# Lean Digital Twins in Production Machines: Case Study in Pharmaceutical Industry

Leandro Silva, Rodrigo Franco Gonçalves

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Leandro Silva, Rodrigo Franco Gonçalves. Lean Digital Twins in Production Machines: Case Study in Pharmaceutical Industry. IFIP International Conference on Advances in Production Management Systems (APMS), Sep 2022, Gyeongju, South Korea. pp.145-151, 10.1007/978-3-031-16407-1_18 . hal-05386039

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# Lean Digital Twins in Production Machines: Case Study in Pharmaceutical Industry

Leandro Nunes da Silva (✉) and Rodrigo Franco Gonçalves

Universidade Paulista – UNIP, São Paulo SP, Brasil
leandro.silva405@aluno.unip.br

**Abstract.** The present work has the objective to present a lean digital twin applied in a production line of medications in a pharmaceutical industry. Digital twins are standardization of design of software or digital representations of an active. The proposal of a lean digital twin starts from the concept of lean manufacture. The adoption of a practical solution, agile, flexible, innovative and efficient meets a framework that cuts costs and risks from long and time-consuming projects, but with applicability and investment return in a shorter time. Adjusts of the product or process are more dynamic and its efficiency is validated in a short period. The focus of its development is to identify the main problems and present a solution in a general manner and easy understanding. A lean digital twin requires a reduced effort in its development from the hypothesis and evaluations of the problem to be solved and it is dimensioned according to each life cycle previously evaluated.

**Keywords:** Digital twin · Lean digital twin · Pharmaceutical industry

## 1 Introduction

Throughout many years the pharmaceutical industry has been attracting the attention of society, academics and big governments and private corporations. Pandemics outbreaks, degenerative diseases, and the aging of the populations have made this sector very important and fundamental in the social wellbeing of each citizen.

This sector is in the avant-garde of the development of high technological products that help to cure and treat ill patients. Biotechnology, digital twins, internet of things, Big Data, Blockchain, among others technologies from the so called 4.0 industry, take these two areas to a higher position inside the manufactory.

These technologies meet the needs and expectations of the population, providing a better quality in the products, management of patients and providing tools to improve the quality of life and the products. Among them the digital twin has arisen as a promising tool for the pharmaceutical industry concerning digitalization of the production line and processes inside the manufacture and patient care.

Even though, and in spite of great advantages of the digital twin, the researchers and authors ensure that it is far from being consolidated in its application in the industry of medications and similar.
The biggest part of the applications is focused on the simulations of substances or parts of the processes. Others are the applications of big technological companies which do it in a wide fashion demanding huge financial investments.

Thanks to this a lot of projects and applications end up getting undermined and some do not meet the particular demands in each case inside the production line.

The objective of this work is to present a solution that fills this gap: leaning digital twin focusing on a dynamic application in the pharmaceutical industry.

To do so it has been developed a leaning digital twin with devices of the internet of things, sensors, camera and interface man-machine in one powder compressor machine to produce pills with two layers.

The machine in which the twinning was made had its main functions transferred to the virtual world and received new functions in the real world. For this interaction was made a connection via communication protocol joining the two worlds.

To understand how the work was done the following sections describe the theory referential, including applications and studies of digital twin in the pharmaceutical industry and health area e medical care in the Sect. 2. In Sect. 3 is described the real world equipment, the lean digital twin, its concepts and implementation. In Sect. 4 discussions and results are presented. Finally, in Sect. 5 there is the conclusion and proposals for future works.

# 2 Theoretical References

## 2.1 The Concept of Digital Twin

The digital twin, in its fundamental concept, is described as the representation of a device, machine, equipment or real-world system to the digital world. Its application in the modeling of goods tangibles or not tangibles joins these two universes.

It is this union that differs from simulators. The modeling used by digital twins gets mixed up with simulators in the majority of the works. What makes them distinctive is the interaction which the digital twin has (or might have) with his real twin.

Basically, its model is described by physical product, virtual product and its connections. This proposal was presented by Michael Grieves [1], in 2003, in his work about the "life cycle of product management". In spite of this concept not being profoundly specific, it has been conceived as a preliminary form of conceptualization.

