Multi-loop PI control of variable cycle engine and packet loss compensation method for distributed platform simulation

Abstract

The present invention discloses a method for multi-loop PI control of a variable cycle engine and distributed platform simulation packet loss compensation. First, based on the characteristics of distributed simulation, a multi-loop PI controller with limit protection for the transition process of the variable cycle engine is designed, and a software program is developed and deployed and debugged on a hardware platform. Secondly, when a certain probability of packet loss occurs in a data transmission channel, the influence of using the real data received at the previous moment instead of the packet loss data to perform control loop calculation on the control performance is analyzed. It is found that conventional processing methods are prone to cause control system instability and excessive control error. Under the premise of limited hardware computing resources, the packet loss data is estimated by the least squares fitting quadratic function curve method based on historical data; finally, a distributed packet loss compensation strategy based on the estimation is designed and experimentally verified on a distributed control simulation platform. The results show that the present invention can maintain a high control quality of the control system when the communication data packet loss rate is less than 60%.

Description

Technical Field

[0001] The present invention belongs to the field of aero-engine control system design, and in particular relates to a variable cycle engine multi-loop PI control and a distributed platform simulation packet loss compensation method. Background Art

[0002] Engines are complex in structure and operate in harsh and variable conditions. The engine control system is an effective way to ensure safe and stable flight. Advanced aircraft engines place higher demands on safety, stability, and reliability. Variable cycle engines, combining the performance advantages of both turbojets and turbofans, are becoming a major research focus for the next generation of aircraft engines. Inevitably, with the increased control volume and more complex control logic required by variable cycle engines, traditional centralized control structures are no longer sufficient. Therefore, distributed engine control structures are key to the further development of variable cycle engine control systems. In the practical application of aircraft engine distributed control systems, each intelligent node needs to transmit data via a data bus. During actual flight, when encountering harsh environments, electromagnetic interference, and other issues, transmitted data may experience delays and packet loss, resulting in reduced control performance, control system instability, and compromised flight safety. Summary of the Invention

[0003] The technical problem to be solved by the present invention is that in a distributed architecture, packet loss occurs in each intelligent node during communication, resulting in a decrease in control performance and an unstable control system. A variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method is provided. During the dynamic process of the engine, historical cache data is used to estimate the packet loss data and substitute it into the control calculation, thereby improving the robustness of the control system.

[0004] Technical solution: The present invention adopts the following technical solution to solve the above technical problems:

[0005] Step 1) Based on the characteristics of distributed simulation, a multi-loop PI controller with limit protection for the transient state process of the variable cycle engine is designed, and the software program is developed and deployed and debugged on the hardware platform;

[0006] Step 2) Analyze the impact on control performance when a certain probability of packet loss occurs in the data transmission channel and the real data received at the previous moment is used instead of the lost packet data for control loop calculation;

[0007] Step 3) Under the premise of limited hardware computing resources, the packet loss data is estimated using the least squares fitting quadratic function curve method based on historical data;

[0008] Step 4) Based on the estimated packet loss data, a compensation strategy is designed and simulated for verification.

[0009] As an implementation scheme of the variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method of the present invention, step 1) includes:

[0010] Step 1.1) Based on the variable cycle engine control plan, the control structure is designed in the typical working mode: the main fuel flow W f Control high-pressure rotor speed n H The tail nozzle throat area A8 controls the engine pressure ratio EPR, and other geometric adjustment parameters are open-loop control. The adjustable ejector area A 114 、A 163 、A 224 and adjustable guide vane angle α Fan , α CDFS , α Comp , α LTurb ;

[0011] Step 1.2) Use the Min-Max structure for limiting protection during acceleration and deceleration control;

[0012] Step 1.3) Use CodeWarrior software to deploy the variable cycle engine mathematical model and controller to the intelligent simulation node to complete the hardware environment configuration.

[0013] As an implementation scheme of the variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method of the present invention, step 1.2) specifically includes: the selected limiting protection parameters are (1) high-pressure rotor speed; (2) high-pressure compressor outlet total pressure; (3) low-pressure turbine outlet total temperature; (4) minimum fuel quantity limit. In the mode switching process, the limiting protection parameter (5) engine thrust needs to be added. The fuel increment calculated by each limiting controller and the fuel increment calculated by the acceleration and deceleration controller are compared with the minimum fuel quantity through the high-low selection logic strategy to select the appropriate W. f as input to the engine.

