A spin recovery method

Abstract

The invention belongs to the technical field of flight control and discloses a method for recovering from a tailspin, comprising: S1, judging an aircraft's tailspin based on its angle of attack, yaw rate, roll angle, and vertical rate, judging whether the aircraft has entered a tailspin, and judging the type of the tailspin the aircraft has entered; S2, adopting different tailspin recovery strategies based on the steering effects of ailerons, rudders, and elevators at large angles of attack, and giving control surface instructions; superimposing the control surface instructions output by human control and the control surface instructions output by the tailspin based on the current flight state of the aircraft; an angle of attack with an absolute value greater than 10 degrees is considered a large angle of attack; and S3, judging whether the aircraft has recovered from the tailspin, and if so, repeating S2; otherwise, exiting, so as to improve the aircraft's survivability in a possible tailspin situation.

Description

Technical Field

[0001] The invention belongs to the technical field of flight control, and in particular relates to a spin recovery method. Background Art

[0002] A spin is one of the most complex flight conditions in an aircraft, characterized by an angle of attack exceeding the stalling angle, a large sideslip angle, and significant roll and yaw angular rates. As the aircraft rolls and yaws simultaneously, gravity forces it to descend in a spiral with a very small radius. A spin poses a serious threat to aircraft flight safety. Accurate mathematical models for spins are extremely difficult to obtain through simple theoretical calculations. Research on spin characteristics encompasses three key areas: stall entry and exit, spin entry, spin development, and spin recovery.

[0003] Currently, spin determination and recovery rely primarily on pilot experience gained through training, including three neutral and reverse spins. Automatic spin determination and recovery solutions are primarily designed for specific aircraft models, lacking universal determination criteria. Furthermore, the technical solutions do not clarify how to handle the amount of control surface output when mixed with human control. Summary of the Invention

[0004] The present invention aims to provide a spin recovery method to improve the aircraft's survivability in a potential spin situation. The method first determines the occurrence of a spin using criteria, then determines the required spin recovery actions based on the type of spin. Based on the aircraft's current state, the method dynamically superimposes human control inputs and recovery control outputs until the aircraft recovers from the spin.

[0005] A method for automatically recovering from a spin, comprising the following steps:

[0006] S1, performing a spin determination based on the aircraft's angle of attack, yaw rate, roll angle, and vertical rate to determine whether the aircraft has entered a spin and the type of spin it has entered;

[0007] S2: Based on the effectiveness of the ailerons, rudder, and elevators at high angles of attack, different spin recovery strategies are adopted and control surface commands are given. Based on the aircraft's current flight state, the control surface commands issued by the human operator and the control surface commands issued for the spin are superimposed. An absolute angle of attack greater than 10 degrees is considered a high angle of attack.

[0008] S3: Determine whether the aircraft has recovered from the spin. If it is still in the spin, repeat S2; otherwise, exit.

[0009] Furthermore, in S1, the aircraft spin determination is performed based on the aircraft's angle of attack, yaw rate, roll angle, and vertical rate, specifically including:

[0010] S101: When the absolute value of the aircraft's angle of attack is greater than 30 degrees, the absolute value of the yaw rate is greater than 10 degrees / second, and the vertical rate is less than -10m / s, the aircraft enters the spin determination state. In each control law cycle, the spin determination counter The count is increased by 1;

[0011] S102: If the absolute value of the aircraft's angle of attack is less than 20 degrees and the absolute value of the yaw rate is less than 5 degrees / second, it is considered that a spin is being recovered. The spin determination counter is set every control law cycle. Decrement the count by 1.

[0012] Furthermore, in S1, it is determined whether the aircraft is in a positive or negative spin, and whether the aircraft is in a steep spin, a flat spin, or a slow spin, specifically including:

[0013] S103, when the spin determination counter If it is greater than 200, the aircraft is judged to have entered a spin.

[0014] S104: After the aircraft enters a spin state, a positive or negative spin is determined based on the roll angle. If the absolute value of the roll angle is greater than 90 degrees, it is a negative spin; if the absolute value of the roll angle is less than or equal to 90 degrees, it is a positive spin.

[0015] S105: After the aircraft enters a spin, a steep spin is determined based on the pitch angle. If the absolute value of the pitch angle is greater than 50 degrees, it is a steep spin; if the absolute value of the pitch angle is less than 30 degrees, it is a flat spin; otherwise, it is a slow spin.

