A pitch control mode switching method considering aircraft path interception capability

Abstract

The present invention discloses a method for switching the pitch control mode of a flight guidance and control system. The method includes predicting the position of the aircraft after completing an interception maneuver based on the aircraft's current pitch control mode, interception capability limit, current position, and speed information; determining the timing of pitch control mode switching based on the predicted position and path interception range for different path interception types; and determining the intercepted target altitude. The present invention considers the aircraft's path interception capability when switching pitch control modes, accurately and dynamically determining the timing of mode and altitude target switching. The algorithm is also universal and applicable to pitch control mode switching and altitude target selection for different types of fixed-wing and rotary-wing aircraft.

Description

Technical Field

[0001] The present invention relates to the technical field of avionics flight guidance and control, and in particular to a pitch control mode switching method considering the path interception capability of an aircraft. Background Art

[0002] When guiding an aircraft for autonomous flight, constraints such as the path or altitude limit on the altitude profile must be met. Aircraft pitch control modes include pitch control speed, pitch control vertical velocity, pitch control altitude, and pitch control track inclination angle. During flight, switching between these pitch modes allows you to adhere to a given altitude constraint or reference path during climbs and descents.

[0003] For example, during a civil aircraft climb, there is a mandatory altitude constraint. Below this constraint, the aircraft uses pitch control for speed. When the aircraft approaches a certain range within the constraint, it switches to pitch control for altitude, intercepting the altitude and maintaining level flight. Similarly, during a helicopter descent, there is a mandatory altitude constraint. Above this constraint, the helicopter uses pitch control for vertical speed. When the aircraft approaches a certain range within the constraint, it switches to pitch control for altitude, intercepting the altitude and maintaining level flight.

[0004] During the above process, the guidance effect of altitude-constrained interception is affected by the timing of the aircraft's pitch mode switching. The switching timing judgment method using a fixed vertical interval does not take into account the aircraft's current vertical speed and interception maneuverability, which makes it easy for tracking to overshoot and unnecessary descent maneuvers to occur in the climb phase. Summary of the Invention

[0005] The present invention aims to provide, according to a first aspect, a pitch control mode switching method that takes into account an aircraft's path acquisition capability. The method determines the timing of an aircraft's pitch control mode switch and determines a target altitude after the mode switch, taking into account the relative positional relationship between the aircraft and a reference path altitude constraint and the aircraft's path acquisition capability. The method comprises the following steps:

[0006] S1, according to the current pitch control mode, determine whether switching is required, if yes, go to step S2; if no, end;

[0007] S2, predicting the position of the aircraft after the interception maneuver based on the interception capability;

[0008] S3, determining the path intercept type based on the current vertical speed of the aircraft and the relationship between the current altitude and the path constraint altitude;

[0009] S4, determining a pitch control mode based on the position of the aircraft after the intercept maneuver predicted in step S2 and the path intercept type determined in step S3;

[0010] S5, determining the intercepted target altitude according to the pitch control mode.

[0011] In a possible embodiment, the pitch control mode includes a pitch control speed mode, a pitch control vertical speed mode, a pitch control altitude mode, and a pitch control track tilt angle mode.

[0012] In a possible embodiment, in step S1, judging whether switching is required according to the current pitch control mode specifically includes the following steps:

[0013] S101, when the current aircraft is in the pitch control speed mode or the pitch control vertical speed mode for climbing or descending operation, executing step S2;

[0014] S102: When the current aircraft is in the pitch control altitude mode or the pitch control vertical speed mode for altitude maintenance and level flight, this method is not used and the process ends.

[0015] In a possible embodiment, step S2 specifically includes the following steps:

[0016] S201, when the aircraft's current altitude (ALT)c, current vertical speed (VS)c, and predicted vertical minimum intercept maneuver acceleration limit (an)min, the aircraft's position after completing the intercept maneuver is (ALT)capmin = (ALT)c + 0.5*(VS)c*abs(VS)c / (an)min;

[0017] S202, when the aircraft's current altitude (ALT)c, current vertical speed (VS)c, and predicted maximum vertical intercept maneuver acceleration limit (an)max, the aircraft's position after completing the intercept maneuver is (ALT)capmax = (ALT)c + 0.5*(VS)c*abs(VS)c / (an)max.