Some authors make reference to the concept introduced by teacher Greeves but they also report the review made by National Aeronautics and Space Administration (NASA), in 2012, bringing a new reevaluation of the concepts, with a new perspective about the digital twin, defining it as a simulation Multiphysics, multiscale, probabilistic, high-fidelity which translates the state of the twin, based on its historic, capture of data by sensors in real time and modeling and physical model [2].

## 2.2 Pharmaceutical Industry Application

The application of digital twins in the pharmaceutical industry has grown a lot recently. In spite of this evolution, researchers assure that this process is just in the initial phase and far from being consolidated [3].
In [4] one better application of the digital twins in the industry lacks a pattern that improves the production of modeling tools.

In [5], it presents one application with focus on the dynamism of the production line, synchronizing data in real time, and coming from the equipment for future analyzes.

The work of [6] describes the theoretical modeling of a powder compressing through a digital twin, and also its continuum process of working in the real world.

In a similar study, [7] explains the modeling mathematics of one coated pill machine and how it could be generated as a digital twin of it.

In [8] shows the development of one digital twin for a continuum process with low demand for a mixture of pharmaceutical powder.

In [9] explores the benefits of the simulation to a later adoption of the digital twin in the production line of the multinational pharmaceutical Roche GmbH for supporting the decision in real time of the manufacturing process.

The work of [10] presents one proposal of digital twin in supply chain in the pharmaceutical industry, focusing gaps observed in systems ERP, without considering a product or physical service and the use of a digital twin in co-property with the product or service.

In [11] has proposed a digital twin for projects of processes based on Quality by Design (QbD) in the pharmaceutical industry. In this work he used a device Arduino together with automation devices for a better valorization of the biomass, adapting the extraction process to the comportment of the extracted components.

## 3 Development and Application in the Machine

The machine modeling in the digital world was a powder compress (Fig. 1a), in use in the primary production line of solids. Its origin is from a German manufacturer, from 2007. Its weight, according to the manufacturer, is 1855 kg. It works in shifts of 24 h a day, seven days a week.

The machine works with a capacity to produce between 15000 and 30000 pills per hour (4 to 8 pills per second respectively) because of its current physical conditions.

Information, such as pressure made by punctures hydraulic and pneumatic parts, powders feeders, physical dimensions and signals of the logical controller programmable of the machine were considered irrelevant. So, this information does not add value and was kept out of the digital twin.

Among the relevant information can be cited the distance between the matrixes (shape of the pills) of 34 mm and the diameter of each matrix, of 10 mm. The direction of turn of the table, the perimeter and the position of the discard of the pill also formed were taken in consideration to the digital twin.

We called Lean Digital Twin the idea of only representing the aspects that really add value: information that can improve quality, reduce lead time, loss and costs [12, 13]. The Lean Digital Twin utilizes minimum modeling characteristics; only functions that add value to the process, reducing the modeling and implementation costs.

The lean digital twin electronics was constructed in an Arduino Mega board, placed onboard for prototyping, with a simple plant representation (not 3D representation) in the digital user interface. In it were added additional boards to treat the signals received
<figure><img src="image_3.png" /><figcaption>Fig. 1. a) Real world powder compressor; b) powder compressor Lean digital twin. Finished prototype. (Source: the authors)</figcaption></figure>

by sensors and sending command signals for acting installed in the real twin, as well as, the board for communication and an interface screen between the two (Fig. 1b).

The flow chart presented in the Fig. 2 shows the functioning of the software of the lean digital twin integrated to the real twin.

A camera to register the pills in the matrixes was installed. The communication of the camera controller with the lean digital twin is realized by a net Ethernet and Modbus protocol. The data are transmitted almost instantaneously. The lean digital twin updated the information by a transmission rate between 100 and 200 ms to the screen that makes it possible to visualize the event of the movement of the matrixes almost without delays (considering the speed of the nominal work of 15000 and 30000 pills per hour (between each pill there are 125 ms in the highest and 250 ms in the lowest)).

The camera is installed after the first filling of powder from the matrix and just after the insertion in the nucleon where there is no interference in the acquisition of the image of the pill's nucleon inserted inside the matrix.

Previously established and evaluated the presence of the nucleon inside the pill, the turn of the table and the movement verified, the next step is to realize the transfer of this signal until the segregation of the product considered approved and the product to be rejected.

