Track tracking control method for parafoil system based on switching between linear active disturbance rejection control and predictive control

Abstract

The invention discloses a parafoil system track tracking control method based on switching between linear anti-disturbance control and predictive control, including establishing a parafoil system translation and rotation six-degree-of-freedom model as the track tracking control basis; designing a guide for the parafoil system to eliminate the error between the actual track and the target track by tracking the heading angle of the target track motion; designing a linear anti-disturbance control controller; designing a predictive controller; setting the switching conditions of the two control methods according to the heading angle deviation, and tracking and controlling the homing track of the parafoil system. At the same time, the advantages of good anti-interference ability of linear anti-disturbance control and overcoming time lag of predictive control are brought into play to achieve a better control effect.

Description

Technical Field

[0001] The invention belongs to the technical field of parafoil system trajectory tracking control, and in particular relates to a parafoil system trajectory tracking control method based on switching between linear active disturbance rejection control and predictive control. Background Art

[0002] As a special soft-wing aircraft, the parafoil system uses a flexible ramjet parafoil to provide lift, has good gliding and controllability, and has been widely used in precision airdrops in the military and aerospace fields. The parafoil system is a very complex, strongly coupled, large-time-delay, and strongly nonlinear system. Therefore, it is very necessary to track and control its trajectory during the process of autonomous precision homing. The parafoil system is an underactuated, unpowered system. The parafoil system can only be controlled by changing the aerodynamic force and aerodynamic torque of the parafoil canopy by pulling down the pull ropes on both sides of the trailing edge of the parafoil flap, thereby realizing the parafoil's maneuverable flight in the air and bird landing.

[0003] At present, the research on trajectory tracking control of parafoil systems mainly includes: traditional PD controller and gain-adjusted fuzzy controller for trajectory tracking of parafoil systems, predictive controller by simplifying the parafoil system into a linear model, and auto-disturbance rejection controller designed for wind disturbance.

[0004] Among the above control methods, most of them use a single control method to track and control the homing trajectory of the parafoil system. However, the parafoil system is a high-altitude, unpowered, nonlinear system with a slow flight speed. It is easily disturbed by the external wind field during the homing process. In addition, the parafoil system is controlled by a control rope, and its control response has a large lag phenomenon.

[0005] Therefore, a single control method is often unable to effectively solve the problems of large time delay and susceptibility to wind field interference in the trajectory tracking control process of the parafoil system. Summary of the invention

[0006] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a trajectory tracking control method for a parafoil system based on switching between linear anti-disturbance control and predictive control, perform trajectory tracking control on the gliding section and the energy control section of the parafoil system, and at the same time give full play to the advantages of good anti-disturbance capability of linear anti-disturbance control and overcoming time lag of predictive control to achieve better control effect, with better control accuracy, stronger anti-disturbance capability and good dynamic performance, and solve the problems of strong nonlinearity, strong coupling, large time lag, etc. in the trajectory tracking control of the parafoil system.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0008] The parafoil system trajectory tracking control method based on switching between linear active disturbance rejection control and predictive control includes:

[0009] Step 1, perform force analysis on the parafoil system, and establish a six-degree-of-freedom model of the parafoil system's translation and rotation based on the Newton-Euler equation as the basis for track tracking control;

[0010] Step 2: Based on the guidance path tracking principle, the two-dimensional trajectory tracking guidance strategy is used to design the guide of the parafoil system, calculate the forward error and lateral error between the actual trajectory and the target trajectory, and eliminate the error by tracking the heading angle of the target trajectory movement;

[0011] Step 3, based on the two-dimensional trajectory tracking guidance strategy, the linear active disturbance rejection controller LADRC is designed by constructing the linear extended state observer LESO and PD controller of the system;

[0012] Step 4, based on the two-dimensional trajectory tracking guidance strategy, the predictive controller MPC is designed by constructing a state space model of the system;

[0013] Step 5, setting the switching condition according to the heading angle deviation. When the heading angle deviation does not meet the condition, the controller receives the instruction and adopts the linear anti-disturbance controller control. When the heading angle deviation meets the condition, the controller switches to the predictive controller control to realize the switching control of the parafoil system.

