A flying wing unmanned aerial vehicle anti-skid brake control method

Abstract

The application discloses a flying-wing unmanned aerial vehicle anti-skid brake control method and belongs to the technical field of unmanned aerial vehicle control, and is characterized by comprising the following steps: a, an unmanned aerial vehicle management computer sends an airplane ground speed to a brake control unit, and the brake control unit collects wheel speed; b, the brake control unit calculates the ratio of the wheel speed to the airplane ground speed according to the airplane ground speed and the wheel speed; c, the right wheel anti-skid amount is calculated, and the left wheel anti-skid amount is the same as the right wheel anti-skid amount; d, the unmanned aerial vehicle management computer sends a brake instruction according to the calculated left brake driving instruction and right brake driving instruction. In the case of satisfying left-right differential correction, the application can reduce the asymmetric force generated by the left and right brakes, retain the left-right differential amount during anti-skid disposal, have no influence on the heading control, and effectively reduce the disturbance to the airplane heading.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of unmanned aerial vehicle control, and particularly relates to a flying wing unmanned aerial vehicle anti-skid brake control method. BACKGROUND

[0002] The flying wing layout unmanned aerial vehicle is a hot research direction in the world in recent years due to its high aerodynamic efficiency and strong stealth characteristics. The flying wing layout has the problem of poor lateral stability, and the rudder efficiency is low during ground sliding, so the aircraft is easily deviated from the runway under interference, and thus higher requirements are put forward for the ground sliding direction control. The flying wing unmanned aerial vehicle has a large landing ground speed, and the brake system must have an anti-skid function. In combination with the characteristics of the flying wing layout unmanned aerial vehicle, the anti-skid brake function must minimize the disturbance to the lateral direction of the aircraft, and the anti-skid brake control algorithm of the conventional layout unmanned aerial vehicle is not applicable to the flying wing unmanned aerial vehicle. In addition, the unmanned aerial vehicle also needs to realize the deviation correction control of the ground sliding direction through differential braking, and the anti-skid brake cannot affect the differential deviation correction performance.

[0003] The Chinese patent application document with the publication number CN110450768A and the publication date of November 15, 2019 discloses a low-cost small fixed-wing unmanned aerial vehicle brake anti-skid control method, which is characterized by comprising the following steps:

[0004] (1) setting a condition to be met when the brake anti-skid mechanism is started;

[0005] (2) when the condition in step (1) is met, starting the brake anti-skid monitoring;

[0006] (3) monitoring the ground running speed of the unmanned aerial vehicle and the wheel speed of the unmanned aerial vehicle wheel through the brake anti-skid monitoring, and judging whether the wheel of the unmanned aerial vehicle is slipping; the process of judging whether the wheel of the unmanned aerial vehicle is slipping is:

[0007] (3.1) monitoring the ground running speed of the unmanned aerial vehicle and the wheel speed of the unmanned aerial vehicle wheel;

[0008] (3.2) using the ground running speed of the unmanned aerial vehicle to subtract the wheel speed of the unmanned aerial vehicle wheel to calculate the slip speed of the unmanned aerial vehicle wheel;

[0009] (3.3) calculating the slip speed of the unmanned aerial vehicle wheel every 10-20 microseconds, and when the slip speed of the unmanned aerial vehicle wheel is greater than 30 km / h for three times in succession, it is judged that the wheel of the unmanned aerial vehicle is slipping;

[0010] (4) when the unmanned aerial vehicle is confirmed to be slipping, using the set segmented brake strategy and anti-skid control strategy to control the brake anti-skid of the unmanned aerial vehicle;

[0011] The segmented brake strategy is:

[0012] (A) When the ground running speed of the UAV is not less than 200km / h, the brake amount is the preset pressure, and the brake amount of the preset pressure is 3-5%;

[0013] (B) When the ground running speed of the UAV is between 150km / h and 200km / h, the brake amount is 7%;

[0014] (C) When the ground running speed of the UAV is between 120km / h and 150km / h, the brake amount is 12%;

[0015] (D) When the ground running speed of the UAV is between 80km / h and 120km / h, the brake amount is 25%;

