A method and device for identifying critical skidding state during aircraft braking

Abstract

This invention provides a method and device for identifying critical skid states during aircraft braking, belonging to the field of aircraft braking control technology. This invention determines whether adaptive braking is needed based on aircraft speed, left pilot braking commands, and right pilot braking commands, and when adaptive braking is required, it sets a critical skid state flag L. S Set to 1; calculate the slip ratio of adaptive braking; then identify the critical slip state of braking based on the slip ratio, realize the aircraft braking control in the critical slip state of braking, achieve the purpose of braking torque equal to ground contact torque, put the braking control system in the critical slip state, fully utilize the braking capacity, and significantly improve braking efficiency.

Description

Technical Field

[0001] This invention belongs to the field of aircraft brake control technology, and in particular relates to a method and device for identifying critical slippage state of aircraft brakes. Background Technology

[0002] During takeoff and landing, the efficiency of braking determines the braking distance, directly impacting aircraft safety during takeoff and landing. Braking efficiency generally refers to the ratio of the actual braking pressure used to the source pressure when the pilot fully depresses the accelerator pedal. The braking process involves a combination of rolling and sliding friction, with the slip ratio of sliding friction determining the slippage state during braking. When the braking torque is less than the ground contact torque, it indicates low braking pressure, underutilization of braking power, and low braking efficiency. When the braking torque is greater than the ground contact torque, it indicates high braking pressure; to prevent wheel lock-up, the brake control system reduces braking pressure to prevent slippage, also resulting in low braking efficiency. When the braking torque equals the ground contact torque, the brake control system is in a critical slippage state, where braking capacity is fully utilized, resulting in the highest braking efficiency.

[0003] Conventional braking control methods do not recognize critical slip conditions. After the pilot fully depresses the brakes, they use rated braking pressure for control. Under rated braking pressure, in most cases, the braking torque is either less than or greater than the ground contact torque, resulting in low braking efficiency and incomplete utilization of braking capacity. Conventional anti-skid braking control methods have the following drawbacks: 1. They do not identify critical slip conditions, leading to low braking efficiency and safety; 2. During slippage, the aircraft experiences pitching, resulting in poor comfort; 3. During slippage, tires experience excessive wear, shortening tire life. Summary of the Invention

[0004] To address the problems of low braking efficiency, low safety, poor comfort, and short tire life in existing anti-skid braking control methods that do not identify critical skid states, this invention proposes a method and device for identifying critical skid states during aircraft braking. The technical solution is as follows:

[0005] Firstly, a method for identifying critical skidding states during aircraft braking is provided, including:

[0006] Step 1: Determine whether adaptive braking is needed based on aircraft speed, left pilot's braking command, and right pilot's braking command. If adaptive braking is needed, set the critical skid state flag L. S Set to 1;

[0007] Step 2: Mark L at the critical braking slippage state. S When set to 1, calculate the slip ratio of adaptive braking;

[0008] Step 3: Identify the critical slippage state of braking based on slip ratio.

[0009] Optionally, step one includes:

[0010] Determine the aircraft speed V P Is it greater than or equal to the anti-slip failure speed 'a'?

[0011] Determine the left pilot's brake command U L Right pilot brake command U R Are they all greater than or equal to the full travel U of the pilot's braking command? M b%; b is the percentage of the full travel of the pilot's braking command, U M Full-stroke voltage for the pilot's braking command;

[0012] If the aircraft speed V P ≥a, Left pilot brake command U L ≥b%U M And the right pilot's brake command U R ≥b%U M It was determined that adaptive braking was required.

[0013] Furthermore, when adaptive braking is not required, the braking critical slippage state flag L is set. S Set to 0.

[0014] Optionally, step two includes:

[0015] L, the indicator for critical brake slippage S When set to 1, the slip ratio is calculated based on the aircraft speed and wheel speed.

[0016] Optionally, step three includes:

[0017] Calculate the slip ratio variation trend of adaptive braking based on slip ratio;

[0018] When the adaptive braking slip ratio changes trend close to 0, the adaptive braking slip ratio change trend is determined as the critical braking slip state.

[0019] Optionally, the adaptive braking slip ratio change trend is calculated once per calculation cycle, with a calculation cycle of 40ms to 100ms.

[0020] Secondly, a device for identifying critical skidding states during aircraft braking is provided, comprising:

[0021] The judgment module is used to determine whether adaptive braking is needed based on aircraft speed, left pilot's braking command, and right pilot's braking command. When adaptive braking is needed, it sets the braking critical slip state flag L. S Set to 1;

[0022] The calculation module is used to detect the critical skid state flag L during braking. S When set to 1, calculate the slip ratio of adaptive braking;

[0023] The identification module is used to identify the critical slippage state of braking based on the slip ratio.

