1 Federal State Educational Institution of Higher Education «Sevastopol State University» Russian Federation, Sevastopol, Universitetskaya St., 33
2 Institute of Natural and Technical Systems, Russian Federation, Sevastopol, Lenin St., 28
An approach is proposed to improve the method developed by the author for determining the vertical profile of water density using an autonomous sea probe (a profiler), which performs motion (immersion) in a vertical plane in the marine environment with horizontal stratification under the influence of gravity and buoyancy, as well as forces exerting resistance to this movement. In this case, the desired profile is formed by the on-board computer as a function of depth according to measurements of the trajectory parameters of the probe movement, obtained from its on-board navigation system. The essence of the proposal consists in additional processing of measurement data in order to minimize the square of the deviation of the normalized acceleration energy of the computer model of the measurement process from the corresponding indicator of the instrumentation system placed on a mobile platform, which is the body part of the profiler. In this case, the calculation of the density of seawater and its increment is performed under conditions of maximum proximity to the phase trajectories of the measurement process in the instrumentation system and the phase trajectories of the corresponding digital measurement model. The basic mathematical relationships for calculating the parameters of the model and the optimization algorithm based on the gradient descent method were obtained. On this basis, an information structure has been built that provides optimal dynamic measurements of the vertical density profile of seawater. Verification of the models and approbation of the proposed method were carried out by means of modeling using the MATLAB & Simulink system of scientific and engineering calculations at various speeds in a highly stratified marine environment of an autonomous marine probe. In this case, a specially developed model of the water stratified over depth, a model of movement of an autonomous diving buoy in this environment, and a dynamic model of measuring the density of seawater taking into account the inertial properties of the used acceleration sensors and hydrostatic pressure were used.
Keywords: autonomous marine probe, vertical density profile, mathematical model, inverse problem of dynamics, local optimization, onboard information system.
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