Rescheduling of Multi-Scenario and Multi-Objective Dynamic Changes of Ship Group Construction

A multi-scenario and multi-objective dynamic change rescheduling algorithm is proposed to address the production schedule delays and the need for adjustments caused by frequent abnormal conditions, such as material delivery delays and equipment failures in the vertical assembly welding process of shipbuilding teams. First, the objective function is selected based on different production stage and abnormal disturbance, and a mathematical model is then developed, incorporating site constraints, task precedence constraints, and human resource constraints. Next, a site allocation algorithm is introduced, and an improved non-dominated sorting algorithm based on reference points is adopted to solve the problem. A cross-checking mechanism implemented, alongside a task-sequence-based mutation operator, and the multi-chromosome mechanism is integrated with the site allocation algorithm. Afterwards, a method for calculating the chromosome sequence distance in the ship group vertical assembly welding rescheduling is proposed, and the difference between the rescheduling algorithm solution and initial plan is described. An R2 indicator is combined with a Pareto-R2 double standard selection operator, which ensures both diversity and convergence of the algorithm. Finally, comparative experiments are conducted based on engineering cases to validate the effectiveness of the proposed rescheduling algorithm.