# A Conceptual Digital Assistance System Supporting Manual Changeovers in High-Variety Production

Rasmus Andersen, Christopher Ketelsen, Kjeld Nielsen, Ann-Louise Andersen, Thomas D. Brunoe, Sofie Bech

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Rasmus Andersen, Christopher Ketelsen, Kjeld Nielsen, Ann-Louise Andersen, Thomas D. Brunoe, et al.. A Conceptual Digital Assistance System Supporting Manual Changeovers in High-Variety Production. IFIP International Conference on Advances in Production Management Systems (APMS), Aug 2018, Seoul, South Korea. pp.449-455, 10.1007/978-3-319-99707-0_56. hal-02177867

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# A Conceptual Digital Assistance System Supporting Manual Changeovers in High-Variety Production

Rasmus Andersen(✉)[0000-0001-6788-8217], Christopher Ketelsen[0000-0003-1735-4617], Kjeld Nielsen[0000-0002-3720-167X], Ann-Louise Andersen[0000-0002-7923-6301], Thomas D. Bru-noe[0000-0002-9847-6562], and Sofie Bech

Department of Materials and Production, Aalborg University, Denmark

therasmusandersen@gmail.com

**Abstract.** The advent of production strategies such as Mass Customization and Changeable Manufacturing requires that production systems be increasingly flexible towards diverse customer needs. Although humans remain the most flexible entity in modern production systems, the increasing complexity of these systems presents a challenge for the operators with regards to remaining efficient. Research related to Industry 4.0 has promoted the application of digital assistance systems, as a method of augmenting human operators to handle the complexity of these production systems better. However, no digital assistance system that supports human operators in performing manual changeover operations in complex production systems has been identified. This paper, therefore, presents a conceptual digital assistance system, which utilizes information about two consecutive production configurations, and processes this data through an algorithm, to determine which specific changeover operations are required to perform a changeover most efficiently. Potentials of implementing the proposed digital assistance system are briefly introduced, and topics for further research are outlined.

**Keywords:** Digital Assistance System, Changeover Ability, Changeability, Changeable Manufacturing, Mass Customization

## 1 Introduction

The production strategy of Mass Customization, which focuses on offering customers individualized products at near mass production costs, has become increasingly relevant since the 1980's, where a shift in market circumstances has challenged the practice of traditional mass producers in many industries [1]. To cope with these changed circumstances, many companies see the ability to adapt to changes in production mix and volume as providing superior competitive advantages [2]. From a production perspective, one of the enablers of mass customization concerns robust processes, which can be achieved through changeability. In seminal works on the subject, changeability is defined as "[...] the characteristics to accomplish early and foresighted adjustments of the factory's structures and processes on all levels, due to change impulses, economi-
cally.” [3] Although changeability must permeate all levels of the factory, its foundation constitutes the workstation level performing the actual operations [4], meaning that to obtain changeable production systems, the individual stations comprising the system must themselves be changeable. Enablers of changeability on the station level are changeover ability, which relates to the individual work station’s ability to process a given part or component as efficiently as possible in terms of both time and resources [3]. Although changeover ability can be facilitated using automation [3] most changeovers are still performed by human operators [5]. The increase in product variety and simultaneous decrease in production batch sizes, resulting from introducing Mass Customization to a production system, has a negative effect on the learning and memory performance of the human operators [6, 7]. Besides these impacts, six additional challenges for human operators in relation to changeover ability have been identified [8]. Based on a review of existing literature Ketelsen et al. [8] concluded that there are two overall gaps concerning solutions to support human operators. These are related to overcoming the negative effects of increased task variety and decreased task repetition. Research related to human operators in Industry 4.0 points towards utilization of digital information [9] or assistance systems [10–12] as solutions for augmenting human operators to better manage the increasing complexity of modern production systems. Assistance systems have been classified as one of five major research branches within Industry 4.0 [13]. However, despite this recognition, no solutions have been identified, which directly address the issue of assisting human operators in efficiently handling manual changeover tasks in high-variety settings. Failing to support operators cognitively results in a hampered ability to deliver a high variety of products cost effectively [8], which in turn decreases the competitiveness of a company. Recognizing this gap, this paper presents a concept for a digital assistance system designed to support human operators in efficiently carrying out highly varying manual changeover tasks. The remainder of the article is structured as follows; Section 2 introduces digital assistance systems in the context of high-variety manufacturing. Then, Section 3 presents the conceptual design and functioning of the proposed digital assistance system. Section 4 discusses potential improvements to be gained from implementing the proposed assistance system. Finally, Section 5 points out directions for further research related to the development of the digital assistance system.

