A METHOD OF NAVIGATION SUPPORT FOR A GROUP OF AUVS WHICH INCLUDES AN AUV WITH HIGH-PRECISION NAVIGATION TOOLS

Abstract

A method of providing navigation support for a group of UAVs, which includes a leader UAV with high-precision navigation equipment, in the implementation of which the leader UAV and the group of UAVs are deployed in a given area to perform a given task, each underwater vehicle contains speed, course and depth sensors, as well as systems for receiving and transmitting signals via a hydroacoustic communication channel with other UAVs, after the group has dived to a given depth, a master AUV is designated and, in the first stage, its location is determined with the required accuracy, while a special trajectory of the leader AUV's movement relative to the master AUV is organized on the basis of data on its coordinates and the covariance matrix of errors transmitted by it to the leader AUV via an acoustic communication channel, in such a way that at each moment of the emission of a navigation signal, the leader AUV is on the major axis of the error ellipse of the master AUV, which leads to a maximum reduction in its uncertainty region, then, when the error in determining the location of the master AUV decreases to a specified limit, the second stage is implemented - the high-precision location of the master AUV is maintained by continuing the movement of the leader AUV along a special trajectory relative to the master AUV, and the coordinates of the remaining AUVs in the group are determined with the required accuracy based on the ranges D obtained during the operation of the synchronous GANS JMk and D jлk before the master AUV and the leader AUV, two equations are formed for each AUV in the group (k is the cycle number): (x jk -x мk ) 2 +(y jk -y мk ) 2 +(z jk -z jмk ) 2 =D jмk 2 , (x jk -x лk ) 2 +(y jk -y лk ) 2 +(z jk -z лk ) 2 =D jлk 2 where z jk , z лk and z мk- depths of movement of the AUV measured with the required accuracy j , the leader AUV and the master AUV, on the basis of which two solutions are obtained (x 1jk , y 1jk ) their 2jk , y 2jk ), (j is the number of the AUV in the group), it is assumed that the weight of these decisions is the same p jik =1 / 2 (i=1.2, the weight of the solution determines the probability that the coordinates of this solution coincide with the actual coordinates of the AUV), then the location of the i-th AUV is calculated for two solutions during the k+1 GANS cycle in accordance with the expressions: x jik+1 =x jik +τΣ n=1 N ν jnk ⋅cos(ψ jnk ), y jik+1 =y jik +τΣ n=1 N ν jnk ⋅sin(ψ jnk ), where ν jnk and ψ jnk - the speed and course of the j-th AUV obtained by the GNSS during the k+1 cycle of the GANS operation, τ - the GNSS operation period, n=1,…, N, T=τ ⋅ N - the GANS operation period, after measuring in k+1 cycle of the GANS distances D jмk+1 and D jлk+1 , a new posterior probability is calculated for each solution according to the expression: p ik+1 =p ik +1 / [(D jмk+1 - d jмk+1 ) 2 +(D jлk+1 - d jлk+1 ) 2 +∈], where d jмk+1 and d jлk+1 - calculated ranges from AUV j to the master AUV and the leader AUV, obtained using solutions (x jik+1 , y jik+1 ), ∈ is a given small positive constant, and the updated weights are normalized according to the expression: P ji k+1 =p jik+1 / (p jl k+1 +p j2 k+1 ), when in the next h cycle of GANS operation the difference between the a posteriori probability of the true and false decisions exceeds the given threshold P, that is, the condition |p is fulfilled jlh - p j2h |>P, the decision with a higher a posteriori probability is accepted as the resulting decision (x jh , y jh) and further calculation for the j-th AUV in the SSP is performed from the obtained point, in subsequent GANS cycles for each AUV, after measuring the distances to the master and leader AUVs and determining two solutions based on them, the SSP correction is performed using the solution closest to the current location of the AUV.