[0016] Furthermore, in S2, different spin recovery strategies are adopted based on the effectiveness of the ailerons, rudder, and elevator at high angles of attack, and control surface commands are given, including:

[0017] S201: When the aileron and rudder efficiency is less than the set threshold at the current angle of attack , and the elevator rudder effect is greater than In the event of a spin, use the following spin recovery strategy:

[0018] a) If the angle of attack is greater than 0, the control surface direct command mode is adopted. The left and right aileron commands are the control surface positive limit deflection, the rudder command is 0 degrees, and the elevator command is the control surface positive limit deflection;

[0019] b) If the angle of attack is less than or equal to 0, the left and right aileron commands are the negative limit deflection of the control surface, the rudder command is 0 degrees, and the elevator command is the negative limit deflection of the control surface.

[0020] Furthermore, in S2, different spin recovery strategies are adopted based on the effectiveness of the ailerons, rudder, and elevators at high angles of attack, and control surface commands are given, specifically including:

[0021] S202, when the aileron and rudder effect is greater than the current angle of attack , and the elevator rudder effect is greater than In the event of a spin, use the following spin recovery strategy:

[0022] a) If the angle of attack is greater than 0, the control surface direct command mode is adopted. According to the current roll rate and yaw rate, the aileron and rudder commands that can suppress the roll rate and yaw rate are given. The elevator command is the control surface positive limit deflection;

[0023] b) If the angle of attack is less than or equal to 0, the control surface direct instruction mode is adopted. According to the current roll rate and yaw rate, the aileron and rudder instructions that can suppress the roll rate and yaw rate are given. The elevator instruction is the negative limit deflection of the control surface.

[0024] Furthermore, according to the current roll rate and yaw rate, the aileron and rudder commands that can suppress the roll rate and yaw rate are given. Specifically, the control surface commands are given using the following rules:

[0025]

[0026]

[0027] If the roll axis moment generated by the ailerons is negative, then is positive, with a typical value of 2. If the roll axis moment generated by the aileron is positive, then It is negative, with a typical value of -2.

[0028] If the yaw axis moment produced by the positive rudder is negative, then is positive, with a typical value of 2. If the yaw axis moment generated by the positive rudder is positive, then It is negative, with a typical value of -2.

[0029] Furthermore, in S2, based on the current flight state of the aircraft, the control surface command output by the human operator and the control surface command output by the tailspin are superimposed, specifically including:

[0030] Based on the control surface instructions given in S201 and S202, the ratio of the upper limit of the instructions that can be applied by the user to the maximum deflection of the control surface is calculated according to the following rules: ;

[0031] a) If the angle of attack ,but Calculated using the following formula:

[0032]

[0033] b) If the angle of attack , if the yaw rate ,but Calculated using the following formula:

[0034]

[0035] If the yaw rate or ,but Calculated using the following formula:

[0036]

[0037] c) If the absolute value of the angle of attack is not greater than 10 degrees, the proportion of the upper limit of the command applied to the control surface limit deflection It is 80%.

[0038] The ratio of the upper limit of the command that can be applied by humans to the maximum deflection of the control surface The control surface commands output by human manipulation are restricted, and the control surface commands output by the tailspin in steps S201 and S202 are superimposed as the final control surface commands for controlling the aircraft.

[0039] Further, S3, it is determined whether the aircraft has recovered from the spin, specifically: determining the spin determination counter Is it equal to zero? If so, it is determined that the aircraft has recovered from the spin.

[0040] Compared with other methods, this method has the following innovations:

[0041] 1. Based on data analysis and model simulation of possible spins, the occurrence characteristics of spins are obtained to improve the effectiveness and sensitivity of the judgment criteria.

[0042] 2. Taking into account the superposition of human control input, it can more effectively deal with the problems of human-machine hybrid control systems.

[0043] Beneficial effects of the present invention:

[0044] This invention combines spin detection and spin recovery strategies to enable spin detection and recovery for a variety of aircraft models. By superimposing these strategies with human input, human-in-the-loop control is achieved. Dynamically adjusting the human input ratio effectively prevents erroneous inputs during spins. This method provides a clear path and effectively addresses aircraft control and flight safety issues in spin situations. DETAILED DESCRIPTION

[0045] In some examples, a method for automatically recovering from a spin includes the following steps:

[0046] S1: Determine the aircraft's spin based on its angle of attack, yaw rate, roll angle, and vertical rate to determine whether it is a positive or negative spin, and whether it is a steep spin, a flat spin, or a slow spin.

