Control method for near hovering point of double-layer flapping-wing flying robot with tail

Abstract

The invention relates to a control method for a near hovering point of a tailed double-layer flapping-wing flying robot, and the method comprises the following steps: constructing a disturbance linearization equation of a longitudinal motion equation of the tailed double-layer flapping-wing flying robot at a balance point, constructing a state feedback gain matrix, and forming an attitude stabilization controller with the disturbance linearization equation; four control variables are obtained through an attitude stabilization controller according to the control variables and are respectively used for controlling the forward flight speed, the vertical flight speed, the pitch angle speed around the pitch axis of the fuselage and the pitch angle under the coordinate system of the fuselage. According to the near-hovering-point control method for the double-layer flapping-wing flying robot with the tail, the designed longitudinal motion equation comprises the aerodynamic model of the wings and the aerodynamic model of the empennage, and compared with longitudinal motion models of other double-layer flapping-wing robots, the double-layer flapping-wing flying robot has the advantage that a wing motion mechanism of the flapping-wing robot can be simplified.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-miniature bionic robots, in particular to a control method for a near-hovering point of a double-layer flapping-wing flying robot with a tail. Background Art

[0002] Micro flapping-wing flying robots are suitable for flying in small spaces, and their bionic appearance makes them concealed to a certain extent, so they have great application potential. Compared with fixed-wing micro air vehicles and rotary-wing micro air vehicles, flapping-wing micro air vehicles rely on their unsteady aerodynamic mechanism to effectively overcome the problem of low aerodynamic efficiency under small Reynolds number conditions. By imitating the movement of insect and bird wings, it is hoped that the controllability and flexibility of micro air vehicles will be further improved. In order to obtain a micro flapping-wing flying robot with high aerodynamic efficiency, compact structure and flexible control, it is necessary not only to comprehensively consider its unsteady aerodynamic force, the design and optimization of the wing movement mechanism, but also to design a flight control method that is suitable for it.

[0003] In the study of the longitudinal attitude stabilization and flight control near the hovering point of a double-layer flapping-wing flying robot with a tail, it was found that although longitudinal static stability can be achieved by balancing the tail, the flapping wing is still dynamically unstable under certain disturbances. Summary of the invention

[0004] The purpose of the present invention is to provide a control method for a double-layer flapping-wing flying robot with a tail near a hovering point. In order to improve the stability of the flapping-wing flying robot with a tail and stabilize its attitude during disturbance, a state feedback controller is designed with the horizontal deflection angle of the tail as the control variable. The feedback controller can not only suppress the disturbance of the hovering state quickly, but also has less oscillation in the response process and better stability of the system. On the basis of longitudinal attitude stability, the flight control of the double-layer flapping-wing flying robot near the hovering point can be achieved through two control signals.

[0005] The technical solution adopted by the present invention to achieve the above-mentioned purpose is: a control method for a double-layer flapping-wing flying robot with a tail near a hovering point, comprising the following steps:

[0006] Construct the disturbance linearization equation of the longitudinal motion equation of the tailed double-layer flapping-wing flying robot at the equilibrium point, construct the state feedback gain matrix, and form an attitude stabilization controller with the disturbance linearization equation;

[0007] According to the control variable β, four control variables are obtained through the attitude stabilization controller, which are used to control the forward flight speed u, the vertical flight speed w, and the pitch axis Y around the fuselage in the body coordinate system. b The pitch velocity q and pitch angle θ.

[0008] The perturbation linearization equation is as follows:

[0009]

[0010] Among them, A is the system matrix, B is the control matrix; C Tu , C Tw , C Tq , C Nu , C Nw , C Nq , C Mu , C Mw , C Mq is the aerodynamic derivative; C Tβ , C Nβ , C Mβ is the control derivative; m + , g + ,I y + are respectively the mass of the aircraft m, the acceleration of gravity g, and the pitch moment of inertia of the aircraft I y The dimensionless quantity of .

