A Method to Synthesize High-Precision Motion Control Systems for Underwater Manipulator

Abstract

The development of a method to synthesize combined systems that provide high-precision motion control of multi-joint manipulators mounted on underwater vehicles is presented. This method consists of the following steps. (1) A preliminary analytical calculation of the external torques that occur in all the degrees of mobility of moving underwater manipulators is performed using a recurrent algorithm for solving the inverse dynamics problem. (2) Additional diagnostic observers are then synthesized using the manipulator electric drive's dynamic models and taking into account the analytically estimated external torques. These observers can precisely determine the values of unexpected variations in viscous and coulomb friction torque in all the drives. (3) After that, the precisely identified torque effects on the drives of all the degrees of manipulator's mobility are fully compensated by the adaptive compensator devices that provide stabilization of the dynamic properties of these drives at the nominal level. Results of a numerical simulation showed a significant increase in accuracy of various technological operations performed with an underwater manipulator when the synthesized system was used.