[0047] S2, based on the analysis of the rudder effectiveness, adopts different spin recovery strategies, gives rudder instructions, and combines the manual input and method output with the current flight status of the aircraft.

[0048] S3: Determine whether the aircraft has recovered from the spin based on the criteria. If it is still in the spin, repeat S2; otherwise, exit.

[0049] In some examples, a method for automatically recovering from a spin includes the following steps:

[0050] S101: When the absolute value of the aircraft's angle of attack is greater than 30 degrees, the absolute value of the yaw rate is greater than 10 degrees / second, and the vertical rate is less than -10 m / s, the aircraft enters a spin determination state. The spin determination counter, SpinRangeCount, is incremented by 1 in each control law cycle.

[0051] S102: If the conditions of S101 are not met, when the aircraft angle of attack is less than -30 degrees, the absolute value of the roll angle is greater than 90 degrees, the absolute value of the yaw rate is greater than 5 degrees / second, and the vertical rate is less than -10m / s, the aircraft enters the spin determination state. In each control law cycle, the spin determination counter SpinRangeCount is incremented by 1.

[0052] S103: If the absolute value of the aircraft's angle of attack is less than 20 degrees and the absolute value of the yaw rate is less than 5 degrees / second, it is considered that a spin is being recovered. In each control law cycle, the spin determination counter SpinRangeCount is decremented by 1.

[0053] S104: When the spin determination counter SpinRangeCount is greater than 200, it is considered that the aircraft has entered a spin state.

[0054] S105: After the aircraft enters a spin state, a positive or negative spin is determined based on the roll angle. If the absolute value of the roll angle is greater than 90 degrees, it is a negative spin; if the absolute value of the roll angle is less than or equal to 90 degrees, it is a positive spin.

[0055] S106: After the aircraft enters a spin, a flat or steep spin is determined based on the pitch angle. If the absolute value of the pitch angle is greater than 50 degrees, it is a steep spin; if the absolute value of the pitch angle is 30 degrees, it is a flat spin; otherwise, it is a slow spin.

[0056] S201: When the aileron and rudder efficiency is less than the set threshold at a large angle of attack , and the elevator rudder effect is greater than In this case, the following recovery operation is adopted: An angle of attack greater than 50 degrees is called a high angle of attack.

[0057] a) If the angle of attack is greater than 0, the control surface is directly given instructions. The left and right aileron instructions are 20 degrees, the rudder instruction is 0 degrees, and the elevator instruction is 20 degrees.

[0058] b) If the angle of attack is less than or equal to 0, the left and right aileron commands are -10 degrees, the rudder command is 0 degrees, and the elevator command is -10 degrees.

[0059] S202, when the aileron and rudder have a greater rudder effect at a large angle of attack, , and the elevator rudder effect is greater than In the case of , take the following recovery actions:

[0060] a) If the angle of attack is greater than 0, use the control surface direct command mode. According to the current roll rate and yaw rate, give the aileron and rudder commands that can reduce the roll rate and yaw rate. The elevator command is 20 degrees.

[0061] b) If the angle of attack is less than or equal to 0, the control surface direct command mode is used. According to the current roll rate and yaw rate, the aileron and rudder commands that can reduce the roll rate and yaw rate are given. The elevator command is -20 degrees.

[0062] S203, based on the rudder instructions given in S201 and S202, calculate the ratio of the upper limit of the instructions that can be applied by the human to the maximum deflection of the rudder according to the following rules: .

[0063] a) If the absolute value of the angle of attack is not less than 40 degrees, use the interpolation method, using the yaw rate as the node, to calculate the ratio of the upper limit of the command that can be applied by the human to the maximum deflection of the control surface. The nodes are 10, 20, 40 and 60 degrees / second respectively, and the corresponding upper limit of the command that can be applied by the person accounts for the proportion of the maximum deflection of the control surface They are 40%, 30%, 20% and 10% respectively.

[0064] b) If the absolute value of the angle of attack is greater than 20 degrees but not greater than 40 degrees, a two-dimensional linear interpolation method is used, with the angle of attack and yaw rate as nodes. From the nodes of 0 and 200 degrees / second at the yaw rate at 40 degrees of attack, the corresponding upper limit of the command that can be applied by the human is the ratio of the maximum deflection of the control surface. The linear interpolation of 40%, 30%, 20%, and 10% to the yaw rate nodes of 0 degrees / second and 20 degrees / second at an angle of attack of 20 degrees is respectively the ratio of the upper limit of the command that can be applied by the person to the maximum deflection of the control surface. 80% and 60% respectively.

