CN108427430A - Quadrotor control method based on network-control - Google Patents
Quadrotor control method based on network-control Download PDFInfo
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
- G05D1/08—Control of attitude, i.e. control of roll, pitch, or yaw
- G05D1/0808—Control of attitude, i.e. control of roll, pitch, or yaw specially adapted for aircraft
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
- G05D1/10—Simultaneous control of position or course in three dimensions
- G05D1/101—Simultaneous control of position or course in three dimensions specially adapted for aircraft
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Abstract
The quadrotor control method based on network-control that the invention discloses a kind of, for solving to there is technical issues that in quadrotor control, it is first location subsystem and posture subsystem by quadrotor model decomposition, it is directed to influence of the communication delay to posture subsystem stability simultaneously, it is proposed delay compensation scheme, and using the system model of the tool boxes Truetime setup delay compensation scheme, and the scheme of proposition is verified.By simulating, verifying, network-control, which is applied to, has certain feasibility and validity in the quadrotor flight control system under communication delay.
Description
Technical Field
The invention relates to a control method of a four-rotor aircraft, in particular to a control method of a four-rotor aircraft based on network control.
Background
In the unmanned aerial vehicle field, four rotor crafts have can hover, low in cost, small, can low-altitude flight, noise is low, control advantage such as nimble. Therefore, the method has wide application in military and civil fields, such as: pesticide spraying, aerial photography, safety patrol, traffic supervision, earthquake rescue and the like.
Because the state of the aircraft cannot be monitored on the aircraft body by an operator of the aircraft, the flight state of the aircraft can only be monitored on the ground and the flight task of the aircraft can only be controlled, the ground station is responsible for monitoring various flight data and flight states of the aircraft by establishing a two-way communication link, and meanwhile, an instruction input interface is provided for ground personnel, so that the operator can send various instruction data to the aircraft. Aircraft for collecting ground or ambient data encounter a wide variety of complex environments where parameters change and problems arise that interfere with the communication between the aircraft and the ground station, all of which reduce the flight stability of the aircraft to a greater or lesser extent.
The four-rotor aircraft and the ground station are communicated through wireless signals, the accuracy of the system positioning of the four-rotor aircraft is directly influenced by the strength of the wireless signals, the wireless signals are lossy in air, and various obstacles can reflect and refract the wireless signals, so that communication time delay inevitably exists in the whole system, the requirement on real-time performance of the four-rotor unmanned aerial vehicle is high, and in order to accurately control the motion of the four-rotor aircraft, the attitude control without time delay is necessary. To achieve accurate pose estimation for a quad-rotor aircraft, communication delays of various durations in the system need to be compensated. In the existing method, the problem of communication delay between the quad-rotor aircraft and the ground station in various working environments is rarely considered, so that the unmanned aerial vehicle is difficult to realize in remote control and task execution.
Disclosure of Invention
The purpose of the invention is as follows: aiming at the problems, the invention provides a control method of a four-rotor aircraft based on network control, which is used for solving the technical problem of time delay in the control of the four-rotor aircraft.
The technical scheme is as follows: in order to realize the purpose of the invention, the technical scheme adopted by the invention is as follows: a control method of a four-rotor aircraft based on network control comprises the following steps:
(1) establishing a dynamic model of the four-rotor aircraft;
(2) decoupling into an attitude subsystem and a position subsystem, and designing a state space model for each channel of the subsystems;
(3) each state space model constructs a state feedback controller with a communication time delay condition;
(4) constructing an event trigger mechanism, wherein the trigger time in the controller is updated when the event trigger mechanism is met;
(5) solving a sufficient condition for realizing stable control of an event trigger mechanism under the communication time delay;
(6) constructing a state feedback gain matrix which meets sufficient conditions;
(7) and building a network control system model based on the TrueTime toolbox.
In the step (1), the kinetic model is as follows:
wherein x, y and z represent coordinate values in a ground coordinate system; phi, theta and psi respectively represent roll angle, pitch angle and yaw angle; u. ofth,uφ,uθ,uψRespectively representing virtual control input quantities in vertical, roll, pitch and yaw directions; g represents acceleration due to gravity; m represents the mass of the quad-rotor aircraft; i isxx,Iyy,IzzRespectively representing inertia moment of inertia of a roll shaft, a pitch shaft and a yaw shaft; kt,KmRespectively representing a lift coefficient and a drag coefficient; l represents the four-rotor arm length.
In the step (3), the state feedback controller with communication delay is:
u(t)＝Kx(t),K＜0
where K is the state feedback gain.