[0014] To optimize the above technical solutions, the specific measures taken also include:

[0015] The above step 1 is specifically as follows:

[0016] Assume that the position vector of the parafoil system in the inertial coordinate system is P I =[x I y I z I ] T , the velocity vector of the parafoil system in the parafoil body coordinate system is V B =[u B v B w B ] T , the attitude angle vector of the parafoil system in the inertial coordinate system is A I =[φ θψ] T The attitude angular velocity vector of the parafoil system in the parafoil body coordinate system is W B =[pqr] T ;

[0017] According to the Newton-Euler equation, the six-degree-of-freedom model of the parafoil system translation and rotation can be obtained:

[0018] (1) Translational three-degree-of-freedom equation:

[0019]

[0020]

[0021] (2) Rotational three-degree-of-freedom equation:

[0022]

[0023]

[0024] Where M is the total mass of the parafoil system, R IB is the transformation matrix from the parachute body coordinate system B to the earth coordinate system I, F G is the gravity of the parafoil system in the parafoil coordinate system, F A is the aerodynamic force of the parafoil system in the parafoil body coordinate system, F S is the effective resistance of the load in the parachute body coordinate system, F AW It is the additional power generated by the additional mass of the parafoil system in the parafoil body coordinate system. is the antisymmetric matrix generated by the angular velocity, M A is the aerodynamic moment of the parafoil system in the parafoil body coordinate system, M AM is the additional aerodynamic torque generated by the additional mass of the parafoil system in the parafoil body coordinate system, and J is the moment of inertia of the parafoil system.

[0025] The above step 2 is specifically as follows:

[0026] Point p is defined as a point on the actual homing trajectory of the parafoil system, and p = [xy] T and Denote the inertial position and velocity vector of point p, using Indicates the velocity of point p, using Indicates the direction angle of the point p's motion;

[0027] Define point p p is a point on the parafoil system target homing trajectory, respectively. and Represents point p p The inertial position and velocity vector are expressed as Represents point p p The direction angle of movement;

[0028] Among them, point p p The location of the scale variable changes with the changes in

[0029] Establish a target trajectory coordinate system with the target trajectory motion direction as the x-axis, and the conversion matrix from the inertial coordinate system to the target trajectory coordinate system is:

[0030]

[0031] Then point p and point p p The error between is:

[0032]

[0033] Where s represents the forward error and e represents the lateral error.

[0034] For the parafoil system, during the trajectory tracking process, the forward error is given by the target trajectory point p p To U p and Therefore, it is only necessary to set the controller to control the heading angle χ of the parafoil system. d Tracking target trajectory heading angle χ p That's it.

[0035] The above step 3 is specifically as follows:

[0036] The current heading angle of the parafoil system is: According to the parafoil system dynamics model, the second-order form of the parafoil system heading angle is expressed as:

[0037]

[0038] Where f is the total disturbance of the parafoil system, u(t) is the control quantity of the parafoil system, and b is the controller gain;

[0039] Assuming f is differentiable, we can expand it into a new state variable and reconstruct the LESO equation to obtain:

[0040]

[0041] In the formula, is the state variable of LESO, β1, β2, β3 are the observer gains;

[0042] Perform Laplace transform on the LESO equation and assign the characteristic equation poles to the left semi-real axis -ω in the s-plane o The observer gain is thus determined as: β1 = 3ω o ,

[0043] After the LESO estimates the disturbance and compensates it, the controller is essentially a PD controller, let:

[0044]

[0045]

[0046]

[0047] In the formula, χ pis the direction angle of the target trajectory, ψ e is the heading deviation, u0 is the virtual control amount, β 01 , β 02 is the controller gain. Calculate the controller χ according to the above formula p →u0 transfer function is:

[0048]

[0049] Then the characteristic equation is: C(s) = s 2 +β 02 s+β 01 The two poles of the PD controller are configured to the left half axis of the s-plane -ω c At this point, we get: C(s)=(s+ω c ) 2

[0050] The PD controller gain is thus determined as: β 02 =2ω c .

