Mimo Sliding-mode and H‘ Controller Design for Dynamic Coupling Reduction in Underwater-manipulator Systems

In underwater remote vehicle-manipulator system (URVM) applications, it is beneficial to have the underwater remote vehicle (URV) hold station using its thrusters while a human pilot operates the serial manipulator. This provides a stable platform for the manipulator and eases the pilot’s job drastically when current and/or tether disturbances are present. The contribution of this work is twofold: Firstly, the reduction of dynamic coupling in the URVM systems is realized using two robust control techniques namely Sliding-mode control and H‘ control, and the performance of both controllers in the dynamic coupling reduction problem is reported. Secondly, a new control scheme is proposed that involves both controllers in the control loop. Numerical case studies are developed to demonstrate the effectiveness of the controllers. It is concluded that sliding-mode and H‘ controller combined approach provides superior dynamic coupling reduction performance.