CN110989348B - Sliding mode control method of reusable carrying system based on event trigger mechanism - Google Patents

Abstract

The invention discloses a sliding mode control method of a reusable carrying system based on an event trigger mechanism, which simplifies the reusable carrying system into a second-order linear system, effectively solves the problem of continuous change of the system operating environment by utilizing an intelligent method of sliding mode control, obtains ideal dynamic characteristics, has certain robustness on system parameters and external interference signal change, and ensures that the system has good stability; in addition, an event trigger communication mechanism is introduced, transmission data in the network is reduced, the burden of the network bandwidth occupancy is lightened, limited communication resources are saved, and the power consumption of network nodes is reduced.

Description

Sliding mode control method of reusable carrying system based on event trigger mechanism

Technical Field

The invention relates to the technical field of nonlinear system control, in particular to a sliding mode control method of a reusable carrying system based on an event trigger mechanism.

Background

The reusable vehicle is the most complex aircraft in the flight process so far, and in the reentry stage, the reusable vehicle needs to traverse a complex flight environment under the condition of extremely large initial reentry kinetic energy and potential energy to realize the safe landing of the aircraft, and simultaneously, overload, dynamic pressure and pneumatic heating are within the allowable range. Reentry flight of the reusable carrier has the flight characteristics of large airspace and cross-speed domain, and aerodynamic characteristics change strongly in the flight process, so that the external environment generates interference torque, and the control of the reusable carrier is difficult work. In addition to this, it is very important to ensure the stability of the control system, and although various methods based on classical linear control theory and advanced control theory have been proposed at present, general linear control theory is not applicable due to the complexity of the reusable vehicle system.

On the one hand, the linear control theory is no longer applicable due to the complexity of the reusable vehicle system.

On the other hand, the reusable carrier system is implemented by wireless network connection, and one of the problems to be considered is whether there is enough bandwidth in the network control system, feeding back information to the controller, and then sending control commands to the actuators and objects.

Disclosure of Invention

Aiming at the defects in the prior art, the sliding mode control method of the reusable carrying system based on the event trigger mechanism solves the problems that a linear control theory in the reusable carrying system is not suitable and a network in a network control system is crowded.

In order to achieve the purpose of the invention, the invention adopts the technical scheme that: a sliding mode control method of a reusable carrying system based on an event trigger mechanism comprises the following steps:

s1, establishing a dynamic model of the reusable carrying system according to the aerodynamic principle to obtain a relational expression of the control moment and the posture of the carrying device;

s2, obtaining a control signal by adopting a sliding mode control method according to a relational expression of the control moment and the carrier;

s3, acquiring a tracking error through a sensor;

s4, judging whether the tracking error is larger than the error threshold value, if so, marking the time t_cIs updated to t_c+1And will t_c+1At the moment, a control signal generated by the controller is sent to the actuator through the network; if not, the process goes to step S3.

The relationship between the control torque and the attitude of the vehicle in step S1 is:

e_ψ＝ψ-ψ_c (2)

ψ_c＝[α_c β_c σ_c]^T (3)

ψ＝[α β σ]^T (4)

ω＝[p q r]^T (7)

T＝[M_x M_yM_z]^T (8)

wherein e is_ψFor tracking error, R is attitude angle matrix, I is 3 × 3 rotational inertia matrix, omega is attitude angle rate vector, T is control moment, d is external interference factor, psi_cIs an attitude angle reference trajectory vector, psi is an attitude angle vector, alpha_cFor angle of attack reference trajectory, beta_cFor reference trajectory of sideslip angle, σ_cIs a roll angle reference trajectory, alpha is an attack angle, beta is a sideslip angle, sigma is a roll angle, p is a roll angle rate, q is a pitch angle rate, r is a yaw angle rate, M_xFor roll moment, M_yFor pitching moment, M_zIs the yaw moment.

The expression of the control signal in step S2 is:

wherein T (t) is a control signal, t is time, k₁For the first positive definite diagonal matrix of the tracking trajectory, k₂A second positive definite diagonal matrix for the tracking trajectory, m being an error threshold, epsilon being a factor for the tracking trajectory,

in order to be the track factor,

is a tracking factor.

In the present embodiment, it is preferred that,

m＝[39000；39000；39000]，

ψ_c＝ [18；0；-20+t]，

e_ψ(0)＝[2；-0.5；78]，z_ψ(0)＝[0；0；0]，k₁＝diag[101212],k₂＝ diag[201412]the data results are shown in fig. 2-7, and it can be seen that the design can ensure that the system effectively tracks a given curve and the tracking error converges to 0 within a limited time.

The invention has the beneficial effects that: a sliding mode control method of a reusable carrying system based on an event trigger mechanism simplifies the reusable carrying system into a second-order linear system, utilizes an intelligent sliding mode control method, effectively solves the problem that the system operation environment changes continuously, obtains ideal dynamic characteristics, has certain robustness on system parameters and external interference signal changes, and ensures that the system has good stability; in addition, an event trigger communication mechanism is introduced, transmission data in the network is reduced, the burden of the network bandwidth occupancy is lightened, limited communication resources are saved, and the power consumption of network nodes is reduced.

Drawings

Fig. 1 is a flowchart of a sliding mode control method of a reusable carrier system based on an event trigger mechanism.

FIG. 2 shows an angle of attack α and an angle of attack reference trajectory α_cThe condition response graph of (1).

FIG. 3 is a side slip angle β and a side slip angle reference trajectory β_cThe condition response graph of (1).