[0051] From this, the control law of the linear active disturbance rejection controller can be obtained as follows:

[0052]

[0053] The above step 4 is specifically as follows:

[0054] First, the unilateral downward braking δ is given with the heading angle ψ of the parafoil system as the output a The state space model for the input: x k+1 =Ax k +Bu k ,y k =Cx k ;

[0055] Assume the prediction interval is H p , the direction angle of the target trajectory is w k , then the estimation error is In order to calculate the control input at a given time, the cost function is introduced as:

[0056]

[0057] In the formula, is the expected value of the system, is the system predicted output, Q and R are the system weight coefficient matrices, and U is the system input control sequence. The system state equation is:

[0058]

[0059]

[0060]

[0061] J=(WK CA x k -K CAB U) T Q·(WK CA x k -K CAB U)+U T RU

[0062] By minimizing the cost function, the expression of the control quantity U is solved as follows:

[0063]

[0064] The above formula represents the optimal control quantity input of the predictive control in the entire control range, but at time k, only the first control quantity u is needed. k .

[0065] In step 5 above, the heading angle deviation switching condition is set to ψ e ≤π / 20, after the parafoil system is deployed, ψ e ≤π / 20, the controller receives instructions and uses a linear anti-disturbance controller. e When ≤π / 20, switch to predictive controller control.

[0066] The present invention has the following beneficial effects:

[0067] In view of the problems that the parafoil system is easily disturbed by the external wind field and the aerodynamic force of the parafoil system is inaccurate, the present invention adopts a control strategy of switching between linear anti-disturbance control and predictive control, combining the advantages of strong anti-disturbance ability and fast response speed of linear anti-disturbance control with the ability of predictive control to effectively overcome the system lag and high tracking accuracy, and adopts a two-dimensional guidance trajectory tracking strategy to design the guidance law to track and control the homing trajectory of the parafoil system, which not only improves the tracking accuracy of the parafoil system, making the parafoil system have good dynamics and anti-interference ability in the process of trajectory tracking, but also reduces the input of the control amount, avoiding the instability caused by frequent pulling of the control rope by the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 It is a principle flow chart of the parafoil system switching control method disclosed in the present invention;

[0069] Figure 2 A two-dimensional track tracking strategy diagram based on guidance according to a specific embodiment of the present invention;

[0070] Figure 3 A diagram of a switching strategy control process according to a specific embodiment of the present invention;

[0071] Figure 4 It is the target homing trajectory of a specific embodiment of the present invention;

[0072] Figure 5 This is a comparison diagram of the heading angle tracking curve;

[0073] Figure 6 This is a comparison diagram of the horizontal trajectory tracking curve;

[0074] Figure 7 This is a comparison diagram of the control quantity change effect;

[0075] Figure 8 Schematic diagram of three-dimensional tracking curve under switching control. DETAILED DESCRIPTION

[0076] The embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0077] Combination Figure 1 The present invention provides a parafoil system trajectory tracking control method based on switching between linear active disturbance rejection control and predictive control, comprising:

[0078] Step 1, perform force analysis on the parafoil system, and establish a six-degree-of-freedom model of the parafoil system's translation and rotation based on the Newton-Euler equation as the basis for track tracking control;

[0079] The present invention ignores the relative movement between the parachute body and the load, regards the parafoil system as a whole, and establishes a 6-DOF nonlinear dynamic model of the parafoil system.

