Four-dimensional route control method based on speed override

Abstract

The invention discloses a four-dimensional route control method based on speed override, and belongs to the technical field of aircraft navigation and control. Time consideration is added in route management, and estimated time for arriving at a waypoint is calculated in real time; in the course flight process, an adjusting instruction for the arrival time of a target waypoint can be sent, and the algorithm can dynamically adjust a speed instruction according to the remaining time and the distance to be flied to compensate for the time accumulation deviation in the flight process; and meanwhile, a speed override algorithm with quick response is adopted, so that the speed is quickly converged to a speed instruction, and accurate control on the speed instruction is realized. According to the method, the punctuality of reaching the target waypoint by the aircraft is improved, the flight safety and the working efficiency of the aircraft can be effectively improved, and an effective technical means is provided for the safety and the stability of time precision control aircrafts.

Description

Technical Field

[0001] The invention belongs to the technical field of aircraft navigation and control, and in particular relates to a four-dimensional route control method based on speed override. Background Art

[0002] With the rapid development of aviation technology, aircraft (including drones, cruise missiles, commercial airliners, etc.) are increasingly used in military operations, logistics transportation, disaster relief and other fields. Traditional route control technology focuses on trajectory tracking in three-dimensional space (longitude, latitude, altitude), but in the face of complex mission scenarios (such as multi-target collaboration, high dynamic environment, precise time window constraints), control that relies solely on the spatial dimension can no longer meet the needs. This has spawned a technological upgrade from "spatial trajectory tracking" to "space-time collaborative control", and four-dimensional route control has become the core direction for solving high-precision space-time constraint problems.

[0003] The traditional speed control loop only designs the controller for the spatial position deviation, and does not include the time error in the feedback loop, which is not adaptable to the dynamic environment. The realization of four-dimensional route control requires a high-precision time prediction method and speed override technology. Under complex targets, the attributes of waypoints will become increasingly diverse, such as circling waypoints, obstacle avoidance waypoints, etc. The range calculation for these non-general waypoints is particularly difficult, which poses a challenge to the accuracy of time prediction. Common route control algorithms mainly control the aircraft to reach the waypoints of predetermined positions and altitudes in sequence according to the preset route. If time constraints are added and the target waypoints are required to be reached at a specified time, manual intervention is required to adjust the flight speed, and it is impossible to achieve "fixed-time fixed-point" flight autonomously; moreover, this places high demands on the operator, and the deviation between the arrival time and the preset time cannot be guaranteed. For instructions with large time adjustment, the speed instruction is bound to change significantly in a short period of time. A speed override method that can quickly respond to speed instructions and avoid the adverse effects of sudden changes in speed on other state quantities is particularly important. Summary of the invention

[0004] The present invention provides a four-dimensional route control method based on speed override, which adopts a "throttle speed control" strategy, takes into account both the rapidity and stability of speed command response, improves the punctuality of waypoint arrival, and can significantly improve the space-time coordination capability of the aircraft.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions:

[0006] A four-dimensional route control method based on speed override comprises the following steps:

[0007] S1: Obtain route information containing multiple waypoints, measure the position information of the aircraft, update the waypoint number in real time, and calculate the estimated time to reach each waypoint to be flown;

[0008] S2: Obtain the target waypoint number and arrival time adjustment instruction to be reached on time, calculate the distance to be flown to the target waypoint based on the currently measured aircraft position information, and dynamically plan the speed instruction based on the remaining time;

[0009] S3: Calculate the speed error based on the current measured speed, and use the classic PI control law to directly map the speed deviation to the throttle command. Adjust the thrust directly through the change in fuel quantity to make the speed converge to the target speed.

[0010] In the above steps, the route information includes waypoint attributes and waypoint locations;

[0011] Given the waypoint number and the total number of waypoints, we can traverse all the waypoints to be flown, calculate the distance to be flown and the estimated time to reach the waypoint. The distance to be flown is given by , It consists of two parts. is the distance between the current position and the waypoint, is the distance between the flying waypoint and the target waypoint;

[0012] According to the measured flight speed, the time required to reach the desired flight point can be obtained. , plus the current UTC time, we can get the UTC time to reach the waypoint to be flown; set the time adjustment amount to reach the target waypoint as , the ground speed command is: , , In the formula, Indicates the remaining time to reach the destination waypoint.

[0013] The control goal is to make the aircraft speed Able to quickly approach and maintain Nearby, thus achieving precise speed control, the final control law output is: , in, is the throttle command, , are the speed controller gains, is the aircraft mass, For maximum thrust.

