Adaptive control method for fixed-point braking of airplane

Abstract

The invention discloses an adaptive control method for fixed-point braking of an airplane, and particularly relates to the field of airplane braking control. After the braking instruction is received, a preset braking distance is determined; determining load utilization indexes corresponding to different brake speeds based on a relation curve of the load utilization indexes and the brake speeds; according to the load utilization index and the relationship between the load utilization index and the target deceleration rate, determining the target deceleration rate at different moments; and controlling the aircraft to perform fixed-point braking according to the target deceleration rate and the preset braking distance. The problems that according to a conventional brake control method, the fixed-point brake distance is difficult to accurately match, deviation is large, and the probability of exceeding the fixed-point distance is large are solved. And the pressure of a pilot or remote control can be greatly reduced, so that the brake maneuverability is remarkably improved.

Description

Technical Field

[0001] The present application relates to the field of aircraft brake control, and in particular to an aircraft fixed-point brake adaptive control method. Background Art

[0002] Before the plane lands, the pilot can set the level of automatic braking in the flight management system, such as light, medium, heavy and other different braking intensity levels, according to factors such as runway conditions and aircraft load. The system starts working the moment the plane lands, and the sensors monitor the aircraft's speed, wheel speed, brake pressure and other parameters in real time. The deceleration rate control controller continuously adjusts the brake pressure by comparison and calculation based on the preset deceleration rate target and the actual measured speed and other parameters to keep the aircraft decelerating at the set deceleration rate. With the increase in the demand for landing brakes, the necessity of landing fixed-point braking continues to increase. Fixed-point braking adaptive control can greatly reduce the pressure on pilots or remote controls, and significantly improve the braking maneuverability. However, conventional braking control methods are difficult to accurately match the fixed-point braking distance, with large deviations and a high probability of exceeding the fixed-point distance. Summary of the invention

[0003] The main purpose of the present application is to provide an adaptive control method for aircraft fixed-point braking, aiming to solve the problem that the existing braking control method is difficult to control the fixed-point braking distance.

[0004] To achieve the above-mentioned purpose, the present application provides an aircraft fixed-point braking adaptive control method, including: after receiving a braking command, determining a preset braking distance; based on a relationship curve between the load utilization index and the braking speed, determining the load utilization index corresponding to different braking speeds; according to the load utilization index, and the relationship between the load utilization index and the target deceleration rate, determining the target deceleration rate at different times; according to the target deceleration rate and the preset braking distance, controlling the aircraft to perform fixed-point braking.

[0005] Optionally, a relationship curve between the original load utilization index and the braking speed is established based on the historical load utilization index and the braking speed; based on the capacity margin of the preset value, the historical load utilization index in the relationship curve between the original load utilization index and the braking speed is adjusted to obtain the relationship curve between the load utilization index and the braking speed.

[0006] Optionally, the preset value is 0.5-1%.

[0007] Optionally, after controlling the aircraft to perform fixed-point braking according to the target deceleration rate, the method further includes: when the braking speed reaches a preset braking speed, determining the average deceleration rate of the aircraft according to the remaining braking distance, and controlling the aircraft to perform fixed-point braking according to the average deceleration rate.

[0008] Optionally, the preset braking speed is 25-30km / h.

[0009] Optionally, the method for determining the remaining braking distance includes: obtaining the runway terminal position, the preset braking point and the current position of the aircraft, and determining the remaining braking distance based on the runway terminal position, the preset braking point and the current position of the aircraft.

[0010] Optionally, the target deceleration rate is directly proportional to the load utilization index.

[0011] Optionally, the aircraft is controlled to perform fixed-point braking according to the target deceleration rate and the preset braking distance, including: determining the actual braking distance, and when it is determined that the actual braking distance is equal to the preset braking distance, controlling the aircraft to perform fixed-point braking according to the target deceleration rate; when it is determined that the actual braking distance is greater than or less than the preset braking distance, adjusting the load utilization index so that the actual braking distance is equal to the preset braking distance; determining a revised target deceleration rate according to the adjusted load utilization index, and controlling the aircraft to perform fixed-point braking according to the revised target deceleration rate.

[0012] Optionally, when it is determined that the actual braking distance is greater than or less than the preset braking distance, the load utilization index is adjusted, including: when the actual braking distance is greater than the preset braking distance, the load utilization index is adjusted upward; when the actual braking distance is less than the preset braking distance, and the difference between the actual braking distance and the preset braking distance is greater than the preset difference, the load utilization index is adjusted downward.

