Unmanned ship heading tracking control strategy with state quantization and input quantization

Objective This paper develops a heading tracking design strategy for unmanned ships with state quantization and input quantization in order to address the problem of limited communication at sea for unmanned ships on the water surface.

Methods  First, a control law is designed on the basis of backstepping and combined with dynamic surface control to reduce the computational complexity of the virtual control law. An extended state observer is also designed to estimate uncertainties and unknown disturbances. Second, all state variables and control variables in the control system are assumed to be quantized by the uniform quantizer, and the quantized state feedback information is only available for the tracking control design. A controller of unmanned ships based on the extended state observer and using quantized states is recursively designed to ensure the tracking of the desired heading. The boundedness of the quantization errors between quantized variables and non-quantized variables in the closed-loop system is analyzed by presenting several theoretical lemmas.

Results Based on the Lyapunov stability theory, the stability of the designed unmanned ship heading tracking control system with state quantization and input quantization is demonstrated, and the simulation results verify the effectiveness of the resulting tracking scheme.

Conclusion  The results of this study can provide references for the heading tracking of unmanned ships.