[0024] Optionally, the judgment module is specifically used for:

[0025] Determine the aircraft speed V P Is it greater than or equal to the anti-slip failure speed 'a'?

[0026] Determine the left pilot's brake command U L Right pilot brake command U R Are they all greater than or equal to the full travel U of the pilot's braking command? M b%; b is the percentage of the full travel of the pilot's braking command, U M Full-stroke voltage for the pilot's braking command;

[0027] If the aircraft speed V P ≥a, Left pilot brake command U L ≥b%U M And the right pilot's brake command U R ≥b%U M It was determined that adaptive braking was required.

[0028] Optionally, the calculation module is specifically used for:

[0029] L, the indicator for critical brake slippage S When set to 1, the slip ratio is calculated based on the aircraft speed and wheel speed.

[0030] Optionally, the identification module is specifically used for:

[0031] Calculate the slip ratio variation trend of adaptive braking based on slip ratio;

[0032] When the adaptive braking slip ratio changes trend close to 0, the adaptive braking slip ratio change trend is determined as the critical braking slip state.

[0033] Compared to conventional anti-skid braking control methods, this invention identifies the critical skid state by calculating the trend η of adaptive braking slip ratio change. It has the function of identifying the critical skid state of braking. When working in the critical skid state, there is no anti-skid and no pitching phenomenon, so the comfort is high. When working in the critical skid state, there is no anti-skid and no excessive tire wear, so the tire life is long.

[0034] The aircraft braking critical slip state identification method provided by this invention uses aircraft speed V P Left pilot brake command U LRight pilot brake command U R The system determines whether adaptive braking should be initiated. If adaptive braking is initiated, the adaptive braking slip ratio λ is calculated, and then the trend of the adaptive braking slip ratio change η is calculated. When the trend of the adaptive braking slip ratio change η approaches 0, the critical braking slip state η0 is confirmed, thus completing the identification of the aircraft's critical braking slip state.

[0035] This invention enables aircraft braking control under the critical slip condition η0, achieving a braking torque equal to the ground contact torque. This keeps the braking control system in a critical slip condition, fully utilizing braking capacity and significantly improving braking efficiency. In contrast, conventional anti-slip braking control methods cannot identify the critical slip condition, cannot prevent slippage, and suffer from low braking efficiency, low safety, poor comfort, and short tire life. Attached Figure Description

[0036] Figure 1 This is a flowchart of a method for identifying critical skidding state of aircraft braking provided by an embodiment of the present invention. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0038] This invention provides a control method based on an anti-skid braking system. The anti-skid braking system is applicable to fly-by-wire anti-skid braking systems.

[0039] This invention provides a method for identifying critical skid states during aircraft braking, which is an adaptive anti-skid braking control method based on road condition recognition. This method uses pilot braking commands, aircraft speed, and wheel speed as inputs. Through calculation, it identifies critical skid states during aircraft braking, achieves adaptive braking control, fully utilizes braking performance, and improves braking efficiency. Figure 1 As shown, the present invention provides a method for identifying critical skidding states during aircraft braking, comprising the following steps:

[0040] Step 1: Determine whether adaptive braking is needed based on aircraft speed, left pilot's braking command, and right pilot's braking command. If adaptive braking is needed, set the critical skid state flag L. S Set to 1.

[0041] Step one specifically includes the following sub-steps:

[0042] 1. Determine the aircraft's speed V P Is it greater than or equal to the anti-slip failure speed a km / h?

[0043] 2. Determine the left pilot's brake command U L Right pilot brake command UR Are they all greater than or equal to the full travel U of the pilot's braking command? M b%. Where a is the anti-skid failure speed, typically 20km / h to 30km / h; b is the percentage of the full travel of the pilot's braking command, typically 80% to 90%. M The voltage at full stroke for the pilot's braking command is typically 4V to 5V.

[0044] 3. If the aircraft speed V P ≥a, Left pilot brake command U L ≥b%U M And the right pilot's brake command U R ≥b%U M Determine if adaptive braking is needed, and when adaptive braking is needed, set the braking critical slip state flag L. S Set to 1; otherwise, set the brake critical slippage status flag L. S Set to 0.

[0045] This step determines whether adaptive braking should be performed. If adaptive braking is performed, it indicates an urgent need for emergency braking, requiring identification of critical skidding conditions to improve braking efficiency and shorten braking distance. If adaptive braking is not performed, it indicates that the pilot does not have an urgent need for emergency braking, and the response output can be adjusted according to the pilot's actual braking command.

[0046] Step 2: Mark L at the critical braking slippage state. S When set to 1, calculate the slip ratio of adaptive braking.

[0047] L, the indicator for critical brake slippage S When set to 1, according to formula (1), based on the aircraft speed V P and wheel speed V W Calculate the slip ratio λ:

[0048]

[0049] The slip ratio reflects the slip speed of the wheels. A higher slip ratio results in better braking and deceleration, but also a greater risk of wheel lockup; a lower slip ratio results in worse braking and deceleration. This step is an intermediate calculation process for identifying the critical slip state during braking.

