Modelling time efficiency of cobot-supported kit preparation

Patrik Fager,Fabio Sgarbossa,Martina Calzavara

doi:10.1007/s00170-019-04679-x

Abstract

Kitting – meaning to supply assembly with components in presorted kits – is widely seen as beneficial for assembly quality and efficiency when there is a multitude of component variants. However, the process by which kits are prepared – the kit preparation – is labour-intensive, and kit errors are problematic at assembly processes. The use of robotics to support kit preparation has received some attention by researchers, but literature is lacking with respect to how collaborative robots – cobots – can support kit preparation activities. The purpose of this paper is to identify the potential of a cobot to support time-efficient batch preparation of kits. To address the purpose, the paper presents a mathematical model for estimation of the cycle time associated with cobot-supported kit preparation. The model is applied in a numerical example with experimental data from laboratory experiments, and cobot-supported kit preparation is compared with manual kit preparation. The findings suggest that cobot-supported kit preparation is beneficial with diverse kits and smaller components quantities per SKU (Stock Keeping Unit) and provides less variability of the outcome, when compared to manual kit preparation. The paper reveals several insights about cobot-supported kit preparation that can be valuable for both academics and practitioners. The model developed can be used by practitioners to assess the potential of cobots to support kit-batch preparation in association with assembly, spare parts, repair and maintenance, or business to business industry.

Highlights

Introduction and aim of the studyMixed-model assembly often involves a multitude of component variants and effective materials supply is essential
The purpose of this paper is to identify the potential of a cobot to support time-efficient batch preparation of kits
This paper has modelled and compared kit preparation when the work is performed manually with an application whereby kit preparation is performed collaboratively by an operator and a cobot

Summary

Introduction

Mixed-model assembly often involves a multitude of component variants and effective materials supply is essential. The purpose of this paper is to identify the potential of a cobot to support time-efficient batch preparation of kits. The paper presents a mathematical model for estimating the cycle time of cobot-supported kit preparation, useful for understanding how the operator’s time allocation among tasks change when a cobot is introduced. The considered cobot-application consists of a cobot mounted on an AGV that sorts components that have been picked by an operator into a batch of kits. An operator and a cobot collaborate throughout the work cycle, and the cycle time of the process depends on how well the collaboration works. The application was already presented in Fager et al [10], showing

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