In the step (4), the event triggering mechanism is as follows:
wherein omega1,Ω2,Ω3Is a positive definite symmetric constant matrix, α and β are event trigger coefficients and are positive values.
Has the advantages that: the invention has the following beneficial effects:
(1) according to the invention, data communication is limited through the trigger condition, so that the calculation load and the communication frequency of the four-rotor flight control system are reduced, the network transmission load is reduced, and the problem that the four-rotor remote control relying on real-time continuous information exchange in the prior art is difficult to implement in practical application is solved;
(2) according to the invention, through analyzing the upper and lower bounds of the communication time delay, the sufficient condition for controlling the four-rotor flight control system in the form of a linear matrix inequality under the communication time delay is obtained, and the problem that only the time delay is considered in the prior art is solved;
(3) the four-rotor aircraft dynamic model is decomposed into a position subsystem and an attitude subsystem, the time delay problem of each channel of the subsystem is controlled, and the accuracy of model network control is improved;
(4) the gain of the state feedback controller is established by a linear matrix inequality, which is easier to be verified by advanced algorithm and can reduce conservative of conclusion.
Drawings
FIG. 1 is a flow chart of a four-rotor aircraft control method based on network control of the present invention;
FIG. 2 is a control block diagram of a four-rotor aircraft flight system according to the method of the present invention;
FIG. 3 is a diagram of a simulation model of a quad-rotor attitude subsystem in the practice of the present invention;
FIG. 4 shows simulation results of a four-rotor aircraft attitude subsystem model under time delay in the implementation process of the invention.
Detailed Description
The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.
Fig. 1 is a flow chart of a control method of a four-rotor aircraft based on network control according to the invention, and fig. 2 is a control block diagram of a system of the four-rotor aircraft. The invention discloses a control method of a four-rotor aircraft based on network control, which comprises the following steps:
(1) a dynamic model of the four-rotor aircraft is established, and the specific form is as follows:
wherein six state variables [ x, y, z, phi, theta, psi are included]T(ii) a x, y and z represent coordinate values in a ground coordinate system; phi, theta and psi respectively represent roll angle, pitch angle and yaw angle; u. ofth,uφ,uθ,uψRespectively representing virtual control input quantities in vertical, roll, pitch and yaw directions; g represents acceleration due to gravity; m represents the mass of the quad-rotor aircraft; i isxx,Iyy,IzzRespectively representing inertia moment of inertia of a roll shaft, a pitch shaft and a yaw shaft; kt,KmRespectively representing a lift coefficient and a drag coefficient; l represents the four-rotor arm length.
Four virtual control inputs uth,uφ,uθ,uψ]TIs defined as follows:
wherein u is1,u2,u3,u4Representing the PWM input generated by the motor on each rotor.
(2) Decomposing according to a double closed-loop control algorithm to obtain an inner loop attitude subsystem and an outer loop position subsystem, designing a state space model for each channel of each subsystem, and defining roll angles as an exampleThe subsystem of roll angle is then:
wherein,C＝[1 0]。
(3) and designing a state feedback controller with a communication time delay condition according to the state space model of each channel so as to be stable.
Let the communication time delay be tau (t) and satisfy 0 < tau (t) to taumIn which τ ismWhich is an upper bound on the communication delay.
The expression for the state feedback controller with communication delay condition is as follows:
u(t)＝Kx(t),K＜0
where K is the state feedback gain.
(4) And constructing an event trigger mechanism, wherein the trigger time in the controller is updated when the event trigger mechanism is met.
(4.1) the error vector is constructed as:
eφ(ikh)＝xφ((tk+s)h)-xφ(tkh)，
wherein h is the sampling period of the sensor; x is the number ofφ(tkh) And xφ((tk+ s) h) respectively represent the most recently transmitted system state value of the event trigger and the state value currently sampled by the sensor.
(4.2) the novel event triggering mechanism is designed as follows:
wherein omega1,Ω2,Ω3Is a positive definite symmetric constant matrix, αAnd β are event trigger coefficients and are positive values.
