Protection method for abnormal pitch pointing of airborne SAR large-load eccentric one-axis platform

Abstract

The present invention discloses a pitch pointing abnormal protection method for an airborne SAR large-load eccentric one-axis platform, which belongs to the field of airborne radar technology. The method comprises: S10, calculating the angular velocity of the one-axis platform at the current moment; S20, updating the count values ​​of counter A and counter B based on the angular velocity of the one-axis platform; S30, judging whether the count value of the counter A or the counter B is greater than the corresponding threshold value, if so, executing step S40, otherwise executing step S50; S40, starting the pitch pointing abnormal protection action; S50, updating the pitch pointing angle of the one-axis platform at each moment through an iterative assignment method, and then executing step S10. The present invention can ensure that when an abnormal phenomenon occurs in the sine-cosine rotary transformer link, before the system is powered off, the antenna can be smoothly returned to near the zero position at a low speed and the motor is prohibited from being enabled.

Description

Technical Field

[0001] The invention relates to the technical field of airborne radars, and in particular to a method for protecting an airborne SAR large-load eccentric single-axis platform from pitching and pointing anomalies. Background Art

[0002] Synthetic Aperture Radar (SAR) is an active earth observation system that can be installed on aircraft, satellites, spacecraft and other flying platforms to conduct earth observations around the clock and in all weather conditions. It has a certain ability to penetrate the ground.

[0003] Airborne SAR is a high-resolution two-dimensional imaging radar. Its clear imaging requires the antenna to maintain stability in the inertial space under the swaying of the carrier aircraft, airflow disturbances, etc., and always remain stable in a fixed inertial space direction. When the carrier aircraft changes its attitude, a stable platform can be used to support the antenna. The stable platform can be used to drive the antenna to rotate, and the reverse motion can be used to compensate for the changes in the carrier aircraft, so that the azimuth and pitch pointing of the antenna beam are stable.

[0004] According to the number of rotating axes, the stable platform can be divided into four-axis, three-axis, two-axis, and one-axis platforms. Among them, the one-axis platform omits the azimuth axis of the two-axis platform and only uses the pitch axis to adjust the pitch pointing angle of the antenna through mechanical rotation, thereby changing the pitch pointing angle of the beam. The large-load eccentric one-axis platform for airborne SAR has three structural characteristics:

[0005] (1) The antenna has a large envelope, is heavy, and has a certain eccentricity.

[0006] (2) The airborne environment requires the shaft support structure to be small in size and light in weight.

[0007] (3) Set the left and right mechanical limits at -95° and +95° respectively.

[0008] The left mechanical limit refers to the mechanical limit in the left direction of the aircraft nose viewing angle; the right mechanical limit refers to the mechanical limit in the right direction of the aircraft nose viewing angle.

[0009] The pitch pointing angle of the antenna carried by the large-load eccentric one-axis stabilized platform of the airborne SAR (hereinafter referred to as the one-axis platform pitch pointing) is collected, solved, and fed back in real time through the sine-cosine rotary transformer link. Furthermore, the rotational angular velocity of the antenna carried by the one-axis stabilized platform (hereinafter referred to as the one-axis platform angular velocity) can be directly read by the velocity sensor, or obtained by real-time differential calculation of the feedback angle of the sine-cosine rotary transformer link. The motion compensation strategy of the one-axis stabilized platform can be summarized as follows: the closed-loop control system calculates the error between the command angle sent by the ground monitoring station and the current one-axis platform pitch pointing, and after the PI controller and driver, adjusts the running state of the motor in real time, cooperates with the shaft and gear transmission mechanism, and drives the antenna to rotate to the specified position.

[0010] According to the signal channel division, the sine-cosine resolver link includes an excitation link, a sine link, and a cosine link. Any abnormality in any link will lead to abnormal angle acquisition, solution, or feedback. At this time, the closed-loop control system will receive the abnormal one-axis platform pitch pointing, obtain the wrong angle error value, and finally drive the antenna to rotate in the wrong direction. The main manifestations are as follows:

[0011] (1) If the excitation link is abnormal, the pitch pointing of the one-axis platform will show a positive and negative jump trend, and the jump range is [-95°, 95°]. At this time, the one-axis stable platform will not be able to achieve motion compensation control, and the antenna will repeatedly impact the mechanical limit. Due to the large antenna envelope size, heavy weight, and a certain eccentric moment; coupled with the small size and light weight of the platform shaft support structure, this impact phenomenon will reduce the life of the support structure, and in severe cases will cause the motor shaft to break.

[0012] (2) If the sine / cosine link is abnormal, the pitch pointing direction of the one-axis platform will be fixed at a singular value in the range of [-95°, 95°]. At this time, the one-axis stabilized platform will not be able to achieve motion compensation control, and the antenna will remain at the mechanical limit.

[0013] (3) If the excitation link, sine link, and cosine link are all abnormal, the abnormal phenomenon is the same as "excitation link abnormality".

