Zhenzhong Chu

Model updating and thruster fault diagnosis for underwater vehicle

As the impact of underwater vehicle dynamics modeling error on fault diagnosis system, a method using improved Elman neural network to modify underwater vehicle dynamics model in the current is proposed. The neural network parameter adjustment law under the Lyapunov stability is given. Sliding mode observer is constructed for state estimation based on the modified dynamics model. The change of state estimation residual of each DOF is analyzed when fault occurs in different thrusters of under vehicle. A thruster fault diagnosis method based on residual state fusion is presented, which has been validated through AUV sea trials data.

Fault-tolerant control based on adaptive sliding mode for underwater vehicle with thruster fault

An adaptive sliding mode backstepping fault-tolerant control is proposed for autonomous underwater vehicle(AUV) with thruster faults. Thruster faults are treated as uncertainties. Gaussian radial-basis-function networks are used to approximate these general uncertainties. In addtion, no Fault Detection and Diagnosis unit is needed in the proposed method.The controller can guarantee closed-stability regardless of thruster fault occurs or not. Due to the controlled system is strict-feedback in the traditional backstepping scheme, an improved backstepping scheme integrating with adaptive sliding mode algorithm. Finally, simulations are carried out to verify the validity of the proposed strategy.

Study on qualitative modeling of underwater robot

To deal with the difficulty of establishing the accurate dynamics mathematical model of the underwater robots, a qualitative modeling method of underwater robots dynamics is presented based on qualitative simulation. Considering the complexity of the working environment and particularity of the non-linear movement process of underwater robots, through determining the landmark values and distinguished time-point selection method as well as qualitative state representation in the qualitative behavior of reasoning, an approach about qualitative processing quantitative information is proposed. Moreover, the qualitative constraints in different operating modes are analyzed. As a result, the qualitative state transition sequence is determined. The water tank experiment validates the feasibility of dynamics modeling of underwater robot based on qualitative simulation.