(5) Solving the sufficient condition for realizing stable control of the event trigger mechanism under the communication time delay;
the following sufficient conditions are obtained by integrating the Linear Matrix Inequality (LMI) and the communication time-varying characteristic, so that the four-rotor flight control time delay system is stable:
wherein, the expression of the elements in the LMI is as follows:
Γ＝[0 BKC 0 BK]
wherein e isi,P,Qi,Ri,M,Mi,Ni,ΦiAre suitably dimensioned matrices and satisfy:
except for zero, the elements of the matrix Ω are:
Ω11＝Q1+τmR2-0.25π2M-M3+γM2-1.5R4,
Ω13＝0.25π2M+M3-γM1-πM2+ATN2,Ω1,11＝Ω2,12＝Ω3,13＝1.5R4,
Ω1,14＝ATN1,Ω22＝-π(Q1-Q2)-1.5(R3+R4),Ω28＝Ω39＝Ω4,10＝1.5R3,
Ω58＝Ω69＝Ω7,10＝3R3,Ω5,11＝Ω6,12＝Ω7,13＝3R4,Ω88＝Ω99＝Ω10,10＝-4.5R3,
Ω15,15＝αΦ2-Φ1
(6) constructing a state feedback gain matrix K ═ Z-1L, the matrices Z and L satisfy the following linear matrix inequality:
wherein, the expression of the elements in the LMI is as follows:
Π1＝[0 B 0 B 0],Γ1＝[0 L 0 L]
wherein, P, Qi,Ri,Xi,NiZ, L, J are matrices of appropriate dimensions.
(7) And (3) aiming at each channel state space model of the four-rotor flight control system, a simulation platform based on a TrueTime toolbox is built. Fig. 3 is a simulation model diagram of the four-rotor attitude subsystem based on network control. As can be seen from fig. 4, when the communication delay existing in the network is considered, it can be seen that an overshoot phenomenon exists in the response process, the steady-state error is small, the system attitude control performance is not greatly affected, and the expected effect is achieved.
A network control system model is built by utilizing a TrueTime simulation tool box, tracking information of an expected attitude angle and an actual attitude angle is obtained according to a random time delay value, feasibility judgment can be carried out on the method, communication time delay is introduced into the four-rotor flight control system, the value of the maximum allowable time delay upper bound is improved by analyzing the upper bound and the lower bound of the communication time delay, and meanwhile, when the time delay change rate is 0, the time delay is constant, so the method has wider application field.
Claims (4)
1. A control method of a four-rotor aircraft based on network control is characterized in that: the method comprises the following steps:
(1) establishing a dynamic model of the four-rotor aircraft;
(2) decoupling into an attitude subsystem and a position subsystem, and designing a state space model for each channel of the subsystems;
(3) each state space model constructs a state feedback controller with a communication time delay condition;
(4) constructing an event trigger mechanism, wherein the trigger time in the controller is updated when the event trigger mechanism is met;
(5) solving a sufficient condition for realizing stable control of an event trigger mechanism under the communication time delay;
(6) constructing a state feedback gain matrix which meets sufficient conditions;
(7) and building a network control system model based on the TrueTime toolbox.
2. The network control-based quad-rotor aircraft control method of claim 1, wherein: in the step (1), the kinetic model is as follows:
wherein x, y and z represent coordinate values in a ground coordinate system; phi, theta and psi respectively represent roll angle, pitch angle and yaw angle; u. ofth,uφ,uθ,uψRespectively representing virtual control input quantities in vertical, roll, pitch and yaw directions; g represents acceleration due to gravity; m represents the mass of the quad-rotor aircraft; i isxx,Iyy,IzzRespectively representing inertia moment of inertia of a roll shaft, a pitch shaft and a yaw shaft; kt,KmRespectively representing a lift coefficient and a drag coefficient; l represents the four-rotor arm length.
3. The network control-based quad-rotor aircraft control method of claim 2, wherein: in the step (3), the state feedback controller with communication delay is:
u(t)＝Kx(t),K＜0
where K is the state feedback gain.
4. A method of controlling a quad-rotor aircraft based on network control according to claim 3, wherein: in the step (4), the event triggering mechanism is as follows:
wherein omega1,Ω2,Ω3Is a positive definite symmetric constant matrix, α and β are event trigger coefficients and are positive values.
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| CN109976361A (en) * | 2019-03-14 | 2019-07-05 | 天津大学 | Quadrotor drone attitude control method towards event triggering |
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| CN113031644A (en) * | 2021-02-06 | 2021-06-25 | 中南大学 | Communication time lag oriented aircraft formation control system event triggering method, device and medium |
| CN115544673A (en) * | 2022-11-28 | 2022-12-30 | 四川腾盾科技有限公司 | Method for assisting in taking off and landing of large unmanned aerial vehicle |
| CN116227151A (en) * | 2023-01-06 | 2023-06-06 | 华东理工大学 | Universal estimation method and device for four-rotor unmanned aerial vehicle system |
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