[0014] When a single-axis stabilized platform cannot achieve motion compensation control, the ground monitoring station will generally power off and restart the entire radar system. However, in a large load eccentricity environment, after the system is powered off, the antenna will return to zero position at a high speed. At this time, the power MOS tube in the driver will be impacted by the reverse voltage, and the reliability will decrease. In severe cases, the MOS tube will burn out, causing the driver to fail. Furthermore, the overload environment of the aircraft will amplify the impact of the eccentric moment, and the unstable rotation characteristics of the antenna will generate a large number of interference signals, making the main control chip of the PI controller unable to work normally, and ultimately causing the platform closed-loop control system to fail.

[0015] To solve the above problems, there are currently related solutions, such as the Chinese patent application with publication number CN109491404A, which discloses a method for limiting protection of a servo-stabilized platform, including judging whether the current frame angle of the seeker exceeds a preset electrical limit angle value; judging whether the polarity of the master command signal and the current frame angle position meet the master command signal reset condition; judging whether the current frame angle of the seeker exceeds a preset mechanical limit angle value; judging whether the polarity of the master command signal and the current frame angle position meet the reset condition of the power amplifier enable signal; and the controller shuts down the power amplifier of the servo-stabilized platform. However, the method of directly shutting down the power amplifier after the controller determines that the angle value is abnormal is not suitable for airborne SAR large-load eccentric single-axis platform.

[0016] The Chinese invention patent application with publication number CN111338320A discloses a protection method for a control system failure caused by an abnormal angular velocity sensor signal of a stable platform. The method uses the existing position sensor of the system to generate a redundant angular velocity signal through a certain algorithm. When the real angular velocity sensor signal is detected to have a fault, it switches to the redundant signal to ensure the normal operation of the stable platform. However, this method solves the problem of the stable platform losing control due to a speed sensor failure; but it cannot handle the abnormality of the angle sensor, especially the abnormality of the sine-cosine rotary transformer.

[0017] The Chinese invention patent application with the publication number CN113359876A discloses a control method and device for a large-load eccentric one-axis platform of an airborne SAR radar, which adopts a position-speed dual closed-loop PI control method and a speed single PI control method to compensate for angle errors and speed errors, so that the actual angle sensor feedback value and the angle command value are closer during the operation of the platform, and the speed error is compensated during the adjustment process, so that the platform can perform angle compensation more smoothly. The whole process ensures the stability of the large-load eccentric one-axis platform, so that the stability of the operation process of the airborne SAR radar equipped with the large-load eccentric one-axis platform is guaranteed. However, the method does not describe the protection method for the fault of the sine-cosine rotary transformer link; furthermore, the method lacks the calibration system and measures of the eccentric torque. If combined with the conventional protection method, it still cannot solve the problem that under the fault environment of the sine-cosine rotary transformer, the abnormal pitch pointing of the one-axis platform causes the antenna to move in the wrong direction, resulting in the inability of the one-axis stable platform to achieve motion compensation control.

[0018] In summary, there is an urgent need to design an abnormal protection scheme for the pitch pointing of an airborne SAR large-load eccentric single-axis platform, so as to ensure that when an abnormal phenomenon occurs in the sine-cosine rotary transformer link, the antenna can return to near the zero position at a low speed and smoothly before the system is powered off, and the motor is prohibited from being enabled, thereby protecting the performance of the motor, supporting structure, driver, and main control chip from damage. Summary of the invention

[0019] The technical problem to be solved by the present invention is how to protect a single-axis platform from abnormal pitch pointing when an abnormal phenomenon occurs in a sine-cosine rotary transformer link.

[0020] The present invention solves the above technical problems through the following technical means:

[0021] On the one hand, the present invention proposes a method for protecting an abnormal pitch pointing of an airborne SAR large-load eccentric one-axis platform, the method comprising the following steps:

[0022] S10, calculating the angular velocity of the one-axis platform at the current moment;

[0023] S20, updating the count values ​​of counter A and counter B based on the angular velocity of the one-axis platform;

[0024] S30, determining whether the count value of the counter A or the counter B is greater than the corresponding threshold value, if so, executing step S40, otherwise executing step S50;

[0025] S40, start the pitch pointing abnormal protection action;

[0026] S50, updating the pitch pointing angle of the one-axis platform at each moment through an iterative assignment method, and then executing step S10.

[0027] The method of the present invention can ensure that when an abnormal phenomenon occurs in the sine-cosine rotary transformer link, before the system is powered off, the antenna can return to near the zero position at a low speed and smoothly and prohibit the motor from being enabled, thereby protecting the performance of the motor, supporting structure, driver, and main control chip from being damaged.

[0028] Furthermore, in the step S10, the angular velocity of the one-axis platform at the current moment is calculated, including:

[0029] Every C seconds, calculate the absolute value V of the angular velocity of the one-axis platform at the current time t t , the calculation formula is as follows:

[0030] V t =|(3·W t -2·W t-1 -W t-2 ) / 4C|

[0031] Where: W t、 W t-1、 W t-2 They are the pitch pointing angles of the one-axis platform at time t, time t-1, and time t-2 respectively.

