A Preset Performance Increment Fault-Tolerant Control Method for Stratospheric Airships

Abstract

The present invention discloses a method for preset performance incremental fault-tolerant control of a stratospheric airship, belonging to the technical field of automatic control, and comprising the following steps: S1, performing the conversion of the error between the current state and the expected value to achieve performance error conversion; S2, calculating the outer-loop control quantity and the inner-loop virtual control quantity to achieve incremental control output; S3, performing fault-tolerant control correction on the virtual control quantity to achieve fault-tolerant module correction; S4, performing error module correction on the virtual control quantity to obtain the input vector of the actual control channel and achieve error module correction. By adopting the above method for preset performance incremental fault-tolerant control of a stratospheric airship, through the combination of preset performance incremental control and active fault-tolerant strategy, precise control, dynamic performance optimization and fault adaptive reconfiguration ability of the stratospheric airship under complex conditions such as environmental interference, parameter uncertainty and actuator failure can be realized, and the robustness of the airship control system can be greatly enhanced.

Description

Technical Field

[0001] The present invention relates to the technical field of automatic control, and particularly to a preset performance incremental fault-tolerant control method for a stratospheric airship. Background Art

[0002] In the prior art, with the increasing attention paid to stratospheric airships, their control systems have gradually entered extensive research. However, they also have certain inherent characteristics, which lead to many adverse influencing factors in the system, such as parameter uncertainty, strong coupling, unknown external interference, etc. At the same time, it is difficult to achieve passive fault tolerance by setting redundant mechanisms in such a system.

[0003] To address the control problems of stratospheric airships caused by environmental interference, parameter uncertainty, and actuator failures during operation, this paper proposes a preset performance-based incremental fault-tolerant control method. Since stratospheric airships are affected by factors such as installation errors, weight throwing, and center-of-gravity movement in practical applications, and it is difficult to repair actuators, traditional methods are difficult to ensure the robustness and stability of their control systems. Existing non-linear control strategies have been applied in fields such as multi-rotor, fixed-wing, and hybrid unmanned aerial vehicles, but they rely on accurate system models and are easily affected by uncertainties. Incremental control methods have gradually become an alternative due to their model-free characteristics. Incremental control, such as incremental backstepping, effectively improves the system robustness and reduces model dependence. However, existing incremental control does not fully consider the dynamic performance of the system. Summary of the Invention

[0004] The object of the present invention is to provide a preset performance incremental fault-tolerant control method for a stratospheric airship. By combining preset performance incremental control with an active fault-tolerant strategy, precise control, dynamic performance optimization, and fault adaptive reconfiguration capabilities of the stratospheric airship under complex conditions such as environmental interference, parameter uncertainty, and actuator failures can be achieved, which can greatly enhance the robustness of the airship control system.

[0005] To achieve the above object, the present invention provides a preset performance incremental fault-tolerant control method for a stratospheric airship, including the following steps:

[0006] S1. Perform the conversion of the error between the current state and the expected value to achieve performance error conversion;

[0007] S2. Calculate the outer-loop control quantity and the inner-loop virtual control quantity to achieve incremental control output:

[0008] S3. Perform fault-tolerant control correction on the virtual control quantity to achieve fault-tolerant module correction;

[0009] S4. Perform error module correction on the virtual control quantity to obtain the actual control channel input vector to achieve error module correction.

[0010] Preferably, in S1, the specific method is as follows: First, establish a basic dynamic model of a stratospheric airship with some unknowns, and the formula is as follows:

[0011] ;

[0012] Where, represents the three attitude angles of the stratospheric airship: pitch angle, roll angle, and yaw angle, represents the three angular velocity vectors: pitch angular velocity, roll angular velocity, and yaw angular velocity, represents the control inputs in three directions: pitch control input, roll control input, and yaw control input; , and both represent the function vectors of the system, represents the unknown disturbance within the system;

[0013] Define the error vector , where, is the expected value of the input;

[0014] Define the transformed error vector as: , and the transformation method is as follows:

[0015] ;

[0016] Where, is the design control parameter, is the design transformation function.

[0017] Preferably, in S2, the specific calculation method is as follows: First, calculate the outer loop control quantity after error transformation;

[0018] Take the derivative of the transformed error to obtain the derivative of the new error as follows:

[0019] ;

[0020] Where, is the derivative of the error before transformation, and are intermediate calculation variables, is the derivative of the design parameter;

[0021] Give the inner loop control quantity as follows:

[0022] ;

[0023] Where, represents the derivative component of the expected value, represents the inverse of the function, represents the component of the inner loop expected value; Design parameters for the control system

[0024] Perform a first-order Taylor expansion on the inner-loop model, and the result is as follows:

[0025] ;

[0026] Among them, represents the value at the current moment, represents the first-order expansion value of the system error, and the expanded model is as follows:

[0027] ;

[0028] Among them, represents G the first-order Taylor expansion at the current moment of represents the error value to be estimated.