An encoder programmable was installed by contact to the turntable. It was parameterized so each pulse corresponded to a certain distance measure. When starting moving the pulses begin to be transmitted. For each lap, a certain quantity of pulses is generated, according to what was initially programmed through the software supplied by the encoder manufacturer. For each application, one millimeter of distance corresponds to three pulses in the encoder.

One resolution of three pulses per millimeter was considered to provide precision of reading realized by the encoder. This information assures the exact moment of the inspection of the pill inserted, located inside the matrix and also the moment of the expulsion of the defected pill to be rejected in the exit of the machine.
<figure><img src="image_4.png" /><figcaption>Fig. 2. Flow chart of the functioning of software of the lean digital twin (Source: from the author)</figcaption></figure>

To determine the speed and the functioning of the machine in turning, two inductive sensors were added to identify each passage of puncture and know the rotation direction of the table.

The lean digital twin determines the expulsion of the pill to be rejected. It is realized when the lean digital twin determines the end of the cycle.

In the end of the movement cycle of the pill there is a transfer gutter for two recipients to accommodate the pills according to their previous evaluation.
Two actuators electropneumatic (solenoids valves) were installed, one to blow (eject) the bad pill and the other to make the opening of the door (flap) redundant.

Through one valve electro pneumatic, the lean digital twin sends the command to blow the air through the holes opened in one piece of real twin, which also serves as a guide to the pills in the turn table exit in the direction of a gutter in the table exit that leads to the segregation recipients.

To ensure that these pills do not mix in the gutter a door opens and closes at the moment of this decision. This door is prompted by the lean digital twin together with the blow valve, ensuring one bigger redundancy on the safety of this step against a possible mix with the good pills.

For the interaction between the parts, real and virtual, was put one interface screen man machine (IHM) touch screen so the operator can interact with both worlds.

The configurations and parameterizations of the twins are realized by the user in IHM, which serves as the interface of the lean digital twin. All the process is followed in real time by the user.

# 4 Discussion and Results

The lean twinning of the compressor was the best alternative found to solve the problem. The automatization is not capable to solving with efficiency and with the same results without a significant rise in the implementation costs and pieces availability, considering the available physical space.

It is necessary to put sensors in excess to know the exact position of each pill in the matrixes and as a new controller to meet the cyclic speed, as well as, interactivity with an interface in real time by the user.

A complete twinning, with 3D modeling and high-speed communication, is more expensive, involving more company sectors, big suppliers or integrators of digital twins, software developers, cutting edge advanced equipment and performance, larger team and more time consumed in the system integration. In this sense, the company project sector had considered that the better solution was the lean twinning.

The lean digital twin was also useful to give a new sense in the use of the equipment. It made possible the digitalization of an equipment considered old without modern technological resources widespread nowadays through the so-called industry 4.0, in a kind of digital retrofit. It was possible to integrate digital systems and virtual in a machine almost all mechanized.

Some obstacles were found along the twinning compressor project. The first one was the impossibility to connect to the internet but soon it was realized that it was not necessary. All the contact and interactivity were made in real time, by the sensors, with the virtual side.

# 5 Conclusion and Future Works

This work had the objective to use a lean digital twin applied in the pharmaceutical industry. In one powder compressor to make double coated pills in manufactory demonstrated its viability as a process improvement tool and allowed a longer life to the machine.
The digital twin also can be an efficient tool able to provide a longer life to machines and equipment. It is very important in the pharmaceutical industry which follows rigid processes and manufacturing protocols. These protocols do not permit change machines frequently, let alone the high costs to acquire one.

From this project, the new step is to integrate the lean digital twin in an internal communication net between machines (machine to machine – M2M), with the application of block chain to validate parameters modifications done by the digital twin and/or by the users via interface.

## References

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2. Glaessgen, E., Stargel, D.: The digital twin paradigm for future NASA and US Air Force vehicles. In: 53rd AIAA/ASME/ASCE/AHS/ASC Structures, 14th AIAA Structural Dynamics and Materials Conference 20th AIAA/ASME/AHS Adaptive Structures Conference, p. 1818 (2012)

3. Augustine, P.: The industry use cases for the digital twin idea. In: Advances in Computers. Elsevier, pp. 79–105 (2020)

4. Tao, F., et al.: Digital twin in industry: state-of-the-art. IEEE Trans. Ind. Inf. 15(4), 2405–2415 (2018)

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