[0032] Further, in the step S20, based on the angular velocity of the one-axis platform, updating the count value of the counter A or the counter B includes:

[0033] If V t ≥D·V max , then the value of the counter A is increased by 1, otherwise, the value of the counter A is set to 0, where V t is the absolute value of the angular velocity of the one-axis platform, D is the aircraft overload factor, V max The absolute value of the maximum angular velocity of the antenna when it rotates from the left mechanical limit to the right mechanical limit in the ground joint test environment;

[0034] If V t =0, the value of the counter B is increased by 1, otherwise, the value of the counter B is set to 0.

[0035] Furthermore, the method further comprises:

[0036] When the value of counter A is set to 0 or the value of counter B is set to 0 or the count value of counter A is greater than 1 and less than or equal to its corresponding threshold value E A Or the count value of counter B is less than or equal to its corresponding threshold value E B The pitch pointing angle of the one-axis platform at each moment is updated through the iterative assignment method.

[0037] Furthermore, when the count value of the counter A is greater than the corresponding threshold value E A When the pitch pointing abnormal protection action is initiated, the action includes:

[0038] Determine the eccentric moment M according to the eccentric moment calculation formula A , the eccentric moment calculation formula is:

[0039] M A =M max ·|sin(W A -J A )|·[1-cos(W A -J A )] / D

[0040] Where: M max is the absolute value of the maximum eccentric moment; W A is the pitch pointing angle of the one-axis platform at time t-4, if W A ≥0, then J A =J R ; If W A <0, then J A =J L ; J R It is the angle feedback value when the antenna rotates freely from the right mechanical limit and stays at the equilibrium position; J Lis the angle feedback value when the antenna rotates freely from the left mechanical limit and stays at the equilibrium position; D is the aircraft overload factor;

[0041] The threshold value G is determined by a threshold value determination formula, and the threshold value determination formula is:

[0042] If M A >(2M max / 3-M F ), then G=G1;

[0043] If (M max / 3-M F )≤M A ≤2M max / 3, then G=G2;

[0044] If 0≤M A <M max / 3, then G=G3;

[0045] Where: M max is the absolute value of the maximum eccentric moment, M F is the torque fine-tuning value, G1, G2, and G3 are output thresholds, G1 is in the interval [-1.6, -2.5], G2 is in the interval (-2.5, -2.9], G3 is in the interval (-2.9, -3.5], M A is the eccentric moment of the current antenna;

[0046] Based on the position open-loop-speed closed-loop control, the threshold G and the speed of the speed sensor are used as input quantities to drive the antenna at a constant speed state V A Rotate to zero position and rotate for a time T A After that, the motor is turned off and the excitation link fault is reported. A =W A / V A .

[0047] Furthermore, when the count value of the counter B is greater than the corresponding threshold value E B When the pitch pointing abnormal protection action is initiated, the action includes:

[0048] Assume the command angle is +95°;

[0049] After waiting for a set time, set the threshold H; based on the position open-loop-speed closed-loop control, take the threshold H and the speed of the speed sensor as input, and drive the antenna at a constant speed state V B Rotate to zero position and rotate for a time T B After that, the motor is turned off and the sine / cosine link fault is reported. B =95 / V B .

[0050] Furthermore, the position open-loop-speed closed-loop control comprises:

[0051] Subtracting the input threshold from the speed feedback of the speed sensor to obtain a speed error, and inputting the speed error into the PI controller, wherein the input threshold is a threshold G or a threshold H;

[0052] The PI controller outputs a modulated pulse width signal and adjusts the running state of the motor in real time after being amplified by the driver, and cooperates with the rotating shaft and the gear transmission mechanism to drive the antenna to rotate towards the zero position at a constant speed.

[0053] Furthermore, the updating of the pitch pointing angle of the one-axis platform at each moment by the iterative assignment method includes:

[0054] Through the formula W t-4 =W t-3 ; W t-3 =W t-2 ; W t-2 =W t-1 ; W t-1 =W t , iteratively update the pitch pointing angle of the one-axis platform at each moment.

[0055] Furthermore, the method further comprises:

[0056] If the value of the counter A is equal to 1, then by formula W A =W t-4 , store W A The value of W A It is the pitch pointing angle of the one-axis platform at time t-4.

[0057] In addition, the present invention also proposes an airborne SAR large-load eccentric single-axis platform pitch pointing abnormal protection system, the system comprising:

[0058] Angle calculation module, used to calculate the angular velocity of one-axis platform at the current moment;

[0059] an abnormality determination module, used for updating the count values ​​of counter A and counter B based on the angular velocity of the one-axis platform, and determining whether the count value of counter A or counter B is greater than a corresponding threshold value;

[0060] An abnormality protection module, used for starting a pitch pointing abnormality protection action when the abnormality determination module outputs a yes result;

[0061] The pitch pointing update module is used to update the pitch pointing angle of the one-axis platform at each moment through an iterative assignment method when the output result of the abnormality determination module is no.

