A novel adaptive second order sliding mode path following control for a portable AUV

Accurate path following control plays an important role for autonomous underwater vehicles (AUV) in the oceanic surveys and exploration. In the consideration with nonlinearity and external disturbance, the dynamic model of a portable AUV has been established on the basis of its actuation and control characteristics. An adaptive nonlinear second order sliding mode controller has been deduced to eliminate the chattering motion through a sliding surface during the path following control. On the uncertainties of external disturbances, an adaptive tuning law has been selected to estimate the upper bound of disturbance. In the lake experiments, the proposed controller not only provides better response with faster convergence and smaller overshoot, but also eliminates the chattering effect of control output, in compare with the controller with linear and PID second order sliding mode surface.