[0018] In a possible embodiment, step S3 specifically includes the following steps:

[0019] S301: When the current vertical speed of the aircraft is greater than zero and the current altitude is less than or equal to the path constraint altitude, it is determined to be climb intercept type 1;

[0020] S302: When the current vertical speed of the aircraft is greater than zero and the current altitude is greater than the path constraint altitude, it is determined to be climb intercept type 2;

[0021] S303: When the current vertical speed of the aircraft is less than zero and the current altitude is greater than or equal to the path constraint altitude, it is determined to be descent intercept type 1;

[0022] S304: When the current vertical speed of the aircraft is less than zero and the current altitude is less than the path constraint altitude, it is determined to be a descent intercept type 2.

[0023] In a possible embodiment, step S4 specifically includes the following steps:

[0024] S401, when the path interception type is climb interception type 1, execute S402, otherwise execute S408;

[0025] S402, determining the relative relationship between the predicted position after the minimum intercept maneuver and the lower boundary of the constrained altitude intercept range, where (ALT)constraint represents the constrained altitude, and (ALT)capzone represents the set altitude intercept range. If condition 1 is met: (ALT)capmin < (ALT)constraint – (ALT)capzone, execute S405; otherwise, execute S403;

[0026] S403, determining the relative relationship between the predicted position after the maximum intercept maneuver and the upper boundary of the constrained altitude intercept range. If condition 2 is satisfied: (ALT)capmax>(ALT)constraint+(ALT)capzone, execute S406; otherwise, execute S404.

[0027] S404: Determine the relative relationship between the predicted position interval of the aircraft after the intercept maneuver and the constrained altitude intercept range. If condition 3 is met: (ALT)capmin >= (ALT)constraint – (ALT)capzone, and (ALT)capmax <= (ALT)constraint + (ALT)capzone, execute S407; otherwise, execute S405.

[0028] S405, the pitch control mode continues to maintain the current mode;

[0029] S406, the pitch control mode is switched to the pitch control altitude mode;

[0030] S407, the pitch control mode is switched to the pitch control altitude mode;

[0031] S408: When the path interception type is climb interception type 2, execute S409; otherwise, execute S413;

[0032] S409, determining the relative relationship between the predicted position after the maximum intercept maneuver and the upper boundary of the constrained altitude intercept range. If condition 1 is satisfied: (ALT)capmax<=(ALT)constraint+(ALT)capzone, execute S411; otherwise, execute S410.

[0033] S410, determining the relative relationship between the predicted position after the maximum intercept maneuver and the upper boundary of the constrained altitude intercept range. If condition 2 is satisfied: (ALT)capmax>(ALT)constraint+(ALT)capzone, executing S412;

[0034] S411, the pitch control mode is switched to the pitch control altitude mode;

[0035] S412, the pitch control mode is switched to the pitch control altitude mode;

[0036] S413: When the path interception type is descent interception type 1, execute S414; otherwise, execute S420;

[0037] S414, determining the relative relationship between the predicted position after the minimum intercept maneuver and the upper boundary of the constrained altitude intercept range. If condition 1 is satisfied: (ALT)capmin>(ALT)constraint+(ALT)capzone, execute S417; otherwise, execute S415.

[0038] S415, determining the relative relationship between the predicted position after the maximum intercept maneuver and the lower boundary of the constrained altitude intercept range. If condition 2 is satisfied: (ALT)capmax<(ALT)constraint–(ALT)capzone, execute S418; otherwise, execute S416.

[0039] S416, determining the relative relationship between the predicted position interval of the aircraft after the intercept maneuver and the constrained altitude intercept range. If condition 3 is met: (ALT)capmin <= (ALT)constraint + (ALT)capzone, and (ALT)capmax >= (ALT)constraint – (ALT)capzone, execute S419; otherwise, execute S417.

[0040] S417, the pitch control mode continues to maintain the current mode;

[0041] S418, the pitch control mode is switched to the pitch control altitude mode;

[0042] S419, the pitch control mode is switched to the pitch control altitude mode;

[0043] S420, when the path interception type is descent interception type 2, execute S421;

[0044] S421, determining the relative relationship between the predicted position after the maximum intercept maneuver and the lower boundary of the constrained altitude intercept range. If condition 1 is satisfied: (ALT)capmax>=(ALT)constraint–(ALT)capzone, execute S423; otherwise, execute S422.