[0080] Assume that the position vector of the parafoil system in the inertial coordinate system is P I =[x I y I z I ] T , the velocity vector of the parafoil system in the parafoil body coordinate system is V B =[u B v B w B ] T , the attitude angle vector of the parafoil system in the inertial coordinate system is A I =[φ θψ] T The attitude angular velocity vector of the parafoil system in the parafoil body coordinate system is W B =[pqr] T .

[0081] According to the Newton-Euler equation, the six-degree-of-freedom equation of the parafoil system can be obtained:

[0082]

[0083] Where M is the total mass of the parafoil system, R IB is the transformation matrix from the parachute body coordinate system B to the earth coordinate system I, F G is the gravity of the parafoil system in the parafoil coordinate system, F A is the aerodynamic force of the parafoil system in the parafoil body coordinate system, F S is the effective resistance of the load in the parachute body coordinate system, F AW It is the additional power generated by the additional mass of the parafoil system in the parafoil body coordinate system. is the antisymmetric matrix generated by the angular velocity. A is the aerodynamic moment of the parafoil system in the parafoil body coordinate system, M AM is the additional aerodynamic torque generated by the additional mass of the parafoil system in the parafoil body coordinate system, and J is the moment of inertia of the parafoil system.

[0084] Step 2, Combine Figure 2 ,Based on the guidance path tracking principle, a two-dimensional trajectory tracking guidance strategy is used to design the guide of the parafoil system, and the forward error and lateral error between the actual trajectory and the target trajectory are calculated. The error can be eliminated by tracking the heading angle of the target trajectory movement;

[0085] Generally, the descent speed of the parafoil system in the gliding section and the energy control section is constant, and the horizontal trajectory error is corrected by controlling the motor to pull down the control rope at the trailing edge of the parafoil flap system on one side. The present invention adopts a two-dimensional trajectory tracking guidance strategy to design the guidance law of the parafoil system.

[0086] Point p is defined as a point on the actual homing trajectory of the parafoil system, and p = [xy] T and Denote the inertial position and velocity vector of point p, using Indicates the velocity of point p, using Indicates the direction angle of the movement of point p.

[0087] Define point p p is a point on the parafoil system target homing trajectory, respectively. and Represents point p p The inertial position and velocity vector are expressed as Represents point p p The direction angle of motion. p The location of the scale variable changes with the changes of.

[0088] Establish a target trajectory coordinate system with the target trajectory motion direction as the x-axis, and the conversion matrix from the inertial coordinate system to the target trajectory coordinate system is:

[0089]

[0090] Then point p and point p p The error between is:

[0091]

[0092] In the formula, s represents the forward error and e represents the lateral error. For the parafoil system, during the trajectory tracking process, the forward error is calculated by the target trajectory point p p To U p and Therefore, it is only necessary to set the controller to control the heading angle χ of the parafoil system. d Tracking target trajectory motion direction angle χ p That's it.

[0093] Step 3, based on the two-dimensional trajectory tracking guidance strategy, the linear active disturbance rejection controller LADRC is designed by constructing the linear extended state observer LESO and PD controller of the system;

[0094] First, a linear active disturbance rejection controller is designed. According to the guidance strategy, by controlling the heading angle χ d The lateral error between the current position and the target position of the parafoil system can be eliminated, and the current heading angle of the parafoil system is:

[0095]

[0096] According to the dynamic model of the parafoil system, the second-order form of the heading angle of the parafoil system can be expressed as:

[0097]

[0098] In the formula, f is the total disturbance of the parafoil system, u(t) is the control quantity of the parafoil system, and b is the controller gain. Assuming f is differentiable, it is expanded into a new state variable, and we can get:

[0099]

[0100] In the formula, χ1=y, χ3=f.

[0101] The state observer theory proposed by Luenberger solves the state reconstruction problem of the controlled system under deterministic conditions. The LESO equation is as follows:

[0102]

[0103] In the formula, is the state variable of LESO, β1, β2, β3 are the observer gains.

