Aiming at the problem of current flexible integrated scheduling, most of the current research shortens the total processing time of products and ignores the loss of the equipment in the processing, which affects the scheduling ability of the equipment; in this context, a flexible integrated scheduling algorithm considering periodic maintenance (FIS-PM) is proposed. The algorithm flexibly mobilizes the processing sequence of the selected processing equipment, and uniformly maintains all equipment at a certain time. First, the ISA-PM algorithm adopts the strategy combination of the layer priority, the short-time, and the equipment priority strategy to schedule the operations. Then, based on the forest firefighting model, the maintenance start point and duration of the equipment are determined by the relationship between the number of the processed operations and the number of the unprocessed operations and the loss of equipment during the maintenance. Finally, the dynamic adjustment strategy is adopted, which not only realizes the maintenance of the equipment, but also reduces the makespan of the products. The experimental results show that the proposed ISA-PM algorithm realizes the optimization effect of reducing the makespan of complex products, completing the maintenance, and improving the overall utilization rate of equipment systems.

In the field of manufacturing, complex products with a tree structure often naturally exhibit asymmetric characteristics due to the uniqueness of their constituent elements and hierarchical relationships. In the production scheduling of such small-batch and multi-variety products, due to the influence of process constraints, many pieces of equipment will be idle for a long time in the production process. This increases the makespan of production and reduces the utilization rate of the equipment. Aiming at improving this situation, a resource cooperative scheduling algorithm is proposed to dynamically adjust the idle time of equipment: the integrated scheduling algorithm with dynamic adjustment of machine idle time based on an improved semi-numerical algorithm (ISA_DA). This algorithm adopts the critical path chain and the optimal scheduling strategy. On this basis, an adjustment strategy based on the semi-numerical algorithm considering the backward movement of the process is proposed, which improves the strength of the close connection of the process and the strength of parallel processing. Experimental results show that the effect of the proposed algorithm is better than the comparison algorithms: the hierarchical scheduling order algorithm and the process tree cyclic decomposition algorithm. It can increase the equipment utilization rate by 10% and 11.5%, respectively, and reduce the makespan by 28.6%. These experimental results strongly prove that the proposed algorithm can effectively reduce the total processing time and improve the production efficiency, whether it is for complex products with a symmetric structure or asymmetric structure.

In the field of scheduling, complex products with a tree structure often exhibit inherent asymmetric characteristics, while their processing resources are usually provided by symmetric workshops with functionally equivalent and interchangeable processing equipment. Aiming at the complex product integrated scheduling problem with due date constraints, this paper proposes a reverse integrated scheduling algorithm considering the workpieces’ time urgency degree and migration cost. Firstly, internet-connected equipment with the same function as the main workshop and the lowest transportation cost is virtualized as symmetrical outsourcing workshop equipment. Secondly, the workpiece scheduling strategy and distributed integrated scheduling strategy are proposed. Taking each workpiece as the trial scheduling unit, under the premise of meeting the delivery time, the quasi-scheduling scheme with the minimum total migration cost for the current workpiece is selected as the workpiece scheduling scheme. If not unique, the scheme with the minimum outsourcing processing time is selected. Finally, the algorithm in this paper is compared with other algorithms in the same research field. The experimental results show that the algorithm in this paper reduces the total cost of workpiece migration by 25% and the total time of outsourcing processing by 20% while meeting the order delivery time. It is proven that the symmetric processing resource scheduling system constructed by the algorithm in this paper can achieve the parallel scheduling optimization of workpiece processing, assembly, and migration for both symmetric-structure and asymmetric-structure complex products.