, P2, P3, and P6 airbags are all deflated.

[0033] After a delay of 10 to 15 ms, the remaining P4 and P5 airbags are deflated.

[0034] Furthermore, in the above method, the quadrant III is facing forward and the head is lowered in the control mode, specifically:

[0035] Sort the pressure values ​​of P1, P2, P3, and P6, and select the airbag corresponding to the minimum value to exhaust first;

[0036] Delay 10ms, refresh the P1, P2, P3, P6 pressure values ​​after sampling and filtering, assign 0XFFF to the pressure values ​​corresponding to the exhausted airbags and sort them;

[0037] When the same pressure value appears, the airbags P1, P2, P3, and P6 are sorted from high to low in priority, and the one with the lowest priority is used for exhaust;

[0038] When all values ​​are in the extreme state of 0XFFF, the airbags are sorted in order of priority from large to small in order of P1, P2, P3, and P6, and the un-deflated airbags with large priority are deflated first;

[0039] This process is repeated at 10ms intervals until the four airbags P1, P2, P3, and P6 are exhausted.

[0040] Delay 10ms and deflate the remaining P4 and P5 airbags.

[0041] Furthermore, in the above method, the front exhaust mode in quadrant I is specifically:

[0042] If min(PP1,PP2)>max(PP4,PP5), perform quadrant I forward and head down control mode;

[0043] If min(PP4,PP5)>max(PP1,PP2), perform quadrant I forward and head-up control mode;

[0044] If the posture is not determined within the preset time, the exhaust is carried out in a time-sharing manner, specifically: the airbags P3, P4, P5, and P6 are exhausted first, and the airbags P1 and P2 are exhausted after a delay of 30 to 40ms.

[0045] Furthermore, in the above method, the quadrant I forward-facing and head-down control mode is specifically:

[0046] Sort the pressure values ​​of P4, P5, P6, and P3, and select the airbag corresponding to the minimum value to exhaust first;

[0047] Delay 10ms, refresh the pressure values ​​of P4, P5, P6, and P3 after sampling and filtering, assign 0XFFF to the pressure values ​​corresponding to the exhausted airbags, and then sort them;

[0048] When the same pressure value appears, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the one with the lowest priority is used for exhaust;

[0049] When all values ​​are in the 0XFFF limit state, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the un-deflated airbags with the highest priority are deflated first;

[0050] This process is repeated at 10ms intervals until the P4, P5, P6, and P3 airbags are completely deflated.

[0051] Delay 10ms and deflate the remaining P1 and P2 airbags.

[0052] Furthermore, in the above method, the quadrant I forward-facing and head-up control mode is specifically:

[0053] Sort the pressure values ​​of P4, P5, P6, and P3, and select the airbag corresponding to the maximum value to deflate first;

[0054] Delay 10ms, refresh the pressure values ​​of P4, P5, P6, and P3 after sampling and filtering, assign 0X0 to the pressure values ​​corresponding to the exhausted airbags, and then sort them;

[0055] When the same pressure value appears, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the one with the highest priority is used for exhaust;

[0056] When all values ​​are in the 0X0 limit state, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the un-deflated airbags with the highest priority are deflated first;

[0057] This process is repeated at 10ms intervals until the P4, P5, P6, and P3 airbags are completely deflated.

[0058] Delay 10ms and deflate the remaining P1 and P2 airbags.

[0059] The beneficial effects of the present invention and the prior art are:

[0060] (1) The present invention provides a three-board synchronization method by calculating the AD reference voltage difference between boards and the static pressure altitude change rate, which can solve the problem of airbag inflation command asynchronization caused by the difference between boards in the redundant control system. It can also be extended to the redundant control system that uses static pressure for altitude parachute opening control.

[0061] (2) The exhaust strategy adopted by the present invention takes the forward direction and pitch angle of the return capsule as the main determining factors, uses the sampling data of the overload X and overload Y directions at the moment of landing to determine the direction of the return capsule at the moment of landing, and uses the sampling values ​​of the airbag pressure in different directions at the moment of landing to determine the pitch attitude of the return capsule.

[0062] (3) The present invention formulates different exhaust strategies according to different modes of quadrant III facing forward and raising the head, quadrant III facing forward and lowering the head, quadrant I facing forward and lowering the head, and quadrant I facing forward and raising the head, to accurately control the exhaust timing and sequence of different airbags, thereby improving the landing stability and anti-rollover capability of the return capsule, avoiding the return capsule from tipping over and causing structural damage when the horizontal speed is high, the swing angle of the return capsule is too large, or the ground slope is large, thereby ensuring the reusability of the return capsule.

[0063] (4) The present invention adds monitoring and interpretation of changes in airbag pressure. On the basis of controlling the impact overload peak of the return capsule during the landing buffer process to ensure the safety of astronauts, the exhaust strategy takes the forward direction and pitch angle of the return capsule as the main determining factors according to the motion characteristics of the capsule-parachute system. The exhaust timing and sequence of different airbags are accurately controlled through the combination of overload and pressure, thereby improving the landing stability and anti-rollover capability of the return capsule, avoiding the tipping of the return capsule and causing structural damage when the horizontal speed is high, the swing angle of the return capsule is too large, or the ground slope is large, thereby ensuring the reusability of the return capsule.