[0029] Preferably, in S3, the specific calculation method is: First, design the airship actuator fault model as follows:

[0030] ;

[0031] Among them, represents the actuator multiplicative fault coefficient, represents the virtual control quantity, represents the actuator additive fault coefficient, represents the actual control quantity;

[0032] Define the fault observer error , , Obtain the update rates of the multiplicative fault coefficient and the additive fault coefficient:

[0033] ;

[0034] ;

[0035] Among them, and respectively represent and the estimated error vector components, and are the designed controller parameters.

[0036] Preferably, in S4, the specific calculation method is: First, apply a first-order filter to the system, and the filtered effect is as follows:

[0037] ;

[0038] Among them, and are respectively and filtered signals of and are respectively and derivatives of is a design parameter;

[0039] The design error estimation algorithm is as follows:

[0040] ;

[0041] wherein, is estimated value of;

[0042] Define the inner loop control error as , and correct the virtual control quantity as follows:

[0043] ;

[0044] wherein, is a control system design parameter, represents the inverse of vector.

[0045] Therefore, the beneficial effects of the present invention adopting the above-mentioned preset performance increment fault-tolerant control method for a stratospheric airship are as follows:

[0046] (1) Enhanced fault-tolerant ability: By designing an incremental adaptive fault observer, it can quickly identify and estimate the fault situation when the actuator fails, realize the autonomous reconstruction of the control strategy, and significantly improve the active fault-tolerant ability of the system.

[0047] (2) Compatibility of robustness and model uncertainty: While considering the parameter uncertainty and complex dynamic characteristics of the stratospheric airship, through the combination of incremental control and preset performance bounds, it ensures the control accuracy, effectively reduces the dependence on the model accuracy, and improves the robustness of the system.

[0048] (3) Precise dynamic performance control: Design a predicted performance boundary, transform the tracking error to improve the dynamic response effect of the system, and ensure the dynamic performance of the closed-loop system, so as to achieve precise trajectory tracking even under complex environmental interference conditions.

[0049] (4) Effectively suppress external interference: Use an unknown input observer to estimate and compensate for the matched interference, enhance the ability of the system to resist external interference, and ensure that the stratospheric airship can still maintain stable and reliable control effects when affected by external interference.

[0050] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Description of the Drawings

[0051] Figure 1 is a step diagram of an embodiment of a preset performance incremental fault-tolerant control method for a stratospheric airship of the present invention;

[0052] Figure 2 is a schematic flowchart of an embodiment of a preset performance incremental fault-tolerant control method for a stratospheric airship of the present invention. Detailed Embodiments

[0053] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0054] Unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the ordinary meanings understood by those of ordinary skill in the field to which the present invention belongs. The "first", "second" and similar terms used in the present invention do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "comprising" or "including" mean that the elements or objects appearing before the term cover the elements or objects listed after the term and their equivalents, without excluding other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left" and "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0055] Embodiment 1

[0056] As Figure 1 shown, the present invention provides a preset performance incremental fault-tolerant control method for a stratospheric airship, including the following steps:

[0057] S1. Perform the conversion of the error between the current state and the expected value to achieve performance error conversion.

[0058] As Figure 2 shown, specifically: First, establish a basic dynamic model of a partially unknown stratospheric airship, and the formula is as follows:

[0059] ;

[0060] Among them, represents the three attitude angles of the stratospheric airship: pitch angle, roll angle and yaw angle, represents the three angular velocity vectors: pitch angular velocity, roll angular velocity and yaw angular velocity, Represents the control inputs in three directions: pitch control input, roll control input, and yaw control input; , and both represent the function vectors of the system, represents the unknown disturbance within the system.

[0061] Define the error vector , where is the expected value of the input.

[0062] Define the transformed error vector as: , and the transformation method is as follows:

[0063] ;

[0064] where is the design control parameter, is the design transformation function.

[0065] S2. Calculate the outer-loop control quantity and the inner-loop virtual control quantity to achieve incremental control output.

[0066] Specifically: First, calculate the outer-loop control quantity after error transformation.

[0067] Take the derivative of the transformed error to obtain the derivative of the new error as follows:

[0068] ;

[0069] where is the derivative of the error before transformation, and are intermediate calculation variables, is the derivative of the design parameter.

[0070] Give the inner-loop control quantity as follows:

[0071] ;

[0072] where represents the derivative component of the expected value, represents taking the inverse of the function, represents the component of the inner-loop expected value; is the design parameter of the control system.

[0073] Perform a first-order Taylor expansion on the inner-loop model, and the result is as follows:

[0074] ;

[0075] where represents The value at the current moment, represents the first - order expansion value of the system error. The expanded model is as follows:

[0076] ;

[0077] where, represents G the first - order Taylor expansion at the current moment of represents the error value to be estimated.