[0062] The advantages of the present invention are:

[0063] (1) The method of the present invention can ensure that when an abnormal phenomenon occurs in the sine-cosine rotary transformer link, before the system is powered off, the antenna can return to near the zero position at a low speed and smoothly and the motor is prohibited from being enabled, thereby protecting the performance of the motor, supporting structure, driver, and main control chip from damage.

[0064] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a flow chart of a pitch pointing abnormal protection method for an airborne SAR large-load eccentric one-axis platform in one embodiment of the present invention;

[0066] Figure 2 This is a flow chart of a method for protecting a one-axis platform from pitch and pointing abnormality in one embodiment of the present invention;

[0067] Figure 3 This is a flow chart of a method for protecting a one-axis platform from pitch and pointing abnormality in one embodiment of the present invention;

[0068] Figure 4 is a structural block diagram of a position open-loop-speed closed-loop system in one embodiment of the present invention;

[0069] Figure 5 It is a structural diagram of a pitch pointing abnormal protection system for an airborne SAR large-load eccentric one-axis platform in another embodiment of the present invention. DETAILED DESCRIPTION

[0070] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0071] like Figure 1 As shown, the first embodiment of the present invention proposes a method for protecting the pitch pointing abnormality of an airborne SAR large-load eccentric one-axis platform, and the method comprises the following steps:

[0072] S10, calculating the angular velocity of the one-axis platform at the current moment.

[0073] S20. Update the count values ​​of counter A and counter B based on the angular velocity of the one-axis platform.

[0074] S30, determining whether the count value of the counter A or the counter B is greater than the corresponding threshold value, if so, executing step S40, otherwise executing step S50.

[0075] S40: Start the pitch pointing abnormal protection action.

[0076] S50, updating the pitch pointing angle of the one-axis platform at each moment through an iterative assignment method, and then executing step S10.

[0077] This embodiment can ensure that when an abnormal phenomenon occurs in the sine-cosine rotary transformer link, the antenna can return to near the zero position at a low speed and smoothly before the system is powered off, and the motor is prohibited from being enabled, thereby protecting the performance of the motor, supporting structure, driver, and main control chip from damage.

[0078] Specifically, after the system is powered on, the angular velocity solution, abnormality determination, pitch pointing update and abnormality protection cycle iterative work. When an abnormality occurs in the sine-cosine resolver link, it is directly manifested as an excessive angular velocity or a continuous angular velocity of 0. At this time, the abnormality determination unit will be based on the value of counter A or counter B. If the value of counter A or counter B exceeds the threshold, it will jump to the abnormal protection step and directly use the speed single closed loop method to make the antenna return to the vicinity of zero at a uniform speed within the specified time. Once the specified time is reached, the motor enable is turned off to protect the antenna.

[0079] In one embodiment, in the step S10, calculating the angular velocity of the one-axis platform at the current moment specifically includes:

[0080] Every C seconds, calculate the absolute value V of the angular velocity of the one-axis platform at the current time t t , the calculation formula is as follows:

[0081] V t =|(3·W t -2·W t-1 -W t-2 ) / 4C|

[0082] Where: W t、 W t-1、 W t-2 They are the pitch pointing angles of the one-axis platform at time t, time t-1, and time t-2 respectively.

[0083] It should be noted that the value of C is any value greater than zero and is not specifically limited in this embodiment.

[0084] According to design experience and actual debugging results, this embodiment selects the first three moments for speed calculation, among which the difference between moment t and moment t-1; the difference between moment t-1 and moment t-2 accounts for a weight of 3:1.

[0085] In one embodiment, in the step S20, updating the count value of the counter A or the counter B based on the angular velocity of the one-axis platform includes the following steps:

[0086] If V t ≥D·V max , then the value of the counter A is increased by 1, otherwise, the value of the counter A is set to 0, where V t is the absolute value of the angular velocity of the one-axis platform, D is the aircraft overload factor, V max The absolute value of the maximum angular velocity of the antenna when it rotates from the left mechanical limit to the right mechanical limit in the ground joint test environment;

[0087] If V t =0, the value of the counter B is increased by 1, otherwise, the value of the counter B is set to 0.

[0088] It should be noted that the initialization values ​​of counter A and counter B are both equal to 0. The purpose of setting counter A in this embodiment is mainly to determine the number of times the angular velocity exceeds the threshold value to prevent the occurrence of false alarms. When the number of times the angular velocity exceeds the threshold value reaches the upper limit, it can be determined that the sine-cosine resolver link has a fault, and the fault cause is "angular velocity exceeds the threshold value", then enter step 5 to start protecting the antenna back to zero position.

[0089] The purpose of setting counter B is mainly to determine the number of times the angular velocity is continuously 0 to prevent false alarms. When the number of times the angular velocity is continuously 0 reaches the upper limit, it can be determined that the sine-cosine resolver link is faulty, and the fault cause is "angular velocity is continuously 0", then go to step 5 to start protecting the antenna back to zero position.