[0011] The state feedback gain matrix is ​​constructed to form an attitude stabilization controller with the disturbance linearization equation, and the steps include:

[0012] Construct the state feedback gain matrix K = (k u , k w , k q ,k θ ), k u , k w , k q , k θ They are forward flight speed u, vertical flight speed w, and pitch axis Y around the fuselage. b The pitch angular velocity q, around the fuselage pitch axis Y b The feedback gain coefficient of the pitch angle θ;

[0013] The feedback gain coefficients are respectively related to the corresponding forward flight speed u, vertical flight speed w, and pitch axis Y around the fuselage. b The pitch angular velocity q, around the fuselage pitch axis Y b The feedback gain is obtained by multiplying the pitch angle θ and the control variable β. The difference between the control variable β and the feedback gain is used as the control variable β again and input into the disturbance linearization equation to obtain four control variables.

[0014] The body coordinate system is constructed as follows:

[0015] The center of gravity of the tailed double-layer flapping-wing flying robot is taken as the origin, and the robot's forward direction is X b Axis, the extension direction of the flapping wing is Y b Axis, establish the body coordinate system X b Yb Z b .

[0016] The four control quantities are respectively used as the forward flight speed u, the vertical flight speed w, the pitch axis Y around the fuselage b The target values ​​of the pitch velocity q and the pitch angle θ are used to control the forward flight actuator, the vertical flight actuator, and the pitch mechanism.

[0017] A control system for a near-hovering point of a double-layer flapping-wing flying robot with a tail, comprising:

[0018] A controller building module is used to construct the perturbation linearization equation of the longitudinal motion equation of the tailed double-layer flapping-wing flying robot at the equilibrium point, construct the state feedback gain matrix, and form an attitude stabilization controller with the perturbation linearization equation;

[0019] The hover control module is used to obtain four control variables through the attitude stabilization controller according to the control variable β, which are used to control the forward flight speed u, the vertical flight speed w, and the pitch axis Y around the fuselage in the body coordinate system. b The pitch velocity q and pitch angle θ.

[0020] A control device for a double-layer flapping-wing flying robot with a tail near a hovering point comprises a memory and a processor; the memory is used to store a computer program; the processor is used to implement a control method for a double-layer flapping-wing flying robot with a tail near a hovering point when executing the computer program.

[0021] A computer-readable storage medium stores a computer program. When the computer program is executed by a processor, a control method for a double-layer flapping-wing flying robot with a tail near a hovering point is implemented.

[0022] The present invention has the following beneficial effects and advantages:

[0023] 1. Compared with the flight modes of other micro flapping-wing robots, which are mainly based on continuous flight at a certain speed, the present invention proposes a control method for realizing the flight states of a double-layer flapping-wing robot such as hovering, low-speed straight-line cruising and circling in a longitudinal plane by using a tail wing, which helps the flapping-wing robot to complete more complex flight tasks.

[0024] 2. The near-hovering point control method of the tailed double-layer flapping-wing flying robot proposed in the present invention has modes in the control process including an oscillating divergent mode, a fast convergent mode, and a slow convergent mode, which indicates that the tailed flapping-wing has a natural motion mode similar to that of tailless insects and is closer to a bionic state.

[0025] 3. In order to improve the stability of the tail-flapping wing robot and stabilize its attitude due to disturbances, a state feedback controller is added to the horizontal deflection angle control variable of the tail wing during the control process of the present invention, and the poles of the closed-loop state feedback control system are configured. The feedback controller can not only suppress the disturbances in the hovering state more quickly, but also has less oscillation in the response process, thereby improving the stability of the system.

[0026] In the near-hovering point control method of the double-layer flapping-wing flying robot with a tail proposed in the present invention, the designed longitudinal motion equation includes the aerodynamic model of the wing and the aerodynamic model of the tail. Compared with other longitudinal motion models of double-layer flapping-wing robots, the advantage of this method is that it is conducive to simplifying the wing motion mechanism of the flapping-wing robot.