[0016] (E) When the ground running speed of the UAV is not more than 80km / h, the brake amount is 35%;

[0017] The anti-skid control strategy comprises:

[0018] (a) When the single-side skid state of the wheel of the UAV lasts for 0.6s, the single-side anti-skid function is exited, and after 0.5s, it is continuously judged whether the skid occurs;

[0019] (b) When the two-side anti-skid treatment of the wheel of the UAV lasts for 2s, the brake anti-skid mechanism is exited, and if the left and right sides both satisfy the exit skid criterion, the brake anti-skid mechanism is re-enabled;

[0020] (5) When the UAV no longer skids, the brake pressure control is executed according to the normal strategy, and the brake anti-skid mechanism is closed.

[0021] The low-cost small fixed-wing UAV brake anti-skid control method disclosed in the patent application document can enable the low-cost fixed-wing UAV without the anti-skid brake system to realize the brake anti-skid function, improve the brake efficiency and safety, and can be applied to the brake anti-skid system of small fixed-wing UAVs with small mass, which has no complex system equipment and low cost. However, the difference between the wheel speed and the ground speed greater than 30km / h is used as the judgment basis, which requires high accuracy of the error between the wheel speed and the ground speed, and the wheel speed must be corrected by the ground speed; on the other hand, the criterion requires continuous 3 times, which will cause delay and aggravate the tire dragging time; on the other hand, after the tire dragging occurs, the brake pressure is reduced to the minimum value, and the brake efficiency is low. The anti-skid treatment method is to reduce the left and right brake pressures to the minimum value, which is easy to cause differential correction conflict, and when the flight control is performing differential brake correction, if the anti-skid occurs at this time, the anti-skid algorithm keeps the left and right brake pressures consistent, loses the differential ability, affects the aircraft heading control, and cannot effectively reduce the disturbance to the aircraft heading. SUMMARY

[0022] In order to overcome the defects of the above-mentioned prior art, the present invention provides an anti-skid braking control method for a flying wing UAV. While meeting the requirements of left and right differential correction, the present invention can reduce the asymmetric forces generated by the left and right brakes, retain the left and right differential amounts during anti-skid treatment, have no effect on heading control, and can effectively reduce disturbances to the aircraft heading.

[0023] The present invention is achieved through the following technical solutions:

[0024] A flying wing UAV anti-skid brake control method, characterized by comprising the following steps:

[0025] a. The UAV management computer sends the aircraft ground speed to the brake control unit, which then collects the wheel speed.

[0026] b. The brake control unit calculates the ratio of wheel speed to aircraft ground speed based on the aircraft ground speed and wheel speed. ;

[0027] c. Calculate the anti-slip amount of the right wheel , left wheel anti-slip and right wheel anti-slip same;

[0028] d. The UAV management computer calculates the left brake drive instruction and right brake actuation command Issue a brake command.

[0029] In step b, the ratio of wheel speed to aircraft ground speed is Calculated by formula 1;

[0030] Formula 1;

[0031] in, is the aircraft ground speed, is the wheel speed.

[0032] In step c, the right wheel anti-slip amount is calculated by formula 2 ;

[0033] Formula 2.

[0034] In step d, the left brake drive instruction Calculated by formula 3;

[0035] Formula 3.

[0036] In step d, the right brake drive instruction Calculated by formula 4;

[0037] Formula 4.

[0038] In step d, the brake command is issued after the main wheels of the aircraft have been on the ground for 3s, and the brake command is greater than the pressure loss value of the wheel brake device.

[0039] The brake command is softened from a small brake of 2MPa to 80% of the rated brake command over 2s, and is maintained until the ground speed of the aircraft is 200km / h.

[0040] When the ground speed of the aircraft is below 200km / h, the unmanned aerial vehicle management computer gives a brake command according to the rated brake pressure.

[0041] The beneficial effects of the present application mainly include the following aspects:

[0042] 1. The present application can reduce the asymmetric force generated by the left and right brakes in the case of left-right differential correction, and can retain the left-right differential amount in the anti-skid treatment without affecting the heading control, thereby effectively reducing the disturbance to the aircraft heading.