[0013] Optionally, the method for determining the preset braking distance includes: obtaining the runway terminal position, the preset braking point and the starting braking point, and determining the preset braking distance according to the runway terminal position, the fixed braking point and the starting braking point.

[0014] Optionally, the method for determining the actual braking distance includes: obtaining the current braking speed and current deceleration rate of the aircraft, and determining the remaining actual braking distance based on the current braking speed and current deceleration rate; obtaining the braking distance, and taking the sum of the braking distance and the remaining actual braking distance as the actual braking distance.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses an adaptive control method for fixed-point braking of an aircraft. On the premise of considering the capacity margin, a relationship curve between an aircraft load utilization index and an aircraft speed is established. According to the aircraft load utilization index, target deceleration rates at different times are determined. The capacity margin is eliminated below the anti-skid failure speed to realize fixed-point braking of the aircraft. In the process of braking the aircraft, the aircraft load utilization index is used to correct the target deceleration rate in combination with the difference between the actual braking distance and the preset braking distance, so as to avoid the difference between the actual braking distance and the preset braking distance caused by other factors. The invention solves the problems that the conventional braking control method is difficult to accurately match the fixed-point braking distance, has a large deviation, and has a high probability of exceeding the fixed-point distance. The invention can greatly reduce the pressure on the pilot or the remote control, so as to significantly improve the braking maneuverability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A flowchart of an adaptive control method for fixed-point braking of an aircraft is provided in this application; Figure 2 The present invention discloses a relationship curve between load utilization index and braking speed in an adaptive control method for fixed-point braking of an aircraft.

[0017] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0019] The first embodiment of the present invention provides an aircraft fixed-point braking adaptive control method, such as Figure 1 As shown, the specific steps include: Step S1, after receiving the braking command, determining a preset braking distance; Specifically, the method for determining the preset braking distance includes: obtaining the runway terminal position s 0 , preset braking point z and starting braking point s q , according to the runway terminal position, fixed braking point and starting braking point, determine the preset braking distance. The calculation formula of the preset braking distance s is as follows: s=s q-0 -s z-0 Step S2, based on the relationship curve between load utilization index and braking speed, such as Figure 2 , determine the load utilization index corresponding to different braking speeds; wherein, the relationship curve between the load utilization index and the braking speed is obtained by adjusting the original relationship curve between the load utilization index and the braking speed according to the capacity margin of the preset value, and the preset value can be 0.5-1%.

[0020] It can be understood that the load utilization index refers to the ability to utilize the ground friction force, which is related to the variable load process and speed of the aircraft landing braking process. The smaller the load, the smaller the ground friction force, and the smaller the load utilization index: the smaller the speed, the easier it is to lock the wheels, and the smaller the load utilization index. On the contrary, the larger it is. Specifically, the relationship curve between the load utilization index and the braking speed of this embodiment is an original curve pre-established based on empirical values. The empirical values ​​include the original braking speed and the corresponding load utilization index. On the original relationship curve, the original load utilization index is adjusted upward under the condition of considering the capacity margin to obtain the relationship curve. In addition, the integral value generated by the original relationship curve is the preset braking distance. After the load utilization index is adjusted upward, the integral value generated by the obtained relationship curve becomes smaller, and the difference between the relationship curves before and after the adjustment is obtained by reserving the capacity margin. Further, the increase in the load utilization index is carried out in the 210km / h~50km / h stage.

[0021] Step S3, determining the target deceleration rate at different times according to the load utilization index and the relationship between the load utilization index and the target deceleration rate; wherein the target deceleration rate a t It is directly proportional to the load utilization index m, specifically: a t =km, k is a constant with a value of 0.5-1.5.

[0022] In this embodiment, after the load utilization index is determined in the relationship curve according to the braking speed, the target deceleration rate at the current moment can be obtained according to the relationship between the target deceleration rate and the load utilization index.

[0023] Step S4, controlling the aircraft to perform fixed-point braking according to the target deceleration rate and the preset braking distance; Specifically, the current actual braking distance is determined, the preset braking distance and the actual braking distance are compared, and based on the comparison result, the aircraft is controlled to perform fixed-point braking.

[0024] In this embodiment, during the braking process of the aircraft, the aircraft may slip due to changes in ground conditions, resulting in an increase in the actual braking distance, or the actual braking distance may decrease due to factors such as large brake disc torque, so the difference between the preset braking distance and the actual braking distance is determined in real time after the braking begins. For these two abnormal situations, the target deceleration rate needs to be corrected to make the actual braking distance equal to the preset braking distance, that is, the aircraft stops at the preset braking point, and the fixed-point braking is achieved. The specific method is as follows.