[0014] As an implementation scheme of the variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method of the present invention, step 2) includes:

[0015] Step 2.1) When data packet loss occurs in the sensor→controller (SC) channel, the controller uses the last successfully received signal to calculate the control quantity;

[0016] Step 2.2) When data packet loss occurs in the controller→actuator (CA) channel, the engine operates using the control command that was successfully received last time;

[0017] Step 2.3) Data transmission between the control node and the data processing node is performed using the TTP / C communication protocol;

[0018] Step 2.4) Test the impact on the control system when different probabilities of data packet loss occur in the SC channel and CA channel.

[0019] Preferably, step 2.3) builds a distributed control simulation platform based on the TTP / C communication protocol.

[0020] As an implementation scheme of the variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method of the present invention, step 3) includes:

[0021] Step 3.1) Cache the data of n historical moments in the data processing node and the control node, and use a quadratic function curve to fit the n data;

[0022] Step 3.2) When the data processing node and the intelligent control node fail to receive the data check frame, i.e., packet loss occurs, determining whether the current packet loss process occurs during the engine dynamic process;

[0023] Step 3.3) When data loss occurs during the dynamic phase of the engine, the data fitting function is executed to predict the packet loss data. When data loss occurs during the steady-state phase of the engine, the data value at the previous moment is used for the calculation.

[0024] Step 4) Complete simulation verification on the distributed control simulation platform.

[0025] Step 4.1) When packet loss occurs during the SC channel dynamic process, the variable cycle engine output parameter n H , EPR respectively uses the strategy of fitting and estimating the sampling data of the first 10 moments to compensate;

[0026] Step 4.2) When packet loss occurs during the dynamic process of the CA channel, the controller outputs the parameter W f , A8, and A9 respectively use the strategy of fitting and estimating the sampling data of the first 10 moments to compensate;

[0027] Step 4.3) Use CodeWarrior software to encapsulate and deploy the control algorithm and actuator data processing functions that incorporate the compensation mechanism to the corresponding intelligent simulation node;

[0028] Step 4.4) Complete the hardware connection and experimental verification of the distributed control simulation platform.

[0029] The beneficial effects of the present invention are: 1. The present invention designs a variable cycle engine transition state controller and conducts experimental verification on a distributed control simulation platform. It not only adopts a distributed control architecture that is more in line with future development trends for controller design, but also integrates the control algorithm design, hardware platform construction, simulation experimental verification and other stages together, and can quickly deploy and verify the engine model and controller.

[0030] 2. The present invention proposes a method of least squares fitting a quadratic function curve to estimate packet loss data. Compared with the method of replacing packet loss data with the sampled data at the previous moment, the method proposed by the present invention can maintain a high control quality of the control system when the communication data packet loss rate is less than 60%. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the architecture diagram of the distributed control simulation platform;

[0032] Figure 2 This is a schematic diagram of data transmission on a distributed control simulation platform;

[0033] Figure 3 This is a diagram of packet loss on a distributed control simulation platform;

[0034] Figure 4(a) shows the distributed control platform simulation of the time-varying cycle engine W before compensation. f Input curve;

[0035] Figure 4(b) is the input curve of the time-varying cycle engine A8 simulated by the distributed control platform before compensation;

[0036] Figure 5(a) shows the simulation of the distributed control platform before compensation. f Control loop simulation results;

[0037] Figure 5(b) shows the simulation results of the A8 control loop when simulating the distributed control platform before compensation;

[0038] Figure 6(a) shows the distributed control platform simulation of the time-varying cycle engine W after compensation. f Input curve;

[0039] Figure 6(b) is the input curve of the time-varying cycle engine A8 simulated by the distributed control platform after compensation;

[0040] Figure 7(a) shows the simulation of the distributed control platform after compensation. f Control loop simulation results;

[0041] Figure 7(b) shows the simulation results of the A8 control loop during the distributed control platform simulation after compensation. DETAILED DESCRIPTION

[0042] In order to help those skilled in the art better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with specific implementation methods.

[0043] The idea of ​​the present invention is to address the problems of increased control variables and adjustment mechanisms in variable-cycle engines and more complex control structures. Based on a distributed control simulation platform, a multi-loop PI controller with limit protection is designed. Furthermore, in response to the packet loss problem that occurs during the communication process of each intelligent node, a least squares fitting quadratic function curve method is proposed to estimate the packet loss data. Compared with the method of replacing the packet loss data with the sampled data at the previous moment, the method proposed by the present invention can enable the control system to maintain a high control quality when the communication data packet loss rate is less than 60%.