## 2 Digital Assistance Systems

Although fully automated and autonomous production systems are gaining increasing interest, this does not translate to the complete exclusion of humans from the production system [14]. Despite advances in manufacturing technology, the human is still recognized as the most flexible entity in a production system [11]. However, as outlined above, human operators are still subject to certain limitations mainly related to their cognitive abilities. Together with the increased complexity of modern production systems, the need to support human operators in their work tasks is, therefore, essential [10, 12, 13, 15]. In the Operator 4.0 typology proposed by Romero et al. [15] one of the
eight archetypes of the typology is the “Augmented Operator”. This archetype encom-
passes the use of digital assistance systems as a means of offloading cognitive work for
human operators. Specifically, this is realized through digital assistance systems utiliz-
ing augmented reality as a facilitator for integrating humans and computer systems on
the factory floor. [15] Augmenting operators can be accomplished using mobile smart
devices [11] that are connected to different data sources within the factory [13], and
can thus be considered as a type of cyber-physical system [7]. A digital assistance sys-
tem relies on the ability to collect and display data from multiple data sources within
the company [13] in order to present these to the operators in an efficient and easily
understandable way [11]. This involves catering to the individual preferences of human
operators [10, 11] by designing the digital assistance system to support multi-modal
information presentation [12]. Furthermore, to increase the usability of the digital as-
sistance system, it is suggested that design of the user interface is inspired by apps for
smartphones and tablets since most operators will be familiar with these interfaces [11].
Reviewing literature on digital assistance systems have produced several solutions re-
lated to augmenting human operators in a product assembly scenario (e.g. [7, 12]).
However, no literature was identified, which addresses this issue in a manual produc-
tion changeover scenario.

3 Conceptual Assistance System in Support of Manual Changeover Operations

The purpose of the proposed digital assistance system is to support human operators in performing complex changeovers, whether it is on individual workstations or entire production lines, in order to achieve changeability. Fig. 1, left side, presents a flowchart illustrating the functioning of the digital assistance system in transforming individual production configurations into actionable changeover tasks. First, information about the next product changeover is obtained. Then, based on this information, the corresponding production configuration for each of the products is extracted from a database. Hereafter, an algorithm analyzes the two production configurations and filters out any identical rows, representing specific configurations of settings, across them. This produces a new table containing only the actual changes that must be made to the current production configuration to change over to the next, as per the production plan. The changeover operations are then analyzed by a second algorithm, which matches sets of individual changeover operations with continuous improvement initiatives logged in another database. These initiatives are then appended to the relevant changeover operation. The result is then visualized for the human operators performing the changeover. Following this brief introduction to the functioning of the digital assistance system, the aspects of collecting, processing, and presenting the data for the digital assistance system is explained in more detail.
**3.1 Information Gathering**

The digital assistance system relies on data from three different sources, which are the production planning module in the enterprise resource planning (ERP) system, the production configuration database, and the changeover instruction database. The production planning module in the ERP system provides the digital assistance system with the current production plan, from which the unique product IDs for the product being changed from as well as the product being changed to can be obtained. The instruction database contains structured data about all changeover instructions for existing product variations. This database is updated through a database interface where changes to existing instructions are applied centrally and then automatically propagate to the changeover instructions for all related product variants. The database interface also allows the creation of changeover instructions for new product variants.

<figure><img src="image_2.png" /><figcaption>**Fig. 1.** (Left side) Flowchart of the digital assistance system. (Right side) Sorting and filtering algorithm illustrated following drawing style of Tausworthe [16].</figcaption></figure>