[0090] In one embodiment, the method further comprises the following steps:

[0091] When the value of counter A is set to 0 or the value of counter B is set to 0 or the count value of counter A is greater than 1 and less than or equal to its corresponding threshold value E A Or the count value of counter B is less than or equal to its corresponding threshold value E B At each moment, the pitch pointing angle of the one-axis platform is updated through the iterative assignment method.

[0092] It should be noted that the role of pitch pointing update is to iterate the angle, which is convenient for the subsequent iterative calculation of angular velocity; the calculation formula of angular velocity is V t =|(3·W t -2·W t-1 -W t-2 ) / 4C|, when calculating in software, it is impossible to assign a variable at each moment, such as W t-1 …………W t-n; The angle can be continuously updated in an iterative manner to facilitate calculations within the software.

[0093] In one embodiment, if Figures 2 to 3 As shown, when the count value of the counter A is greater than its corresponding threshold value E A When the pitch pointing abnormal protection action is started in step S40, the step S40 includes the following steps:

[0094] S41', determine the eccentric moment M according to the eccentric moment calculation formula A , the eccentric moment calculation formula is:

[0095] M A =M max ·|sin(W A -J A )|·[1-cos(W A -J A )] / D

[0096] Where: M max is the absolute value of the maximum eccentric moment; W A is the pitch pointing angle of the one-axis platform at time t-4, if W A ≥0, then J A =J R ; If W A <0, then J A =J L ; J R It is the angle feedback value when the antenna rotates freely from the right mechanical limit and stays at the equilibrium position; J L is the angular feedback value when the antenna rotates freely from the left mechanical limit and stays at the equilibrium position; D is the aircraft overload factor; |·| is the operator of the absolute value function; sin(·) is the operator of the sine function; cos(·) is the operator of the cosine function.

[0097] S42', determine the threshold value G by a threshold value determination formula, the threshold value determination formula is:

[0098] If M A >(2M max / 3-M F ), then G=G1;

[0099] If (M max / 3-M F )≤M A ≤2M max / 3, then G=G2;

[0100] If 0≤M A <M max / 3, then G=G3;

[0101] Where: M max is the absolute value of the maximum eccentric moment, M F is the torque fine-tuning value, G1, G2, and G3 are output thresholds, G1 is in the interval [-1.6, -2.5], and only one decimal place is retained; G2 is in the interval (-2.5, -2.9], and only one decimal place is retained; G3 is in the interval (-2.9, -3.5], and only one decimal place is retained.

[0102] Furthermore, M F is the torque fine-tuning value, which is generally recommended to be in the range [0, M max / 6] to obtain the value.

[0103] S43', based on the position open loop-speed closed loop control, the threshold G and the speed of the speed sensor are used as input quantities to drive the antenna at a constant speed state V A Rotate to zero position and rotate for a time T A After seconds, the motor is turned off and the excitation link fault is reported. A =W A / V A .

[0104] Furthermore, the threshold value E A is the threshold value corresponding to counter A, which is a positive integer in the interval [30,40].

[0105] In one embodiment, when the count value of the counter B is greater than the corresponding threshold value E B When the pitch pointing abnormal protection action is started in step S40, the steps include:

[0106] S41”, set the command angle to +95°.

[0107] S42”, after waiting for a set time, set the threshold H.

[0108] It should be noted that the set time length here can be specifically set to 30 seconds, and those skilled in the art can also set it to other values ​​according to actual conditions, which is not specifically limited in this embodiment.

[0109] S43", based on the position open loop-speed closed loop control, the threshold H and the speed of the speed sensor are used as input quantities to drive the antenna at a constant speed state V B Rotate to zero position and rotate for a time T B After seconds, the motor is turned off and a sine / cosine link fault is reported. B =95 / V B .

[0110] Furthermore, V A 、VB They are all single-axis platform angular velocities, which can be detected, recorded and written into the protection program in a ground joint test environment according to different values ​​of G and H.

[0111] Furthermore, E B is the threshold value corresponding to counter B, and its value is a positive integer in the interval [50,60].

[0112] In one embodiment, if Figure 4 As shown, the position open-loop-speed closed-loop control specifically includes:

[0113] Subtracting the input threshold from the speed feedback of the speed sensor to obtain a speed error, and inputting the speed error into the PI controller, wherein the input threshold is a threshold G or a threshold H;

[0114] The PI controller outputs a modulated pulse width signal and adjusts the running state of the motor in real time after being amplified by the driver, and cooperates with the rotating shaft and the gear transmission mechanism to drive the antenna to rotate towards the zero position at a constant speed.

[0115] This embodiment adopts the position open-loop-speed closed-loop control algorithm without obtaining angle feedback data for control calculation. In other words, even if the angle feedback is abnormal, the algorithm is still normal and can drive the output normally.

[0116] Furthermore, under different conditions, the threshold G is equal to G1, G2, and G3, respectively, and only one decimal place is retained; the threshold H is in the interval [-1.6, -1.8], and only one decimal place is retained.

