## 1 Introduction
To build trajectories of movements of the MM working tool, special methods are required for various manipulative operations over the bottom surface and certain objects with already known shapes [8; 18; 23; 24; 25]. These methods take into account the positions of the object's surface, the MM's working zone and the angle of approach to the object relative to each other. In particular, the method [25] allows building complex spatial trajectories of the MM working tool on the object surface using point clouds obtained from MVS. However, it is unsuitable for automated manipulations, since the type of trajectory and its location on the object are determined by the operator and set by pointing the UUV camera optical axis. The MM working tool should execute the programmed trajectories with specified accuracy. This necessitates using the method [26] that, thanks to the introduction of self-adjusting correction devices (SCD) of the manipulator's electric drives, compensates for the negative interactions between all its degrees of freedom that occur during movement at a high speed in the aquatic environment, and also for the coulomb and viscous friction torques in the drives. These interactions are calculated by the recurrent algorithm for solving IDP [13]. The introduction of additional observers provides identification of unknown external torques on the shafts of the respective electric drives. During a manipulative operation, the UUV inevitably, although slightly, shifts from its initial position, even if a system of stabilization in the hovering mode is used [11; 12; 13; 14]. As a result, the MM working tool deviates from the programmed trajectories, thus, reducing the operation accuracy. To maintain the specified accuracy in the work [27], a method for continuous automatic correction of programmed trajectories of MM's movements is proposed, which takes into account actual displacements of UUV relative to its initial position. When the MM grips a massive object, the UUV acquires undesirable list and trim angles under the effect of its weight. A lot of studies have addressed the issue of controlling movements of UUV exposed to external disturbances ([11; 28], etc.). In particular, a method has been proposed in the work [28], which allows adjustment of thrusters' propulsions depending on the information about the difference between the programmed and current UUV movement vectors that come from a gyroscope and a Doppler velocity log. An analysis of the above-mentioned methods and algorithms shows that a substantial basis has already been created for synthesizing an efficient multilevel control system of UUV to perform automatic manipulative operations. However, the known methods for determining the shape and location of an object relative to UUV have a number of disadvantages that restrict the range of their applications. In particular, the method [18] suggests alignment of the point clouds received from MVS with the clouds formed on the basis of previously constructed 3D models of the object. However, the point clouds of the scanned object obtained in the model were evenly distributed over the object's surface, which is impossible in actual conditions due to unidirectional scanning. Furthermore, the alignment of the point cloud of the constructed model with that of the actual object scanned needs to be tested for accuracy. A decision about the further execution of the trajectory built on the object's surface should be made on the basis of the test results. However, when forming desired trajectories of the MM working tool, this method does not take into account the probability of silting, fouling and deformation of the object, which can negatively affect the accuracy of manipulative operations. In this article, we propose an upgrade of the method [18] to eliminate these weaknesses.