[0045] S422, determining the relative relationship between the predicted position after the maximum intercept maneuver and the lower boundary of the constrained altitude intercept range. If condition 2 is satisfied: (ALT)capmax<(ALT)constraint–(ALT)capzone, executing S424;

[0046] S423, the pitch control mode is switched to the pitch control altitude mode;

[0047] S424, the pitch control mode is switched to the pitch control altitude mode.

[0048] In a possible embodiment, step S5 specifically includes the following steps:

[0049] S501, when the path intercept type is climb intercept type 1, the pitch control mode continues to maintain the current mode, and the predicted minimum intercept maneuver end point does not reach the climb altitude target intercept range, the intercept target altitude is invalid;

[0050] S502, when the path intercept type is climb intercept type 1, the pitch control mode is switched to the pitch control altitude mode, the predicted maximum intercept maneuver end point has exceeded the climb altitude target intercept range, and the intercept target altitude is equal to (ALT)capmin;

[0051] S503, when the path intercept type is climb intercept type 1, the pitch control mode is switched to the pitch control altitude mode, the predicted intercept maneuver end altitude range overlaps with the climb altitude target intercept range, and the intercept target altitude is equal to the (ALT) constraint;

[0052] S504, when the path capture type is climb capture type 2, the pitch control mode is switched to the pitch control altitude mode, the predicted maximum capture maneuver end point is still within the climb altitude target capture range, and the capture target altitude is equal to the (ALT) constraint;

[0053] S505, when the path intercept type is climb intercept type 2, the pitch control mode is switched to the pitch control altitude mode, the predicted maximum intercept maneuver end point has exceeded the climb altitude target intercept upper boundary range, and the intercept target altitude is equal to (ALT)capmin;

[0054] S506, when the path intercept type is descent intercept type 1, the pitch control mode continues to maintain the current mode, and the predicted minimum intercept maneuver end point does not reach the descent altitude target intercept range, and the intercept target altitude is invalid;

[0055] S507, when the path intercept type is descent intercept type 1, the pitch control mode is switched to the pitch control altitude mode, the predicted maximum intercept maneuver end point has exceeded the descent altitude target intercept range, and the intercept target altitude is equal to (ALT)capmin;

[0056] S508, when the path intercept type is descent intercept type 1, the pitch control mode is switched to the pitch control altitude mode, the predicted intercept maneuver end altitude range overlaps with the descent altitude target intercept range, and the intercept target altitude is equal to the (ALT) constraint;

[0057] S509, when the path intercept type is descent intercept type 2, the pitch control mode is switched to the pitch control altitude mode, the predicted maximum intercept maneuver end point is still within the descent altitude target intercept range, and the intercept target altitude is equal to the (ALT) constraint;

[0058] S510, when the path intercept type is descent intercept type 2, the pitch control mode is switched to the pitch control altitude mode, the predicted maximum intercept maneuver end point has exceeded the descent altitude target intercept lower boundary range, and the intercept target altitude is equal to (ALT)capmin.

[0059] According to a second aspect of the present invention, a storage medium is provided, wherein the storage medium includes a stored program, wherein the program executes the method steps described above when running.

[0060] The advantages and effects of the present invention may be:

[0061] (1) The aircraft's path capture capability is taken into account when switching pitch control modes. Based on the aircraft's current position and vertical velocity, the aircraft's position at the end of the capture maneuver is predicted, allowing for accurate and dynamic determination of the mode and altitude target switching timing.

[0062] (2) Categorize the climb and descent intercept types to avoid situations where significant descent maneuvers are performed during climb or significant climb maneuvers are performed during descent to intercept path altitude constraints;

[0063] (3) The algorithm is universal and can be applied to pitch control mode switching and altitude target selection of different types of fixed-wing aircraft and rotary-wing aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0065] Figure 1 1 is a schematic diagram showing the principle of a pitch control mode switching method taking into account the aircraft path interception capability according to a preferred embodiment of the present invention;

[0066] Figure 2 It is a flowchart of a pitch control mode switching method used in the process of capturing a climb altitude constraint in a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0067] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0068] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed in order to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific arrangement and method proposed below, but rather encompasses any improvements, replacements, and modifications to structures, methods, and devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, well-known structures and techniques are not shown to avoid unnecessary ambiguity in the present invention.

[0069] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0070] Figure 1 The figure is a schematic diagram of the principle of a pitch control mode switching method considering the aircraft path interception capability according to an embodiment of the present invention.