[0064] (5) The cushioning airbag of the present invention uses the altitude signal to control inflation at a preset altitude in the air. For high-reliability control, the general control system adopts redundant hot backup. The altitude signal is generally used after AD conversion using the analog signal of the static pressure altitude sensor. The difference in AD reference voltage between multiple control boards causes asynchrony in inflation control commands. The present invention provides a three-board synchronization method by calculating the difference in AD reference voltage between boards and the static pressure altitude change rate, which can solve the problem of asynchrony in airbag inflation commands caused by the difference between boards in the redundant control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is a schematic diagram of the synchronization of the board with the slowest height point detected by the present invention;

[0066] Figure 2 A schematic diagram of the synchronization of the board with the fastest height point detected by the present invention;

[0067] Figure 3 It is a schematic diagram of the output of the synchronization signal in an abnormal state in which the synchronization signal is not detected in the present invention;

[0068] Figure 4 This is a connection diagram of the control system of the present invention;

[0069] Figure 5 The definition of the large bottom quadrant of the return capsule of the present invention and the schematic diagram of the positions of various sensors and airbags;

[0070] Figure 6 Flow chart of air bag exhaust control of the present invention; (a) is the main flow chart; (b) is the flow chart of sub-flow 1; (c) is the flow chart of sub-flow 2;

[0071] Figure 7 It is a schematic diagram of the synchronization signal and the airbag inflation command signal of the present invention. DETAILED DESCRIPTION

[0072] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0073] The present invention discloses a method for controlling the inflation and time-sharing exhaust of a spacecraft cushion airbag, comprising:

[0074] Set the waiting time parameters for synchronization signal;

[0075] When the spacecraft cushion airbag reaches the airbag inflation determination altitude, the airbag inflation command is sent according to the waiting synchronization signal time parameter;

[0076] When the overload information reaches the preset threshold, the return capsule is judged to have landed;

[0077] Determine the attitude of the return capsule. If the III quadrant is facing forward, enter the III quadrant forward exhaust mode; if the I quadrant is facing forward, enter the I quadrant forward exhaust mode; if the attitude is not determined within the preset time, control all airbags to exhaust at the same time, and exhaust ends. Figure 5 shown.

[0078] To determine whether the airbag inflation judgment height has been reached, the specific method is as follows: the height information of the static pressure height sensors a~c is sampled and filtered in real time by the AD modules 1~3, and compared with the digital threshold of the control point height. After a two-out-of-three decision is made and a certain time period is met, it is determined that the airbag inflation judgment height has been reached.

[0079] According to the effective time of the waiting detection synchronization signal, the airbag inflation command is sent, specifically:

[0080] After a single control board determines the airbag inflation height H (m), it sends the "BOARD_SYNC_OUT signal for inter-board synchronization". The synchronization output signals of the three FPGAs are processed by a hardware two-out-of-three logic externally to form the "BOARD_SYNC_IN signal for inter-board synchronization" and input into each FPGA. After a single FPGA reads the two-out-of-three return signal for inter-board synchronization, it is considered that at least two control boards have reached the airbag inflation determination height. At this time, an airbag inflation instruction is sent. The instruction width T_comd is determined according to the ignition performance index of the pyrotechnic device. At the same time, the time parameter T_sync of the synchronization signal is continuously sent so that the slow board can read the synchronization signal.

[0081] Preferably, the time parameter for waiting for the synchronization signal is specifically:

[0082] T_wait = ΔRef / M

[0083] ΔRef = Max{|Ref1 - Ref2|, |Ref1 - Ref3|, |Ref2 - Ref3|}

[0084] M = V2 - V1

[0085] Among them, T_wait is the longest waiting time for inter-board synchronization; ΔRef is the maximum value of the voltage difference between boards; M is the change rate of the voltage at the synchronization control point height and is M; Ref1, Ref2, and Ref3 are the reference voltages of the AD chips of the three boards respectively; V2 is the voltage value corresponding to the atmospheric pressure at a height 0.5 s backward from the control point, and V1 is the voltage value corresponding to the atmospheric pressure at a height 0.5 s forward from the control point.

[0086] Preferably, the attitude of the return capsule is judged. The specific method is:

[0087] When AD1_G_FIT_X < YZ and AD2_G_FIT_X < YZ and AD3_G_FIT_Y > YZ, it is judged that the third quadrant is facing forward;

[0088] When AD1_G_FIT_X > YZ and AD2_G_FIT_X > YZ and AD3_G_FIT_Y < YZ, it is judged that the first quadrant is facing forward;

[0089] Among them, AD1_G_FIT_X is the value after AD sampling and filtering of the X-direction overload at position a of the overload sensor; AD2_G_FIT_X is the value after AD sampling and filtering of the X-direction overload at position b of the overload sensor; AD3_G_FIT_Y is the value after AD sampling and filtering of the Y-direction overload at position c of the overload sensor; YZ is the minimum overload threshold for judging the movement direction.

