Ship Track Keeping Control Based On Artificial Neural Networks And Navigation Safety Application Research

With the vigorous development of the shipbuilding and shipping area industry, the developments of ship also gradually become large-scale, high speed and automation, the requirement of ship handling is becoming more and more higher, research and development of ship autopilot has received the unprecedented attention. When the ship is navigating in the ocean, due to the change of speed and loading condition and also the influence of external environment disturbance, ship control system shows strong uncertainty, nonlinearity and instability. Therefore, the nonlinear ship-tracking autopilot which has the control performance of excellent and easy to realize project implementation is particularly important.Based on the control theories and methods, such as Lyapunov stability theory, Artificial Neural Networks, Backstepping technique, Dynamic Surface Control technology and Minimal Learning Paramaters algorithm, this paper proposes a new class of self-adaptive neural network control algorithm for the non-linear single input and output system. Artificial Neural networks is used to approach the unknown uncertain functions in the control system, and the closed-loop system can achieve semi-globally uniformly ultimately bounded. The most significant feature of the algorithm are:(1) This paper introduces DSC technology which can slove the problem of "explosion of complexity" caused by the traditional Backstepping technique during the process of the controller design.(2) When employing neutral networks to approximate the uncertain functions in the control system, sometimes it will cause the problem of "dimension curse" which will enlarge the designing workload. For this reason, MLP algorithm is introduced to cope with this problem. For the sake of solving the above-mentioned problems simultaneously, MLP algorithm and DSC method is combined. In this way it can not only use less parameters and reduce computational load, but also avoid the possible existing problem of controller singularity. In addition, the stability of the closed-loop system is guaranteed and the tracking error converges around zero.On the other hand, the motion of ship shows nonlinearity, strong uncertainty and complexity, for these reason the proposed self-adaptive neural network control algorithm of the non-linear single input and output system in this paper is being applied to the ship liner-track keeping control system.Three kinds of linear-track keeping control algorithm with good robustness, self-adaptively, reliability and real-time are put forward finally.. The proposed three control algorithms are focused on adjusting the adaptive learning parameters in the ship, track keeping control system, so the number of the parameters in each subsystem are different. Matlab simulation results validate the effectiveness of the proposed algorithm. To further illustrate the performance of the proposed algorithm with tradition PD autopilot, change the parameters of ship’s control system, through comparing the simulation results, we find that the proposed algorithm has the property of adaptive, robustness, simple, and easy to be implemented in applications.Finally, a new assessment technique for ship navigation safety in the constrained waters is proposed based on ship’s linear-track keeping control technique. By embedding the linear-track keeping control module in the ship handling simulator (SHS), a traffic simulation method based on autoSHS for the safety of ship navigation is finally proposed. By applying this simulation method to the evaluation of the safety of the ship navigating in restricted water, the defect of handSHS which is affected by human factors can be make up, and the SHS technology can be improved greatly. A scientific and objective reference decision can also be gained due to the safety of the ship manipulating. Intelligent navigation safety assessment methods for ships in restricted waters, such as a variety of ports, channels and rivers will be developed further. Meanwhile, objective and feasible reference strategies will also be given for the safety of ship manipulation in restricted waters. What’s more, safety and efficiency of the ship traffic will be improved practically by providing guidance how to behave safely and speedy; Scientific and effective navigation simulation and evaluation methods will be provided for navigation safety demonstration and evaluation of channel improvement projection and the new port facilities.