[0027] 5. Unlike the multi-input multi-output system, the complex motion mechanism limits the further miniaturization of flapping-wing aircraft. The present invention proposes to stabilize the longitudinal state disturbance by only using the horizontal deflection angle of the tail wing, which is a typical state feedback control problem of a single-input system and has good system controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the tailed double-layer flapping-wing flying robot mechanism;

[0029] Figure 2 Schematic diagram of a state feedback control system. DETAILED DESCRIPTION

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0031] A double-layer flapping-wing flying robot with a tail Figure 1 The robot consists of two pairs of wings, arranged in an X shape. A motor drives two crank rocker mechanisms to generate flapping motion. The rear of the robot has a horizontal tail, which can generate a horizontal deflection angle under the control of the electromagnetic rudder. We establish the following inertial coordinate system X e Y e Z e and the body coordinate system X b Y b Z b , the origin of the coordinate system is located at the center of gravity of the aircraft. Under the condition that the robot does not produce lateral movement, the aircraft only produces b The tangential force T b and along Z b Normal force N b .

[0032] Although flapping-wing flying robots generate unsteady aerodynamic forces, since the flapping frequency of their wings is much greater than their natural motion frequency, a time-averaged aerodynamic force model based on the quasi-static assumption can be used. First, the wing kinematic equation is established, and the aerodynamic forces and aerodynamic moments in all directions are numerically solved based on the Navier-Stokes equation; then the time-averaged aerodynamic force and aerodynamic moment are calculated, and the tangential aerodynamic force coefficient C is fitted. T , normal aerodynamic coefficient C N and the pitch aerodynamic moment coefficient C M :

[0033]

[0034] Where X is along X b The tangential aerodynamic force on the axis Z is along the Z b The normal aerodynamic force is about the Y axis, M is the aerodynamic force about the Y axis. b axis, ρ is the air density, S is the wing area, and v is the reference speed.

[0035] Using Newton-Euler equations of motion, in the body coordinate system X b Y b Z b The flight dynamics equation is established in . Since the left and right structures and movements of the aircraft are symmetrical, and the lateral movement speed is zero, the longitudinal dynamics equation is obtained as follows:

[0036]

[0037] Among them, u and w are the forward flight speed and vertical flight speed in the body coordinate system, respectively, and q and θ are the pitch axis Y around the fuselage. b The direction of each state variable points to the positive direction of the coordinate axis of the body coordinate system. m is the mass of the aircraft, g is the gravitational acceleration, I y is the pitch moment of inertia of the aircraft. We non-dimensionalize (2) and obtain:

[0038]

[0039] Among them, m + , g + ,I y + is a dimensionless quantity, S is the wing area, c is the chord length, and ρ is the air density. The tangential aerodynamic force X, the normal aerodynamic force Z, and the pitching aerodynamic moment M are generated from the wings and the tail:

[0040]

[0041] Among them, the subscript w represents the wing, and t represents the tail. We mainly use the deflection angle of the horizontal tail as the control variable. Finally, the empirical formula for the tangential force and normal force generated by the interaction between the tail and the leading edge vortex wake in the near-hover state is obtained:

[0042]

[0043] Among them, C T0,t , C Tπ / 2 ,C N0,t is a constant, and this formula is the aerodynamic model of the tail wing of the double-layer flapping-wing microrobot.

[0044] Before linearizing the longitudinal dynamics nonlinear model, the aircraft needs to be trimmed longitudinally. Since the left and right wings move symmetrically and the roll angular velocity is zero, the lateral forces and moments of the robot can be considered to be balanced. The aircraft is trimmed longitudinally by the horizontal deflection angle of the tail. When the flapping-wing aircraft is trimmed, the aerodynamic resultant force and moment of the wings and tail at the center of gravity of the aircraft are zero. Combined with (4), we can get:

[0045]

[0046] Among them, C M,t is the pitching moment produced by the tail at the center of gravity.

