Developing an innovative production scheduler based on an intelligent machine learning algorithm

The manufacturing industry is ever-evolving. Circumstances such as fluctuating demand, dynamic supply conditions, and the far-reaching trend of customisation and personalisation, bring the necessary challenges in terms of production planning. In bigger factories, shop floors are laid out to meet the production requirements of today’s world, with back-to-back and parallel production possibilities. The problem manufacturers run into, is that their scheduling tools cannot keep up.

The dynamic market circumstances and highly customised products entail unique, complex production flows. Due to urgent requests from customers and shortages in the supply chain, manufacturers need smart, advanced planning and scheduling tools, that are able to incorporate and react upon those dynamic changes and uncertainty.

Existing production scheduling tools are often rule-based and run by computer power. These tools take long times to solve scheduling problems, e.g., up to an hour for computing a reschedule. This is not suitable for handling the dynamic nature of orders and the flexibility required in make-to-order production environments. This results in tardiness in the entire production process. For example, the quotation process for new projects is slowed down due to this and the production environment is not utilised to its full capacity.

To develop a solution to this, the AMP-subsidised project TIMELY was initiated. The project consortium consists of Limis from Enschede, specialist in production planning software, Hittech Bihca, part of the Hittech Group – a system supplier for high-tech equipment, that manufactures semiconductors or electronic components, and the FIP-AM@UT.

The goal of the project is to design, train, and implement a computationally efficient scheduling demonstrator for hybrid job-shop production systems. The scheduling tool will make use of reinforcement learning, a form of artificial intelligence, for stronger computational power and quicker system responses to changes in the demand or production. It is important that the scheduler can quickly produce a new schedule upon an urgent customer request, while creating robust schedules that account for uncertainty. In turn, this will lead to optimised operations.

Industry partners

APPROACH

To address these challenges, the project aims to develop an innovative scheduling tool utilising reinforcement learning, a form of artificial intelligence. This AI-powered scheduler will be designed to handle the complexities of hybrid job-shop production systems, offering rapid computation and flexibility.

The project involves researching SME manufacturers’ needs, analysing job-shop production data, and evaluating existing AI schedulers to identify limitations. The end goal is to create a computationally efficient scheduling demonstrator that can swiftly adapt to urgent changes and uncertainties, thus optimising manufacturing operations and improving overall production efficiency. The tool will be validated for its speed and robustness across various problem scenarios, ensuring it meets the diverse needs of high-tech SMEs.

OUTCOME

The TIMELY project led to the implementation of two AI based end–to–end schedulers for swift production planning. The first implementation consisted of a refactored codebase for a similar paper, tailored for chipmaking and order deadlines. The second implementation was built from the ground up with python libraries for neural networks and databases. Both implementations focused on solving the Flexible Job Shop Scheduling Problem (FJSP) using Deep Reinforcement Learning (DRL) techniques.

The schedulers were tested on various scenarios, including standard 8-hour workdays, reduced 6-hour and 4-hour workdays, and cases with and without priorities. While the AI models showed promise in handling complex scheduling scenarios, they also revealed areas for improvement, particularly in consistently outperforming traditional methods like the Earliest Due Date (EDD) heuristic and the Limis Planner in all scenarios.

• Successfully incorporated variable machine hours and availability
• Tested on both salesdemo case (1 machine with multiple working hours) and Hittech case (multiple machines with varied hours)
• Successfully tested on problems with up to 30 jobs and 4 machines
• Demonstrated ability to handle larger problem sizes than previous methods
• Tested on real-world datasets from Hittech (precision parts manufacturer)
• Validated feasibility for practical manufacturing scenarios

This project was made possible through the Regio Deal supported by the Province of Overijssel and the Dutch State.

“Collaborating with FIP-AM@UT on the TIMELY project has been a positive experience for us at Limis. Thanks to the support from the RegioDeal subsidy funding, we were able to engage in this project, which has help advanced our capabilities in handling complex, real-world manufacturing challenges. Through this partnership, we have gained insights into the application of AI to production scheduling tools by leveraging real production data in end-to-end approaches in machine learning.”
– Jur ten Brug
Commercieel Manager, Limis B.V

FOR MORE INFORMATION ABOUT TIMELY, PLEASE FEEL FREE TO REACH OUT TO

Can Ölmezoğlu

Can Ölmezoğlu

Engineering Support, Software Development

Engin Topan

Associate Professor Smart Manufacturing and Supply Chain Planning