Trajectory tracking method for under-actuated unpiloted ship controlled based on limited backstepping method

The invention discloses a trajectory tracking method for an under-actuated unpiloted ship controlled based on a limited backstepping method, and the method comprises the steps: (1), model building: building a three-freedom-degree kinetic and dynamic model of the under-actuated water surface unpiloted ship in an inertial coordinate system; (2), distance control design: giving an expected trajectory, calculating a position virtual control law through a position error, further deducing the actual input control law with the output constraint for controlling the longitudinal speed through the virtual control law, and carrying out the estimation and compensation of the external interference through a neural network, so as to reduce the distance difference between the unpiloted ship and a reference trajectory; (3), angle control design: calculating an angle error, calculating an angle virtual control law, further deducing the actual input control law with the output constraint for controllingyawing angular speed thr