[0025] Step S41, determining the current actual braking distance, and when it is determined that the preset braking distance is equal to the actual braking distance, controlling the aircraft to perform fixed-point braking according to the target deceleration rate; Step S42, when it is determined that the actual braking distance is greater than or less than the preset braking distance, the load utilization index is adjusted to make the actual braking distance equal to the preset braking distance, that is, to ensure that the integral value of the relationship curve remains unchanged, and the corrected target deceleration rate is determined according to the adjusted load utilization index, and the aircraft is controlled to perform fixed-point braking according to the corrected target deceleration rate.

[0026] There are two specific situations: Case 1: When the actual braking distance is greater than the preset braking distance, the load utilization index is adjusted upward; In this case, if the current control strategy is followed, the aircraft will stop after the preset braking point. At this time, the load utilization index needs to be adjusted upward to obtain the corrected target deceleration rate, thereby reducing the actual braking distance and automatically compensating for the distance loss. When it is determined that the value of the load utilization index increase is greater than the preset increase, an over-limit alarm is issued.

[0027] Case 2: When the actual braking distance is less than the preset braking distance, and the difference between the actual braking distance and the preset braking distance is greater than the preset difference, the load utilization index is lowered.

[0028] In this case, if the current control strategy is followed, the aircraft will stop before the preset braking point. At this time, the load utilization index needs to be lowered to obtain the corrected target deceleration rate, thereby increasing the actual braking distance and automatically extending the distance.

[0029] The method for determining the actual braking distance includes: obtaining the current braking speed and current deceleration rate of the aircraft, and determining the actual braking distance according to the current braking speed v n and the current deceleration rate a n , determine the remaining real braking distance; the remaining real braking distance s r The calculation formula is: v n 2 -v 0 2 =2a n s r The braking distance is obtained, and the sum of the braking distance and the remaining actual braking distance is taken as the actual braking distance.

[0030] Since the relationship curve between load utilization index and braking speed is obtained by considering the capacity margin of the preset value, it is necessary to consider eliminating the capacity margin in the later stage so that the actual braking distance is equal to the preset braking distance, that is, to ensure that the integral value of the relationship curve remains unchanged and achieve fixed-point braking. The specific method of eliminating the capacity margin is as follows.

[0031] Step S5, when the braking speed reaches the preset braking speed, the average deceleration rate of the aircraft is determined according to the remaining braking distance, and the aircraft is controlled to perform fixed-point braking according to the average deceleration rate. The preset braking speed can be 25-30 km / h. The calculation formula of the average deceleration rate a is as follows: v t 2 -v 0 2 =2as In the formula, v t is the current braking speed, v 0 is the termination braking speed, generally 0, and s is the remaining braking distance.

[0032] It can be understood that the remaining braking distance is the distance between the current position and the preset braking point. The method for determining the remaining braking distance includes: obtaining the runway terminal position, the preset braking point and the current position of the aircraft, and determining the remaining braking distance based on the runway terminal position, the preset braking point and the current position of the aircraft. Specifically, the distance from the current position of the aircraft to the runway terminal position minus the distance from the preset braking point to the runway terminal position.

[0033] In this embodiment, under the premise of considering the capacity margin, a relationship curve between the aircraft load utilization index and the aircraft speed is established, the target deceleration rate at different times is determined according to the aircraft load utilization index, and the capacity margin is eliminated below the anti-skid failure speed to achieve aircraft fixed-point braking; in the process of aircraft braking, the aircraft load utilization index is used to correct the target deceleration rate in combination with the difference between the actual braking distance and the preset braking distance to avoid the difference between the actual braking distance and the preset braking distance due to other factors, thereby solving the problem that conventional braking control methods are difficult to accurately match the fixed-point braking distance, have large deviations, and have a high probability of exceeding the fixed-point distance; the aircraft fixed-point braking adaptive control method greatly reduces the pressure on the pilot or remote control, and significantly improves the braking maneuverability.

