CN114859851A - Method for evaluating time delay tolerance of unmanned aerial vehicle control system - Google Patents

Abstract

The invention relates to the technical field of aircraft flight control, and discloses a method for evaluating the time delay tolerance of an unmanned aerial vehicle control system, which comprises the following steps: s1, acquiring an open loop phase angle margin of an unmanned aerial vehicle control system; s2, calculating a lag phase of the unmanned aerial vehicle control system based on the relation between the bandwidth and the time delay; s3, comparing the lag phase of the unmanned aerial vehicle control system with the open-loop phase angle margin, and judging whether the unmanned aerial vehicle control system has tolerance capacity to time delay; s4, calculating a tolerable maximum time delay value based on the relation between the phase angle margin and the bandwidth of the unmanned aerial vehicle control system; and S5, acquiring the tolerable maximum time delay in the whole flight control system according to the tolerable maximum time delay value. The method is used for evaluating the time delay tolerance capability of the unmanned aerial vehicle control system, and further improves the safety of the unmanned aerial vehicle.

Description

A method for evaluating the delay tolerance of UAV control system

technical field

The invention relates to the technical field of aircraft flight control, in particular to a method for evaluating the delay tolerance capability of an unmanned aerial vehicle control system, which is used for evaluating the time delay tolerance capability of the unmanned aerial vehicle control system, thereby improving the performance of the unmanned aerial vehicle. safety.

Background technique

At present, with the development of UAV technology, the control system of UAV has received more and more attention. In order to improve the safety and reliability of the UAV, the UAV control system needs to have a certain tolerance to the delay. Delays caused by sensors, actuators, etc. are often ignored when designing UAV controllers. For UAVs, if the delay exceeds the tolerable range of the UAV, the originally stable UAV control system will become unstable. Therefore, it is necessary to propose a method for evaluating the delay tolerance of the UAV control system, which can evaluate the delay tolerance of the UAV control system, thereby improving the safety of the UAV.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a method for evaluating the delay tolerance of the UAV control system, to realize the function of evaluating the delay tolerance of the UAV control system, and to improve the safety of the UAV.

The present invention is achieved through the following technical solutions: a method for evaluating the delay tolerance of an unmanned aerial vehicle control system, comprising the following steps:

Step S1. Obtain the open-loop phase angle margin of the UAV control system;

Step S2. Calculate the lag phase of the UAV control system based on the relationship between the bandwidth and the time delay;

Step S3. Compare the lag phase of the UAV control system with the open-loop phase angle margin, and determine whether the UAV control system has tolerance for time delay;

Step S4. Calculate the tolerable maximum delay value based on the relationship between the phase angle margin and the UAV control system bandwidth;

Step S5. Obtain the tolerable maximum delay in the entire flight control system according to the tolerable maximum delay value.

In order to better realize the present invention, further, step S1 includes:

Step S1.1. Obtain the open-loop phase angle margin Pm of the UAV control system;

Step S1.2. According to the cut-off frequency w _c of the UAV control system, the transfer function G (jw _c ) of the forward channel, the transfer function H (jw _c ) of the feedback channel and the open-loop phase angle margin Pm to obtain the unmanned aerial vehicle And the critical stability expression after the open-loop phase angle margin of the control system is reduced by Pm, and expressed as: ∠G( _jwc )∠H( _jwc )-Pm=-180°.

In order to better realize the present invention, further, step S2 includes:

The expression for calculating the lag phase φ of the UAV control system is φ=ωt, where ω is the bandwidth of the UAV control system, in rad/s, and t is the time delay, in s.

In order to better realize the present invention, further, step S3 includes:

Compare the lag phase φ of the UAV control system with the open-loop phase angle margin Pm;

When φ<Pm, it is judged that the UAV control system has tolerance to the delay under the current lag phase φ;

When φ=Pm, it is judged that the UAV control system is in a critical stable state;

When φ>Pm, it is judged that the UAV control system cannot tolerate the delay under the current lag phase φ.

In order to better realize the present invention, further, step S4 includes:

According to the open-loop phase angle margin and bandwidth, the maximum time delay t _max that can be tolerated by the UAV control system is calculated and expressed as:

，其中，t_max的单位为毫秒，并调整时延t，使t＜t_max。

, where the unit of t _max is milliseconds, and the time delay t is adjusted so that t < t _max .

In order to better realize the present invention, further, step S5 includes:

Obtain the maximum delay that each loop can tolerate according to the controlled amount of each loop channel and the bandwidth of each loop in the UAV control system;

Take the minimum value of the maximum delay values that each loop can tolerate as the maximum delay that the entire flight control system can tolerate.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The method of the present invention is simple, easy to implement, and has strong engineering practicability;

(2) The present invention utilizes the relationship between bandwidth, time delay and phase angle margin to realize the evaluation of time delay tolerance and improve the safety and reliability of the UAV control system;

(3) The present invention can not only evaluate the rationality of the delay, but also give the desirable range of the delay.