[0044] The specific embodiment of the present invention takes the case where the SC channel and CA channel of a variable cycle engine have different probability of packet loss as an example, and describes the present invention in detail, including the following steps:

[0045] Step 1) Based on the characteristics of distributed simulation, a multi-loop PI controller with limit protection for the transient state process of the variable cycle engine is designed, and the software program is developed and deployed and debugged on the hardware platform;

[0046] Step 1.1) Based on the variable cycle engine control plan, the control structure is designed in the typical working mode: the main fuel flow W f Control high-pressure rotor speed n H The tail nozzle throat area A8 controls the engine pressure ratio EPR, and other geometric adjustment parameters are open-loop controlled, including the adjustable ejector area A 114 、A 163 、A 224 and adjustable guide vane angle α Fan , α CDFS , α Comp , α LTurb ;

[0047] Step 1.2) Use the Min-Max structure for limiting protection during acceleration and deceleration control;

[0048] Step 1.3) Use CodeWarrior software to deploy the variable cycle engine mathematical model and controller to the intelligent simulation node to complete the hardware environment configuration.

[0049] Step 2) Analyze the impact on control performance when a certain probability of packet loss occurs in the data transmission channel and the real data received at the previous moment is used instead of the lost packet data for control loop calculation;

[0050] Step 2.1) When data packet loss occurs in the sensor→controller (SC) channel, the controller uses the last successfully received signal to calculate the control quantity;

[0051] Step 2.2) When data packet loss occurs in the controller→actuator (CA) channel, the engine operates using the control command that was successfully received last time;

[0052] Step 2.3) Data transmission between the control node and the data processing node is performed using the TTP / C communication protocol;

[0053] Step 2.4) Test the impact on the control system when different probabilities of data packet loss occur in the SC channel and CA channel.

[0054] Step 3) Under the premise of limited hardware computing resources, the packet loss data is estimated using the least squares fitting quadratic function curve method based on historical data;

[0055] Step 3.1) Cache the data of n historical moments in the data processing node and the control node, and use a quadratic function curve to fit the n data;

[0056] Step 3.2) When the data processing node and the intelligent control node fail to receive the data check frame, i.e., packet loss occurs, determining whether the current packet loss process occurs during the engine dynamic process;

[0057] Step 3.3) When data loss occurs during the dynamic phase of the engine, the data fitting function is executed to predict the packet loss data. When data loss occurs during the steady-state phase of the engine, the data value at the previous moment is used for the calculation.

[0058] Step 4) Based on the estimated packet loss data, a compensation strategy is designed and simulated for verification.

[0059] Step 4.1) When packet loss occurs during the SC channel dynamic process, the variable cycle engine output parameter n H , EPR respectively uses the strategy of fitting and estimating the sampling data of the first 10 moments to compensate;

[0060] Step 4.2) When packet loss occurs during the dynamic process of the CA channel, the controller outputs the parameter W f , A8, and A9 respectively use the strategy of fitting and estimating the sampling data of the first 10 moments to compensate;

[0061] Step 4.3) Use CodeWarrior software to encapsulate and deploy the control algorithm and actuator data processing functions that incorporate the compensation mechanism to the corresponding intelligent simulation node;

[0062] Step 4.4) Complete the hardware connection and experimental verification of the distributed control simulation platform.

[0063] In order to verify the effectiveness of the variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method proposed in this invention, an experimental verification was carried out on a distributed control simulation platform. The specific scheme is as follows:

[0064] (1) This paper selects the variable cycle engine to be tested in single mode at the ground working point. The packet loss environment is the packet loss in the SC channel. The control instructions of the engine at t = 0 ~ 7.5s are [N H ,EPR]=[0.907,0.630],the control instruction of t=7.5~25s is [N H ,EPR]=[0.935,0.880],the control instruction of t=25~40s is [N H ,EPR]=[0.960,0.940], the simulation results before compensation at different packet loss rates are shown in the attached figure. Figure 4(a) 、 4(b) , Attachment Figure 5(a) 、 5(b) The simulation results after compensation are shown in the attached Figure 6(a) 、 6(b) , Attachment Figure 7(a) 、 7(b) shown.

[0065] As shown in Figures 4(a) to 7(b), the method proposed in this invention, which uses least squares fitting of a quadratic function curve to estimate packet loss data, effectively addresses the issue of excessive control system adjustment time compared to the pre-compensation state. Compared to the case without packet loss, the maximum error in the dynamic process at a packet loss rate of 60% is less than 1%, and the optimized control system still maintains good control performance. This data fitting method can avoid the problems of excessive control time and excessive dynamic process errors in control systems with limited hardware computing resources.

[0066] The present invention's variable-cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method can achieve this goal, even with limited hardware computing resources, by preventing excessive control system adjustment times and large dynamic process errors when packet loss occurs during communication between nodes. Furthermore, by integrating control algorithm design, hardware platform construction, and simulation experimental verification into the simulation process, the engine model and controller can be rapidly deployed and verified.