[0034] Example 1 Step S1, after receiving a brake command with a fixed-point brake flag abs_auto=1 and a brake command data voting flag abs_vote=1, q-0 200m,s z-0 is 1000m, determine the preset braking distance s=800m; Step S2, establishing a relationship curve between the original load utilization index and the braking speed based on the empirical value, taking into account the 0.5% capacity margin, and adjusting the original load utilization index upward at a braking speed of 210 km / h to 50 km / h to obtain a relationship curve between the load utilization index and the braking speed, and the integral value generated by the relationship curve, i.e., the braking distance s=795m, is calculated based on the preset relationship curve between the load utilization index and the braking speed to determine the load utilization index corresponding to different braking speeds; Step S3, determining the target deceleration rate at different times according to the load utilization index and the relationship between the load utilization index and the target deceleration rate; Step S4, during the braking process, there was a slip at 200km / h, causing the actual braking distance to be greater than the preset braking distance by 20m, i.e. an increase of 20m. After the system stabilized after the slip, the load utilization index was increased, the target deceleration rate was corrected, the distance loss was automatically compensated, and the braking distance s=795m remained unchanged, and no alarm was given.

[0035] Step S5: after the braking speed is less than 25 km / h, the average deceleration rate of the aircraft is determined to be 1.15 m / s based on the remaining braking distance. 2 , reduce the brake pressure to match the average deceleration rate, and control the aircraft to perform fixed-point braking. The reduced brake pressure can eliminate the capacity margin of 5m and achieve fixed-point braking.

[0036] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. An adaptive control method for aircraft fixed-point braking, characterized in that: include: After receiving the braking command, determining the preset braking distance; Based on the relationship curve between load utilization index and braking speed, determine the load utilization index corresponding to different braking speeds; Determining target deceleration rates at different times according to the load utilization index and the relationship between the load utilization index and the target deceleration rate; The aircraft is controlled to perform fixed-point braking according to the target deceleration rate and the preset braking distance.

2. The aircraft fixed-point braking adaptive control method according to claim 1, characterized in that: The method for determining the relationship curve between the load utilization index and the braking speed includes: A relationship curve between the original load utilization index and the braking speed is established based on the historical load utilization index and the braking speed; According to the capacity margin of the preset value, the historical load utilization index in the relationship curve between the original load utilization index and the braking speed is adjusted to obtain the relationship curve between the load utilization index and the braking speed.

3. The aircraft fixed-point braking adaptive control method according to claim 2, characterized in that: The preset value is 0.5-1%.

4. The aircraft fixed-point braking adaptive control method according to claim 2, characterized in that: After controlling the aircraft to perform fixed-point braking according to the target deceleration rate, the method further includes: When the braking speed reaches the preset braking speed, the average deceleration rate of the aircraft is determined according to the remaining braking distance, and the aircraft is controlled to perform fixed-point braking according to the average deceleration rate.

5. The aircraft fixed-point braking adaptive control method according to claim 4, characterized in that: The preset braking speed is 25-30 km / h.

6. The aircraft fixed-point braking adaptive control method according to claim 4, characterized in that: The method for determining the remaining braking distance includes: The runway terminal position, the preset braking point and the current position of the aircraft are obtained, and the remaining braking distance is determined according to the runway terminal position, the preset braking point and the current position of the aircraft.

7. The aircraft fixed-point braking adaptive control method according to claim 1, characterized in that: The target deceleration rate is in direct proportion to the load utilization index.

8. The aircraft fixed-point braking adaptive control method according to claim 1, characterized in that: The step of controlling the aircraft to perform fixed-point braking according to the target deceleration rate and the preset braking distance includes: determining a real braking distance, and when it is determined that the real braking distance is equal to a preset braking distance, controlling the aircraft to perform fixed-point braking according to the target deceleration rate; When it is determined that the actual braking distance is greater than or less than the preset braking distance, the load utilization index is adjusted so that the actual braking distance is equal to the preset braking distance; The modified target deceleration rate is determined according to the adjusted load utilization index, and the aircraft is controlled to perform fixed-point braking according to the modified target deceleration rate.

9. The aircraft fixed-point braking adaptive control method according to claim 8, characterized in that: When determining that the actual braking distance is greater than or less than the preset braking distance, adjusting the load utilization index includes: When the actual braking distance is greater than the preset braking distance, the load utilization index is adjusted upward; When the actual braking distance is less than the preset braking distance, and the difference between the actual braking distance and the preset braking distance is greater than the preset difference, the load utilization index is adjusted downward.

10. The aircraft fixed-point braking adaptive control method according to claim 8, characterized in that: The method for determining the preset braking distance includes: The runway terminal position, the preset braking point and the starting braking point are obtained, and the preset braking distance is determined according to the runway terminal position, the fixed braking point and the starting braking point. The method for determining the actual braking distance includes: Acquire the current braking speed and the current deceleration rate of the aircraft, and determine the remaining actual braking distance according to the current braking speed and the current deceleration rate; The braking distance is obtained, and the sum of the braking distance and the remaining actual braking distance is used as the actual braking distance.

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