[0047] It is generally believed that the system state only experiences small disturbances near the equilibrium point. Therefore, we take the small deviation δ of the longitudinal dynamic equation (3) of the double-layer flapping wing with tail near its equilibrium point and calculate the aerodynamic force C T , C N and aerodynamic moment C M The linear expansion is performed on the state variables u, w, q and the control variable β. T Take the linear expansion of as an example:

[0048] C T =C T0 +C Tu δu + +C Tw δw + +C Tq δq + +C Tβ δβ (7)

[0049] Among them, C T0 is the initial tangential aerodynamic force, + indicates dimensionless, C Tu , C Tw , C Tq is the corresponding aerodynamic derivative. Substituting formula (6) into (3), and using the method of (7) to linearize (3), we obtain:

[0050]

[0051] Among them, C Nu , C Nw , C Nq , C Mu , C Mw , C Mq is the aerodynamic derivative, C Tβ , C Nβ , C Mβ is the control derivative. The aerodynamic derivative is obtained through bionic experiments, and the control derivative is set through experiments and experience. For the convenience of subsequent analysis, we convert it into state space form:

[0052]

[0053] Where A is the system matrix and B is the control matrix. The specific expression is shown in (10):

[0054]

[0055] So far, the small perturbation linearized equation of the longitudinal motion equation of the tailed double-layer flapping-wing flying robot near the equilibrium point is obtained.

[0056] Since flapping-wing aircraft are unstable in the longitudinal direction, they will quickly enter an oscillating divergent state when disturbed during hovering, so real-time feedback control is required to achieve stabilization of disturbances. In the study of the longitudinal motion of insects, there is a typical control idea that treats the longitudinal motion of insects as a multi-input multi-output system. This control method requires more control degrees of freedom, and its complex motion mechanism also limits the further miniaturization of flapping-wing flying robots. Therefore, the present invention proposes to stabilize the longitudinal state disturbance only by using the horizontal deflection angle of the tail wing, which is a typical state feedback control problem of a single-input system. First, the controllability analysis of the system is performed. The system controllability matrix is:

[0057] S=[B AB A 2 BA 3 B] (11)

[0058] The matrix order is 4. In order to meet the controllability conditions of the system, the flapping-wing flying robot is fed back to its state. The schematic diagram of the control system is shown in Figure 2 As shown. Assume that the state feedback gain matrix is:

[0059] K=(ku,kw,kqq,kθ)(12)

[0060] It should be pointed out that the current linearized longitudinal motion model and attitude stabilization controller are based on the small disturbance assumption and are therefore not suitable for large disturbance environments such as gusts.

[0061] Biological research shows that birds assist in the realization of their flight function by controlling the movement of their tails. Different tail movement control signals have similar effects on the flight control of flapping-wing flying robots near the hovering point. Therefore, the flight of a double-layer flapping-wing flying robot with a tail can be controlled by the horizontal deflection angle of the tail under two typical control signals: step and sine.

[0062] When the input signal is a step signal as shown in formula (13), where β m is a constant, is the amplitude of the step signal.

[0063]

[0064] When the tail deflection angle β m When it is a step function, the aircraft is in a cruising state, the attitude will remain stable, and the attitude pitch angle is almost unchanged compared to hovering. The flight trajectory is an inclined upward or downward straight line, which depends on β m symbol.

[0065] When the horizontal deflection angle of the tail is a sinusoidal signal and the flapping frequency of the horizontal tail is the same as that of the wings, the tail control signal is as shown in formula (14).

[0066] β(t)=β m ·sin t,t≥0 (14)

[0067] When the horizontal tail starts to swing periodically from the trim state, it not only improves the passive stability of the aircraft, but also produces a hovering flight state in the longitudinal plane.

