Control method for restraining aircraft brake pressure overshoot

Abstract

The invention discloses a control method for inhibiting aircraft brake pressure overshoot, and aims to solve the problems that aircraft wheels enter a frequent slipping state due to sudden torque change caused by step change of brake pressure, and brake pitching, low brake efficiency and tire wear are extremely easy to occur if pressure is not released in time. Brake pressure acceleration control is carried out, frequent slipping of airplane wheels caused by overshoot change of brake torque can be effectively avoided, meanwhile, left / right brake pressure consistency control is carried out on the basis of the pressure acceleration control, stable and efficient braking can be completed in the normal landing braking process of an airplane, the reliability and safety of a braking system are improved, and the service life of the airplane is prolonged. And the rear brake system with the overshoot suppression control function is added, so that the brake distance is shortened under the same working condition, the speed reduction rate is improved, anti-skid work is avoided, and the brake performance is obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft brake control, in particular to a control method for suppressing aircraft brake pressure overshoot based on aircraft taxiing speed and left wheel brake command value / right wheel brake command value. Background Art

[0002] There are many nonlinear factors in the aircraft anti-skid brake system, among which the brake disc performance and brake pressure control are the important factors that directly affect the performance of the anti-skid brake. The aircraft landing roll process is short, so when the anti-skid brake system is controlled, the pressure overshoot problem should be avoided as much as possible to ensure the stability of the brake control.

[0003] An analysis of the brake performance of existing aircraft brake discs found that when braking, if a large brake pressure step occurs to the brake device, the brake disc will experience a braking torque surge, which is more prominent in high-speed aircraft and carbon-ceramic brake discs. Torque surges can easily cause frequent wheel slippage, and the aircraft may experience pitch problems, increasing braking distance, reducing braking efficiency, and reducing pilot comfort.

[0004] Based on the above analysis, most aircraft use the command-pressure following control method, which has the following disadvantages:

[0005] 1. When the braking command is large, the pressure control step rises, which may cause the brake disc to have a braking torque charge, causing deep skidding, and in severe cases, causing the aircraft to pitch;

[0006] 2. When the left and right brake pressures are inconsistent, the pilot's correction operation burden increases;

[0007] 3. Frequent skidding after the torque charge reduces braking efficiency and increases braking distance.

[0008] When the aircraft brakes in an emergency landing situation, the shortcomings of the step pressure control method become more and more obvious. In this state, the pilot urgently needs to brake the aircraft quickly. Usually, the control input braking command is large, and the torque generated by the brake disc increases sharply, causing the wheels to slip frequently, the left and right brake pressures to be inconsistent, and the aircraft's braking heading to deviate, resulting in reduced braking efficiency and, in severe cases, "tire gnawing" problems.

[0009] Essentially, these factors are due to the fact that the torque characteristics of the brake disc were not considered when the brake control was designed. Braking control requires the rational use of the combined force provided by the runway to stop the aircraft in the shortest possible distance. Therefore, when the aircraft brakes, the pressure rise method should be reasonably controlled to match the torque characteristics of the brake disc; at the same time, the aircraft usage status should be considered to minimize the operating burden on the pilot.

[0010] To sum up, based on the brake disc characteristics and aircraft usage status, designing a control method to suppress brake pressure overshoot is particularly important for the safety and reliability of the brake system.

[0011] By searching domestic and foreign patent documents and paper databases, no technology identical to the present invention was found.

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

[0013] In order to overcome the shortcomings of the prior art that brake pressure overshoot causes frequent skidding and reduces braking efficiency, the present invention proposes a control method for suppressing aircraft brake pressure overshoot.

[0014] The specific process of the present invention is:

[0015] Step 1, obtain the current braking instruction and taxiing speed status of the aircraft;

[0016] When obtaining the current braking command and taxiing speed status of the aircraft, the braking command signal of the braking command sensor is collected through the braking controller; the braking command signal includes the left braking command V L and right brake command V R The brake controller obtains the aircraft taxiing speed V through the host computer. 滑 .

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

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

[0019] The control threshold includes a left control threshold V 0L and right control threshold V 0R , and the left control threshold = 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 a of the left brake command signal. 0L and the pressure ramp command increase rate a of the right brake command signal 0R ; and the pressure ramp command increase rate a of the left brake command signal 0L =Rate of increase of pressure ramp command of right brake command signal a 0R .

[0022] Step 3, pressure overshoot control:

[0023] When the aircraft taxis at a speed V 滑 ≥25 +5 The following controls are performed at km / h:

[0024] Left brake command V L and right brake command V R Processing is performed to obtain the desired instruction V that directly participates in the brake control LC and V RC ; Among them, V LC V is the instruction for the left side to directly participate in the brake control. RC This is the instruction for the right side to directly participate in the brake control.

