A method for suppressing aircraft brake pressure overshoot control

Abstract

The application discloses a kind of inhibiting aircraft brake pressure overshoot control method, considering that the step change of brake pressure can produce moment mutation, so as to cause wheel to enter frequent skidding state, if not timely pressure relief, brake pitch, brake efficiency is low, tire wear problem is prone to appear, the application is based on aircraft sliding speed according to left / right brake command signal, brake pressure speed-up control is carried out, can effectively avoid the frequent skidding of wheel caused by brake moment overshoot change, simultaneously, on the basis of pressure speed-up control, left / right brake pressure consistency control is carried out, so that aircraft can complete stable, efficient brake in normal landing brake process, improve the reliability and safety of brake system, and increase the brake distance of inhibiting overshoot control rear brake system under the same working condition, improve the deceleration rate, and avoid anti-skid work, brake performance is obviously improved.

Description

Technical Field

[0001] This invention relates to the field of aircraft brake control technology, specifically a method for suppressing aircraft brake pressure overshoot based on aircraft taxiing speed and left wheel brake command value / right wheel brake command value. Background Technology

[0002] Aircraft anti-skid braking systems involve numerous nonlinear factors, among which brake disc performance and brake pressure control are crucial factors directly affecting anti-skid braking performance. Since the aircraft landing roll is relatively short, the anti-skid braking system must be designed to minimize pressure overshoot and ensure brake control stability.

[0003] Analysis of the braking performance of existing aircraft brake discs revealed that during braking, a significant increase in braking pressure to the braking system can cause a braking torque surge in the brake disc. This problem is more pronounced at high speeds and on carbon-ceramic brake discs. This torque surge can lead to frequent wheel slippage, potentially causing pitching issues, increasing braking distance, reducing braking efficiency, and decreasing pilot comfort.

[0004] In summary, most aircraft use a command-pressure-following control method, which has the following drawbacks:

[0005] 1. When the braking command is large, the pressure control increases sharply, which can easily cause the brake disc to experience a braking torque surge, resulting in deep slippage and, in severe cases, causing the aircraft to pitch down.

[0006] 2. When the left and right brake pressures are inconsistent, it increases the pilot's workload in correcting course.

[0007] 3. Frequent slippage after the moment of impact reduces braking efficiency and increases braking distance.

[0008] When an aircraft brakes during an emergency landing, the shortcomings of the step pressure control method become increasingly apparent. In this situation, the pilot urgently needs the aircraft to brake quickly, and the control input braking command is usually large. The torque generated by the brake disc increases sharply, causing the wheels to slip frequently, the braking pressure on the left and right sides to be inconsistent, the aircraft to deviate from its braking course, and the braking efficiency to be reduced. In severe cases, it can cause tire wear.

[0009] Essentially, these issues stem from the fact that the brake control design failed to consider the torque characteristics of the brake discs. Braking control requires making efficient use of the runway's engagement force to bring the aircraft to a stop in the shortest possible distance. Therefore, during braking, the pressure rise mechanism should be appropriately controlled to match the brake disc torque characteristics; simultaneously, the aircraft's operational status should be considered to minimize the pilot's workload.

[0010] In summary, based on the characteristics of the brake disc and the aircraft's operating conditions, designing a method to suppress brake pressure overshoot is crucial for the safety and reliability of the braking system.

[0011] A search of domestic and international patent literature and academic paper databases revealed no technology identical to this invention.

[0012] In the existing technology, the brake pressure is controlled by outputting a brake control signal in real time according to the magnitude of the brake command signal. The shortcoming of this technology is that it does not take into account the torque overshoot of the brake disc. When the brake pressure approaches the rated brake pressure value, the brake torque surges sharply, causing frequent slippage and affecting braking efficiency. Summary of the Invention

[0013] To overcome the shortcomings of existing technologies that cause frequent slippage due to brake pressure overshoot, leading to reduced braking efficiency, this invention proposes a method for controlling aircraft brake pressure overshoot.

[0014] The specific process of this invention is as follows:

[0015] Step 1: Obtain the aircraft's current braking command and taxiing speed status;

[0016] When acquiring the aircraft's current braking command and taxiing speed status, the brake command signal from the brake command sensor is collected via the brake controller; the brake command signal includes the left brake command V. L And right brake command V R The brake controller obtains the aircraft's taxiing speed V from the host computer. 滑 .