[0071] refer to Figure 1 , the method may include the following steps:

[0072] S1, according to the current pitch control mode, determine whether switching is required, if yes, go to step S2; if no, end;

[0073] S2, predicting the position of the aircraft after the interception maneuver based on the interception capability;

[0074] S3, determining the path intercept type based on the current vertical speed of the aircraft and the relationship between the current altitude and the path constraint altitude;

[0075] S4, determining a pitch control mode based on the position of the aircraft after the intercept maneuver predicted in step S2 and the path intercept type determined in step S3;

[0076] S5, determining the intercepted target altitude according to the pitch control mode.

[0077] In some embodiments, while the pitch control vertical velocity mode is currently being used for climbing or descending, the pitch control vertical velocity mode is still used after the path altitude target is captured. In this case, although the pitch control mode has not been switched, the altitude target for vertical velocity command calculation does switch when the pitch control vertical velocity mode is used to capture the path altitude target, and the switching judgment conditions of the present invention still apply.

[0078] In some embodiments, the aircraft uses a fixed vertical acceleration for interception. In this case, the aircraft's position after the interception maneuver is predicted to be a certain altitude based on the interception capability. In this case, the maximum interception maneuver predicted altitude and the minimum interception maneuver predicted altitude are equal, and the judgment switching condition of the present invention still applies.

[0079] Figure 2 The present invention is a flowchart of a pitch control mode switching method used in the process of capturing a climb altitude constraint in one embodiment of the present invention.

[0080] like Figure 2 As shown, the method may include the following steps:

[0081] Step 1: Start and determine whether the aircraft is in the climb phase and the pitch control mode is in the altitude hold level flight state. If it is in the altitude hold level flight state, end; if not, proceed to step 2;

[0082] Step 2: Predict the position of the aircraft after the intercept maneuver based on the intercept capability. The current altitude of the aircraft is (ALT)c, the current vertical speed is (VS)c, the predicted minimum vertical acceleration limit for the intercept maneuver is (an)min, and the predicted maximum vertical acceleration limit for the intercept maneuver is (an)max. Assuming that the intercept process is a uniformly accelerated motion, calculate the position after the maneuver is completed with the minimum intercept vertical acceleration: (ALT)capmin = (ALT)c + 0.5*(VS)c*abs(VS)c / (an)min. Calculate the position after the maneuver is completed with the maximum intercept vertical acceleration: (ALT)capmax = (ALT)c + 0.5*(VS)c*abs(VS)c / (an)max.

[0083] Step 3: Determine whether it is climb intercept type 1. If the current altitude is less than or equal to the constraint altitude (ALT) constraint, it is climb intercept type 1 and execute step 4; otherwise, it is climb intercept type 2 and execute step 13;

[0084] Step 4: Determine whether the predicted minimum capture maneuver altitude is less than the lower bound of the constrained altitude capture range. (ALT)capzone is the altitude capture range. When the aircraft is stably flying within the altitude range [(ALT)constraint–(ALT)capzone, (ALT)constraint+(ALT)capzone], the altitude capture is complete. If condition 1 is met: (ALT)capmin < (ALT)constraint–(ALT)capzone, proceed to step 5; otherwise, proceed to step 7.

[0085] Step 5: The pitch control mode remains in the current mode and proceed to step 6;

[0086] Step 6: The predicted minimum intercept maneuver end point does not reach the climb altitude target intercept range, so the intercept target altitude is invalidated and the judgment ends;

[0087] Step 7: Determine whether the predicted altitude after the maximum intercept maneuver is greater than the lower limit of the constrained altitude intercept range. If condition 2 is met: (ALT)capmax > (ALT)constraint + (ALT)capzone, proceed to step 8; otherwise, proceed to step 10.

[0088] Step 8: Switch the pitch control mode to pitch control altitude mode and proceed to step 9;

[0089] Step 9: The predicted maximum intercept maneuver end point has exceeded the climb altitude target intercept range. Set the intercept target altitude to (ALT)capmin and end the judgment.

[0090] Step 10: Determine the relative relationship between the predicted position interval of the aircraft after the intercept maneuver [(ALT)capmin, (ALT)capmax] and the constrained altitude intercept range [(ALT)constraint–(ALT)capzone, (ALT)constraint+(ALT)capzone]. If condition 3 is met: (ALT)capmin>=(ALT)constraint–(ALT)capzone, and (ALT)capmax<=(ALT)constraint+(ALT)capzone, execute step 11; otherwise, execute step 5.