[0050] Step 3: Identify the critical slippage state of braking based on slip ratio.

[0051] The adaptive braking slip ratio change trend η is calculated using formula (2). When the adaptive braking slip ratio change trend η approaches 0, it is determined as the critical braking slip state η0. The adaptive braking slip ratio change trend η approaching 0 refers to a certain threshold range, usually ranging from 0.05 to 0.

[0052] η=df(λ) / dλ (2)

[0053] This step calculates the adaptive braking slip ratio change trend η. When the adaptive braking slip ratio change trend η approaches 0, the critical braking slip state η0 is obtained, indicating that the braking slip ratio has reached its optimal state, and the braking torque is approximately equal to the ground contact torque, thus realizing the identification of the critical braking slip state. If the adaptive braking slip ratio change trend η becomes negative, it indicates that the braking torque is greater than the ground contact torque, which will cause the braking system to release pressure during anti-skid maneuvers, thereby reducing braking efficiency. Setting a threshold range for the adaptive braking slip ratio change trend η to approach 0 is to prevent system overshoot. The adaptive braking slip ratio change trend η is calculated once per calculation cycle, with a calculation cycle of 40ms to 100ms.

[0054] An embodiment of the present invention provides a method for identifying critical skidding state of aircraft braking, comprising the following steps:

[0055] Step 1: Determine whether adaptive braking should be performed.

[0056] The anti-skid failure speed 'a' is set to 25 km / h; the pilot's braking command full travel U M The value is 5V; the percentage b of the full travel of the pilot's braking command is 85%.

[0057] When the aircraft speed V P =202km / h, and the left pilot brake command U L =5V, and the right pilot's brake command U R =5V, meets the requirements for adaptive braking, braking critical slip state indicator L S Set to 1.

[0058] Step 2: Calculate the slip ratio λ of adaptive braking.

[0059] In the first calculation cycle, the aircraft speed V P =202km / h, wheel speed V W =187.86km / h. Using formula (1), the slip ratio λ1 = 0.07 is calculated.

[0060] The second calculation cycle, aircraft speed V P =199km / h, wheel speed V W=179.1km / h. Using formula (1), the slip ratio λ2 = 0.1 is calculated.

[0061] The third calculation cycle, aircraft speed V P =198km / h, wheel speed V W =174.24km / h. Using formula (1), the slip ratio λ3 = 0.12 is calculated.

[0062] The fourth calculation cycle, aircraft speed V P =197km / h, wheel speed V W =172.375km / h. Using formula (1), the slip ratio λ4 = 0.125 is calculated.

[0063] Step 3: Identify the critical braking slip state η0 based on the slip ratio λ.

[0064] In the first calculation cycle, λ1 = 0.07; in the second calculation cycle, λ2 = 0.1; in the third calculation cycle, λ3 = 0.12; and in the fourth calculation cycle, λ4 = 0.13. η2 = 0.3; η3 = 0.17; and η4 = 0.04 are calculated using formula (2).

[0065] When the adaptive braking slip ratio change trend η4 = 0.04, the critical braking slip state η0 = η4 is confirmed, indicating that the braking slip ratio has reached the optimal state and the braking torque is basically equal to the ground contact torque, thus realizing the identification of the critical braking slip state.

[0066] Another embodiment of the present invention provides a method for identifying critical skidding state of aircraft braking, comprising the following steps:

[0067] Step 1: Determine whether adaptive braking should be performed.

[0068] The anti-skid failure speed 'a' is set to 30 km / h; the pilot's braking command full travel U M The value is 5V; the percentage b of the full travel of the pilot's braking command is 85%.

[0069] When the aircraft speed V P =200km / h, and the left pilot brake command U L =4.8V, and the right pilot's brake command U R =4.8V, meets the requirements for adaptive braking, braking critical slippage state indicator L S Set to 1.

[0070] Step 2: Calculate the slip ratio λ of adaptive braking.

[0071] In the first calculation cycle, the aircraft speed V P =200km / h, wheel speed VW =185km / h. Using formula (1), the slip ratio λ1 = 0.075 is calculated.

[0072] The second calculation cycle, aircraft speed V P =198km / h, wheel speed V W =183km / h. Using formula (1), the slip ratio λ2 = 0.076 is calculated.

[0073] Step 3: Identify the critical braking slip state η0 based on the slip ratio λ.

[0074] In the first calculation cycle, λ1 = 0.075; in the second calculation cycle, λ2 = 0.076, and η2 = 0.013 is calculated using formula (2).