[0065] The interpolation method is:

[0066] In step S204, when the control surface command output by the human operator and the control surface command output by the tailspin in steps S201 and S202 exist at the same time, the ratio of the upper limit of the command that can be applied by the human operator to the maximum deflection of the control surface is calculated. The control surface commands output by human manipulation are restricted, and the control surface commands output by the tailspin in steps S201 and S202 are superimposed.

[0067] S3, if the spin determination counter SpinRangeCount=0, it is determined that the aircraft has recovered from the spin.

[0068] Example

[0069] Exemplarily, the method may include the following steps:

[0070] Step 1: When the absolute value of the aircraft's angle of attack is greater than 30 degrees, the absolute value of the yaw rate is greater than 10 degrees / second, and the vertical rate is less than -10m / s, the aircraft enters the spin determination state. In each control law cycle, the spin determination counter The count is increased by 1;

[0071] Step 2: Spin Detection Counter If it is greater than 200, the aircraft is judged to have entered a spin.

[0072] Step 3: After the aircraft enters a spin state, determine whether it is a positive or negative spin based on the roll angle. If the absolute value of the roll angle is greater than 90 degrees, it is a negative spin; if the absolute value of the roll angle is less than or equal to 90 degrees, it is a positive spin.

[0073] Step 4: After the aircraft enters a spin, determine whether it is a flat or steep spin based on the pitch angle. If the absolute value of the pitch angle is greater than 50 degrees, it is a steep spin; if the absolute value of the pitch angle is less than 30 degrees, it is a flat spin; otherwise, it is a slow spin.

[0074] Step 5: When the aileron and rudder efficiency is less than the set threshold at the current angle of attack , and the elevator rudder effect is greater than In the event of a spin, use the following spin recovery strategy:

[0075] a) If the angle of attack is greater than 0, the control surface direct command mode is adopted. The left and right aileron commands are the control surface positive limit deflection, the rudder command is 0 degrees, and the elevator command is the control surface positive limit deflection;

[0076] b) If the angle of attack is less than or equal to 0, the left and right aileron commands are the negative limit deflection of the control surface, the rudder command is 0 degrees, and the elevator command is the negative limit deflection of the control surface.

[0077] When the aileron and rudder have a rudder effect greater than , and the elevator rudder effect is greater than In the event of a spin, use the following spin recovery strategy:

[0078] a) If the angle of attack is greater than 0, the control surface direct command mode is adopted. According to the current roll rate and yaw rate, the aileron and rudder commands that can suppress the roll rate and yaw rate are given. The elevator command is the control surface positive limit deflection;

[0079] b) If the angle of attack is less than or equal to 0, the control surface direct instruction mode is adopted. According to the current roll rate and yaw rate, the aileron and rudder instructions that can suppress the roll rate and yaw rate are given. The elevator instruction is the negative limit deflection of the control surface.

[0080] Among them, according to the current roll rate and yaw rate, the aileron and rudder instructions that can suppress the roll rate and yaw rate are given. The specific rules for giving the control surface instructions are as follows:

[0081]

[0082]

[0083] If the roll axis moment generated by the ailerons is negative, then is positive, with a typical value of 2. If the roll axis moment generated by the aileron is positive, then It is negative, with a typical value of -2.

[0084] If the yaw axis moment produced by the positive rudder is negative, then is positive, with a typical value of 2. If the yaw axis moment generated by the positive rudder is positive, then It is negative, with a typical value of -2.

[0085] Step 6: Based on the control surface instructions given in step 5, calculate the ratio of the upper limit of the instructions that can be applied by the human to the maximum deflection of the control surface according to the following rules: ;

[0086] a) If the angle of attack ,but Calculated using the following formula:

[0087]

[0088] b) If the angle of attack , if the yaw rate ,but Calculated using the following formula:

[0089]

[0090] If the yaw rate or ,but Calculated using the following formula:

[0091]

[0092] c) If the absolute value of the angle of attack is not greater than 10 degrees, the proportion of the upper limit of the command applied to the control surface limit deflection It is 80%.

[0093] Step 7: The ratio of the upper limit of the command that can be applied by humans to the maximum deflection of the control surface Limit the control surface commands output by human manipulation, and superimpose the control surface commands output by the tailspin in step 5 as the final control surface commands for controlling the aircraft.