[0090] Preferably, the exhaust mode with the third quadrant facing forward is specifically:

[0091] If min(PP1,PP2)>max(PP4,PP5), perform quadrant III forward and head-up control mode;

[0092] If min(PP4,PP5)>max(PP1,PP2), perform quadrant III forward and head-down control mode;

[0093] If the posture is not determined within the preset time, the exhaust is performed in different time periods, specifically: the airbags P1, P2, P3, and P6 are exhausted first, and the airbags P4 and P5 are exhausted after a delay of 30 to 40 ms.

[0094] Preferably, the III quadrant faces forward and the head-up control mode is specifically:

[0095] Sort the pressure values ​​of airbags P1, P2, P3, and P6, and select the airbag corresponding to the maximum value to exhaust first;

[0096] Delay 10 to 15 ms, refresh the pressure values ​​of airbags P1, P2, P3, and P6 after sampling and filtering, assign 0X 0 to the pressure values ​​corresponding to the exhausted airbags, and then sort them;

[0097] When the same pressure value appears, the airbags are sorted in order of priority from high to low in order of P1, P2, P3, and P6, and the airbag with the highest priority is deflated first;

[0098] When all values ​​are 0, the airbags are sorted in order of priority from high to low in order of P1, P2, P3, and P6, and the airbags with high priority are deflated first;

[0099] Repeat this process at intervals of 10 to 15 ms until the P1, P2, P3, and P6 airbags are all deflated.

[0100] After a delay of 10 to 15 ms, the remaining P4 and P5 airbags are deflated.

[0101] Preferably, the III quadrant is facing forward and the head is lowered control mode, specifically:

[0102] Sort the pressure values ​​of P1, P2, P3, and P6, and select the airbag corresponding to the minimum value to exhaust first;

[0103] Delay 10ms, refresh the P1, P2, P3, P6 pressure values ​​after sampling and filtering, assign 0XFFF to the pressure values ​​corresponding to the exhausted airbags and sort them;

[0104] When the same pressure value appears, the airbags P1, P2, P3, and P6 are sorted from high to low in priority, and the one with the lowest priority is used for exhaust;

[0105] When all values ​​are in the extreme state of 0XFFF, the airbags are sorted in order of priority from large to small in order of P1, P2, P3, and P6, and the un-deflated airbags with large priority are deflated first;

[0106] This process is repeated at 10ms intervals until the four airbags P1, P2, P3, and P6 are exhausted.

[0107] Delay 10ms and deflate the remaining P4 and P5 airbags.

[0108] Preferably, the front exhaust mode in quadrant I is as follows:

[0109] If min(PP1,PP2)>max(PP4,PP5), perform quadrant I forward and head down control mode;

[0110] If min(PP4,PP5)>max(PP1,PP2), perform quadrant I forward and head-up control mode;

[0111] If the posture is not determined within the preset time, the exhaust is carried out in a time-sharing manner, specifically: the airbags P3, P4, P5, and P6 are exhausted first, and the airbags P1 and P2 are exhausted after a delay of 30 to 40ms.

[0112] Preferably, the I quadrant is facing forward and the head is lowered control mode, specifically:

[0113] Sort the pressure values ​​of P4, P5, P6, and P3, and select the airbag corresponding to the minimum value to exhaust first;

[0114] Delay 10ms, refresh the pressure values ​​of P4, P5, P6, and P3 after sampling and filtering, assign 0XFFF to the pressure values ​​corresponding to the exhausted airbags, and then sort them;

[0115] When the same pressure value appears, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the one with the lowest priority is used for exhaust;

[0116] When all values ​​are in the 0XFFF limit state, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the un-deflated airbags with the highest priority are deflated first;

[0117] This process is repeated at 10ms intervals until the P4, P5, P6, and P3 airbags are completely deflated.

[0118] Delay 10ms and deflate the remaining P1 and P2 airbags.

[0119] Preferably, the I quadrant faces forward and the head-up control mode is specifically:

[0120] Sort the pressure values ​​of P4, P5, P6, and P3, and select the airbag corresponding to the maximum value to deflate first;

[0121] Delay 10ms, refresh the pressure values ​​of P4, P5, P6, and P3 after sampling and filtering, assign 0X0 to the pressure values ​​corresponding to the exhausted airbags, and then sort them;

[0122] When the same pressure value appears, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the one with the highest priority is used for exhaust;

[0123] When all values ​​are in the 0X0 limit state, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the un-deflated airbags with the highest priority are deflated first;

[0124] This process is repeated at 10ms intervals until the P4, P5, P6, and P3 airbags are completely deflated.

[0125] Delay 10ms and deflate the remaining P1 and P2 airbags.