[0104] The Laplace transform of the LESO equation yields:

[0105]

[0106] The corresponding characteristic equation is:

[0107] L * (s)=s 3 +β1s 2 +β2s+β3

[0108] The three poles of the observer are uniformly configured to the left semi-real axis -ω of the s-plane o At, we get:

[0109] L * (s)=(s+ω o ) 3

[0110] Therefore, the observer gain can be determined as:

[0111] β1=3ω o ,

[0112] After the LESO estimates the disturbance and compensates it, the controller is essentially a PD controller. Let:

[0113]

[0114] Right now,

[0115]

[0116]

[0117] In the formula, χ p is the direction angle of the target trajectory, ψ e is the tracking error, u0 is the virtual control amount, β 01 , β 02 is the controller gain. Calculate the controller χ according to the above formula p →u0 transfer function is;

[0118]

[0119] Then the characteristic equation is:

[0120] C(s)=s 2 +β 02 s+β 01

[0121] The two poles of the controller are configured to the left half axis -ω of the s plane. c At, get:

[0122] C(s)=(s+ω c ) 2

[0123] The controller gain can then be determined as:

[0124] β 02 =2ω c

[0125] From this, the control law of the linear active disturbance rejection controller can be obtained as follows:

[0126]

[0127] Step 4, based on the two-dimensional trajectory tracking guidance strategy, the predictive controller MPC is designed by constructing a state space model of the system;

[0128] Next, the predictive controller is designed. First, the heading angle ψ of the parafoil system is given as the output, and the unilateral downward braking δ a The state space model for the input is:

[0129] x k+1 =Ax k +Bu k ,y k =Cx k

[0130] Where A, B and C are system matrices, x k is the state vector, u k is the control input, y k is the output at time k.

[0131] Assume the prediction interval is H p , the direction angle of the target trajectory is w k , then the estimation error is In order to calculate the control input at a given time, the cost function is introduced as:

[0132]

[0133] In the formula, is the expected value of the system, is the system predicted output, Q and R are the system weight coefficient matrices, and U is the system input control sequence. The system state equation can be obtained as follows:

[0134]

[0135]

[0136]

[0137] J=(WKCA x k -K CAB U) T Q·(WK CA x k -K CAB U)+U T RU

[0138] By minimizing the cost function, the expression of the control quantity U is solved as follows:

[0139]

[0140] The above formula represents the optimal control quantity input of the predictive control in the entire control range, but at time k, only the first control quantity u is needed. k .

[0141] Step 6, Combine Figure 3 , set the heading angle deviation switching condition. When the heading angle deviation does not meet the condition, the controller receives the instruction and adopts the linear anti-disturbance controller control. After a period of control tracking, when the heading angle deviation meets the condition, the controller switches to the predictive controller control, thereby realizing the switching control of the parafoil system.

[0142] According to the guidance strategy, after the parafoil system is deployed, the lateral error between the flight trajectory and the target trajectory is eliminated by controlling the heading angle of the parafoil system. e Greater than a given value ψ e ≤π / 20, the controller receives the command and adopts linear anti-disturbance control. After a period of control tracking, when the heading deviation ψ e Less than or given value ψ e When ≤π / 20, the controller switches to predictive control and continues to accurately track the target trajectory.

[0143] Example 1

[0144] The geometric and mass characteristic parameters of the parafoil system mainly include: wingspan b = 13.98m, chord length c = 5.59m, canopy effective area S p =62.5m 2 , installation angle The length of the parachute rope is L = 7.45m, and the effective area of ​​the load body is S s =1.9m 2 , the total mass of the system M = 620kg.

[0145] like Figure 4 As shown, the initial position of the parafoil system target homing trajectory is set to x0 = 1000m, y0 = 500m, z0 = 2000m, and the heading angle of the initial movement is x p=π / 3, the end position is x1=0m, y1=0m, z1=0m.