[0043] 2. The present application can calculate the anti-skid amount according to the ground speed of the aircraft and the wheel speed, and the two sides of the wheel can execute anti-skid control synchronously after detecting that the unilateral wheel starts the anti-skid function, thereby greatly reducing the disturbance to the aircraft heading.

[0044] 3. In step d of the present application, the brake command is issued after the main wheels of the aircraft have been on the ground for 3s, and the brake command is greater than the pressure loss value of the wheel brake device. The main wheels of the flying wing unmanned aerial vehicle are on the ground for 2s-3s, and the front wheels are on the ground. The brake is started after the main wheels of the aircraft have been on the ground for 3s, so that the front wheel load signal can be used to determine whether the front wheels are on the ground. In addition, the front wheel load signal appears late, which causes the brake to be started late, thereby increasing the taxi distance. By issuing a brake command greater than the pressure loss value of the wheel brake device after the main wheels of the aircraft have been on the ground for 3s, the reliability can be improved without relying on the wheel load, and the brake can be started early, thereby shortening the taxi distance.

[0045] 4. In the present application, the brake command is softened from a small brake of 2MPa to 80% of the rated brake command over 2s, and is maintained until the ground speed of the aircraft is 200km / h. At high speed, the main wheel support reaction force is small due to the influence of aerodynamic force, and the ground provides a small combined moment. By softening the brake command, the tire dragging phenomenon can be avoided in the initial landing segment, thereby ensuring the safety of the aircraft. According to the ground speed of the aircraft, the maximum ground combined coefficient is calculated, so that the brake moment generated by the brake command is close to the combined moment, thereby improving the brake efficiency.

[0046] 5. During the braking process, the present invention performs anti-skid calculations by real-time monitoring of the wheel speed. When anti-skid is detected on one side, the braking amount on both sides is reduced simultaneously, and the reduced braking amount is the same. This can effectively reduce the impact of inconsistent left and right braking on the aircraft's lateral heading, and can also meet the differential braking function, ensuring that when the anti-skid function is activated, it does not affect the control of the aircraft's ground sliding direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments:

[0048] Figure 1 This is the anti-skid brake control block diagram of the present invention;

[0049] Figure 2 This is a schematic diagram of the brake recovery process after the anti-skid function is released according to the present invention. DETAILED DESCRIPTION

[0050] Example 1

[0051] See also Figure 1 and Figure 2 , a flying wing UAV anti-skid brake control method, comprising the following steps:

[0052] a. The UAV management computer sends the aircraft ground speed to the brake control unit, which then collects the wheel speed.

[0053] b. The brake control unit calculates the ratio of wheel speed to aircraft ground speed based on the aircraft ground speed and wheel speed. ;

[0054] c. Calculate the anti-slip amount of the right wheel , left wheel anti-slip and right wheel anti-slip same;

[0055] d. The UAV management computer calculates the left brake drive instruction and right brake actuation command Issue a brake command.

[0056] This embodiment is the most basic implementation method. While meeting the requirements of left and right differential correction, it can reduce the asymmetric forces generated by the left and right brakes, retain the left and right differential amounts during anti-skid treatment, have no effect on heading control, and can effectively reduce disturbances to the aircraft's heading.

[0057] Example 2

[0058] See also Figure 1 and Figure 2 , a flying wing UAV anti-skid brake control method, comprising the following steps:

[0059] a、UAV management computer sends the ground speed of the aircraft to the brake control unit, and the brake control unit collects the wheel speed;

[0060] b、The brake control unit calculates the ratio of the wheel speed to the ground speed of the aircraft according to the ground speed of the aircraft and the wheel speed ;

[0061] c、Calculate the right wheel anti-skid amount , the left wheel anti-skid amount and the right wheel anti-skid amount are the same;

[0062] d、UAV management computer sends brake command according to the calculated left brake driving instruction and right brake driving instruction .

[0063] In step b, the ratio of the wheel speed to the ground speed of the aircraft is calculated by formula 1;

[0064] Formula 1;

[0065] Wherein, is the ground speed of the aircraft, is the wheel speed.

[0066] In step c, the right wheel anti-skid amount is calculated by formula 2;

[0067] Formula 2.

