Engine rotating speed control and verification method
Through the method of scanning frequency identification and dominant pole method design control parameters, the fluctuation of the engine speed of the unmanned helicopter under different working conditions is solved, the stability and immunity are improved, and the quality of flight control is ensured.
Patent Information
- Application Number
- CN202510225893.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-27
- Publication Date
- 2025-05-27
AI Technical Summary
The speed of the unmanned helicopter engine fluctuates greatly when the gusts, maneuverable flight and maneuverable torque changes rapidly, affecting the quality of flight control. The existing technology has unclear stability margin and anti-interference performance of the control system.
The engine speed model was obtained through the sweep frequency identification test, the control parameters were designed using the dominant pole method, and the parameters were adaptively scheduling were realized in the speed controller. The stability and immunity of engine speed control are verified by load disturbance, delay disturbance and throttle disturbance.
It realizes stable control of engine speed under different working conditions, improves disturbance immunity, ensures the quality of flight control, and provides a clear evaluation of the stability margin and anti-interference performance of the control system.
Smart Images
Figure CN120042702A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for controlling and verifying the engine speed, and particularly to the speed control of an unmanned helicopter. Background Art
[0002] The rotor speed of an unmanned helicopter is constant. On this basis, the flight actions of the helicopter are controlled by changing the control torques (collective pitch, tail rotor pitch, longitudinal cyclic pitch, and lateral cyclic pitch). The engine is connected to the rotor through a transmission system. Therefore, the stable engine speed is the basis for controlling the flight of the helicopter. The speed control parameters of an unmanned helicopter are usually obtained by the method of experimental trial and error. The stability margin and anti-interference performance of the control system are not clear. When encountering gusts, large maneuvering flights, and rapid changes in control torques, the engine speed may fluctuate greatly, affecting the flight control quality. Therefore, it is necessary to develop an engine speed control method with better stability and fully verify the stability and anti-interference ability. Summary of the Invention
[0003] The purpose of the present invention is to solve the problems proposed in the above background art, and provide a method for controlling and verifying the engine speed of an unmanned helicopter, obtaining a speed control law with better stability and anti-interference ability, and being able to maintain the stable engine speed under various working conditions of the helicopter.
[0004] The present invention provides a method for controlling and verifying the engine speed of an unmanned helicopter. The engine speed model is obtained through a frequency sweep identification test, and the control parameters are designed. Finally, the stability and anti-disturbance ability of the engine speed control are verified by methods such as load disturbance, delay disturbance, and throttle disturbance. The specific steps are as follows:
[0005] Step 1, under different collective pitch working conditions, use the frequency sweep identification method to obtain different models of the engine speed response;
[0006] Step 2, adopt the dominant pole method to complete the control parameter design of different engine speed models, and realize parameter adaptive scheduling in the speed controller;
[0007] Step 3, verify the stability degree of the speed control by delaying the output of the calculation result of the speed controller; verify the anti-interference ability of the speed control by superimposing a throttle disturbance amount on the basis of the throttle setting output by the controller or by changing the collective pitch to cause a load change.
[0008] In Step 1, using the frequency sweep identification method, select the frequency band with coherence greater than 0.6 for model identification, obtain the transfer function of the model, obtain the engine speed system model, and obtain the transfer function G(s) of the following first-order system model:
[0009]
[0010] The above formula is an algebraic equation of s, which means the ratio of the Laplace transform of the system output to the Laplace transform of the input quantity. Here, T represents the inertia of the speed response (the time constant of the first-order system), K represents the amplitude of the speed response, τ represents the delay of the speed response, and e is the natural constant. Under different total pitch load conditions, the parameters T, K, and τ in the engine speed system model will be slightly different.
[0011] In step 2, based on the sisotool tool, for different transfer functions of the engine speed models, the dominant pole method is used to complete the design of the control law parameters; the design performance indicators are as follows: overshoot of 20%, and adjustment time of 6 seconds (2% error band).
[0012] In step 2, the speed controller automatically retrieves the control parameters corresponding to the corresponding engine model according to different engine states. For intermediate states, the linear interpolation method is used to schedule the parameters, and finally the parameter adaptive scheduling is realized.
[0013] In step 2, the final realization of the parameter adaptive scheduling includes: first establishing a control parameter array K array in the speed controller, which characterizes different speed model states col n corresponding to different parameters k n , and the array is in the following form:
[0014]
[0015] where, T represents the matrix transpose, col n represents the nth speed model state, and k n represents the parameter corresponding to the nth speed model state;
[0016] The linear interpolation scheduling formula is as follows:
[0017]
[0018] where, K P represents the retrieved control parameter, pcol represents the real-time total pitch, and j represents the total pitch interpolation sequence number of the real-time total pitch in the control parameter array.