[0117] In one embodiment, in step S50, the pitch pointing angle of the one-axis platform at each moment is updated by an iterative assignment method, specifically including:

[0118] Through the formula W t-4 =W t-3 ; W t-3 =W t-2 ; W t-2 =W t-1 ; W t-1 =W t , iteratively update the pitch pointing angle of the one-axis platform at each moment.

[0119] It should be noted that the role of pitch pointing update is to iterate the angle, which is convenient for the subsequent iterative calculation of angular velocity; the calculation formula of angular velocity is V t =|(3·W t -2·W t-1 -W t-2 ) / 4C|, when calculating in software, it is impossible to assign a variable at each moment, such as W t-1 …………Wt-n ; The angle can be continuously updated in an iterative manner to facilitate calculations within the software.

[0120] In one embodiment, the method further comprises:

[0121] If the value of the counter A is equal to 1, then by formula W A =W t-4 , store W A The value of W A It is the pitch pointing angle of the one-axis platform at time t-4.

[0122] It should be noted that the prerequisite for storing the pitch pointing is that the value of counter A or counter B is 1, at which time the sine-cosine resolver link may have problems; t-4 This is the only correct angle value before the sine-cosine resolver link has problems. This angle value will be used to determine the antenna eccentric torque.

[0123] In addition, the second embodiment of the present invention further proposes a pitch pointing abnormal protection system for an airborne SAR large-load eccentric one-axis platform, the system comprising:

[0124] Angle calculation module 10, used to calculate the angular velocity of the one-axis platform at the current moment;

[0125] The abnormality determination module 20 is used to update the count values ​​of the counter A and the counter B based on the angular velocity of the one-axis platform, and determine whether the count value of the counter A or the counter B is greater than the corresponding threshold value;

[0126] An abnormality protection module 30, used to start a pitch pointing abnormality protection action when the abnormality determination module outputs a yes result;

[0127] The pitch pointing updating module 40 is used to update the pitch pointing angle of the one-axis platform at each moment by an iterative assignment method when the output result of the abnormality determination module is negative.

[0128] After the system is powered on, the angular velocity calculation module, the abnormality determination module, the pitch pointing update module and the abnormality protection module of this embodiment work in a loop. When an abnormality occurs in the sine-cosine rotary transformer link, it is directly manifested as an excessive angular velocity or a continuous angular velocity of 0. At this time, the abnormality determination unit will be based on the value of counter A or counter B. If the value of counter A or counter B exceeds the threshold, it will jump to the abnormality protection step and directly adopt the speed single closed loop method to make the antenna return to the vicinity of zero at a uniform speed within the specified time. Once the specified time is reached, the motor is turned off to protect the antenna.

[0129] In one embodiment, the angle calculation module 10 is specifically used for:

[0130] Every C seconds, calculate the absolute value V of the angular velocity of the one-axis platform at the current time t t , the calculation formula is as follows:

[0131] V t =|(3·W t -2·W t-1 -W t-2 ) / 4C|

[0132] Where: W t、 W t-1、 W t-2 They are the pitch pointing angles of the one-axis platform at time t, time t-1, and time t-2 respectively.

[0133] It should be noted that, according to design experience and actual debugging results, this embodiment selects the first three moments for speed calculation, among which the difference between moment t and moment t-1; the difference between moment t-1 and moment t-2 has a weight ratio of 3:1.

[0134] In one embodiment, the abnormality determination module 20 includes:

[0135] Value update unit for V t ≥D·V max , the value of the counter A is increased by 1, otherwise, the value of the counter A is set to 0, where V t is the absolute value of the angular velocity of the one-axis platform, D is the aircraft overload factor, V max is the absolute value of the maximum angular velocity of the antenna from the left mechanical limit to the right mechanical limit in the ground joint test environment; and is used to t =0, the value of the counter B is increased by 1, otherwise, the value of the counter B is set to 0.

[0136] The abnormality determination unit is used to determine the abnormality when the count value of the counter A is greater than the corresponding threshold value E. A When the count value of the counter B is greater than the corresponding threshold value E B , it is determined that an abnormality has occurred.

[0137] In one embodiment, the abnormality protection module 30 includes:

[0138] The first protection unit is used to perform the following steps:

[0139] S41', determine the eccentric moment M according to the eccentric moment calculation formula A , the eccentric moment calculation formula is:

[0140] M A =M max ·|sin(W A -JA )|·[1-cos(W A -J A )] / D

[0141] Where: M max is the absolute value of the maximum eccentric moment; W A is the pitch pointing angle of the one-axis platform at time t-4, if W A ≥0, then J A =J R ; If W A <0, then J A =J L ; J R It is the angle feedback value when the antenna rotates freely from the right mechanical limit and stays at the equilibrium position; J L is the angular feedback value when the antenna rotates freely from the left mechanical limit and stays at the equilibrium position; D is the aircraft overload factor; |·| is the operator of the absolute value function; sin(·) is the operator of the sine function; cos(·) is the operator of the cosine function.