[0068] This embodiment is a preferred embodiment, according to the ground speed of the aircraft and the wheel speed to solve the anti-skid amount, when detecting unilateral wheel start anti-skid function, both sides of the wheel can synchronous execute anti-skid control, greatly reduce the disturbance to the aircraft heading.

[0069] Embodiment 3

[0070] Referring to Figure 1 and Figure 2 , a flying-wing UAV anti-skid brake control method, comprising the following steps:

[0071] a、UAV management computer sends the ground speed of the aircraft to the brake control unit, and the brake control unit collects the wheel speed;

[0072] b、The brake control unit calculates the ratio of the wheel speed to the ground speed of the aircraft according to the ground speed of the aircraft and the wheel speed ;

[0073] c、Calculate the right wheel anti-skid amount , the left wheel anti-skid amount and the right wheel anti-skid amount are the same;

[0074] d、the UAV management computer sends out brake instructions according to the calculated left brake driving instruction and right brake driving instruction .

[0075] In step b, the ratio of the wheel speed to the ground speed of the aircraft is calculated by formula 1;

[0076] Formula 1;

[0077] wherein, the ground speed of the aircraft is, the wheel speed.

[0078] In step c, the right wheel anti-skid amount is calculated by formula 2 ;

[0079] Formula 2.

[0080] Further, in step d, the left brake driving instruction is calculated by formula 3;

[0081] Formula 3.

[0082] In step d, the right brake driving instruction is calculated by formula 4;

[0083] Formula 4.

[0084] This embodiment is another preferred embodiment, in step d, the brake instruction is sent out after the main wheels of the aircraft are grounded for 3s, and the brake instruction is greater than the pressure loss value of the wheel brake device. The main wheels of the flying wing UAV are grounded for 2s-3s, the front wheels are grounded, and the brake is used after the main wheels of the aircraft are grounded for 3s. In this way, the front wheel grounding can be determined without relying on the front wheel load signal. In addition, the front wheel load signal appears late, which results in a late brake time and increases the taxi distance. By sending out a brake instruction greater than the pressure loss value of the wheel brake device after the main wheels of the aircraft are grounded for 3s, the reliability can be improved without relying on the wheel load, and the taxi distance can be shortened by braking early.

[0085] Embodiment 4

[0086] Referring to Figure 1 and Figure 2 , a flying wing UAV anti-skid brake control method comprises the following steps:

[0087] a. The UAV management computer sends the ground speed of the aircraft to the brake control unit, and the brake control unit collects the wheel speed;

[0088] b. The brake control unit calculates the ratio of the wheel speed to the ground speed of the aircraft from the ground speed of the aircraft and the wheel speed ;

[0089] c. The right wheel slip amount is calculated , the left wheel slip amount is calculated , and the right wheel slip amount is calculated ;

[0090] d. The UAV management computer sends a brake command according to the calculated left brake drive command and the right brake drive command .

[0091] In the step b, the ratio of the wheel speed to the ground speed of the aircraft is calculated by formula 1 .

[0092] Formula 1

[0093] wherein, V is the ground speed of the aircraft, and Vw is the wheel speed.

[0094] In the step c, the right wheel slip amount is calculated by formula 2 .

[0095] Formula 2

[0096] In the step d, the left brake drive command is calculated by formula 3 .

[0097] Formula 3

[0098] In the step d, the right brake drive command is calculated by formula 4 .

[0099] Formula 4

[0100] In the step d, the sending of the brake command refers to sending a brake command greater than the pressure loss value of the wheel brake device after the main wheel of the aircraft is grounded for 3s.

[0101] In this embodiment, which is another preferred embodiment, the brake command is softened from a small brake of 2MPa to 80% of the rated brake command for 2s, and is maintained until the ground speed of the aircraft is 200km / h. At high speed, the aerodynamic force is affected, the main wheel support reaction force is small, and the ground provides a small combined torque. Softening the brake command can avoid the phenomenon of dragging the tire at the initial landing stage, ensuring the safety of the aircraft. According to the ground speed of the aircraft, the maximum ground combined coefficient is calculated to make the brake torque generated by the brake command close to the combined torque, thereby improving the brake efficiency.

