# A Scheduling Solution for Robotic Arm-Based Batching Systems with Multiple Conveyor Belts +
###### Abstract  
In this study, we tackle a key scheduling problem in a robotic arm-based food processing system, where multiple conveyors--an infeed conveyor that feeds food items to robotic arms and two tray lane conveyors, on which trays to batch food items are placed--are implemented. The target scheduling problem is to determine what item on an infeed conveyor belt is picked up by which robotic arm at what position, and on which tray the picked up item will be placed. This problem involves critical constraints, such as sequence-dependent processing time and dynamic item and tray positions. Moreover, due to the speed of the infeed conveyor and latency in the information about entering items into the system, this scheduling problem must be solved in near real time. To address these challenges, we propose a scheduling solution that first decomposes the original scheduling problem into sub-problems, where a sub-problem formulated as a goal program schedules robotic arms only for a single tray. The performance of the proposed solution approach is then tested under a simulation environment, and from the experiments, the proposed approach produces acceptable performance. robotic arm-based batching systems; scheduling robotic arms; robotic task-sequencing problem; real-time decision making; give-away minimization +
Footnote † †: This article is written based on the first author’s master thesis for the Mathematics-Economics program of Aalborg University. With a conveyor belt, a robotic arm can significantly improve the throughput of a manufacturing and production system. A robotic arm can also provide flexibility in a system's item flows by transferring an item from one conveyor belt to another. Compared to batching machines that simply push the items out of a conveyor belt, robotic arms also provide more flexibility in the way the items are handled. If the items to carry are heavy or hazardous, the risk of injury to human operators is further minimized by the robotic arm implementation. Moreover, a robotic arm with a conveyor belt has demonstrated its capability to perform tasks that are simple and repetitive. The tasks that should be performed quickly with quality can also be performed successfully by a robotic arm. Picking, placing and sorting tasks are examples of these tasks [2]. The food processing and packaging business are some of the industrial sectors where such advantages of robotic arms with conveyor belts can improve the profits of the business [3]. Imagine a food batching and packaging process where food items of different sizes are grouped into trays of a predetermined standard size or weight. Here, a robotic arm-based system with a sophisticated control mechanism can identify food items moving fast over a conveyor belt and choose the right pieces of food items from a conveyor belt. In this way, the productivity and efficiency of the process can be dramatically improved, and the need for human labor in the process can be minimized [4]. Moreover, a robotic arm-based system is easy to maintain and provides a high level of hygiene and food quality. It should be noted that the benefits of a robotic arm-based system will not be achieved by simply equipping and implementing the system. An operating system that controls the robotic arm's motion and action is essential for fully exploiting the capability of the robotic arm-based system. The core of the operating system is to address the scheduling problem involved in a robotic arm-based system operation, which addresses a number of nested decision-making problems. For example, given a target weight of a food package, a robotic arm should determine which item would be picked up and put into which package tray in what order so that the productivity of the system (e.g., the number of food items packed per time unit) is maximized and give-away (additional weights given over a target weight) in a tray is minimized.