[0126] Example

[0127] According to the natural environmental conditions of the landing area and the motion characteristics of the capsule-parachute system, the exhaust sequence selection strategy takes the forward direction and pitch angle of the return capsule as the main determining factors. The sampling data of overload X and overload Y directions at the moment of landing are used to determine the direction of the return capsule. The sampling values ​​of the airbag pressure in different directions at the moment of landing are used to determine the pitch attitude of the return capsule. According to different exhaust strategies, the exhaust timing and sequence of different airbags are accurately controlled to improve the landing stability and anti-rollover capability of the return capsule, avoid the return capsule tipping over and causing structural damage when the horizontal speed is high, the swing angle of the return capsule is too large, or the ground slope is large, thereby ensuring the reusability of the return capsule.

[0128] like Figure 4 As shown, the control system includes: static pressure altitude sensors a~c, overload sensors a~c, pressure sensors a~f, AD modules 1~9, FPGA chips 1~3, 2 sets of three-out-of-two circuit modules (used for altitude synchronization and command synchronization respectively), and the software modules included in the FPGA are: AD sampling filter detection modules 1~3, synchronization module, airbag inflation control module, and airbag exhaust control module. Three overload sensors are installed on the bottom of the return capsule, and the X, Y, and Z axes are parallel to the X, Y, and Z axes of the return capsule respectively. The X axis of overload sensor a points to the return capsule III quadrant, the X axis of overload sensor b points to the return capsule III quadrant, and the Y axis of overload sensor c points to the return capsule I quadrant.

[0129] The specific connection relationship is: the height analog signal of static pressure height sensor a, the overload analog signal of overload sensor a in the three directions of X, Y, and Z, and the pressure analog signal of pressure sensors a and b are output to FPGA1 through the AD1 chip, output to FPGA2 through the AD4 chip, and output to FPGA3 through the AD7 chip.

[0130] The height analog signal of static pressure height sensor b, the overload analog signal of overload sensor b in the three directions of X, Y, and Z, and the pressure analog signal of pressure sensors c and d are output to FPGA1 through the AD2 chip, output to FPGA2 through the AD5 chip, and output to FPGA3 through the AD8 chip.

[0131] The height analog signal of static pressure height sensor c, the overload analog signal of overload sensor c in the three directions of X, Y, and Z, and the pressure analog signal of pressure sensors e and f are output to FPGA1 through the AD3 chip, output to FPGA2 through the AD6 chip, and output to FPGA3 through the AD9 chip.

[0132] The AD sampling, filtering and detection modules 1 to 3 of FPGA1 to 3 drive the AD conversion chip and output the information after digital signal sampling and filtering to the airbag inflation control module. After the airbag inflation control module detects the inflation height point, it enables the synchronization module to output the synchronization signal to the synchronization three-to-two circuit, and outputs the airbag inflation command to the command three-to-two circuit based on the signal after the synchronization is returned.

[0133] The AD sampling and filtering detection modules 1 to 3 of FPGA1 to 3 drive the AD conversion chip and output the information after digital signal sampling and filtering to the airbag exhaust control module. The airbag exhaust control module outputs the airbag exhaust command to the three-to-two command circuit according to the exhaust strategy.

[0134] like Figure 6 As shown, this embodiment provides a method for controlling the inflation and time-sharing exhaust of a spacecraft cushion airbag, comprising the following steps:

[0135] Step 1: During the return process of the return capsule, the three FPGAs drive the corresponding AD chips in real time to read the three-way static pressure altitude information. Since the redundant power supply of the control system is independent, the AD module reference voltages corresponding to the three FPGAs are different. The airbag inflation altitude control point is H(m). The theoretical voltage of the altitude point H(m) is calculated according to the AD reference voltage. By inputting the theoretical voltage, the AD voltage output values ​​corresponding to the three FPGAs are tested: the voltages of AD1 to AD3 are Ref1, the voltages of AD4 to AD6 are Ref2, and the voltages of AD7 to AD9 are Ref3. The maximum voltage difference is ΔRef = {|Ref1-Ref2|, |Ref1-Ref3|, |Ref2-Ref3|} max, the speed of the return capsule at the H(m) control point is V(m / s), and the voltage change rate at this point is M(V / s) based on the theoretical reference voltage. The standard atmospheric calculation formula can be used, or the national military standard "Altitude Pressure Conversion Table GJB365.2-87" can be used to calculate the atmospheric pressure P1 at HV / 2, and the atmospheric pressure P2 at H+V / 2. According to the voltage and pressure relationship formula of the static pressure altitude sensor, the V1 corresponding to P1 is calculated, and the V2 corresponding to P2 is calculated. M=V2-V1, and the timing difference of the altitude points sampled by the three FPGAs is ΔRef / M. A synchronization mechanism is designed so that the effective width of the airbag inflation command output by the FPGA after taking two out of three can meet the ignition requirement. In the program parameter list, set the waiting synchronization signal time parameter T_wait = ΔRef / M, and the continuous sending synchronization signal time parameter T_sync = ΔRef / M. When the program samples and filters the three-way height analog signal and reaches the judgment point H, it sends the "inter-board synchronization output signal BOARD_SYNC_OUT". The synchronization output signals of the three FPGAs are processed externally by hardware three-out-of-two logic to form the "inter-board synchronization return signal BOARD_SYNC_IN" which is input to each FPGA. After a single FPGA reads the inter-board synchronization three-out-of-two return signal, it believes that at least two control boards have reached the airbag inflation judgment height. At this time, it sends an airbag inflation command. The command width T_comd is determined according to the ignition performance index of the pyrotechnic product. At the same time, the synchronization signal time parameter T_sync is continuously sent so that the slow board can read the synchronization signal. Figure 1 to Figure 3 shown.