Claims

1. A control method for a double-layer flapping-wing flying robot with a tail near a hovering point, characterized in that: The following steps are involved: Construct the disturbance linearization equation of the longitudinal motion equation of the tailed double-layer flapping-wing flying robot at the equilibrium point, construct the state feedback gain matrix, and form an attitude stabilization controller with the disturbance linearization equation; According to the control variable β, four control variables are obtained through the attitude stabilization controller, which are used to control the forward flight speed u, the vertical flight speed w, and the pitch axis Y around the fuselage in the body coordinate system. b The pitch velocity q and pitch angle θ.

2. The control method of a tailed double-layer flapping-wing flying robot near the hovering point according to claim 1 is characterized in that: The perturbation linearization equation is as follows: Among them, A is the system matrix, B is the control matrix; C Tu , C Tw , C Tq , C Nu , C Nw , C Nq , C Mu , C Mw , C Mq is the aerodynamic derivative; C Tβ , C Nβ , C Mβ is the control derivative; m + , g + ,I y + are respectively the mass of the aircraft m, the acceleration of gravity g, and the pitch moment of inertia of the aircraft I y The dimensionless quantity of .

3. The control method of a tailed double-layer flapping-wing flying robot near the hovering point according to claim 1 is characterized in that: The state feedback gain matrix is ​​constructed to form an attitude stabilization controller with the disturbance linearization equation, and the steps include: Construct the state feedback gain matrix K = (k u , k w , k q , k θ ), k u , k w , k q , k θ They are forward flight speed u, vertical flight speed w, and pitch axis Y around the fuselage. b The pitch angular velocity q, around the fuselage pitch axis Y b The feedback gain coefficient of the pitch angle θ; The feedback gain coefficients are respectively related to the corresponding forward flight speed u, vertical flight speed w, and pitch axis Y around the fuselage. b The pitch angular velocity q, around the fuselage pitch axis Y b The feedback gain is obtained by multiplying the pitch angle θ and the control variable β. The difference between the control variable β and the feedback gain is used as the control variable β again and input into the disturbance linearization equation to obtain four control variables.

4. The control method of a tailed double-layer flapping-wing flying robot near the hovering point according to claim 1 is characterized in that: The body coordinate system is constructed as follows: The center of gravity of the tailed double-layer flapping-wing flying robot is taken as the origin, and the robot's forward direction is X b Axis, the extension direction of the flapping wing is Y b Axis, establish the body coordinate system X b Y b Z b .

5. The control method of a tailed double-layer flapping-wing flying robot near the hovering point according to claim 1 is characterized in that: The four control quantities are respectively used as the forward flight speed u, the vertical flight speed w, the pitch axis Y around the fuselage b The target values ​​of the pitch velocity q and the pitch angle θ are used to control the forward flight actuator, the vertical flight actuator, and the pitch mechanism.

6. A control system for a double-layer flapping-wing flying robot with a tail near the hovering point, characterized in that: include: A controller building module is used to construct the perturbation linearization equation of the longitudinal motion equation of the tailed double-layer flapping-wing flying robot at the equilibrium point, construct the state feedback gain matrix, and form an attitude stabilization controller with the perturbation linearization equation; The hover control module is used to obtain four control variables through the attitude stabilization controller according to the control variable β, which are used to control the forward flight speed u, the vertical flight speed w, and the pitch axis Y around the fuselage in the body coordinate system. b The pitch velocity q and pitch angle θ.

7. A control device for a double-layer flapping-wing flying robot with a tail near the hovering point, characterized in that: It comprises a memory and a processor; the memory is used to store a computer program; the processor is used to implement a control method for a near-hovering point of a tailed double-layer flapping-wing flying robot as described in any one of claims 1 to 5 when executing the computer program.

8. A computer-readable storage medium, characterized in that: The storage medium stores a computer program, and when the computer program is executed by the processor, the method for controlling a near-hovering point of a tailed double-layer flapping-wing flying robot as described in any one of claims 1 to 5 is implemented.

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