[0075] When the adaptive braking slip ratio change trend η2 = 0.013, the critical braking slip state η0 = η2 is confirmed, indicating that the braking slip ratio has reached the optimal state and the braking torque is basically equal to the ground contact torque, thus realizing the identification of the critical braking slip state.

[0076] The present invention also provides an aircraft braking critical slip state identification device, comprising:

[0077] The judgment module is used to determine whether adaptive braking is needed based on aircraft speed, left pilot's braking command, and right pilot's braking command. When adaptive braking is needed, it sets the braking critical slip state flag L. S Set to 1;

[0078] The calculation module is used to detect the critical skid state flag L during braking. S When set to 1, calculate the slip ratio of adaptive braking;

[0079] The identification module is used to identify the critical slippage state of braking based on the slip ratio.

[0080] Optionally, the judgment module is specifically used for:

[0081] Determine the aircraft speed V P Is it greater than or equal to the anti-slip failure speed 'a'?

[0082] Determine the left pilot's brake command U L Right pilot brake command U R Are they all greater than or equal to the full travel U of the pilot's braking command? M b%; b is the percentage of the full travel of the pilot's braking command, U M Full-stroke voltage for the pilot's braking command;

[0083] If the aircraft speed V P ≥a, Left pilot brake command UL ≥b%U M And the right pilot's brake command U R ≥b%U M It was determined that adaptive braking was required.

[0084] Optionally, the calculation module is specifically used for:

[0085] L, the indicator for critical brake slippage S When set to 1, the slip ratio is calculated based on the aircraft speed and wheel speed.

[0086] Optionally, the identification module is specifically used for:

[0087] Calculate the slip ratio variation trend of adaptive braking based on slip ratio;

[0088] When the adaptive braking slip ratio changes trend close to 0, the adaptive braking slip ratio change trend is determined as the critical braking slip state.

[0089] The above description merely illustrates embodiments of the present invention and is quite specific and detailed; however, it should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Furthermore, any parts of the present invention not described in detail are conventional techniques.

Claims

1. A method for identifying critical skidding state during aircraft braking, characterized in that, include: Step one, according to the aircraft speed, left pilot brake instruction, right pilot brake instruction to determine whether to need to carry out adaptive braking, and when need to carry out adaptive braking, the brake critical slip state flag L S is set to 1: Determine the aircraft speed V P Is it greater than or equal to the anti-slip failure speed 'a'? Determine the left pilot's brake command U L Right pilot brake command U R Are they all greater than or equal to the full travel U of the pilot's braking command? M b%; b is the percentage of the full travel of the pilot's braking command, U M Full-stroke voltage for the pilot's braking command; If the aircraft speed V P ≥a, Left pilot brake command U L ≥b%U M And the right pilot's brake command U R ≥b%U M Adaptive braking is required; a) value is 20km / h~30km / h; b) value is 80%~90%, U M Value range: 4V to 5V; Step 2: Mark L at the critical braking slippage state. S When set to 1, the slip ratio is calculated based on the aircraft speed and wheel speed; Step 3: Identify the critical slippage state of braking based on slip ratio.

2. The method according to claim 1, characterized in that, When adaptive braking is not required, the critical brake slippage state flag L is set. S Set to 0.

3. The method according to claim 1, characterized in that, Step three includes: Calculate the slip ratio variation trend of adaptive braking based on slip ratio; When the adaptive braking slip ratio changes trend close to 0, the adaptive braking slip ratio change trend is determined as the critical braking slip state.

4. The method according to claim 3, characterized in that, The adaptive braking slip ratio change trend is calculated once per calculation cycle, which is 40ms to 100ms.

5. A device for identifying critical skidding state during aircraft braking, characterized in that, include: The judgment module is used to determine whether adaptive braking is needed based on aircraft speed, left pilot's braking command, and right pilot's braking command. When adaptive braking is needed, it sets the braking critical slip state flag L. S Set to 1; The calculation module is used to detect the critical skid state flag L during braking. S When set to 1, the slip ratio is calculated based on the aircraft speed and wheel speed; The identification module is used to identify the critical slippage state of braking based on the slip ratio; The judgment module is specifically used for: Determine the aircraft speed V P Is it greater than or equal to the anti-slip failure speed 'a'? Determine the left pilot's brake command U L Right pilot brake command U R Are they all greater than or equal to the full travel U of the pilot's braking command? M b%; b is the percentage of the full travel of the pilot's braking command, U M Full-stroke voltage for the pilot's braking command; If the aircraft speed V P ≥a, Left pilot brake command U L ≥b%UM, and right pilot brake command U R ≥b%UM indicates that adaptive braking is required.

6. The apparatus according to claim 5, characterized in that, The recognition module is specifically used for: Calculate the slip ratio variation trend of adaptive braking based on slip ratio; When the adaptive braking slip ratio changes trend close to 0, the adaptive braking slip ratio change trend is determined as the critical braking slip state.

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