[0019] In step 3, under the condition of different total pitches and stable speeds, the throttle setting results calculated by the speed controller are processed with delayed output. The delay increases from small to large to evaluate the stability of the engine speed control; the total pitch is changed rapidly to change the load condition environment, simulating the load change during flight, to verify the anti-disturbance ability of the engine speed control when dealing with load changes; the throttle is changed rapidly to force the speed to fluctuate, and the magnitude of the speed fluctuation is recorded to verify the anti-disturbance ability of the engine speed control for throttle changes.
[0020] Compared with the prior art, the significant progress of the present invention lies in: 1) The present invention can accurately establish the engine speed system model through the identification of the engine speed system model; 2) The engine speed control parameters designed by the present invention have good stability and anti-interference ability; 3) The design and verification process of the engine speed control parameters for the fully unmanned helicopter proposed by the present invention is highly operable and the results are reliable, which can cope with the engine speed control of unmanned helicopters with different configurations and has high engineering application value.
[0021] The following further specific description of the present invention will be made in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer. Description of the Drawings
[0022] Figure 1 It is a flow chart of the engine speed control and verification method.
[0023] Figure 2 It is a structure diagram of the engine speed system model identification.
[0024] Figure 3 It is a structure diagram of the engine speed control.
[0025] Figure 4 It is a structure diagram for verifying the stability of the engine speed control with introduced delay.
[0026] Figure 5 It is a structure diagram for verifying the anti-interference ability of the engine speed control with introduced throttle disturbance.
[0027] Figure 6 It is a structure diagram for verifying the anti-interference ability of the engine speed control with introduced operating condition disturbance.
[0028] Figure 7 It is a diagram of the desired dominant pole region.
[0029] Figure 8 It is a schematic diagram of the dominant pole selection.
[0030] Figure 9 It is a schematic diagram of the speed curve under throttle disturbance.
[0031] Figure 10 It is a schematic diagram of the speed curve under collective pitch disturbance. Detailed Embodiments
[0032] The present invention proposes a method for controlling and verifying the engine speed of an unmanned helicopter. The engine speed model is obtained through the swept-frequency identification method, and the engine speed control law is designed using the dominant pole method. Finally, through the verification of anti-interference ability and stability, the speed control parameters with good stability and anti-interference ability are obtained. The flow of the engine speed control and verification method is as Figure 1 shown, and specifically includes the following steps:
[0033] Step 1: Under different collective pitch conditions, use the swept-frequency identification method to obtain different models of engine speed response.
[0034] Step 2: Use the dominant pole method to complete the design of control parameters for different engine speed models, and implement the adaptive scheduling of parameters in the speed controller.
[0035] Step 3: Verify the stability of speed control by delaying the output of the calculation result of the speed controller; verify the disturbance resistance of speed control by superimposing a throttle disturbance amount on the basis of the throttle setting output by the controller or by changing the collective pitch to cause a load change.
[0036] In Step 1, under different collective pitch conditions, as Figure 2 shown, first output a throttle setting signal from low frequency to high frequency from the speed controller, with the frequency ranging from 0.05 HZ to 1 HZ, to obtain the corresponding engine speed, that is, perform the engine swept-frequency operation. According to the input-output relationship between throttle and speed, analyze its amplitude-frequency, phase-frequency, and coherence in the frequency domain, select the frequency band with coherence greater than 0.6 for model identification, and obtain the transfer function of the model, that is, perform the model identification of the engine speed system.
[0037] Furthermore, in Step 1, to obtain the engine speed model, that is, to obtain the transfer function of the following first-order system model:
[0038]
[0039] The above formula is an algebraic equation of s, which means the ratio of the Laplace transform of the system output to the Laplace transform of the input quantity. Among them, T represents the inertia of the speed response (the time constant of the first-order system), K represents the amplitude of the speed response, τ represents the delay of the speed response, and e is the natural constant. Under different collective pitch load conditions, the parameters T, K, and τ in the engine speed system model will be slightly different.
[0040] Furthermore, in Step 2, the commonly used classical control method is the proportional + integral + derivative method. However, since the speed differential signal cannot be obtained or collected during speed control, the proportional + integral control method is adopted. As Figure 3 shown in the control structure of the engine speed, the proportional + integral control method is used to control the engine speed.
[0041] Furthermore, in Step 2, based on the sisotool tool, using the proportional + integral control method, for the transfer functions of different engine speed models, use the dominant pole method to complete the design work of control law parameters; the designed performance indicators are as follows: overshoot 20%, settling time 6 seconds (2% error band).
