Positioning of underwater flexible arm with thruster using nonlinear model observer

摘要

For an underwater robot controller, nonlinearity in the system is a critical problem. The nonlinearity is too strong for control techniques based on a linear model even when robust controllers are designed. A sliding mode control technique is of considerable interest due to its capability to deal with nonlinear systems. However, there is no simple, suitable observer for the nonlinear model. In this study, focussing on a second-power nonlinearity, a nonlinear model observer is derived by improving the variable structure systems (VSS) observer for a linear model.