[0025] Compare left brake command V L With the left control threshold V 0L The size of the right brake command V R With the right control threshold V 0R The size of the brake control command V is calculated. LC and V RC ;

[0026] In the pressure overshoot control, the command V that directly participates in the brake control is calculated LC and V RC There are four situations in the results:

[0027] The first one is when V L ≤V 0L And V R ≤V 0R , the left brake command signal V that actually participates in the 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 V 0L As the starting point, the pressure ramp command of the left brake command signal increases the rate a 0L Add the brake command signal that actually participates in the brake control to obtain the left brake command signal V LC ; With the left brake command signal V LC As the brake command signal for the left side to actually participate in the brake control. The right side maintains V RC =V R .

[0029] The third type, when V R >V0R And V L ≤V 0L . With the V 0R As the starting point, the pressure ramp command of the right brake command signal increases the rate a 0R Add the brake command signal that actually participates in the brake control to obtain the left brake command signal V RC ; With the left brake command signal V RC As the brake command signal for the left side to actually participate in the brake control. The left side maintains V LC =V L .

[0030] The fourth type, when V R >V 0R And V L >V 0L The left and right brake commands enter the pressure ramp control and compare V L and V R The size of the left side is obtained to obtain the moment T when the left side enters the pressure ramp control L and the moment T when the right side enters the pressure slope R When V R >V 0R And V L >V 0L There are four control modes:

[0031] ⅠIf V L >V R , and T L >T R , the left brake command is T L V of the moment RC As the starting point, gradually increase at a rate of a0 to V R After the same, exit the pressure ramp control; the right brake command is controlled according to the third case;

[0032] Ⅱ If V L ≤V R , and T L ≤T R The right brake command is T R V of the moment LC As the starting point, gradually increase at a rate of a0 to V L After the two conditions are the same, the pressure ramp control is exited; the left brake command is controlled according to the second case;

[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 situation, and the right brake command is controlled according to the third situation.

[0035] At this point, the overshoot control of suppressing the aircraft braking pressure is completed.

[0036] The present invention is a method for controlling the brake pressure increase rate according to the left / right side brake command signal and based on the taxiing speed of the aircraft. The present invention takes into account that a step change in brake pressure will produce a sudden change in torque, thereby causing the wheels to frequently slip. If the pressure is not released in time, problems such as brake pitch, low brake efficiency, and tire wear are very likely to occur. In response to this problem, the present invention can effectively avoid overshoot changes in the brake torque, which may cause frequent wheel slippage. At the same time, on the basis of pressure increase rate control, the left / right brake pressure consistency control is performed, so that the aircraft can complete stable and efficient braking during normal landing braking, thereby improving the reliability and safety of the brake system. See attached for the front and rear brake curves for adding overshoot control. 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 Unrestrained overshoot control 956m <![CDATA[3.2m / s 2 ]]> 3 Unsteady Increase overshoot control 883m <![CDATA[3.5m / s 2 ]]> 0 smooth

[0039] The rear brake system with added overshoot control shortens the braking distance, increases the deceleration rate, and avoids anti-skid work under the same working conditions, significantly improving the braking performance. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 2 It is an unrestrained overshoot control.

[0042] Figure 3 It is to increase the overshoot suppression control.

[0043] Figure 4 It is a flow chart of the present invention.

[0044] Figure 2 and Figure 3 Chinese: 1. Drum speed; 2. Wheel speed; 3. Braking torque; 4. Braking pressure. DETAILED DESCRIPTION

[0045] This embodiment is a pressure control method for suppressing overshoot of a certain type of aircraft brake system, which is applicable to a front three-point aircraft digital electric hydraulic brake system.

[0046] The specific process of this embodiment is:

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

[0048] Obtain the aircraft taxiing speed through communication. When the aircraft is on the ground and the taxiing speed is ≥ 25 +5 km / h, the brake pressure suppression overshoot control is performed, otherwise, the brake pressure suppression overshoot control is not performed.

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

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

[0051] The aircraft brake system receives the left brake command signal V L and the right brake command signal V R , determine the left brake command V involved in normal braking control LC and right brake command V RC The left brake command V LC The effective range and right brake command V RC The effective range is 1.8V~6.2V. According to the left brake command V LC The effective range of the left brake current is calculated to be 1mA to 18mA according to the linear relationship; according to the right brake command V RC The effective range is calculated based on the linear relationship. The corresponding brake current on the right is 1mA~18mA; when the brake current is 4mA~18mA, the corresponding brake pressure is 0~10MPa.

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

[0053] The design of determining the brake system control parameters includes determining a pressure starting point and determining a pressure command increase rate.