[0136] The following are two situations: normal and abnormal:

[0137] (a) Within a time period less than or equal to T_wait, when BOARD_SYNC_IN is read as low level valid three times with an interval of 1ms, it is considered that the height signal boards are synchronized. At the same time, the timing T_sync continuously sets the BOARD_SYNC_OUT signal to "1". See the timing diagram for details. Figure 1 and Figure 2 ;

[0138] (b) On the contrary, if the T_wait time is exceeded and the BOARD_SYNC_IN low level is not read three times in a row, the program also considers that the height signal boards are synchronized, and the timing T_sync continuously sets the BOARD_SYNC_OUT signal to "1". This means that the time that the control board is out of sync with the other two control boards exceeds T_wait, or the synchronization signal line is abnormal. According to the trajectory height change rate, the probability of the former is extremely small. If it occurs, the control board may be the fastest or slowest control board. See the timing diagram for details. Figure 3 When this fault occurs, the other two FPGAs can still issue airbag inflation commands normally.

[0139] Step 2: After sending the airbag inflation command, the program uses the overload information to determine whether to land.

[0140] The use of overload information to judge "landing" has been discussed in the paper "FPGA Design of Landing Cushion Control System Based on Active Exhaust Airbags" by the patent applicant. It is not within the scope of the claims of this patent and is only briefly described here. The overload information in the three directions of XYZ is used to judge according to the pre-set threshold. When the threshold is reached, it is considered that the return capsule has landed and the process goes to step three.

[0141] Step 3: Use the X-direction overload filter value AD1_G_FIT_X of sensor a, the X-direction overload filter value AD2_G_FIT_X of sensor b, and the Y-direction overload filter value AD3_G_FIT_Y of sensor c to determine whether the return capsule is in quadrant III or quadrant I. This judgment process is protected by the time Tp (30ms from the start of enabling the exhaust module after the landing). During the Tp time, the overload filter value is refreshed every 600us for continuous judgment:

[0142] a) When the X-direction overload filter value AD1_G_FIT_X of sensor a is less than 1g, the X-direction overload filter value AD2_G_FIT_X of sensor b is less than 1g, and the Y-direction overload filter value AD3_G_FIT_Y of sensor c is greater than 1g, and two of the three conditions are met, it is judged that quadrant III is facing forward, and step 4 is entered;

[0143] b) When the X-direction overload filter value AD1_G_FIT_X of sensor a>1g, the X-direction overload filter value AD2_G_FIT_X of sensor b>1g, and the Y-direction overload filter value AD3_G_FIT_Y of sensor c<1g, if two of the three conditions are met, it is judged that quadrant I is facing forward and backward, and step five is entered;

[0144] c) If it is not determined whether quadrant III or quadrant I is facing forward during the timeout, the six airbags are deflated simultaneously, and the airbag deflation command is controlled to be output to the three-to-two command circuit, and the deflation procedure ends.

[0145] Step 4:

[0146] In the forward-facing mode of quadrant III, the size relationship between the pressure values ​​of P4 airbag AD2_P_FIT_B and P5 airbag AD3_P_FIT_A corresponding to quadrant III and the pressure values ​​of P1 airbag AD1_P_FIT_A and P2 airbag AD1_P_FIT_B corresponding to quadrant I is used to determine whether the return capsule is in the head-up or head-down state. This judgment is protected by a time of 10ms (starting from the time when the exhaust module is enabled after the landing is determined). During the protection time, the overload filter value is refreshed every 600us to continuously judge:

[0147] a) When the filtered airbag pressure values ​​of P1 and P2 are greater than P4 and P5, it is determined that the quadrant III is facing forward and the head-up mode is in progress, and step 6 is entered;

[0148] b) When the filtered airbag P4 and P5 pressure values ​​are greater than P1 and P2, it is determined to be quadrant III facing forward and head down mode, and the process goes to step seven;

[0149] c) If the posture is not determined after the timeout, the exhaust is performed directly in time: the airbags P1, P2, P3, and P6 are exhausted first, and the airbags P4 and P5 are exhausted after a delay of 30ms. The airbag exhaust command is controlled to be output to the three-to-two circuit, and the exhaust program ends.