[0091] Step 11: Switch the pitch control mode to the pitch control altitude mode and go to step 12;

[0092] Step 12: The predicted intercept maneuver end altitude range overlaps with the climb altitude target intercept range, and the intercept target altitude is equal to the (ALT) constraint, so the judgment ends.

[0093] Step 13: Determine the relative relationship between the predicted position after the maximum intercept maneuver and the upper boundary of the constrained altitude intercept range. If condition 1 is met: (ALT)capmax<=(ALT)constraint+(ALT)capzone, proceed to step 14; otherwise, proceed to step 15.

[0094] Step 14: The pitch control mode is switched to the pitch control altitude mode. The predicted maximum intercept maneuver end point is still within the climb altitude target intercept range. The intercept target altitude is equal to the (ALT) constraint. The judgment ends.

[0095] Step 15: The pitch control mode is switched to the pitch control altitude mode. The predicted maximum intercept maneuver end point has exceeded the upper boundary range of the climb altitude target interception. The interception target altitude is equal to (ALT)capmin. The judgment ends.

[0096] In some embodiments, when the aircraft is in the descent phase and is intercepting the descent altitude constraint, the judgment switching conditions of the present invention are still applicable;

[0097] It should be noted that the above process operations can be combined to varying degrees. For the sake of simplicity, the implementation of various combinations will not be described in detail. Those skilled in the art can flexibly adjust the order of the steps of the above method according to actual circumstances, or perform other operations in combination.

[0098] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should all be covered by the scope of protection of the present invention.

Claims

1. A pitch control mode switching method considering the aircraft path interception capability, characterized in that: The method comprises the following steps: S1, judging whether switching is required according to the current pitch control mode, and if so, proceeding to step S2; if not, ending; S2, predicting the position of the aircraft after the interception maneuver based on the interception capability; the specific process comprising: when the aircraft has a current altitude (ALT)c, a current vertical speed (VS)c, and a predicted vertical minimum interception maneuver acceleration limit (an)min, the position of the aircraft after completing the interception maneuver is (ALT)capmin=(ALT)c+0.5*(VS)c*abs(VS)c / (an)min; and when the aircraft has a predicted vertical maximum interception maneuver acceleration limit (an)max, the position of the aircraft after completing the interception maneuver is (ALT)capmax=(ALT)c+0.5*(VS)c / (an)min. c*abs(VS)c / (an)max; S3, determine the path interception type according to the current vertical speed of the aircraft and the relationship between the current altitude and the path constraint altitude; determine the path interception type, including the climb segment, the aircraft is below the path altitude constraint; the climb segment, the aircraft is above the path altitude constraint; the descent segment, the aircraft is above the path altitude constraint; the descent segment, the aircraft is below the path altitude constraint; S4, determine the pitch control mode according to the position of the aircraft after the interception maneuver predicted in step S2 and the path interception type determined in step S3; S5, determine the intercepted target altitude according to the pitch control mode, the target altitude includes: the path constraint altitude, the altitude of the aircraft after the interception maneuver predicted based on the interception capability, the current altitude of the aircraft, and any altitude within the path constraint altitude interception range.

2. A pitch control mode switching method considering the aircraft path interception capability according to claim 1, characterized in that: The pitch control modes include pitch control speed mode, pitch control vertical speed mode, pitch control altitude mode, and pitch control track inclination angle mode.

3. The pitch control mode switching method considering the aircraft path interception capability according to claim 1, characterized in that: When the maximum intercept maneuver acceleration limit and the minimum intercept maneuver acceleration limit are equal, intercept with fixed maneuver capability.

4. The pitch control mode switching method considering the aircraft path interception capability according to claim 1, characterized in that: The pitch control mode is determined based on the predicted position and the path interception range. The relationship between the predicted position and the path interception range is based on at least one of the following: the position range of the aircraft after the interception maneuver is predicted to be less than the lower boundary of the constrained altitude interception, greater than the upper boundary of the constrained altitude interception, and overlaps with the constrained altitude interception range based on the interception capability.

5. The pitch control mode switching method considering the aircraft path interception capability according to claim 1, characterized in that: The determined pitch control modes include pitch control altitude mode, pitch control vertical speed mode, and pitch control track inclination angle mode.

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