Design Problem of Hybrid Assembly Line with Humans and Robots Considering Automation Difficulty Level

Since the labor force has declined in the manufacturing industry by aging society, automation by robots for assembly lines is expected from a labor-saving perspective. However, there are many tasks on an assembly line. Thus, some of the assembly tasks can be easily automated using robots, while the others are difficult to automate because different automation difficulty levels exist. Therefore, a line design is required to configure both humans and robots' contributions considering the automation difficulty level. This study proposes a design problem for a hybrid assembly line with humans and robots that considers the automation difficulty from manual works. The proposed design problem consists of two stages. In the first stage, all tasks are selected as either human or robot task based on the automation difficulty level and total assembly time using integer programming. In the second stage, a line balancing problem is solved by integer programming to minimize the number of stations. After that, the proposed method is adopted to an actual electrical product manufacturing line. As a result, there was a case where the restrictions on automation difficulty level were relaxed, and the number of robot tasks were increased.