[0067] It should be noted that the above description is merely a specific embodiment of the present invention, and the scope of protection of the present invention is not limited thereto. Any changes and substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A method for multi-loop PI control of a variable cycle engine and packet loss compensation in a distributed platform simulation, characterized in that: The following steps are involved: Step 1) Based on the characteristics of distributed simulation, a multi-loop PI controller with limit protection for the transient state process of the variable cycle engine is designed, and the software program is developed and deployed and debugged on the hardware platform; Step 2) Analyze the impact on control performance when a certain probability of packet loss occurs in the data transmission channel and the real data received at the previous moment is used instead of the lost packet data for control loop calculation; Step 3) Under the premise of limited hardware computing resources, the packet loss data is estimated using the least squares fitting quadratic function curve method based on historical data; Step 4) Design a compensation strategy based on the estimated packet loss data and perform simulation verification; The step 1) comprises: Step 1.1) Based on the variable cycle engine control plan, the control structure is designed in the typical working mode: the main fuel flow W f Control high-pressure rotor speed n H The tail nozzle throat area A8 controls the engine pressure ratio EPR, and other geometric adjustment parameters are open-loop controlled, including the adjustable ejector area A 114 、A 163 、A 224 and adjustable guide vane angle α Fan , α CDFS , α Comp , α LTurb ; Step 1.2) Use the Min-Max structure for limiting protection during acceleration and deceleration control; Step 1.3) Use CodeWarrior software to deploy the variable cycle engine mathematical model and controller to the intelligent simulation node to complete the hardware environment configuration. The step 4) comprises: Step 4.1) When packet loss occurs during the SC channel dynamic process, the variable cycle engine output parameter n H , EPR respectively uses the strategy of fitting and estimating the sampling data of several previous moments to compensate; Step 4.2) When packet loss occurs during the dynamic process of the CA channel, the controller outputs the parameter W f , A8, and A9 respectively use the strategy of fitting and estimating the sampling data of several previous moments to compensate; Step 4.3) Use CodeWarrior software to encapsulate and deploy the control algorithm and actuator data processing functions that incorporate the compensation mechanism to the corresponding intelligent simulation node; Step 4.4) Complete the hardware connection and experimental verification of the distributed control simulation platform.

2. The variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method according to claim 1 is characterized by: Step 1.2) includes the selection of the limiting protection parameters, specifically (1) high-pressure rotor speed; (2) high-pressure compressor outlet total pressure; (3) low-pressure turbine outlet total temperature; (4) minimum fuel quantity limit; in the mode switching process, the limiting protection parameter (5) engine thrust needs to be added; the fuel increment calculated by each limiting controller and the fuel increment calculated by the acceleration and deceleration controller are compared with the fuel increment calculated by the high-low selection logic strategy to finally determine the optimal fuel instruction and the minimum fuel quantity, and select W f as input to the engine.

3. The variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method according to claim 1 is characterized by: The step 2) comprises: Step 2.1) When data packet loss occurs in the sensor-to-controller SC channel, the controller uses the last successfully received signal to calculate the control quantity; Step 2.2) When data packet loss occurs in the controller-to-actuator CA channel, the engine operates using the control command that was successfully received last time; Step 2.3) Data transmission between the control node and the data processing node is carried out using the TTP / C communication protocol; Step 2.4) Test the impact on the control system when different probabilities of data packet loss occur in the SC channel and CA channel.

4. The variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method according to claim 3 is characterized by: Step 2.3) Build a distributed control simulation platform based on the TTP / C communication protocol.

5. The variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method according to claim 1 is characterized by: The step 3) comprises: Step 3.1) Cache the data of n historical moments in the data processing node and the control node, and use a quadratic function curve to fit the n data; Step 3.2) When the data processing node and the intelligent control node fail to receive the data check frame, i.e., packet loss occurs, determining whether the current packet loss process occurs during the engine dynamic process; Step 3.3) When data loss occurs during the dynamic process of the engine, execute the data fitting function to predict the packet loss data; when data loss occurs during the steady-state process of the engine, continue to use the data value at the previous moment to substitute into the calculation.

6. The variable cycle engine multi-loop PI control and distributed platform simulation packet loss compensation method according to claim 5 is characterized by: Step 3.1) involves finding the polynomial fitting coefficients in such a way that the sum of squares of the errors between the curve fitting value and the actual value is minimized. From this we can get, From formula (2), we can get equation group (3), and then let X be formula (4). According to XA=Y, then A=X -1 Y, that is, to obtain the fitting coefficient of the polynomial,

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