[0150] Step 5:

[0151] In the forward-facing mode of quadrant I, the size relationship between the P4 airbag pressure value AD2_P_FIT_B and the P5 airbag pressure value AD3_P_FIT_A corresponding to quadrant III and the P1 airbag pressure value AD1_P_FIT_A and the P2 airbag pressure value AD1_P_FIT_B corresponding to quadrant I is used to determine whether the return capsule is in the head-up or head-down state. This judgment is protected by a time of 10ms (starting from the time when the exhaust module is enabled after the landing is determined). During the protection time, the overload filter value is refreshed every 600us to continue the judgment:

[0152] a) When the filtered airbag pressure values ​​of P1 and P2 are greater than P4 and P5, it is determined that the quadrant I is facing forward and the head is lowered, and the process goes to step eight;

[0153] b) When the filtered airbag P4 and P5 pressure values ​​are greater than P1 and P2, it is determined that quadrant I is facing forward and the head-up mode is in progress, and the process goes to step nine;

[0154] c) If the posture is not determined after the timeout, the exhaust is carried out directly in a time-sharing manner: airbags P3, P4, P5, and P6 are exhausted first, and airbags P1 and P2 are exhausted after a delay of 30ms. The airbag exhaust command is controlled to be output to the three-to-two circuit, and the exhaust program ends.

[0155] Step 6:

[0156] Determine that quadrant III is facing forward and in head-up mode, sort the pressure values ​​of airbags P1, P2, P3, and P6, select the airbag corresponding to the maximum value to exhaust first, then delay 10ms, refresh the pressure values ​​of P1, P2, P3, and P6 after sampling and filtering, assign 0X0 to the pressure values ​​corresponding to the exhausted airbags and sort them. When the same pressure value appears, take the larger value according to the priority of P1>P2>P3>P6. When all values ​​are in the extreme state of 0X0 (fault), exhaust the unexhausted airbags according to the priority of P1>P2>P3>P6. Repeat this process at intervals of 10ms until all four airbags are exhausted. Finally, exhaust the remaining airbags 4 and 5 after an interval of 10ms, and control the airbag exhaust command output to the command three-to-two circuit, and the exhaust program ends.

[0157] Step 7:

[0158] Determine that quadrant III is facing forward and in head-down mode, sort the pressure values ​​of P1, P2, P3, and P6, select the airbag corresponding to the minimum value to exhaust first, then delay 10ms, refresh the pressure values ​​of P1, P2, P3, and P6 after sampling and filtering, assign 0XFFF to the pressure values ​​corresponding to the exhausted airbags and sort them. When the same pressure value appears, take the smaller value according to the priority of P1>P2>P3>P6. When all values ​​are in the 0XFFF limit state (fault), exhaust the unexhausted airbags according to the priority of P1>P2>P3>P6. Repeat this process at 10ms intervals until all four airbags are exhausted. Finally, exhaust the remaining airbags 4 and 5 after an interval of 10ms, and control the airbag exhaust command output to the command three-to-two circuit, and the exhaust program ends.

[0159] Step 8:

[0160] Determine that quadrant I is facing forward and in head-down mode, sort the pressure values ​​of P4, P5, P6, and P3, select the airbag corresponding to the minimum value to exhaust first, then delay 10ms, refresh the pressure values ​​of P4, P5, P6, and P3 after sampling and filtering, assign 0XFFF to the pressure values ​​corresponding to the exhausted airbags and sort them. When the same pressure value appears, take the smaller value according to the priority of P4>P5>P6>P3. When all values ​​are in the 0XFFF limit state (fault), exhaust the unexhausted airbags according to the priority of P4>P5>P6>P3. Repeat this process at 10ms intervals until all four airbags are exhausted. Finally, exhaust the remaining airbags 1 and 2 after an interval of 10ms, and control the airbag exhaust command output to the command three-to-two circuit, and the exhaust program ends.

[0161] Step 9:

[0162] Determine that quadrant I is facing forward and in head-up mode, sort the pressure values ​​of P4, P5, P6, and P3, select the airbag corresponding to the maximum value to exhaust first, then delay 10ms, refresh the pressure values ​​of P4, P5, P6, and P3 after sampling and filtering, assign 0X0 to the pressure values ​​corresponding to the exhausted airbags and sort them. When the same pressure value appears, take the larger value according to the priority of P4>P5>P6>P3. When all values ​​are in the extreme state of 0X0 (fault), exhaust the unexhausted airbags according to the priority of P4>P5>P6>P3. Repeat this process at intervals of 10ms until all four airbags are exhausted. Finally, exhaust the remaining airbags 1 and 2 after an interval of 10ms, and control the airbag exhaust command output to the command three-to-two circuit, and the exhaust program ends.