[0017] Step 2, determine the overshoot control parameters during braking:

[0018] Determine the control threshold V0 for the braking command to enter the pressure ramp;

[0019] The control thresholds include the left control threshold V. 0L and right control threshold V 0R And the left control threshold equals the right control threshold.

[0020] Determine the pressure ramp command increase rate a0;

[0021] The pressure ramp command increase rate a0 includes the pressure ramp command increase rate a0 of the left brake command signal. 0L The pressure ramp command increase rate a of the right brake command signal 0R Furthermore, the pressure ramp command of the left brake command signal increases at a rate a. 0L =Right brake command signal pressure ramp command increase rate a 0R .

[0022] Step 3, Pressure Overshoot Control:

[0023] When the aircraft's taxiing speed V 滑 ≥25 +5 At speeds of km / h, the following controls shall be applied:

[0024] Left brake command V L And right brake command V R The desired direct braking control command V is obtained through the process. LC and V RC Among them, V LC The command is for the left side to directly participate in braking control, V RC This is a command that directly involves braking control on the right side.

[0025] Compare left brake command V L With left control threshold V 0L The size of the right brake command V is compared simultaneously. R With right control threshold V 0R The magnitude of the value is used to calculate the command V that directly participates in braking control. LC and V RC ;

[0026] In pressure overshoot control, the command V that directly participates in braking control is calculated. LC and V RC The results may fall into one of the following four categories:

[0027] The first type, when V L ≤V 0L And V R ≤V 0R The left brake command signal V that actually participates in brake control LC =V L V RC =V R .

[0028] The second type, when V L >V 0L And V R ≤V 0R With the aforementioned V 0L Starting from the left brake command signal, the pressure ramp command increases at a rate of a. 0L Adding the brake command signal that actually participates in brake control, we obtain the left brake command signal V. LC ; with the left brake command signal V LC This serves as the braking command signal on the left that actually participates in braking control. The right side maintains V. RC =V R .

[0029] The third type, when V R >V0R And V L ≤V 0L With the aforementioned V 0R Starting from the right brake command signal, the pressure ramp command increases at a rate of a. 0R Adding the brake command signal that actually participates in brake control, we obtain the left brake command signal V. RC ; with the left brake command signal V RC This serves as the braking command signal that actually participates in braking control on the left side. The left side maintains V. LC =V L .

[0030] The fourth type, when V R >V 0R And V L >V 0L Left and right brake commands enter pressure ramp control, while V is compared. L and V R The magnitude of the value determines the time T when the left side enters pressure ramp control. L And the moment T when entering the pressure ramp on the right R When V R >V 0R And V L >V 0L At this time, there are four control methods:

[0031] Ⅰ If V L >V R And T L >T R Left brake command with T L V of the moment RC Starting from a point a0, gradually increase the rate until it matches V. R Once the conditions are met, exit pressure ramp control; the right brake command is controlled according to the third scenario described above.

[0032] Ⅱ If V L ≤V R And T L ≤T R The right brake command is T R V of the moment LC Starting from a point a0, gradually increase the rate until it matches V. L Once the conditions are met, exit pressure ramp control; the left brake command is controlled according to the second scenario.

[0033] Ⅲ If V L >V R And T L ≤T R The left brake command is controlled according to the second situation, and the right brake command is controlled according to the third situation.

[0034] IV If V L ≤V R And T L >T R The left brake command is controlled according to the second scenario, and the right brake command is controlled according to the third scenario.

[0035] This completes the overshoot control for suppressing aircraft brake pressure.

[0036] This invention relates to brake pressure increase control based on left / right brake command signals and aircraft taxiing speed. The invention considers that abrupt changes in brake pressure can cause sudden torque shifts, leading to frequent wheel slippage. If pressure is not released promptly, this can easily result in brake pitch, low braking efficiency, and tire wear. To address this issue, this invention effectively avoids brake torque overshoot that causes frequent wheel slippage. Furthermore, it implements consistent left / right brake pressure control on top of the pressure increase control, enabling stable and efficient braking during normal landing, thus improving the reliability and safety of the braking system. Braking curves before and after overshoot suppression control are attached. Figure 2 and attached Figure 3 The data comparison is shown in Table 1.