**3.2 Information Processing**

Part of augmenting human operators through the digital assistance system is done by processing data to deliver context-specific and timely data. The data processing is performed by algorithms, which provide a means of computing a solution to a problem, based on an explicitly defined computational process [17]. The first algorithm that is
applied to the data is concerned with sorting and filtering the production configuration
settings based on both the product that is changed from, as well as the product that is
changed to. The purpose of the algorithm is to filter out any setup constants across the
two setup configurations. This leaves only the relevant changeover tasks to be
performed for that specific changeover. Fig. 1, right side, presents a flowchart detailing
the functioning of the algorithm, using symbols and drawing styles following Taus-
worthe [16]. First, the algorithm loads the two matrices A and B, containing the pro-
duction configurations or bill-of-operations (BOO) for the product being changed from
and the product being changed to, respectively. Then, the algorithm successively eval-
uates each row, *m*, and all variables, *n*, in *A* against its corresponding counterpart *B*.
Thus, for every row the algorithm evaluates the value of *A*<sub>*nm*</sub> against the value of *B*<sub>*mn*</sub>.
If the evaluation returns TRUE, the algorithm registered a constant prompting it to pro-
ceed to the next variable. The algorithm proceeds by evaluating every remaining vari-
able in the current row, and if no FALSE conditions are returned, the row is marked as
a constant across the two production configurations, thereby prompting the algorithm
to ignore it and proceed to the next row. However, if any of the variable evaluations
returns a FALSE, the algorithm copies the two configurations to a new matrix *C*. This
behavior is performed successively until all rows have been processed, after which the
algorithm stops. Hereafter, the individual changeover operations are applied to the sets
of production configurations, forming a document containing all the operations neces-
sary to perform a changeover between two given production setup configurations, as
illustrated in Fig. 1, left side. It is proposed that the resulting document is referred to as
the bill-of-changeover-operations (BOCO).

Extending the processing power of the digital assistance system further, machine
learning could be utilized by the system to acquire knowledge of how to best present
information to the users based on their previous interaction with the system. This would
provide the assistance system with the ability to present varying detail levels of change-
over instructions to the operators based on their experience or based on data analyses
of, e.g., error prone changeover operations. [18]

3.3 Information Presentation

The final aspect of the digital assistance system is the user interface, which is the part
of the system that the human operator will interact with. It is, therefore, an essential
aspect of a digital assistance system, as even an assistance system with a powerful data
processing ability will be of little use if this data cannot be communicated efficiently to
the operator. It is proposed that the digital assistance system interacts with users through
a touchscreen interface on a tablet, as it is expected that smaller smart devices will have
insufficient display size to communicate the processed changeover instructions
efficiently. Alternatively, with the prevalence of augmented reality technology it has
been proposed that an even higher level of digital assistance would be provided by
progressing from tablet-based instructions to augmented reality glasses [19]. However,
regardless of the choice of smart devices to visualize changeover instructions, Mattsson
et al. [20] found that humans prefer graphical rather than text-based instructions for
assembly work. The changeover instructions are, therefore, to be presented primarily
as graphical entities, with the option of switching between multiple modes of graphics,
such as animations or figures.

4 Conclusion

In this paper, a conceptual digital assistance system supporting manual changeovers in
high-variety production was proposed to increase changeability in production. Since
the digital assistance system is still in a conceptual stage, there are not yet actual results
from implementation to report. However, literature presents several aspects related to
production performance, where a digital assistance system is expected to deliver im-
proved results. Hold et al. [7] state that the primary purpose of a digital assistance sys-
tem is to improve productivity, which in turn results in a positive influence on key
performance indicators like the overall equipment effectiveness [13]. More specifically,
for the described conceptual digital assistance system, the general benefits mentioned
by Romero et al. [15] may translate into faster and more consistent changeover times.
This may be attributed to the reduced cognitive load on the operators caused by the
focused changeover instructions. Furthermore, a digital assistance system may reduce
errors made by operators [15] by assisting them with choosing the correct setups and
tools [7]. The authors expect that improvements of the same parameters are possible
through the implementation of the proposed digital assistance system as well. Besides
the potential benefits, implementing the conceptual digital assistance system in a high-
variety production setting may incur extensive costs related to the production of the
required changeover instructions. However, research suggests the possibility of using
reconfigurable instruction sequences to facilitate cost-effective, high-variety instruc-
tions [21].

5 Further Research

For the conceptual digital assistance system introduced in this paper to fulfill the above-described potentials, additional work is needed. First, further research into how the briefly described continuous improvement element of the system should be designed is required. This is particularly important as the ability of the operators to share experiences and best-practices with their colleagues is essential for the performance of the production system [11]. Once a prototype of the digital assistance system has been finished, real-life experiments in a production company are required to validate the potentials of the digital assistance system regarding increasing production performance. Looking even further into the future, the potential of utilizing changeover data from the digital assistance system to optimize production planning is seen as a relevant research topic.

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