[0042] Further, in step 2, the speed controller adopts a proportional + integral control method, completes control calculations based on the deviation between the target speed and the actual speed and control parameters, and outputs a throttle setting signal. Additionally, the speed controller automatically retrieves the control parameters of the corresponding engine model according to different engine states. For intermediate states, a linear interpolation method is used to schedule the parameters, ultimately achieving adaptive parameter scheduling.
[0043] Further, in the speed controller, first establish a control parameter array K array , which represents different speed model states col n corresponding to different parameters k n , and the array is in the following form:
[0044]
[0045] where T represents matrix transpose, and col n represents the nth speed model state, and k n represents the parameter corresponding to the nth speed model state;
[0046] Further, the linear interpolation scheduling formula is as follows:
[0047]
[0048] where K P represents the control parameter to be searched, pcol represents the real-time collective pitch, and j represents the collective pitch interpolation sequence number of the real-time collective pitch in the control parameter array.
[0049] Further, in step 3, as Figure 4 shown, by delaying the output of the calculation result of the speed controller control law, a delay link is introduced into the speed closed-loop system. By introducing different time delays, observe whether the engine speed fluctuates or oscillates; gradually increase the delay until the engine speed shows an oscillatory divergence situation to verify the stability of speed control.
[0050] Further, in step 3, as Figure 5 shown, by superimposing a throttle perturbation amount on the basis of the throttle output by the speed controller, a perturbation link is introduced into the speed closed-loop system. By introducing different throttle perturbations, observe the engine speed fluctuation situation to verify the disturbance resistance of speed control caused by control errors.
[0051] Further, in step 3, as Figure 6 shown, by quickly changing the collective pitch to change the load working condition environment of the engine, simulate the load change during flight to verify the disturbance resistance of speed control caused by load changes.
[0052] To describe the embodiments of the present invention in more detail, a specific implementation process is described in detail. A sufficient weight load is placed on the landing gear and fuselage of the unmanned helicopter so that the unmanned helicopter still cannot take off from the ground when the engine is operating at full power.
[0053] Specifically, in this embodiment, first, start the engine, keep the collective pitch at 0%, adjust the throttle so that the engine speed operates near the rated speed. When the engine speed is stable, input throttle signals of different frequencies (0.05 HZ to 1 HZ), observe the change of the speed, record the throttle signal and speed signal under the condition that the collective pitch is 0%, establish the input-output relationship between the throttle and the speed deviation, analyze its amplitude-frequency, phase-frequency and coherence in the frequency domain, select the frequency band with coherence greater than 0.6 for model identification, and obtain the transfer function of the following first-order system model:
[0054] In addition, raise the collective pitch to 10%, 20%, 30%, 40%, 50% and other working conditions with a difference of 10% until the engine runs at full power, and repeat the above steps in each working condition environment to obtain the speed model under each working condition environment.
[0055] Specifically, in this embodiment, secondly, for the speed models of the above-mentioned working conditions, based on the sisotool tool, use the proportional + integral control method, and complete the design of the control law parameters for different engine speed model transfer functions; the designed performance indicators are as follows: overshoot 20%, adjustment time 6 seconds (2% error band).
[0056] The parameter design experience based on a certain model of the engine is as follows: place a pole at the origin and a zero at the -0.4 position to determine the integral parameter. Select the closed-loop dominant poles near the boundary of the expected dominant pole region to determine the system gain. The position of the zero should be close to the dominant pole of the controlled object, but generally the method of keeping the integral parameter unchanged is adopted in engineering, so the position of the zero is selected by synthesizing the dominant poles of the linear models of other design points. Figure 7 Characterizes the expected dominant pole region determined according to the model and performance indicators, Figure 8 Is a schematic diagram of the selection of the dominant poles in a certain state, where the abscissa is the real part of the root locus and the ordinate is the imaginary part of the root locus.
[0057] The speed controller completes the control calculation according to the deviation between the target speed and the actual speed and the control parameters, and outputs the throttle setting signal; in addition, the speed controller automatically retrieves the control parameters of the corresponding engine model according to different engine states, and uses the linear interpolation method to schedule the parameters for the intermediate state, and finally realizes the parameter adaptive scheduling.
[0058] Specifically, in this embodiment, then start the engine, keep the collective pitch at 0%, when the speed control law is turned on, the engine speed operates at the rated speed. Suddenly superimpose a throttle disturbance signal at the output end of the control law to make the engine speed fluctuate by about 50 revolutions, and observe whether the process of the engine speed returning to the rated speed is oscillatory. As Figure 9 shown, the abscissa is time (unit: S (seconds)), and the ordinate is the engine speed (unit: RPM (revolutions per minute)).
