Dynamic modeling and adaptive fuzzy sliding mode control for multi-link underwater manipulators

This paper proposes a method of dynamic modeling and a modified sliding mode control algorithm applied on multi-link underwater manipulators. Firstly, combining Lagrange equation with Morison formula, we establish the dynamic model of a 3 DOF underwater manipulator in hydrostatic environment. Water resistance, additional mass force and buoyancy are calculated to discuss the influences to all joints working in underwater environment. Next, we presented an improved sliding mode control strategy for the accurate trajectory tracking control of underwater manipulator. To address the issue of chattering problem for sliding mode control and unavailable normalization factor, an adaptive fuzzy sliding mode is proposed. In order to validate the effectiveness of the presented controller, two simulations are conducted. The results are compared with other control algorithm and show that no matter in convergence rate or control accuracy, the proposed controller has better control effect. •Combining Lagrange equation with Morison formula, we establish the dynamic model of a 3 DOF underwater manipulator.•We presented an improved sliding mode control strategy for the accuracy trajectory tracking control of manipulator.•An adaptive fuzzy sliding mode is proposed to address the issue of chattering problem for sliding mode control.