[0037] Table 1 Comparison of braking performance after adding overshoot suppression control

[0038] Serial Number Braking distance Deceleration rate Anti-slip working times Braking process Unsuppressed overshoot control 956m <![CDATA[3.2m / s 2 ]]> 3 Unstable Increase overshoot control 883m <![CDATA[3.5m / s 2 ]]> 0 smooth

[0039] The addition of overshoot suppression control to the rear braking system shortens the braking distance and increases the deceleration rate under the same operating conditions, while also eliminating the need for anti-skid operation, resulting in a significant improvement in braking performance. Attached Figure Description

[0040] Figure 1 This is the control logic diagram of the present invention.

[0041] Figure 2 It is unsuppressed overshoot control.

[0042] Figure 3 It increases the control to suppress overshoot.

[0043] Figure 4 This is a flowchart of the present invention.

[0044] Figure 2 and Figure 3 In the middle: 1. Drum speed; 2. Machine wheel speed; 3. Braking torque; 4. Braking pressure. Detailed Implementation

[0045] This embodiment describes a pressure control method for suppressing overshoot in a certain type of aircraft braking system, applicable to tricycle-type aircraft digital electro-hydraulic braking systems.

[0046] The specific process of this embodiment is as follows:

[0047] Step 1: Obtain the aircraft's current braking command and taxiing speed status.

[0048] The aircraft's taxiing speed is obtained through communication, when the aircraft is on the ground and the taxiing speed is ≥25. +5 Brake pressure overshoot suppression control is performed at speeds of km / h; otherwise, brake pressure overshoot suppression control is not performed.

[0049] The brake command sensor sends a left brake command signal V to the control box. L and right-side brake command signal V R The left and right channels of the aircraft braking system respectively receive the left braking command signal V. L and right-side brake command signal V R .

[0050] The left brake command signal V L The time point input to the control box is T. L Right brake command signal V R The time point input to the control box is T. R .

[0051] The aircraft braking system responds to the received left-side braking command signal V L and right-side brake command signal V R Determine the left brake command V that participates in normal braking control. LC And right brake command V RC The left brake command V LC Effective range and right brake command V RC The effective range is 1.8V to 6.2V. According to the left brake command V... LC Based on the effective range and linear relationship, the corresponding braking current on the left is calculated to be 1mA to 18mA; according to the right braking command V... RC The effective range is calculated based on the linear relationship, and the corresponding braking current on the right is 1mA to 18mA; when the braking current is 4mA to 18mA, the corresponding braking pressure is 0 to 10MPa.

[0052] Step 2: Determine the overshoot control parameters during braking:

[0053] The design of the braking system control parameters includes determining the pressure initiation point and the pressure command increase rate.

[0054] During braking control, the braking pressure starts from the design baseline and increases at an initial rate a0 according to the pressure ramp until it reaches the maximum pressure corresponding to the pedal; this process is called the pressure ramp. The initial rate a0 of the pressure ramp is 0.36V / s.

[0055] The pressure initiation point is used as the control threshold V0 for the pressure ramp; this control threshold includes the left control threshold V. 0L and right control threshold V 0R And the left control threshold V 0L =Right control threshold V 0R .

[0056] The pressure ramp command increase rate a0 is adjusted based on the braking torque obtained from the test results. Specifically, during the pressure rise, if the braking torque is greater than 120% of the average torque of the entire braking process, a0 is decreased; if the braking torque is ≤ 80% of the average torque of the entire braking process, a0 is increased; if the braking torque is > 80% and ≤ 120% of the average torque of the entire braking process, a0 remains unchanged. The pressure ramp command increase rate a0 includes the pressure ramp command increase rate a0 of the left brake command signal. 0L The pressure ramp command increase rate a of the right brake command signal 0R Furthermore, the pressure ramp command of the left brake command signal increases at a rate a. 0L =Right brake command signal pressure ramp command increase rate a 0R .

[0057] In this embodiment, the control threshold V of the left brake pressure ramp 0L Control threshold V of right brake pressure ramp 0R They are equal, both at 4V, and the corresponding braking pressure is 4MPa.

[0058] Tests have verified that when the brake pressure increases from 0 MPa to 4 MPa within one brake control cycle, it will not cause a torque surge that would lead to wheel slippage. In this embodiment, one brake control cycle is 10 ms.

[0059] Step 3: Pressure overshoot control

[0060] Compare the left brake command V separately L With left control threshold V 0L Size, right brake command V R With right control threshold V 0R The magnitude of the brake pressure overshoot is determined based on the comparison results.