[0014] Beneficial effects: The present invention provides a four-dimensional route control method based on speed override, which has the following advantages over the prior art:

[0015] 1. The present invention can calculate the distance to be flown and the remaining time in real time according to the measurement data of the sensor and the adjustment time of the target waypoint, and provide real-time and reliable data for the calculation of the speed instruction;

[0016] 2. The speed instruction in the present invention adds a dynamic compensation mechanism for time error, calculates the estimated time to reach the waypoint in real time, and sends an adjustment instruction for the arrival time of the target waypoint during the flight. The speed instruction is dynamically adjusted according to the remaining time and the distance to be flown to compensate for the accumulated time deviation during the flight to meet the time matching requirements;

[0017] 3. The present invention adopts the speed override strategy of "throttle speed control", directly feeds back the speed deviation to the throttle command, and directly adjusts the thrust through the change of the fuel amount, so that the speed converges to the speed command quickly, and realizes the precise control of the speed command; the response to the speed is more linear and fast, especially in the scene that needs rapid acceleration or deceleration. The effect of thrust change on speed is relatively single, and the closed-loop control structure is simple, the parameter setting is easy, and the robustness is higher. It can respond to the speed deviation in a relatively short time, which is conducive to realizing the rapid and reliable acceleration and deceleration of the aircraft in a short time, and finally ensures that the four-dimensional route flight process is safer, smoother and more efficient, improves the safety and tracking accuracy, and is conducive to practical engineering applications;

[0018] 4. The method of the present invention improves the punctuality of the aircraft arriving at the target waypoint, can effectively improve the flight safety and work efficiency of the aircraft, and provides an effective technical means for the safety and stability of aircraft with precise time control; it is suitable for aircraft such as drones and cruise missiles that require precise space-time coordination, and provides a new approach and solution for improving the safety and control accuracy of four-dimensional route flight. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is an example of a simulink block diagram of a four-dimensional route control algorithm in an embodiment of the present invention;

[0020] Figure 2 is the equivalent distance from the circling waypoint in the embodiment of the present invention;

[0021] Figure 3 is a block diagram example of speed override in an embodiment of the present invention;

[0022] Figure 4 is a simulation change curve of the target waypoint number in an embodiment of the present invention;

[0023] Figure 5 It is a simulation change curve of the waypoint number in the embodiment of the present invention;

[0024] Figure 6It is a simulation variation curve of the time required to reach the target waypoint in the embodiment of the present invention;

[0025] Figure 7 The distance simulation change curve to the target waypoint in the embodiment of the present invention is

[0026] Figure 8 : is a simulation change curve of the ground speed and the ground speed command in an embodiment of the present invention;

[0027] Fig. 9 It is a simulation change curve of the throttle command in the embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments:

[0029] The aircraft in this embodiment is equipped with basic inertial measurement unit (IMU), GPS and other sensors, which can provide reliable posture information for flight control. During the flight, the distance and flight time of the aircraft from the waypoint to be flown are updated in real time.

[0030] The initial value of the waypoint number is 1. When the following conditions are met, the waypoint number will be incremented by 1 until all waypoints are flown. , In the above formula, The distance threshold between the current position of the aircraft and the waypoint, usually set to , is the current ground speed.

[0031] If the number of the waypoint in flight and the total number of waypoints are known, the information of all the waypoints to be flown can be traversed to calculate the distance to be flown and the estimated time to reach the waypoint. The calculation of the flight range is divided into two parts: the distance from the current position of the aircraft to the waypoint in flight. And the distance from the waypoint to the waiting waypoint , if the flying waypoint coincides with the target waypoint, then .

[0032] Estimated arrival time for each destination to be flown: , , , In the formula, , , They are the estimated total time to reach the target waypoint A, the time to reach the current waypoint, and the time to reach the target waypoint A from the current waypoint. , They are the distance between the current waypoint and the distance between the current waypoint and the target waypoint. is the current ground speed.

[0033] Figure 2 is a schematic diagram of the equivalent distance from the circling waypoint. The calculation of is affected by the properties of the waypoint. When the waypoint is a general waypoint, it is directly equivalent to the distance to be flown; when the waypoint is a circling waypoint, it is equivalent to the straight-line distance between the current position of the aircraft and the circling point. The calculation is to accumulate the distances between the remaining waypoints section by section.

[0034] When the aircraft's in-flight waypoint number is m, send the target waypoint number n and the arrival time adjustment , at this time the ground speed command for: , In the formula, is the distance between the flight waypoint number m and the target waypoint number n, is the time originally required to reach the waypoint to be flown, Indicates the offset between the expected total time and the estimated total time, which can be adjusted according to the distance to the target waypoint and the remaining time. When it is a negative number, it means that the time to reach the target waypoint needs to be advanced. will increase; when A positive number indicates that the time to reach the target waypoint needs to be delayed. Will decrease.

[0035] In order to track the ground speed command, the output of the aircraft PI control law is: , in, is the throttle command, , are the speed controller gains, is the aircraft mass, For maximum thrust.