[0163] Specific implementation method of airbag inflation control: AD chip uses B128S102RH, reference voltage is 5V, digital length is 12 bits, reads three-way static pressure height information, and the corresponding relationship between the voltage and static pressure of the selected static pressure height sensor is referred to the following formula:

[0164]

[0165] The airbag inflation altitude control point is H = 2800m. According to the "Altitude Pressure Conversion Table GJB365.2-87", the corresponding pressure is 71.91kPa, and the theoretical voltage is 2.996v. The maximum voltage difference of the AD circuits corresponding to the three FPGAs at the altitude point H(m) is 0.007v. The speed of the return capsule at the H(m) control point is 10(m / s). With 2800 as the center, the pressure change from 2795m to 2805m is 0.1kPa, and the corresponding voltage change is M(V / s) = 0.004v / s). In the program parameter list, set T_wait = 1.75s, T_sync = 1.75s, T_comd=0.8s When the program samples and filters the three-way height analog signal and reaches the judgment point H, it sends the "inter-board synchronous output signal BOARD_SYNC_OUT". The synchronous output signals of the three FPGAs are processed by hardware three-out-of-two logic externally to form the "inter-board synchronous return signal BOARD_SYNC_IN" which is input to each FPGA. After a single FPGA reads the inter-board synchronous three-out-of-two return signal, it considers that at least two control boards have reached the airbag inflation judgment height, and sends the airbag inflation command, continuously sending the synchronization signal with a width of T_sync, ensuring that the airbag inflation command meets the external three-out-of-two command width requirement. Figure 7 A schematic diagram of the synchronization signal and the airbag inflation command signal of the C board reference voltage>A board reference voltage>B board reference voltage is given, such as Figure 7 shown.

[0166] Here is an implementation example in Quadrant III leading and head-down mode:

[0167] X-direction overload of overload sensor a: 12'd2063;

[0168] Y-direction overload of overload sensor a: 12'd1646;

[0169] Z-direction overload of overload sensor a: 12'd2711;

[0170] X-axis overload of overload sensor b: 12'd2449

[0171] Overload sensor b's Y-axis overload: 12'd1646

[0172] Z-direction overload of overload sensor B: 12'd2711

[0173] X-direction overload of overload sensor c: 12'd2449

[0174] Overload sensor c's Y-axis overload: 12'd1646

[0175] Z-direction overload of overload sensor C: 12'd2711

[0176] Pressure sensor a: 12'd1234

[0177] Pressure sensor b: 12'd1235

[0178] Pressure sensor c:12'd1236

[0179] Pressure sensor D: 12'd1237

[0180] Pressure sensor E: 12'd1238

[0181] Pressure sensor f:12'd1239

[0182] Airbag deflation sequence results:

[0183] P1

[0184] Delay 10ms P2

[0185] Delay 10ms P3

[0186] Delay 10ms P6

[0187] Delay 10ms P4 P5

[0188] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

[0189] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. A method for controlling the inflation and time-sharing exhaust of a spacecraft buffer airbag, characterized in that, it includes the following steps: Set the waiting synchronization signal time parameter; When the spacecraft buffer airbag reaches the airbag inflation discrimination altitude, send an airbag inflation command according to the waiting synchronization signal time parameter; When the overload information reaches a preset threshold, judge that the return capsule has landed; Judge the attitude of the return capsule. If it is facing forward in the third quadrant, enter the exhaust mode facing forward in the third quadrant; If it is facing forward in the first quadrant, enter the exhaust mode facing forward in the first quadrant; If the attitude cannot be judged after exceeding the predetermined time, control all airbags to exhaust simultaneously, and the exhaust ends.

2. The method for controlling the inflation and time-sharing exhaust of a spacecraft buffer airbag according to claim 1, characterized in that: The waiting synchronization signal time parameter is specifically: T_wait = ΔRef / M ΔRef = Max{|Ref1 - Ref2|, |Ref1 - Ref3|, |Ref2 - Ref3|} M = V2 - V1 Where, T_wait is the longest waiting time for inter-board synchronization; ΔRef is the maximum value of the inter-board voltage difference; M is the change rate of the voltage at the synchronization control point height is M; Ref1, Ref2, and Ref3 are the reference voltages of the three board AD chips respectively; V2 is the voltage value corresponding to the atmospheric pressure at a height 0.5s backward from the control point, and V1 is the voltage value corresponding to the atmospheric pressure at a height 0.5s forward from the control point.

3. The method for controlling the inflation and time-sharing exhaust of a spacecraft buffer airbag according to claim 1, characterized in that: The method for judging the attitude of the return capsule is specifically: When AD1_G_FIT_X < YZ and AD2_G_FIT_X < YZ and AD3_G_FIT_Y > YZ, it is judged as facing forward in the third quadrant; When AD1_G_FIT_X > YZ and AD2_G_FIT_X > YZ and AD3_G_FIT_Y < YZ, it is judged as facing forward in the first quadrant; Where, AD1_G_FIT_X is the value after AD sampling and filtering of the X-direction overload at the position of overload sensor a; AD2_G_FIT_X is the value after AD sampling and filtering of the X-direction overload at the position of overload sensor b; AD3_G_FIT_Y is the value after AD sampling and filtering of the Y-direction overload at the position of overload sensor c; YZ is the minimum overload threshold for judging the movement direction.