[0061] I when V L ≤V0L And V R ≤V 0R At that time, both the left and right brake command values ​​are relatively small, and the actual output value of the control command V is small. LC =V L V RC =V R .

[0062] Ⅱ when V L >V 0L And V R ≤V 0R At that time, the right brake command value is smaller, controlling the output value V of the right brake command. RC =V R Left brake command V L The pressure is relatively large, requiring suppression of abrupt changes in brake pressure. The specific process for suppressing these abrupt changes is as follows: using V... 0L Starting from the left brake command signal, the pressure ramp command increases at a rate of a. 0L Adding the actual brake command signal involved in brake control, we obtain the actual left brake command signal V. LC =V 0L +T×a 0L Where T is the instruction increment time, V LC Increase to a maximum of V L For example, V L When the voltage is 6V, the maximum value of T is T = (6-4) / 0.36 = 5.5s. At this time, V LC =6V.

[0063] Ⅲ When V R >V 0R And V L ≤V 0L At that time, the left brake command values ​​are all relatively small, controlling the output value V of the left brake command. LC =V L Right-side brake command V R The pressure is relatively large, requiring suppression of abrupt changes in brake pressure. The specific process for suppressing abrupt changes in brake pressure is described using V... 0R Starting from the right brake command signal, the pressure ramp command increases at a rate of a. 0R Adding the actual brake command signal involved in brake control, we obtain the actual right brake command signal V. RC =V 0R +T×a 0R Where T is the instruction increment time, V RC Increase to a maximum of V R For example, V R When the voltage is 6V, the maximum value of T is T = (6~4) / 0.36 = 5.5s, at which point V RC =6V

[0064] IV when V R >V 0R And V L >V 0L At that time, the left and right braking commands enter the pressure ramp control, and V is compared. L and V R The magnitude of the value determines the time T when the left side enters pressure ramp control. L And the moment T when entering the pressure ramp on the right R .

[0065] When V R >V 0R And V L >V 0L There are four control scenarios:

[0066] i If V L >V R And T L >T R At this time, the brake command input on the left is 6.0V, and the brake command input on the right is 5.5V, and the time of the left brake command input is T. L Greater than the right brake command input time T R T L -T R =1s, the command pressure changes as follows: The right brake command involved in brake control is: V RC =4+0.36(TT) L When the left brake command enters ramp control, the right brake command is V. RC =4 + 0.36 × (T) L -T R = 4.36V, therefore the braking command involved in the left-side brake control is: V LC =4.36 + 0.36 (TT) L ), in T L 3.2 seconds after the time, V RC =5.5V, at this moment the left side exits the pressure ramp V LC =6.0V.

[0067] ii If V L ≤V R And T L ≤T R At this time, the brake command input on the left is 5.5V, and the brake command input on the right is 6.0V, and the time of the left brake command input is T. L Less than the right brake command input time T R T R -T L =1s, the command pressure changes as follows: The left brake command involved in brake control is: VLC =4+0.36(TT) R When the right-side braking command enters ramp control, the left-side braking command is V. LC =4 + 0.36 × (T) R -T L = 4.36V, therefore the braking command involved in the right-side brake control is: V RC =4.36 + 0.36 (TT) R ), in T R 3.2 seconds after the time, V LC =5.5V, at this moment the right side exits the pressure ramp V RC =6.0V.

[0068] iii If V L >V R And T L ≤T R At this time, the brake command input on the left is 6.0V, which is greater than the brake command on the right (5.5V). Therefore, the brake command on the left that participates in brake control is: V LC =4+0.36(TT) L ), T L 4.2 seconds after the initial time, the command increases to the target value of 6V; the right brake command involved in brake control is: V RC =4+0.36(TT) R ), T R 5.5 seconds after the timer, the instruction increases to the target value of 5.5V.

[0069] iv If V L ≤V R And T L >T R At this time, the brake command input on the left is 5.5V, which is less than the brake command on the right (6.0V). Therefore, the brake command input on the left that participates in brake control is: V LC =4+0.36(TT) L ), T L 5.5 seconds after the initial time, the command increases to the target value of 6V; the command for the right brake involved in braking control is: V RC =4+0.36(TT) R ), T R 4.2 seconds after the time point, the instruction increases to the target value of 5.5V.

[0070] Thus, the pressure control for suppressing overshoot in the braking system of a certain type of aircraft was completed.