Description of drawings

The present invention will be further described with reference to the following drawings and embodiments, and all conceptual innovations of the present invention should be regarded as the disclosed content and the protection scope of the present invention.

FIG. 1 is a flowchart of a method for evaluating the delay tolerance capability of a UAV control system provided by the present invention.

Detailed ways

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the following will clearly and completely describe the technical solutions of the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. It should be understood that the described embodiments are only Some, but not all, embodiments of the present invention should therefore not be construed as limiting the scope of protection. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that, unless otherwise expressly specified and limited, the terms "arranged", "connected" and "connected" should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or integral connection; it can be mechanical connection or electrical connection; it can also be directly connected, or it can be indirectly connected through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations.

Example 1:

As shown in FIG. 1, this embodiment discloses a method for evaluating the delay tolerance of the UAV control system in this embodiment: step S1. Obtaining the open-loop phase angle margin of the UAV control system;

Step S2. Calculate the lag phase of the UAV control system based on the relationship between the bandwidth and the time delay;

Step S3. Compare the lag phase of the UAV control system with the open-loop phase angle margin, and determine whether the UAV control system has tolerance for time delay;

Step S4. Calculate the tolerable maximum delay value based on the relationship between the phase angle margin and the UAV control system bandwidth;

Step S5. Obtain the tolerable maximum delay in the entire flight control system according to the tolerable maximum delay value.

In this embodiment, a method for evaluating the tolerance of the UAV control system to the delay is provided, which is not only simple and easy to implement, but also has strong engineering practical ability. Using the relationship between bandwidth, delay and phase angle margin, the evaluation of delay tolerance is realized, which improves the safety and reliability of the UAV control system

Example 2:

This embodiment is further optimized on the basis of Embodiment 1, and this embodiment discloses:

Step S1.1. Obtain the open-loop phase angle margin Pm of the UAV control system;

Step S1.2. According to the cut-off frequency w _c of the UAV control system, the transfer function G (jw _c ) of the forward channel, the transfer function H (jw _c ) of the feedback channel and the open-loop phase angle margin Pm to obtain the unmanned aerial vehicle And the critical stability expression after the open-loop phase angle margin of the control system is reduced by Pm, and expressed as: ∠G( _jwc )∠H( _jwc )-Pm=-180°.

In this embodiment, G( _jwc ) and H( _jwc ) are both open-loop transfer functions, which are respectively the transfer functions of the control loop, G(jwc) is the forward channel transfer function, and H(jwc) is the feedback The transfer function of the channel is common knowledge in the control theory in the art. In this embodiment, the open-loop phase angle margin of the UAV control system is obtained by calculating the cut-off frequency according to the amplitude of the system, and then calculating the open-loop phase angle margin according to the cut-off frequency. At the cut-off frequency w _c of the system, when the amplitude satisfies the systematic stability condition, the system will reach the critical stability condition after the open-loop phase angle margin is further reduced by Pm.

The other parts of this embodiment are the same as those of Embodiment 1, and thus are not repeated here.

Example 3:

This embodiment is further optimized on the basis of the above-mentioned Embodiment 1 or 2, and this embodiment discloses:

The expression for calculating the lag phase φ of the UAV control system is φ=ωt, where ω is the bandwidth of the UAV control system, in rad/s, and t is the time delay, in s.

In this embodiment, by calculating the lag phase of the UAV control system, it is judged whether the lag phase of the UAV control system is smaller than the phase angle margin. When the lag phase of the UAV control system is smaller than the phase angle margin, then The UAV control system has the tolerance for this delay, and then the control system’s tolerance to the delay can be evaluated later. When the delay phase of the UAV control system is greater than or equal to the phase angle margin, the delay needs to be adjusted. The adjustment of the delay needs to first calculate the maximum delay value, and then adjust the delay so that the delay is less than the maximum delay value. At this time, the delay phase of the UAV control system is less than the phase angle margin, and then evaluate the control system. Delay tolerance.

The other parts of this embodiment are the same as the above-mentioned Embodiment 1 or 2, and thus are not repeated here.

Example 4:

This embodiment is further optimized on the basis of any one of the above-mentioned Embodiments 1-3, and this embodiment discloses:

Compare the lag phase φ of the UAV control system with the open-loop phase angle margin Pm;

When φ<Pm, it is judged that the UAV control system has tolerance to the delay under the current lag phase φ;

When φ=Pm, it is judged that the UAV control system is in a critical stable state;

When φ>Pm, it is judged that the UAV control system cannot tolerate the delay under the current lag phase φ.

