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.572. 智能系统学报 第12卷 former ensures the distance error between the desired that the directed communication topology graph must and the real position converges to 0[4).The real include a spanning tree position of each UAV can be easily acquired and the To attain the desired position for one single UAV UAV's trajectory is drawn. in the moving coordinate system,the error between the Consensus of moving desired and the real position should be treated as an coordinate system extra variable,this can be described by single- State variables of integrator dynamics for simplicity.The math model can Standard moving coordinate Communication be described as state network Errors added with relative er:=u (3) pesition in the formation and the consensus algorithm is in Ref [9]. Consensus of relative position in the moving UAV's u:=- (4) relative position coordinate system -∑ag(e,-er) in the system =rpi+er (5) JA JA JAV,-UAY Where7;is the real position of UAV:,UAV:in the moving coordinate system,er;is the distance error Fig.1 Frame of consensus controller in multi-UAV formation between the real and the desired position of UAVi,rP which is shown in Fig.2,is the desired position of For the formation problem in a multi-UAV UAV;in the moving coordinate system,i1,2,.., system,the UAVs'states should include both position 9.Equations (1~5)above can be transformed into a and velocity,and the control inputs are the collective matrix form, accelerations4.This model is always described by (L☒L)E+(b☒L)E=-K[(L⑧I)E+(b☒L)]- second-order differentiation equations,and as a result, a consensus algorithm for double-integrator dynamics is K[(L☒I3)E+(b☒13)E] required.The dynamic math model of the multi-UAV e=-(L☒I3)e system is given below, r=r+专=p+er+ (6) where Loxo is the Laplace matrix of the communication (1) topology graph,bRreflects which UAV can directly 5=[x] receive information from UAVo,is the desired where专:,i:h,∈R3 represent the position,.the velocity position and also the position of UAVo,which shows and the acceleration of UAV:,respectively and x,y, the desired path for all the UAVs,finally, are the3-dimensional positions,i∈{1,2,…,l0}.The represents the Kronecker product. consensus algorithm can be described as in Ref [14]. K,=diag(K1,K2,…,Kg),K,=diag(Kl,K2, 三,咳-K--&G,-6]+ 1 …,Ky),er=(erer…erg),f=(r7…fg)T,ris := the vector of the real position of each UAV,g is the 心-k-》-k-5】(2 vector of the position of the origin of each UAV's moving coordinate system. Where a;is element (i,j)in the adjacency matrix Equation (6)is the core of the multi-UAV 10 controller,and r provides the necessary positional A66∈R6x6,andk=∑ag,K.,K.isa3×3size information for all the UAVs for use in the next step. symmetric positive definite matrix,i1,2,..,9, After acquiring the target instructions,the UAVs fly in this work this is replaced by a Pascal matrix for toward their destinations. simplicity.The algorithm has been proven effective and 1.2 Multi-UAV formation task can make all the UAVs'both positions and velocities The desired formation shape is designed as converge to the state of the root.This is because the follows: graph satisfies the sufficient and necessary conditionformer ensures the distance error between the desired and the real position converges to 0 [14] . The real position of each UAV can be easily acquired and the UAV’s trajectory is drawn. Fig.1 Frame of consensus controller in multi⁃UAV formation For the formation problem in a multi⁃UAV system, the UAVs’ states should include both position and velocity, and the control inputs are the accelerations [14] . This model is always described by second⁃order differentiation equations, and as a result, a consensus algorithm for double⁃integrator dynamics is required. The dynamic math model of the multi⁃UAV system is given below, ξ · i = ζi ζ · i = μi ξi = [xi yi zi] T ì î í ï ïï ï ï (1) where ξi,ζi,μi∈R 3 represent the position, the velocity and the acceleration of UAVi, respectively and xi,yi,zi are the 3⁃dimensional positions, i∈{1,2,…,10}. The consensus algorithm can be described as in Ref [14]. μi = 1 ki ∑ 9 j = 1 aij[ζ · j - Kri(ξi - ξj) - Kvi(ζi - ζj)] + 1 ki ai10 [ζ · r - Kri(ξi - ξ r ) - Kvi(ζi - ζ r )] (2) Where aij is element ( i, j) in the adjacency matrix A6×6 ∈R 6×6 , and ki = ∑ 10 j = 1 aij , Kri,Kvi is a 3 × 3size symmetric positive definite matrix, i ∈ {1,2,…,9} , in this work this is replaced by a Pascal matrix for simplicity. The algorithm has been proven effective and can make all the UAVs’ both positions and velocities converge to the state of the root. This is because the graph satisfies the sufficient and necessary condition that the directed communication topology graph must include a spanning tree [14] . To attain the desired position for one single UAV in the moving coordinate system, the error between the desired and the real position should be treated as an extra variable, this can be described by single⁃ integrator dynamics for simplicity. The math model can be described as e · ri = ui (3) and the consensus algorithm is in Ref [9]. ui = - ∑ 9 j = 1 aij(eri - erj) (4) r ~ i = rpi + eri (5) Where r ~ i is the real position of UAVi, UAVi in the moving coordinate system, eri is the distance error between the real and the desired position of UAVi, rpi which is shown in Fig. 2, is the desired position of UAVi in the moving coordinate system, i∈{1,2,…, 9}. Equations (1~5) above can be transformed into a collective matrix form, (L 􀱋I3)ξ ¨ + (b 􀱋I3)ξ ¨ r =- Kr[(L 􀱋I3)ξ + (b 􀱋I3)ξ r ]- Kv[(L 􀱋 I3 )ξ · + (b 􀱋 I3 )ξ ·r ] e · = - (L 􀱋 I3 )e r = r ~ + ξ = rp + er + ξ ì î í ï ï ï ï ï ï (6) where L9×9 is the Laplace matrix of the communication topology graph, b ∈ R 9 reflects which UAV can directly receive information from UAV10 , ξ r is the desired position and also the position of UAV10 , which shows the desired path for all the UAVs, finally, 􀱋 represents the Kronecker product. Kr = diag(Kr1 ,Kr2 ,…,Kr9 ),Kv = diag ( Kv1 ,Kv2 , …,Kv9 ),er = (er T 1 er T 2… er T 9 ) T ,r ~ = ( r ~ T 1 r ~ T 2…r ~ T 9 ) T ,r is the vector of the real position of each UAV, ξ is the vector of the position of the origin of each UAV’ s moving coordinate system. Equation ( 6 ) is the core of the multi⁃UAV controller, and r provides the necessary positional information for all the UAVs for use in the next step. After acquiring the target instructions, the UAVs fly toward their destinations. 1.2 Multi⁃UAV formation task The desired formation shape is designed as follows: ·572· 智 能 系 统 学 报 第 12 卷
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