Corresponding author: Konoplin Aleksandr Ju., Assistant, Far Eastern Federal University, Vladivostok, 690950, Russian Federation, Institute of Automation and Control Processes, Far Eastern Branch of RAS, Vladivostok, 690041, Russian Federation, e-mail: kayur-prim@mail.ru

Received on July 05, 2015
Accepted on July 24, 2015

Today most of the manned and telecontrolled underwater vehicles are equipped with multilink underwater manipulators, and the quality of performance of the underwater operations depends on the accuracy and speed of movements of such manipulators. However, an underwater manipulator, moving in the water environment, is subjected to significant force and torque influences. These influences are caused by the inertial and gravitational forces, and also forces determined by interaction of the working manipulator and viscous environment. The specified influences displace the underwater vehicle, operating in a hang mode, from its initial space position. Thus the accuracy of the manipulator's work is reduced. The above effects complicate the qualitative performance of most of the manipulation tasks. The known systems for automatic stabilization of the underwater vehicles in a hang mode near the operating objects allow us to compensate for the negative force and torque influences from the working manipulator. These influences are calculated in real time. The values of these dynamic influences are proportional to the viscous friction coefficients of each manipulator link at the arbitrary spatial movements of a manipulator in water. These coefficients can be determined experimentally and depend on a geometrical form of the links, specific features of their surface and also on the tilt angle of a link to the fluid flow. It is obvious that the accuracy of the underwater vehicle stabilization in a given space point directly depends on the accuracy of definition of the required coefficients. The implemented analysis of the existing approaches and methods shows that today the task of creation of a universal approach to the experimental definition of the viscous friction coefficients of each multilink underwater manipulator link still has to be solved. This paper describes an approach to solving of the assigned task, allowing us to experimentally determine the viscous friction coefficients with the help of an aerodynamic experiment. Herewith, a similarity of the underwater manipulator link and its model in accordance with Reynolds number is observed. The offered approach is based on the momentum-transfer method and is characterized by high accuracy, simplicity and convenience in realization of experiments. For realization of the experimental researches in an aerodynamic tunnel an experimental adjustment was developed. With the help of this adjustment the dependence of the viscous friction coefficients on the tilt angle of a link to the fluid flow was determined. Values of these coefficients are necessary for calculation of the force and torque influences on an underwater vehicle from a moving manipulator with the purpose of their subsequent compensation by means of the vehicle thrusters. For confirmation of the results of the aerodynamic experiment sea tests were done. Herewith, the values of the required coefficients received in the sea and aerodynamic experiments appeared very close.

Keywords: viscous friction coefficient, aerodynamical experiment, aerodynamical tunnel, multilink manipulator, underwater vehicle

Acknowledgements: The work was supported by FEFU Scientific Foundation (agreement no. 13-06-0112-m_a), Ministry of Education of the Russian Federation (public job in 1141), as well as the Russian Federal Property Fund.

For citation:
Filaretov V. F., Konoplin A. Ju., Getman A. V. Experimental Determination of the Viscous Friction Coefficients for Calculation of the Force Impacts on the Moving Links of the Underwater Manipulators, Mekhatronika, Avtomatizatsiya, Upravlenie, 2015, vol. 16, no 11, pp. 738—743.
DOI: 10.17587/mau/16.738-743

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