[0102] Embodiment 5

[0103] Referring to Figure 1 and Figure 2 , a control method for preventing the skidding of a flying-wing unmanned aerial vehicle, comprising the following steps:

[0104] a. The unmanned aerial vehicle management computer sends the ground speed of the aircraft to the brake control unit, and the brake control unit collects the wheel speed;

[0105] b. The brake control unit calculates the ratio of the wheel speed to the ground speed of the aircraft according to the ground speed of the aircraft and the wheel speed;

[0106] c. Calculate the right wheel anti-skid amount , the left wheel anti-skid amount and the right wheel anti-skid amount are the same;

[0107] d. The unmanned aerial vehicle management computer sends the brake command according to the calculated left brake driving instruction and the right brake driving instruction .

[0108] In the step b, the ratio of the wheel speed to the ground speed of the aircraft is calculated by formula 1;

[0109] Formula 1;

[0110] wherein, is the ground speed of the aircraft, is the wheel speed.

[0111] In the step c, the right wheel anti-skid amount is calculated by formula 2;

[0112] Formula 2.

[0113] In the step d, the left brake driving instruction is calculated by formula 3;

[0114] Formula 3.

[0115] In the step d, the right brake driving instruction is calculated by formula 4;

[0116] Formula 4.

[0117] Further, in the step d, the brake command is sent after the main wheel of the aircraft is grounded for 3s, and the brake command is greater than the pressure loss value of the wheel brake device.

[0118] ​The brake command is softened from a small amount of 2MPa brake to 80% of the rated brake command for 2s, and maintained to the aircraft ground speed of 200km / h.

[0119] When the aircraft ground speed is below 200km / h, the unmanned aerial vehicle management computer gives a brake command according to the rated brake pressure.

[0120] This embodiment is the best mode. During braking, the anti-skid solution is performed by real-time monitoring of the wheel speed. When anti-skid is detected on one side, the brake amount on both sides is simultaneously reduced, and the reduced brake amount is the same. This can effectively reduce the impact of inconsistent left and right brakes on the aircraft's lateral direction, and can also meet the differential brake function, ensuring that the control of the aircraft's ground sliding direction is not affected when the anti-skid function is started.

[0121] The brake command recovery process is as follows:

[0122] 0.2s quickly rises to 70% of the unmanned aerial vehicle management computer brake command, and then rises to 100% of the unmanned aerial vehicle management computer brake command for 2s.

[0123] The brake can be quickly recovered, and continuous dragging of the tire is avoided, improving the brake efficiency and shortening the brake distance.

Claims

1. A flying wing UAV anti-skid braking control method, characterized in that: The following steps are involved: a. The UAV management computer sends the ground speed of the flying wing UAV to the brake control unit, which then collects the wheel speed. b. The brake control unit calculates the ratio of the wheel speed to the ground speed of the flying wing UAV based on the ground speed and wheel speed of the flying wing UAV. ; c. Calculate the anti-slip amount of the right wheel , left wheel anti-slip and right wheel anti-slip same; d. The UAV management computer calculates the left brake drive instruction and right brake actuation command Issue a brake command; In step b, the ratio of the wheel speed to the ground speed of the flying wing UAV is Calculated by formula 1; Formula 1; in, is the ground speed of the flying wing drone, is the wheel speed; In step c, the right wheel anti-slip amount is calculated by formula 2 ; Formula 2; In step d, the left brake drive instruction Calculated by formula 3; Formula 3; In step d, the right brake drive instruction Calculated by formula 4; Formula 4; in, For left brake command, It is the right brake command; In the step d, issuing a brake command means issuing a brake command greater than the pressure loss value of the wheel brake device 3 seconds after the main wheels of the aircraft touch down.

2. The anti-skid braking control method for a flying wing UAV according to claim 1, characterized in that: The braking command is softened from a small amount of braking of 2MPa to a rated braking command of 80% over 2s and maintained until the ground speed of the flying wing UAV reaches 200km / h.

3. The anti-skid braking control method for a flying wing UAV according to claim 1, characterized in that: When the ground speed of the flying wing UAV is below 200 km / h, the UAV management computer applies brakes according to the rated brake pressure.

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