4. The method for controlling the inflation and time-sharing exhaust of a spacecraft buffer airbag according to claim 1, characterized in that: The exhaust mode facing forward in the third quadrant is specifically: If min(PP1, PP2) > max(PP4, PP5), perform the control mode of facing forward in the third quadrant and raising the head; If min(PP4, PP5) > max(PP1, PP2), perform the control mode of facing forward in the third quadrant and lowering the head; If the attitude cannot be judged after exceeding the predetermined time, perform time-sharing exhaust, specifically: exhaust airbags P1, P2, P3, and P6 first, and then exhaust airbags P4 and P5 after a delay of 30 - 40 ms.

5. The method for controlling the inflation and time-sharing exhaust of a spacecraft buffer airbag according to claim 4, characterized in that: The quadrant III forward and head-up control mode is specifically: Sort the pressure values ​​of airbags P1, P2, P3, and P6, and select the airbag corresponding to the maximum value to exhaust first; Delay 10 to 15 ms, refresh the pressure values ​​of airbags P1, P2, P3, and P6 after sampling and filtering, assign 0X 0 to the pressure values ​​corresponding to the exhausted airbags, and then sort them; When the same pressure value appears, the airbags are sorted in order of priority from high to low in order of P1, P2, P3, and P6, and the airbag with the highest priority is deflated first; When all values ​​are 0, the airbags are sorted in order of priority from high to low in order of P1, P2, P3, and P6, and the airbags with high priority are deflated first; Repeat this process at intervals of 10 to 15 ms until the P1, P2, P3, and P6 airbags are all deflated. After a delay of 10 to 15 ms, the remaining P4 and P5 airbags are deflated.

6. A method for controlling the inflation and time-sharing exhaust of a spacecraft cushion airbag according to claim 4, Features: Quadrant III forward and head down control mode, specifically: Sort the pressure values ​​of P1, P2, P3, and P6, and select the airbag corresponding to the minimum value to exhaust first; Delay 10ms, refresh the P1, P2, P3, P6 pressure values ​​after sampling and filtering, assign 0XFFF to the pressure values ​​corresponding to the exhausted airbags and sort them; When the same pressure value appears, the airbags P1, P2, P3, and P6 are sorted from high to low in priority, and the one with the lowest priority is used for exhaust; When all values ​​are in the extreme state of 0XFFF, the airbags are sorted in order of priority from large to small in order of P1, P2, P3, and P6, and the un-deflated airbags with large priority are deflated first; This process is repeated at 10ms intervals until the four airbags P1, P2, P3, and P6 are exhausted. Delay 10ms and deflate the remaining P4 and P5 airbags.

7. A method for controlling the inflation and time-sharing exhaust of a spacecraft cushion airbag according to claim 1, Features: The quadrant I forward exhaust mode is specifically as follows: If min(PP1,PP2)>max(PP4,PP5), perform quadrant I forward and head down control mode; If min(PP4,PP5)>max(PP1,PP2), perform quadrant I forward and head-up control mode; If the posture is not determined within the preset time, the exhaust is carried out in a time-sharing manner, specifically: the airbags P3, P4, P5, and P6 are exhausted first, and the airbags P1 and P2 are exhausted after a delay of 30 to 40ms.

8. A method for controlling the inflation and time-sharing exhaust of a spacecraft cushion airbag according to claim 7, Features: The quadrant I forward-facing and head-down control mode is specifically: Sort the pressure values ​​of P4, P5, P6, and P3, and select the airbag corresponding to the minimum value to exhaust first; Delay 10ms, refresh the pressure values ​​of P4, P5, P6, and P3 after sampling and filtering, assign 0XFFF to the pressure values ​​corresponding to the exhausted airbags, and then sort them; When the same pressure value appears, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the one with the lowest priority is used for exhaust; When all values ​​are in the 0XFFF limit state, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the un-deflated airbags with the highest priority are deflated first; This process is repeated at 10ms intervals until the P4, P5, P6, and P3 airbags are completely deflated. Delay 10ms and deflate the remaining P1 and P2 airbags.

9. A method for controlling the inflation and time-sharing exhaust of a spacecraft cushion airbag according to claim 8, Features: The quadrant I forward-facing and head-up control mode is specifically: Sort the pressure values ​​of P4, P5, P6, and P3, and select the airbag corresponding to the maximum value to deflate first; Delay 10ms, refresh the pressure values ​​of P4, P5, P6, and P3 after sampling and filtering, assign 0X0 to the pressure values ​​corresponding to the exhausted airbags, and then sort them; When the same pressure value appears, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the one with the highest priority is used for exhaust; When all values ​​are in the 0X0 limit state, the airbags P4, P5, P6, and P3 are sorted in descending order of priority, and the un-deflated airbags with the highest priority are deflated first; This process is repeated at 10ms intervals until the P4, P5, P6, and P3 airbags are completely deflated. Delay 10ms and deflate the remaining P1 and P2 airbags.

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