[0142] S42', determine the threshold value G by a threshold value determination formula, the threshold value determination formula is:

[0143] If M A >(2M max / 3-M F ), then G=G1;

[0144] If (M max / 3-M F )≤M A ≤2M max / 3, then G=G2;

[0145] If 0≤M A <M max / 3, then G=G3;

[0146] Where: M max is the absolute value of the maximum eccentric moment, M F is the torque fine-tuning value, G1, G2, and G3 are output thresholds, G1 is within the interval [-1.6, -2.5], and only one decimal place is retained; G2 is within the interval (-2.5, -2.9], and only one decimal place is retained; G3 is within the interval (-2.9, -3.5], and only one decimal place is retained. A is the eccentric moment of the current antenna.

[0147] Furthermore, M F is the torque fine-tuning value, which is generally recommended to be in the range [0, M max / 6] to obtain the value.

[0148] S43', based on the open-loop-speed closed-loop control, the threshold G and the speed of the speed sensor are used as input quantities to drive the antenna at a constant speed state V A Rotate to zero position and rotate for a time T A After seconds, the motor is turned off and the excitation link fault is reported. A =W A / V A .

[0149] Furthermore, the threshold value E A is the threshold value corresponding to counter A, which is a positive integer in the interval [30,40].

[0150] The second protection unit is used to perform the following steps:

[0151] S41”, set the command angle to +95°.

[0152] S42”, after waiting for a set time, set the threshold H.

[0153] It should be noted that the set time length here can be specifically set to 30 seconds, and those skilled in the art can also set it to other values ​​according to actual conditions, which is not specifically limited in this embodiment.

[0154] S43", based on the position open loop-speed closed loop control, the threshold H and the speed of the speed sensor are used as input quantities to drive the antenna at a constant speed state V B Rotate to zero position and rotate for a time T B After seconds, the motor is turned off and a sine / cosine link fault is reported. B =95 / V B .

[0155] In one embodiment, the pitch pointing update module 40 is specifically configured to:

[0156] Through the formula W t-4 =W t-3 ; W t-3 =W t-2 ; W t-2 =W t-1 ; W t-1 =W t , iteratively update the pitch pointing angle of the one-axis platform at each moment.

[0157] In one embodiment, the system further comprises:

[0158] The pitch pointing storage module 50 is used to, when the value of the counter A is equal to 1, use the formula W A =W t-4 , store W A The value of W AIt is the pitch pointing angle of the one-axis platform at time t-4.

[0159] It should be noted that other embodiments or implementation methods of the airborne SAR large-load eccentric one-axis platform pitch pointing abnormality protection system of the present invention can refer to the above-mentioned method embodiments, which will not be repeated here.

[0160] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be specifically implemented in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in combination with these instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in combination with these instruction execution systems, devices or apparatuses. More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection portion with one or more wirings (electronic device), a portable computer disk box (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing in other suitable ways if necessary, and then stored in a computer memory.

[0161] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0162] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0163] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0164] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for protecting the pitch pointing abnormality of an airborne SAR large-load eccentric one-axis platform, characterized in that: The method comprises the following steps: S10, calculating the angular velocity of the one-axis platform at the current moment, including: calculating the absolute value V of the angular velocity of the one-axis platform at the current moment t every C seconds t , the calculation formula is as follows: V t = | (3·W t -2·W t-1 - W t-2 ) / 4C| Where: W t、 W t-1、 W t-2 are the pitch pointing angles of the one-axis platform at time t, time t-1, and time t-2 respectively; S20, based on the angular velocity of the one-axis platform, updating the count values ​​of counter A and counter B, including: if V t ≥D·V max , then the value of the counter A is increased by 1, otherwise, the value of the counter A is set to 0, where V t is the absolute value of the angular velocity of the one-axis platform, D is the aircraft overload factor, V max is the absolute value of the maximum angular velocity of the antenna rotating from the left mechanical limit to the right mechanical limit under the ground joint test environment; if V t =0, the value of the counter B is increased by 1, otherwise, the value of the counter B is set to 0; S30, determining whether the count value of the counter A or the counter B is greater than the corresponding threshold value, if so, executing step S40, otherwise executing step S50; S40, start the pitch pointing abnormal protection action; S50, updating the pitch pointing angle of the one-axis platform at each moment through an iterative assignment method, and then executing step S10; The method further includes: when the value of the counter A is set to 0 or the value of the counter B is set to 0 or the count value of the counter A is greater than 1 and less than or equal to the corresponding threshold value E A Or the count value of counter B is less than or equal to its corresponding threshold value E B The pitch pointing angle of the one-axis platform at each moment is updated through the iterative assignment method.