[0094] Step 8: Determine the spin determination counter Is it equal to zero? If so, it is determined that the aircraft has recovered from the spin. Otherwise, repeat step 5 and subsequent steps.

[0095] This invention combines spin detection and spin recovery strategies to enable spin detection and recovery for a variety of aircraft models. By superimposing these strategies with human input, human-in-the-loop control is achieved. Dynamically adjusting the human input ratio effectively prevents erroneous inputs during spins. This method provides a clear path and effectively addresses aircraft control and flight safety issues in spin situations.

Claims

1. A method for automatically recovering from a spin, characterized in that: The steps include: S1, performing a spin determination based on the aircraft's angle of attack, yaw rate, roll angle, and vertical rate to determine whether the aircraft has entered a spin and the type of spin it has entered; S2: Based on the effectiveness of the ailerons, rudder, and elevators at high angles of attack, different spin recovery strategies are adopted and control surface commands are given. Based on the aircraft's current flight state, the control surface commands issued by the human operator and the control surface commands issued for the spin are superimposed. An absolute angle of attack greater than 10 degrees is considered a high angle of attack. S3: Determine whether the aircraft has recovered from the spin. If it is still in the spin, repeat S2; otherwise, exit. In S1, the aircraft spin is determined based on the aircraft's angle of attack, yaw rate, roll angle, and vertical rate, specifically including: S101: When the absolute value of the aircraft's angle of attack is greater than 30 degrees, the absolute value of the yaw rate is greater than 10 degrees / second, and the vertical rate is less than -10m / s, the aircraft enters the spin determination state. In each control law cycle, the spin determination counter The count is increased by 1; S102: If the absolute value of the aircraft's angle of attack is less than 20 degrees and the absolute value of the yaw rate is less than 5 degrees / second, it is considered that the spin is being recovered. The spin determination counter is set every control law cycle. Decrement the count by 1; In S1, the aircraft is judged to be in a positive or negative spin, and whether it is a steep spin, a flat spin, or a slow spin. Specifically, the following are performed: S103, when the spin determination counter If it is greater than 200, the aircraft is judged to be in a tailspin; S104: After the aircraft enters a spin state, a positive or negative spin is determined based on the roll angle. If the absolute value of the roll angle is greater than 90 degrees, it is a negative spin; if the absolute value of the roll angle is less than or equal to 90 degrees, it is a positive spin. S105: After the aircraft enters a spin, a steep spin is determined based on the pitch angle. If the absolute value of the pitch angle is greater than 50 degrees, it is a steep spin; if the absolute value of the pitch angle is less than 30 degrees, it is a flat spin; otherwise, it is a slow spin.

2. The method for automatically recovering from a spin according to claim 1, wherein: In S2, different spin recovery strategies are adopted based on the effectiveness of the ailerons, rudder, and elevators at high angles of attack, and control surface commands are given, including: S201: When the aileron and rudder efficiency is less than the set threshold at the current angle of attack , and the elevator rudder effect is greater than In the event of a spin, use the following spin recovery strategy: a) If the angle of attack is greater than 0, the control surface direct command mode is adopted. The left and right aileron commands are the control surface positive limit deflection, the rudder command is 0 degrees, and the elevator command is the control surface positive limit deflection; b) If the angle of attack is less than or equal to 0, the left and right aileron commands are the negative limit deflection of the control surface, the rudder command is 0 degrees, and the elevator command is the negative limit deflection of the control surface.

3. The method for automatically recovering from a spin according to claim 2, wherein: In S2, different spin recovery strategies are adopted based on the effectiveness of the ailerons, rudder, and elevators at high angles of attack, and control surface commands are given. Specifically, these include: S202, when the aileron and rudder effect is greater than the current angle of attack , and the elevator rudder effect is greater than In the event of a spin, use the following spin recovery strategy: a) If the angle of attack is greater than 0, the control surface direct command mode is adopted. According to the current roll rate and yaw rate, the aileron and rudder commands that can suppress the roll rate and yaw rate are given. The elevator command is the control surface positive limit deflection; b) If the angle of attack is less than or equal to 0, the control surface direct instruction mode is adopted. According to the current roll rate and yaw rate, the aileron and rudder instructions that can suppress the roll rate and yaw rate are given. The elevator instruction is the negative limit deflection of the control surface.

4. The method for automatically recovering from a spin according to claim 1, wherein: S3: Determine whether the aircraft has recovered from a spin. Specifically: Determine the spin determination counter Is it equal to zero? If so, it is determined that the aircraft has recovered from the spin.

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