[0071] In this embodiment, by comparing the left and right brake command signals input to the braking system and designing reasonable command acceleration control and starting threshold, optimal control of brake pressure can be achieved. Theoretical analysis shows that the braking system improves braking performance by adopting the brake pressure overshoot suppression control method.

[0072] This embodiment controls the increase in brake pressure based on the left / right brake command signals and the aircraft's taxiing speed. Simultaneously, based on the left / right brake command values, it controls the consistency of brake pressure. This allows the pressure control to effectively suppress torque overshoot during normal landing braking, thus preventing frequent wheel slippage. It also effectively avoids the increased pilot workload caused by pressure deviation between the left and right sides when the pilot has a strong braking intention, thereby improving the reliability and safety of the braking system.

Claims

1. A method of inhibiting overshoot control of aircraft brake pressure, characterized by, The specific process is: Step 1, obtain the current brake instruction and taxi speed state of the aircraft; Step 2, determine the overshoot control parameters in the brake process: Determine the control threshold V0 of the brake instruction entering the pressure slope; Determine the pressure slope instruction increase rate a0; Step 3, pressure overshoot control: When the aircraft taxi speed V 滑 ≥ 25 +5 km / h, the following control is performed: V L and right brake command V R treatment, get the desired direct participation brake control command V LC and V RC ; Wherein, V LC is the left side direct instruction involved in brake control, RC is the right side direct instruction involved in brake control; Comparing the left brake command V L with the size of the left control threshold V 0L , while comparing the right brake command V R with the size of the right control threshold V 0R , the instructions V LC and V RC directly involved in brake control are calculated; In the pressure overshoot control, the command V directly involved in the brake control is calculated LC and V RC The following four cases exist in the results of The first type, when V L ≤V 0L And V R ≤V 0R The left brake command signal V that actually participates in brake control LC =V L V RC =V R ; Second, when V L > V 0L and V R ≤ V 0R ; the V 0L is the starting point, the left brake command signal pressure ramp command increase rate a 0L Increase the actual brake control brake command signal to get the left brake command signal V LC ; the left brake command signal V LC as the left actual brake control brake command signal; the right side remains V RC = V R ; Third, when V R > V 0R and V L ≤ V 0L ; the V 0R is the starting point, the right brake command signal pressure ramp command increase rate a 0R increase the actual brake control brake command signal, get left brake command signal V RC ; the left brake command signal V RC as the left actual brake control brake command signal; left side keep V LC = V L ; Fourth, when V R > V 0R and V L > V 0L ; left brake command into the pressure ramp control, while comparing the size of V L and V R , get left into the pressure ramp control time T L and right into the pressure ramp control time T R ; When V R > V 0R and V L > V 0L there are four control modes: I if V L > V R , and T L > T R , the left brake command takes V L at time T RC as the starting point, gradually increases at the rate of a0 to the same V R , and then exits the pressure ramp control; the right brake command is controlled according to the third case; II if V L ≤ V R , and T L ≤ T R , the right brake command takes V LC at time T R as the starting point, gradually increases at the rate of a0 to the same V L , and then exits the pressure ramp control; the left brake command is controlled according to the second case; III if V L > V R , and T L ≤ T R , the left brake command is controlled as per the second case and the right brake command is controlled as per the third case; IV if V L ≤ V R , and T L > T R , the left brake command is controlled as in the second case and the right brake command is controlled as in the third case; So far, the overshoot control of the aircraft brake pressure is completed.

2. The method of claim 1, wherein the step of inhibiting the overshoot of the brake pressure of the aircraft is characterized by: When the current brake instruction and taxiing speed state of the airplane are acquired, the brake instruction signal of the brake instruction sensor is collected by the brake controller; the brake instruction signal includes left brake instruction V L and right brake instruction V R ; the brake controller obtains the airplane taxiing speed V 滑 from the host computer.

3. The method of claim 1, wherein the step of inhibiting the overshoot of the brake pressure of the aircraft is characterized by: The control threshold described in step 2 comprises a left control threshold V 0L and a right control threshold V 0R and the left control threshold = right control threshold.

4. The method of claim 1, wherein In Step 2, the pressure ramp command increase rate a0 includes a pressure ramp command increase rate a for the left brake command signal 0L and a pressure ramp command increase rate a for the right brake command signal 0R ; and the pressure ramp command increase rate a for the left brake command signal 0L = the pressure ramp command increase rate a for the right brake command signal 0R .

Images