Identification of Interaction Parameters of Underwater Manipulator Links with a Viscous Medium for Precise Automatic Execution of Manipulation Operations. Part 2

In the first part of the article, the authors proposed a generalized algorithm for solving the inverse dynamics problem for multi-link underwater manipulators (UM), which, during their movement in a viscous medium, allows more correctly taking into account not only viscous friction, but also the added masses and moments of UM links. Using this algorithm, equations are obtained that form the external moments on the output shafts of all UM drives and their individual components, which depend not only on unknown added masses and moments of inertia of links, but also on the forces of viscous friction. These components are presented in an analytical form, convenient for identifying specific parameters of the interaction of a viscous medium with UM links, which should allow the implementation of automatic UM control systems for high-precision execution of even force underwater manipulation operations. In the second part of the article, based on the obtained analytical ratios, a method has been developed for identifying the values of unknown added masses and moments of inertia of the UM links, as well as the coefficients of viscous friction of these links during their arbitrary movement in an viscous medium. The specified method includes two stages. At the first stage, on the output shafts of each UM drive, with the help of diagnostic observers, the values of external moments are determined, depending only on the forces of viscous friction, as well as on unknown added masses and moments of inertia. At the second stage, using analytical representations of these moments and a linear Kalman filter, the desired current values of the added masses and moments of inertia, as well as the coefficients of viscous friction, are determined in a specific ocean zone. The simulation results using a complete mathematical model of an autonomous under- water vehicle with a specific UM installed on it confirmed the operability and high efficiency of the proposed method for the accurate identification of all the desired parameters of the interaction of UM links with a viscous medium.