2. The pitch pointing abnormal protection method for an airborne SAR large load eccentric one-axis platform as claimed in claim 1 is characterized in that: When the count value of the counter A is greater than its corresponding threshold value E A When the pitch pointing abnormal protection action is initiated, the action includes: Determine the eccentric moment M according to the eccentric moment calculation formula A , the eccentric moment calculation formula is: M A =M max ·|sin(W A -J A )|·[1-cos(W A -J A )] / D Where: M max is the absolute value of the maximum eccentric moment; W A is the pitch pointing angle of the one-axis platform at time t-4, if W A ≥0, then J A = J R ; If W A <0, then J A = J L ; J R It is the angle feedback value when the antenna rotates freely from the right mechanical limit and stays at the equilibrium position; J L is the angle feedback value when the antenna rotates freely from the left mechanical limit and stays at the equilibrium position; D is the aircraft overload factor; The threshold value G is determined by a threshold value determination formula, and the threshold value determination formula is: If M A >(2M max / 3 -M F ), then G=G1; If (M max / 3-M F )≤M A ≤2M max / 3, then G= G2; If 0≤M A <M max / 3, then G= G3; Where: M max is the absolute value of the maximum eccentric moment, M F is the torque fine-tuning value, G1, G2, and G3 are output thresholds, G1 is in the interval [-1.6, -2.5], G2 is in the interval (-2.5, -2.9], G3 is in the interval (-2.9, -3.5], M A is the eccentric moment of the current antenna; Based on the position open-loop-speed closed-loop control, the threshold G and the speed of the speed sensor are used as input quantities to drive the antenna at a constant speed state V A Rotate to zero position and rotate for a time T A After that, the motor is turned off and the excitation link fault is reported. A =W A / V A .

3. The pitch pointing abnormal protection method for an airborne SAR large load eccentric one-axis platform as claimed in claim 1 is characterized in that: When the count value of the counter B is greater than its corresponding threshold value E B When the pitch pointing abnormal protection action is initiated, the action includes: Assume the command angle is +95°; After waiting for the set time, set the threshold H; Based on position open-loop-speed closed-loop control, the threshold H and the speed of the speed sensor are used as input quantities to drive the antenna at a constant speed state V B Rotate to zero position and rotate for a time T B After that, the motor is turned off and the sine / cosine link fault is reported. B =95 / V B .

4. The method for protecting the pitch pointing abnormality of an airborne SAR large-load eccentric one-axis platform as claimed in claim 2 or 3, characterized in that: The position open-loop-speed closed-loop control comprises: Subtracting the input threshold from the speed feedback of the speed sensor to obtain a speed error, and inputting the speed error into the PI controller, wherein the input threshold is a threshold G or a threshold H; The PI controller outputs a modulated pulse width signal and adjusts the running state of the motor in real time after being amplified by the driver, and cooperates with the rotating shaft and the gear transmission mechanism to drive the antenna to rotate towards the zero position at a constant speed.

5. The pitch pointing abnormal protection method for an airborne SAR large load eccentric one-axis platform as claimed in claim 1 is characterized in that: The updating of the pitch pointing angle of the one-axis platform at each moment by the iterative assignment method includes: Through the formula W t-4 = W t-3 ; W t-3 = W t-2 ; W t-2 = W t-1 ; W t-1 = W t , iteratively update the pitch pointing angle of the one-axis platform at each moment.

6. The method for protecting the pitch pointing abnormality of an airborne SAR large-load eccentric one-axis platform as claimed in claim 1, characterized in that: The method further comprises: If the value of the counter A is equal to 1, then by formula W A = W t-4 , store W A The value of W A It is the pitch pointing angle of the one-axis platform at time t-4.

7. An airborne SAR large-load eccentric one-axis platform pitch pointing abnormal protection system, characterized in that: The system comprises: The angle calculation module is used to calculate the angular velocity of the one-axis platform at the current moment, including: calculating the absolute value V of the angular velocity of the one-axis platform at the current moment t every C seconds t , the calculation formula is as follows: V t = | (3·W t -2·W t-1 - W t-2 ) / 4C| Where: W t、 W t-1、 W t-2 are the pitch pointing angles of the one-axis platform at time t, time t-1, and time t-2 respectively; The abnormality determination module is used to update the count values ​​of counter A and counter B based on the angular velocity of the one-axis platform, and determine whether the count value of counter A or counter B is greater than the corresponding threshold value, wherein if V t ≥D·V max , then the value of the counter A is increased by 1, otherwise, the value of the counter A is set to 0, where V t is the absolute value of the angular velocity of the one-axis platform, D is the aircraft overload factor, V max is the absolute value of the maximum angular velocity of the antenna rotating from the left mechanical limit to the right mechanical limit under the ground joint test environment; if V t =0, the value of the counter B is increased by 1, otherwise, the value of the counter B is set to 0; An abnormality protection module, used for starting a pitch pointing abnormality protection action when the abnormality determination module outputs a yes result; The pitch pointing update module is used to update the pitch pointing angle of the one-axis platform at each moment through an iterative assignment method when the output result of the abnormal judgment module is no, and to set the value of the counter A to 0 or the value of the counter B to 0 or the count value of the counter A is greater than 1 and less than or equal to its corresponding threshold value E A Or the count value of counter B is less than or equal to its corresponding threshold value E B The pitch pointing angle of the one-axis platform at each moment is updated through the iterative assignment method.

Images