[0078] S3. Perform fault - tolerance control correction on the virtual control quantity to achieve fault - tolerance module correction.

[0079] Specifically: First, design the airship actuator fault model as follows:

[0080] ;

[0081] where, represents the actuator multiplicative fault coefficient, represents the virtual control quantity, represents the actuator additive fault coefficient, represents the actual control quantity.

[0082] Define the fault observer error , , to obtain the update rates of the multiplicative fault coefficient and the additive fault coefficient.

[0083] ;

[0084] ;

[0085] where, and respectively represent and the estimated error vector components, and are the designed controller parameters.

[0086] S4. Perform error module correction on the virtual control quantity to obtain the actual control channel input vector and achieve error module correction.

[0087] Specifically: First, apply a first - order filter to the system to obtain the following filtered effect:

[0088] ;

[0089] where, and are respectively and the filtered signals of and are respectively and 's derivatives, being design parameters.

[0090] The design error estimation algorithm is as follows:

[0091] ;

[0092] wherein, is 's estimated value.

[0093] Define the inner loop control error as , and correct the virtual control quantity as follows:

[0094] ;

[0095] wherein, is a control system design parameter, denotes the inverse of the vector.

[0096] Therefore, the present invention adopts the above-mentioned preset performance increment fault-tolerant control method for a stratospheric airship. By combining preset performance increment control with an active fault-tolerant strategy, it can achieve precise control, dynamic performance optimization, and fault adaptive reconfiguration ability of the stratospheric airship under complex conditions such as environmental interference, parameter uncertainty, and actuator faults, and can greatly enhance the robustness of the airship control system.

[0097] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A preset performance increment fault-tolerant control method for a stratospheric airship, characterized in that, It includes the following steps: S1. Perform the conversion of the error between the current state and the expected value to achieve the conversion of the performance error; S2. Calculate the outer-loop control quantity and the inner-loop virtual control quantity to achieve the incremental control output: S3. Perform the fault-tolerant control correction on the virtual control quantity to achieve the correction of the fault-tolerant module; In S3, the specific calculation method is: First, design the following airship actuator fault model: ； Among them, represents the actuator multiplicative fault coefficient, represents the virtual control quantity, represents the actuator additive fault coefficient, represents the actual control quantity; Define the fault observer error , , Obtain the update rates of the multiplicative fault coefficient and the additive fault coefficient: ； ； Among them, and respectively represent and the estimated error vector components, and are the designed controller parameters; S4. Perform the error module correction on the virtual control quantity to obtain the actual control channel input vector and achieve the error module correction.

2. The preset performance increment fault tolerance control method of a stratospheric airship according to claim 1, characterized in that: In S1, the specific method is: First, establish the basic dynamic model of the stratospheric airship with partially unknown parameters, and the formula is as follows: ； Among them, denote the three attitude angles of the stratospheric airship: pitch angle, roll angle, and yaw angle, denote the three angular velocity vectors: pitch angular velocity, roll angular velocity, and yaw angular velocity, denote the control inputs in three directions: pitch control input, roll control input, and yaw control input; 、 and both denote the function vectors of the system, denote the unknown disturbances within the system; Define the error vector , where is the expected value of the input; Define the transformed error vector as follows: , and the transformation method is as follows: ； Among them, is the design control parameter, is the design conversion function.

3. A preset performance increment fault-tolerant control method for a stratospheric airship according to claim 1, characterized in that: In S2, the specific calculation method is: First, calculate the outer-loop control quantity after the error conversion; Take the derivative of the converted error to obtain the derivative of the new error as follows: ； Among them, is the error derivative before conversion, and are intermediate calculation variables, is the design parameter derivative; Give the inner-loop control quantity as follows: ； Among them, represents the derivative component of the expected value, represents taking the inverse of the function, represents the component of the inner-loop expected value; is the design parameter of the control system; Perform the first-order Taylor expansion on the inner-loop model, and the result is as follows: ； Among them, represents the value at the current moment, represents the first-order expansion value of the systematic error. The expanded model is as follows: ； Among them, represents the first-order Taylor expansion of G at the current moment; represents the error value to be estimated.

4. A preset performance incremental fault-tolerant control method for a stratospheric airship according to claim 1, characterized in that: In S4, the specific calculation method is: First, apply a first-order filter to the system to obtain the following filtered effect: ； Among them, and are respectively and filtered signals of and are respectively and derivatives of is a design parameter; Design the error estimation algorithm as follows: ； Among them, is the estimated value; Define the inner-loop control error as , and correct the virtual control quantity as follows: ； Among them, is the design parameter of the control system, denotes the inverse operation on the vector.

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