[0146] Set the initial position of the parafoil system to x = 950m, y = 600m, z = 2000m, and the initial heading angle to x d =π / 2. Wind disturbance is added during the trajectory tracking of the parafoil system: from 0s to 354s, a steady wind with a wind speed of 8m / s and a wind direction of 180° is applied; from 200s to 300s, a gust with an amplitude of 5m / s and a wind direction of 270° is applied:

[0147] Set the parameters of the linear ADRC to: ω0 = 20, ω c =10,b0=5;

[0148] Set the parameters of the predictive controller as follows: Sampling time T s =0.1s, prediction step length H p =30.

[0149] Figure 5-6 The tracking effects of predictive control and switching control on target direction angle and target trajectory are demonstrated respectively.

[0150] Under predictive control, the dynamic response time of the parafoil system to track the target heading angle is about 4s, and the final landing error is 23m.

[0151] Under switching control, the dynamic response time of the parafoil system to track the target direction angle is about 2s, and the final landing error is 9m.

[0152] at the same time, Figure 6 It is shown that the switching control has a smaller steady-state error than the predictive control in the transition phase and in the case of gust disturbances.

[0153] Figure 7 The homing of a parafoil system controlled by a switching controller with three-dimensional trajectory tracking under wind disturbance conditions is demonstrated.

[0154] Figure 8 The change of control quantity is demonstrated. Compared with predictive control, the change of control quantity of switching control is smoother, which avoids the driving motor from pulling the control rope frequently.

[0155] It can be seen from the simulation curve that, compared with the single predictive control, the switching control method of the present invention has better control accuracy, stronger anti-interference ability and good dynamic performance.