In this embodiment, by judging whether the delayed phase of the UAV control system is smaller than the phase angle margin, the result of evaluating the delay tolerance capability of the UAV control system is obtained.

The other parts of this embodiment are the same as any of the above-mentioned Embodiments 1-3, and thus are not repeated here.

Example 5:

This embodiment is further optimized on the basis of any one of the above-mentioned embodiments 1-4, and step S4 includes:

，其中，t_max的单位为毫秒，并调整时延t，使t＜t_max。According to the open-loop phase angle margin and bandwidth, the maximum time delay t _max that can be tolerated by the UAV control system is calculated and expressed as:

, where the unit of t _max is milliseconds, and the time delay t is adjusted so that t < t _max .

This embodiment can not only evaluate the rationality of the delay, but also give a desirable range of the delay.

The other parts of this embodiment are the same as any of the above-mentioned Embodiments 1-4, and thus are not repeated here.

Example 6:

This embodiment is further optimized on the basis of any one of the above-mentioned embodiments 1-5, and step S5 includes:

Obtain the maximum delay that each loop can tolerate according to the controlled amount of each loop channel and the bandwidth of each loop in the UAV control system;

Take the minimum value of the maximum delay values that each loop can tolerate as the maximum delay that the entire flight control system can tolerate.

In this embodiment, taking the longitudinal channel of a UAV control system as an example, the controlled quantities are q, θ, H ^& , H respectively, and the maximum time delay that the entire control system can tolerate can be expressed as:

Tmax=min(t _{max q} , t max _θ , t _{max H} K ), where,

ω_H分别为各环的带宽。Among them, ω _q , ω _θ ,

ω _H is the bandwidth of each ring, respectively.

The other parts of this embodiment are the same as any of the above-mentioned Embodiments 1-5, and thus are not repeated here.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any form. Any simple modifications and equivalent changes made to the above embodiments according to the technical essence of the present invention fall into the present invention. within the scope of protection.

Claims (6)

1. a method for evaluating the time delay tolerance of an unmanned aerial vehicle control system is characterized in that, comprising the following steps: Step S1. Obtain the open-loop phase angle margin of the unmanned aerial vehicle control system; Step S2. Based on bandwidth and time The relationship between the delays and the delay phase of the UAV control system are calculated; Step S3. Compare the delay phase of the UAV control system with the open-loop phase angle margin to determine whether the UAV control system has tolerance to the delay. capability; Step S4. Calculate the tolerable maximum delay value based on the relationship between the phase angle margin and the UAV control system bandwidth; Step S5. Obtain the tolerable maximum delay in the entire flight control system according to the tolerable maximum delay value. 2. The method for evaluating the delay tolerance of the UAV control system according to claim 1, wherein the step S1 comprises: Step S1.1. Obtaining the open-loop phase of the UAV control system Angle margin Pm; Step S1.2. According to the cut-off frequency w _c of the UAV control system, the transfer function G (jw _c ) of the forward channel, the transfer function H (jw _c ) of the feedback channel and the open-loop phase angle margin The degree Pm obtains the critical stability expression after the open-loop phase angle margin of the unmanned and control system is reduced by Pm, and is expressed as: ∠G( _jwc )∠H( _jwc )-Pm=-180°. 3. a kind of method for evaluating UAV control system to time delay tolerance according to claim 1, is characterized in that, described step S2 comprises: The expression for calculating the lag phase φ of the UAV control system is φ=ωt, where ω is the bandwidth of the UAV control system, in rad/s, and t is the time delay, in s. 4. The method for evaluating the time delay tolerance of the UAV control system according to claim 1, wherein the step S3 comprises: combining the lag phase φ and the open-loop phase angle of the UAV control system The margin Pm is compared; when φ<Pm, it is judged that the UAV control system has tolerance for the delay under the current lag phase φ; when φ=Pm, it is judged that the UAV control system is in a critically stable state; When φ>Pm, it is judged that the UAV control system cannot tolerate the delay under the current lag phase φ. 5. The method for evaluating the time delay tolerance of the UAV control system according to claim 1, wherein the step S4 comprises: calculating the UAV control system according to the open-loop phase angle margin and bandwidth The value of the maximum delay t _max that the system can tolerate, and is expressed as:

, where the unit of t _max is milliseconds, and the time delay t is adjusted so that t < t _max . 6 . The method for evaluating the delay tolerance of the UAV control system according to claim 1 , wherein the step S5 comprises: according to the controlled quantity of each loop channel in the UAV control system. 7 . and the bandwidth of each loop to obtain the maximum delay that each loop can tolerate; take the minimum value of the maximum delay values that each loop can tolerate as the maximum delay that the entire flight control system can tolerate.

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