[0054] During the braking control process, the braking pressure takes the design base point as the pressure starting point, and increases the braking pressure according to the initial increase rate a0 of the pressure slope, so that the braking pressure increases to the maximum pressure corresponding to the pedal; this process is the pressure slope. The initial increase rate a0 of the pressure slope = 0.36V / s.

[0055] The pressure starting point is used as the control threshold V0 of the pressure slope; the 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 pressure command increase rate a0 is modified according to the braking torque obtained from the test results. The specific method is as follows: during the pressure rise period, if the braking torque is greater than 120% of the average torque of the entire braking process, a0 is reduced; if the braking torque is ≤ 80% of the average torque of the entire braking process, a0 is increased; if the braking torque is greater than 80% of the average torque of the entire braking process and ≤ 120% of the average torque of the entire braking process, a0 is kept unchanged. The pressure ramp command increase rate a0 includes the pressure ramp command increase rate a0 of the left brake command signal. 0L and the pressure ramp command increase rate a of the right brake command signal 0R ; and the pressure ramp command increase rate a of the left brake command signal 0L =Rate of increase of pressure ramp command of right brake command signal a 0R .

[0057] In this embodiment, the control threshold value V of the left brake pressure slope 0L The control threshold V of the right brake pressure ramp 0R The same is 4V, and the corresponding brake pressure is 4MPa.

[0058] It has been verified through experiments that when the brake pressure increases from 0 MPa to 4 MPa in one brake control cycle, it will not cause a torque surge to cause the wheels to slip. In this embodiment, the one brake control cycle is 10 ms.

[0059] Step 3: Pressure Overshoot Control

[0060] Compare the left brake command V L With the left control threshold V 0L The size of the right brake command V R With the right control threshold V 0R The corresponding brake pressure overshoot control logic is determined based on the comparison result:

[0061] I when V L ≤V0L And V R ≤V 0R When the left / right brake command values ​​are both small, the actual output value of the control command V LC =V L 、V RC =V R .

[0062] Ⅱ When V L >V 0L And V R ≤V 0R When the right brake command value is small, the right brake command output value V RC =V R . Left brake command V L The specific process of suppressing the step change of brake pressure is as follows: 0L As the starting point, the pressure ramp command of the left brake command signal increases the rate a 0L Add the brake command signal that actually participates in the brake control to obtain the actual left brake command signal V LC =V 0L +T×a 0L , where T is the instruction increase time, V LC Increase up to V L For example, V L When it 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 When the left brake command value is small, the left brake command output value V LC =V L . Right brake command V R The specific process of suppressing the step change of brake pressure is as follows: V 0R As the starting point, the pressure ramp command of the right brake command signal increases the rate a 0R Add the brake command signal that actually participates in the brake control to obtain the actual right brake command signal V RC =V 0R +T×a 0R , where T is the instruction increase time, V RC Increase up to V R . Such as V R When it is 6V, the maximum value of T is T=(6~4) / 0.36=5.5s. At this time, V RC =6V

[0064] IV when V R >V 0R And V L >V 0L When the left and right brake commands enter the pressure ramp control, V L and V R The size of the left side is obtained to obtain the moment T when the left side enters the pressure ramp control L and the moment T when the right side enters the pressure slope R .

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

[0066] ⅰIf V L >V R , and T L >T R At this time, the left side input brake command is 6.0V, the right side input brake command is 5.5V, and the left side brake command input time 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 the brake control is: V RC =4+0.36(TT L ); When the left brake command enters the slope control, the right brake command is V RC =4+0.36×(T L -T R )=4.36V, so the brake command involved in the left brake control is: V LC =4.36+0.36(TT L ), in T L 3.2s after the moment, V RC =5.5V, at this moment, the left side exits the pressure slope V LC =6.0V.

[0067] ⅱIf V L ≤V R , and T L ≤T R , at this time, the left side input brake command is 5.5V, the right side input brake command is 6.0V, and the left side brake command input time 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 the brake control is: VLC =4+0.36(TT R ); When the right brake command enters the slope control, the left brake command is V LC =4+0.36×(T R -T L )=4.36V, so the brake command involved in the right brake control is: V RC =4.36+0.36(TT R ), in T R 3.2s after the moment, V LC =5.5V, at this moment, the right side exits the pressure slope V RC =6.0V.

[0068] ⅲIf V L >V R , and T L ≤T R At this time, the left input brake command is 6.0V, which is greater than the right brake command 5.5V. The left brake command involved in the brake control is: V LC =4+0.36(TT L ), T L At 4.2s after the moment, the command increases to the target value of 6V; the right brake command participating in the brake control is: V RC =4+0.36(TT R ), T R 5.5s after the moment, the command increases to the target value of 5.5V.