[0059] In addition, increase the collective pitch to 10%, 20%, 30%, 40%, 50% and other working conditions with a difference of 10% until the engine runs at full power. Repeat the above steps in each working condition environment to verify the anti-disturbance ability of the control law in each working condition environment.
[0060] Specifically, in this embodiment, then start the engine, keep the collective pitch at 0%, when the speed control law is turned on, the engine speed operates at the rated speed. Suddenly change the collective pitch to 10%, and observe whether the engine speed fluctuates or oscillates. Wait until the speed stabilizes and then suddenly reduce the collective pitch to 0%, and observe whether the engine speed fluctuates or oscillates.
[0061] Make the collective pitch change rapidly in the intervals of 10% - 20%, 20% - 30% etc. until the engine runs at full power, and repeat the above steps to verify the anti-disturbance ability of the control law under the condition of sudden change of the working condition environment. The speed and collective pitch curves of a certain state are as Figure 10 shown, the abscissa is time (unit: S (seconds)), the right ordinate is the engine speed (unit: RPM (revolutions per minute)), and the left ordinate is the collective pitch (unit: %).
[0062] Specifically, in this embodiment, finally, start the engine, keep the collective pitch at 0%, when the speed control law is turned on, the engine speed operates at the rated speed. Delay the output of the control calculation result and observe whether the engine speed fluctuates or oscillates; gradually increase the delay until the engine speed shows an oscillatory divergence situation, and record this delay as the stability margin of the closed-loop system.
[0063] The present invention provides a method for engine speed control and verification. There are many methods and ways to specifically implement this technical solution. The above description is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by using the prior art.
Claims
1. An engine speed control and verification method, characterized in that: The engine speed model is obtained through the frequency sweep identification test, and the control parameters are designed. Finally, the stability and anti-disturbance of the engine speed control are verified through load disturbance, delay disturbance, throttle disturbance and other methods. The specific steps include the following: Step 1, using a frequency sweep identification method to obtain different models of engine speed response under different collective distance conditions; Step 2, using the dominant pole method to complete the control parameter design of different engine speed models, and realize parameter adaptive scheduling in the speed controller; Step 3: Verify the stability of the speed control by delaying the output of the speed controller calculation result; verify the anti-interference ability of the speed control by superimposing the throttle disturbance on the throttle setting output by the controller or by changing the total pitch to cause load changes.
2. The method according to claim 1, characterized in that In step 1, the frequency sweep identification method is used to select a frequency band with a coherence greater than 0.6 for model identification, obtain the transfer function of the model, obtain the engine speed system model, and obtain the following transfer function G(s) of the first-order system model: The above formula is an algebraic equation of s, which means the ratio of the Pull-type transformation of the system output to the Pull-type transformation of the input quantity, where T represents the inertia of the speed response, K represents the amplitude of the speed response, τ represents the delay of the speed response, and e is a natural constant.
3. The method according to claim 2, characterized in that In step 2, based on the sisotool tool, the dominant pole method is used to complete the control law parameter design work for different engine speed model transfer functions; the design performance indicators are as follows: overshoot 20%, adjustment time 6 seconds.
4. The method according to claim 3, characterized in that In step 2, the speed controller automatically retrieves the control parameters of the corresponding engine model according to different engine states, and for the intermediate states, the linear interpolation method is used to schedule the parameters, and finally the parameter adaptive scheduling is realized.
5. The method according to claim 4, characterized in that In step 2, the final implementation of parameter adaptive scheduling includes: first establishing a control parameter array K in the speed controller array , representing different speed model states col n Corresponding to different parameters k n , the array is as follows: Among them, T represents the matrix transpose, col n represents the nth speed model state, k n Indicates the parameters corresponding to the nth speed model state; The linear interpolation scheduling formula is as follows: Among them, k P Represents the control parameter to be searched, pcol represents the real-time collective distance, and j represents the collective distance interpolation order number of the real-time collective distance in the control parameter array.
6. The method according to claim 5, characterized in that In step 3, under the working conditions of different collective pitches and stable speed, the throttle setting result calculated by the speed controller is delayed and outputted, with the delay increasing from small to large, to judge the stability of the engine speed control; the collective pitch is changed rapidly to change the load working environment, simulating the load change during flight, and verifying the anti-interference ability of the engine speed control in response to load changes; the throttle is changed rapidly to force the speed to fluctuate, and the size of the speed fluctuation is recorded to verify the anti-interference ability of the engine speed control to throttle changes.