Development of Self-Tuning Control Systems for Electric Drives of Underwater Manipulators Based on Brushless DC Motors

The paper develops a self-adjusting control system for electric drives with brushless DC motors installed in the joints of multi-link underwater manipulators (UM) described by complex nonlinear differential equations. These systems, through the use of additional observers with a variable structure, make it possible to accurately estimate the values of external moments acting on the output shafts of electric drives and caused by the influence of a viscous environment on the UM links when their working bodies move along prescribed trajectories. Further, the identified moment effects on electric drives of all degrees of mobility of the UM are compensated with the help of self-adjusting corrective devices introduced, which, due to additional control action, stabilize the dynamic properties of these drives at the nominal level. A numerical simulation of the system, synthesized by using the developed method for a multi-link UM, was performed, which showed an increase in the accuracy of the movement of the working body when using the synthesized system.