[0069] ⅳIf V L ≤V R , and T L >T R At this time, the left input brake command is 5.5V, which is less than the right brake command 6.0V. The left brake command involved in the brake control is: V LC =4+0.36(TT L ), T L At 5.5s after the moment, the command increases to the target value of 6V; the right brake command participating in the brake control is: V RC =4+0.36(TT R ), T R 4.2s after the moment, the command increases to the target value of 5.5V.

[0070] At this point, the pressure control for suppressing overshoot of a certain type of aircraft braking system has been completed.

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

[0072] This embodiment performs brake pressure acceleration control according to the left / right brake command signal and the taxiing speed of the aircraft. At the same time, brake pressure consistency control is performed based on the pressure acceleration control according to the left / right brake command value. During the normal landing braking process of the aircraft, the pressure control can effectively suppress the torque overshoot change and cause the wheels to slip frequently. At the same time, it can effectively avoid the deviation between the left and right pressures when the pilot has a strong desire to brake, which increases the pilot's operating burden, thereby improving the reliability and safety of the brake system.

Claims

1. A control method for suppressing aircraft brake pressure overshoot, characterized in that: The specific process is: Step 1, obtain the current braking instruction and taxiing speed status of the aircraft; Step 2: Determine the overshoot control parameters during braking: Determine the control threshold V0 for the brake command to enter the pressure ramp; Determine the pressure ramp command increase rate a0; Step 3, pressure overshoot control: When the aircraft taxis at a speed V 滑 ≥25 +5 The following controls are performed at km / h: Left brake command V L and right brake command V R Processing is performed to obtain the desired instruction V that directly participates in the brake control LC and V RC ; Among them, V LC V is the instruction for the left side to directly participate in the brake control. RC It is the instruction for the right side to directly participate in the brake control; Compare left brake command V L With the left control threshold V 0L The size of the right brake command V R With the right control threshold V 0R The size of the brake control command V is calculated. LC and V RC ; At this point, the overshoot control of suppressing the aircraft braking pressure is completed.

2. The method for suppressing aircraft brake pressure overshoot control as claimed in claim 1, characterized in that: When obtaining the current braking command and taxiing speed status of the aircraft, the braking command signal of the braking command sensor is collected through the braking controller; the braking command signal includes the left braking command V L and right brake command V R ; The brake controller obtains the aircraft taxiing speed V through the host computer 滑 .

3. The method for suppressing aircraft brake pressure overshoot control as claimed in claim 1, characterized in that: The control thresholds in step 2 include the left control threshold V 0L and right control threshold V 0R , and the left control threshold = right control threshold.

4. The method for suppressing overshoot of aircraft brake pressure as claimed in claim 1, characterized in that In step 2, the pressure ramp command increase rate a0 includes the pressure ramp command increase rate a of the left brake command signal. 0L and the pressure ramp command increase rate a of the right brake command signal 0R ; and the pressure ramp command increase rate a of the left brake command signal 0L =Rate of increase of pressure ramp command of right brake command signal a 0R .

5. The method for suppressing aircraft brake pressure overshoot control as claimed in claim 1, characterized in that: Step 3: Calculate the command V that directly participates in the brake control in the pressure overshoot control LC and V RC There are four situations in the results: The first one is when V L ≤V 0L And V R ≤V 0R , the left brake command signal V that actually participates in the brake control LC =V L 、V RC =V R ; The second type, when V L >V 0L And V R ≤V 0R ; With the V 0L As the starting point, the pressure ramp command of the left brake command signal increases the rate a 0L Add the brake command signal that actually participates in the brake control to obtain the left brake command signal V LC ; With the left brake command signal V LC As the brake command signal for the left side to actually participate in the brake control; the right side maintains V RC =V R ; The third type, when V R >V 0R And V L ≤V 0L ; With the V 0R As the starting point, the pressure ramp command of the right brake command signal increases the rate a 0R Add the brake command signal that actually participates in the brake control to obtain the left brake command signal V RC ; With the left brake command signal V RC As the brake command signal for the left side to actually participate in the brake control; the left side maintains V LC =V L ; The fourth type, when V R >V 0R And V L >V 0L ; The left and right brake commands enter the pressure ramp control and compare V L and V R The size of the left side is obtained to obtain the moment T when the left side enters the pressure ramp control L and the moment T when the right side enters the pressure slope R .

6. The method for suppressing overshoot of aircraft brake pressure as claimed in claim 5, characterized in that: When V R >V 0R And V L >V 0L There are four control modes: ⅠIf V L >V R , and T L >T R , the left brake command is T L V of the moment RC As the starting point, gradually increase at a rate of a0 to V R After the same, exit 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 is T R V of the moment LC As the starting point, gradually increase at a rate of a0 to V L After the two conditions are the same, the pressure ramp control is exited; 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 according to the second situation, and the right brake command is controlled according to the third situation; IV 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.

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