[0156] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. Track tracking control method of parafoil system based on switching between linear active disturbance rejection control and predictive control, It is characterized in that include: Step 1, perform force analysis on the parafoil system, and establish a six-degree-of-freedom model of the parafoil system's translation and rotation based on the Newton-Euler equation as the basis for track tracking control; The step 1 is specifically as follows: Assume that the position vector of the parafoil system in the inertial coordinate system is P I =[x I y I z I ] T , the velocity vector of the parafoil system in the parafoil body coordinate system is V B =[u B v B w B ] T , the attitude angle vector of the parafoil system in the inertial coordinate system is A I =[φθψ] T The attitude angular velocity vector of the parafoil system in the parafoil body coordinate system is W B =[pqr] T ; According to the Newton-Euler equation, the six-degree-of-freedom model of the parafoil system translation and rotation can be obtained: (1) Translational three-degree-of-freedom equation: (2) Rotational three-degree-of-freedom equation: Where M is the total mass of the parafoil system, R IB is the transformation matrix from the parachute body coordinate system B to the earth coordinate system I, F G is the gravity of the parafoil system in the parafoil coordinate system, F A is the aerodynamic force of the parafoil system in the parafoil coordinate system, F S is the effective resistance of the load in the parachute body coordinate system, F AW It is the additional power generated by the additional mass of the parafoil system in the parafoil body coordinate system. is the antisymmetric matrix generated by the angular velocity, M A is the aerodynamic moment of the parafoil system in the parafoil body coordinate system, M AM is the additional aerodynamic torque generated by the additional mass of the parafoil system in the parafoil body coordinate system, and J is the moment of inertia of the parafoil system; Step 2, based on the guidance path tracking principle, the two-dimensional trajectory tracking guidance strategy is used to design the guide of the parafoil system, calculate the forward error and lateral error between the actual trajectory and the target trajectory, and eliminate the error by tracking the heading angle of the target trajectory motion; The step 2 is specifically as follows: Point p is defined as a point on the actual homing trajectory of the parafoil system, and p = [xy] T and Denote the inertial position and velocity vector of point p, using To express the velocity of point p, we use Indicates the direction angle of the movement of point p; Define point p p is a point on the parafoil system target homing trajectory, respectively. and Represents point p p The inertial position and velocity vector are expressed as Represents point p p The direction angle of movement; Among them, point p p The location of the scale variable changes with the changes in Establish a target trajectory coordinate system with the target trajectory motion direction as the x-axis, and the conversion matrix from the inertial coordinate system to the target trajectory coordinate system is: Then point p and point p p The error between is: In the formula, s represents the forward error, and e represents the lateral error; For the parafoil system, during the trajectory tracking process, the forward error is given by the target trajectory point p p To U p and Therefore, it is only necessary to set the controller to control the heading angle χ of the parafoil system. d Tracking target trajectory heading angle χ p That's it; Step 3, based on the two-dimensional trajectory tracking guidance strategy, the linear active disturbance rejection controller LADRC is designed by constructing the linear extended state observer LESO and PD controller of the system; The step 3 is specifically as follows: From step 2, we can know that by controlling the heading angle χ of the parafoil system d The lateral error between the current position and the target position of the parafoil system can be eliminated, and the current heading angle of the parafoil system is: According to the parafoil system dynamics model, the second-order form of the parafoil system heading angle is expressed as: Where f is the total disturbance of the parafoil system, u(t) is the control quantity of the parafoil system, and b is the controller gain; Assuming f is differentiable, we expand it into a new state variable and reconstruct the LESO equation to obtain: In the formula, is the state variable of LESO, β 1 , β 2 , β 3 is the observer gain; Perform Laplace transform on the LESO equation and assign the characteristic equation poles to the left semi-real axis -ω in the s-plane o The observer gain is thus determined as: 1 =3ω o , After the LESO estimates the disturbance and compensates it, the controller is essentially a PD controller, let: In the formula, χ p is the direction angle of the target trajectory, ψ e is the heading deviation, u 0 is the virtual control quantity, β 01 , β 02 is the controller gain; the controller χ is calculated according to the above formula p →u 0 The transfer function is: Then the characteristic equation is: C(s) = s 2 +β 02 s+β 01 The two poles of the PD controller are configured to the left half axis of the s-plane -ω c At this point, we get: C(s)=(s+ω c ) 2 Thus the PD controller gain is determined as: β 02 =2ω c ; From this, the control law of the linear active disturbance rejection controller can be obtained as follows: Step 4, based on the two-dimensional trajectory tracking guidance strategy, the predictive controller MPC is designed by constructing a state space model of the system; The step 4 is specifically as follows: First, the unilateral downward braking δ is given with the heading angle ψ of the parafoil system as the output a The state space model for the input: x k+1 =Ax k +Bu k ,y k =Cx k ; Assume the prediction interval is H p , the direction angle of the target trajectory is w k , then the estimation error is In order to calculate the control input at a given time, the cost function is introduced as: In the formula, is the expected value of the system, is the system predicted output, Q and R are the system weight coefficient matrices, and U is the system input control sequence. The system state equation is: J=(W-K CA x k -K CAB U) T Q· (W-K CA x k -K CAB U)+U T RU By minimizing the cost function, the expression of the control quantity U is solved as follows: The above formula represents the optimal control quantity input of the predictive control in the entire control range, but at time k, only the first control quantity u is needed. k ; Step 5, setting the switching condition according to the heading angle deviation. When the heading angle deviation does not meet the condition, the controller receives the instruction and adopts the linear anti-disturbance controller control. When the heading angle deviation meets the condition, the controller switches to the predictive controller control to realize the switching control of the parafoil system.

2. According to claim 1, the parafoil system trajectory tracking control method based on switching between linear active disturbance rejection control and predictive control, It is characterized in that In step 5, the heading angle deviation switching condition is set to ψ e ≤π / 20, after the parafoil system is deployed, ψ e ≤π / 20, the controller receives instructions and uses a linear anti-disturbance controller. e When ≤π / 20, switch to predictive controller control.

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