FIG. 4 is a roll angle σ and a roll angle reference trajectory σ_cThe condition response graph of (1).

FIG. 5 is the angle of attack error e for angle of attack α_ψ1Response curve of the state.

FIG. 6 is a side slip angle error e for the side slip angle β_ψ2Sound of stateIt should be curved.

FIG. 7 is a roll angle error e of the roll angle σ_ψ3Response curve of the state.

Detailed Description

The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.

As shown in fig. 1, a sliding mode control method for a reusable vehicle system based on an event trigger mechanism includes the following steps:

s1, establishing a dynamic model of the reusable carrying system according to the aerodynamic principle to obtain a relational expression of the control moment and the posture of the carrying device;

s2, obtaining a control signal by adopting a sliding mode control method according to a relational expression of the control moment and the carrier;

s3, acquiring a tracking error through a sensor;

s4, judging whether the tracking error is larger than the error threshold value, if so, marking the time t_cIs updated to t_c+1And will t_c+1At the moment, a control signal generated by the controller is sent to the actuator through the network; if not, the process goes to step S3.

The relationship between the control torque and the attitude of the vehicle in step S1 is:

e_ψ＝ψ-ψ_c (2)

ψ_c＝[α_c β_c σ_c]^T (3)

ψ＝[α β σ]^T (4)

ω＝[p q r]^T (7)

T＝[M_x M_y M_z]^T (8)

wherein e is_ψFor tracking error, R is attitude angle matrix, I is 3 × 3 rotational inertia matrix, omega is attitude angle rate vector, T is control moment, d is external interference factor, psi_cIs an attitude angle reference trajectory vector, psi is an attitude angle vector, alpha_cFor angle of attack reference trajectory, beta_cFor reference trajectory of sideslip angle, σ_cIs a roll angle reference trajectory, alpha is an attack angle, beta is a sideslip angle, sigma is a roll angle, p is a roll angle rate, q is a pitch angle rate, r is a yaw angle rate, M_xFor roll moment, M_yFor pitching moment, M_zIs the yaw moment.

The expression of the control signal in step S2 is:

wherein T (t) is a control signal, t is time, k₁For the first positive definite diagonal matrix of the tracking trajectory, k₂A second positive definite diagonal matrix for the tracking trajectory, m being an error threshold, epsilon being a factor for the tracking trajectory,

in order to be the track factor,

is a tracking factor.

In the present embodiment, it is preferred that,

m＝[39000；39000；39000]，

ψ_c＝[18；0；-20+t]，

e_ψ(0)＝[2；-0.5；78]，z_ψ(0)＝[0；0；0]，k₁＝diag[101212]，k₂＝ diag[201412]the data results are shown in fig. 2-7, and it can be seen that the design can ensure that the system effectively tracks a given curve and the tracking error converges to 0 within a limited time, where e_ψ＝ψ-ψ_c＝ [e_ψ1 e_ψ2 e_ψ3]^T＝[α-α_c β-β_c σ-σ_c]^T，e_ψ1As angle of attack error, e_ψ2Error of sideslip angle, e_ψ3Is the roll angle error.

The invention has the beneficial effects that: a sliding mode control method of a reusable carrying system based on an event trigger mechanism simplifies the reusable carrying system into a second-order linear system, utilizes an intelligent sliding mode control method, effectively solves the problem that the system operation environment changes continuously, obtains ideal dynamic characteristics, has certain robustness on system parameters and external interference signal changes, and ensures that the system has good stability; in addition, an event trigger communication mechanism is introduced, transmission data in the network is reduced, the burden of the network bandwidth occupancy is lightened, limited communication resources are saved, and the power consumption of network nodes is reduced.

Claims (1)

1. A sliding mode control method of a reusable carrying system based on an event trigger mechanism is characterized by comprising the following steps:

s1, establishing a dynamic model of the reusable carrying system according to the aerodynamic principle to obtain a relational expression of the control moment and the posture of the carrying device;

s2, obtaining a control signal by adopting a sliding mode control method according to a relational expression of the control moment and the carrier;

s3, acquiring a tracking error through a sensor;

s4, judging whether the tracking error is larger than the error threshold value, if so, marking the time t_cIs updated to t_c+1And will t_c+1At the moment, a control signal generated by the controller is sent to the actuator through the network; if not, jumping to step S3;

the relationship between the control torque and the attitude of the vehicle in step S1 is:

e_ψ＝ψ-ψ_c (2)

ψ_c＝[α_c β_c σ_c]^T (3)

ψ＝[α β σ]^T (4)

ω＝[p q r]^T (7)

T＝[M_x M_y M_z]^T (8)

wherein e is_ψFor tracking error, R is attitude angle matrix, I is 3 × 3 rotational inertia matrix, omega is attitude angle rate vector, T is control moment, d is external interference factor, psi_cIs an attitude angle reference trajectory vector, psi is an attitude angle vector, alpha_cFor angle of attack reference trajectory, beta_cFor reference trajectory of sideslip angle, σ_cIs a roll angle reference track, alpha is an attack angle, beta is a sideslip angle, sigma is a roll angle, p is a roll angle rate, q is a pitch angle rate, and r isFor yaw rate, M_xFor roll moment, M_yFor pitching moment, M_zIs a yaw moment;

the expression of the control signal in step S2 is:

wherein T (t) is a control signal, t is time, k₁For the first positive definite diagonal matrix of the tracking trajectory, k₂A second positive definite diagonal matrix for the tracking trajectory, m being an error threshold, epsilon being a factor for the tracking trajectory,

in order to be the track factor,

is a tracking factor.

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