[0036] Combining Newton's Second Law ,have to , so the transfer function from ground speed command to ground speed is: .

[0037] definition and are the bandwidth and damping ratio of the speed control loop respectively, and the corresponding expressions are: , , By setting the corresponding bandwidth and damping ratio, the gain of the PI speed controller can be obtained. Figure 3 Figure 2 is an example of a block diagram for speed override.

[0038] Test verification and results:

[0039] In the experimental stage, the control strategy of this embodiment can be tested in a simulation environment (such as a semi-physical simulation platform), where the gain of the speed controller is , .

[0040] The experimental results are as follows Figure 4-Figure 9 As shown, it can be seen that when the aircraft is heading towards waypoint 5 at 1577.2s, the estimated time to reach waypoint 10 is 792.765s, that is, 2369.965s. First, a command to reach waypoint 10 50s in advance was sent, and the ground speed command increased by about 2.9m / s. After 30s, the ground speed tracked the ground speed command and maintained it for a period of time. Then a command to reach waypoint 10 100s in advance was sent. After receiving the command, the ground speed command accelerated from 42.9m / s to 50.8m / s, and the ground speed measurement value converged to the command value after about 30s, and maintained the speed to the target waypoint 10. After two time adjustments, it is expected to arrive at waypoint 10 150s in advance, that is, 2219.965s. In fact, the aircraft arrived at waypoint 10 at 2218.8s, and the time arrival time deviation was <2s. During the speed command switching process, the ground speed command tracking takes a short time and has a small error, meeting the high dynamic response requirements.

[0041] The above are only preferred embodiments of the present invention. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the protection scope of the present invention.

Claims

1. A four-dimensional route control method based on speed override, characterized in that: The following steps are involved: S1: Obtain route information containing multiple waypoints, measure the position information of the aircraft, update the waypoint number in real time, and calculate the estimated time to reach each waypoint to be flown; S2: Obtain the target waypoint number and arrival time adjustment instruction to be reached on time, calculate the distance to be flown to the target waypoint based on the currently measured aircraft position information, and dynamically plan the speed instruction based on the remaining time; S3: Calculate the speed error based on the current measured speed, and use the classic PI control law to directly map the speed deviation to the throttle command. Adjust the thrust directly through the change in fuel quantity to make the speed converge to the target speed.

2. The four-dimensional route control method based on speed override according to claim 1 is characterized in that: The route information includes waypoint attributes and waypoint locations.

3. The four-dimensional route control method based on speed override according to claim 1 or 2, characterized in that: The initial value of the waypoint number is 1, satisfying When the flight is completed, the waypoint number will increase by 1 until all the waypoints are completed. The distance threshold between the current position of the aircraft and the waypoint is , is the current ground speed, The distance between the current position and the waypoint.

4. The four-dimensional route control method based on speed override according to claim 3 is characterized in that: Estimated arrival time for each destination to be flown: ， ， ， In the formula, , , They are the estimated total time to reach the target waypoint, the time to reach the current waypoint, and the time to reach the target waypoint from the current waypoint. , They are the distance between the current waypoint and the distance between the current waypoint and the target waypoint. is the current ground speed.

5. The four-dimensional route control method based on speed override according to claim 4 is characterized in that: The calculation of is affected by the properties of the waypoint. When the waypoint is a general waypoint, it is directly equivalent to the distance to be flown; when the waypoint is a circling waypoint, it is equivalent to the straight-line distance between the current position of the aircraft and the circling point. The calculation is to accumulate the distances between the remaining waypoints section by section.

6. The four-dimensional route control method based on speed override according to claim 4 is characterized in that: According to the measured flight speed, the time required to reach the desired flight point can be obtained. , plus the current UTC time, you can get the UTC time of arrival at the destination; Set the time adjustment to reach the target waypoint as , the ground speed command is: ， ， In the formula, Indicates the remaining time to reach the destination waypoint.

7. The four-dimensional route control method based on speed override according to claim 6 is characterized in that: It can be adjusted according to the distance to the target waypoint and the remaining time. When it is a negative number, it means that the time to reach the target waypoint needs to be advanced. Increase; when When it is a positive number, it means that the time to reach the target waypoint needs to be delayed. Reduce.

8. The four-dimensional route control method based on speed override according to claim 6, characterized in that: Combining Newton's Second Law ,have to , so the transfer function from ground speed command to ground speed is ， definition and are the bandwidth and damping ratio of the speed control loop respectively, and the corresponding expressions are: ， ， By setting the corresponding bandwidth and damping ratio, the gain of the PI speed controller can be obtained.

9. The four-dimensional route control method based on speed override according to claim 8, characterized in that: The output of the aircraft PI control law is: ， in, is the throttle command, , are the speed controller gains, is the aircraft mass, For maximum thrust.

Images