I-AM: Interface for Additive Manufacturing

Marco Rodrigues

1,2

, Jo

ao Paulo Pereira

1 a

and Pedro Miguel Moreira

2 b

INEGI – Instituto de Ci

encia e Inovac¸

ao em Engenharia Mec

anica e Engenharia Industrial, Univ. do Porto, Portugal

ARC4DigiT, Applied Research Center for Digital Transformation, Instituto Polit

ecnico de Viana do Castelo, Portugal

Keywords:

Human-Machine Interface, Smart Industry, Industry 4.0, User-centered Design, Web based Interfaces,

Additive Manufacturing.

Abstract:

The shift of the computational paradigm to a model where there is a multiplicity of computational devices ca-

pable of feeling and acting on the environment allied to the digital transformation of manufacturing processes,

with an increasing real-virtual fusion, are two of the pillars of the ongoing industrial revolution industry coined

as Industry 4.0.

In the context of new manufacturing environments, the development interfaces that are usable, intelligible,

interactive and easy-to-implement and deploy across multiple device is a major aspiration to be achieved.

This paper describes the design process of an interface, supported by web standards, adapted for additive man-

ufacturing appliances. This interface aims to allow the monitoring of the production parameters, providing

the operator with all the information related to the manufacturing process and the equipment and materials

involved. Beyond providing an effective tool to monitor and control of the real manufacturing process, it also

allows to virtually simulate the process, thus enabling optimization and anticipation of possible issues.

The adopted user-centered design methodology is described, as well as the proposed architecture. Details are

presented on the developed prototypes, the users studies, and about the information collected from users for

the requirements elicitation process and from the tests. The interface was developed through several iterations

and was evaluated very positively by the users (operators) using established usability assessment instruments

and methods.

In the near future it is intended to generalize the approach and architecture to move towards a framework

dedicated to the design and implementation of universal interfaces for industrial environments.

1 INTRODUCTION

In recent years there have been lively technological

developments, and thus the integration of new tech-

nological trends has become natural in any area or

sector that beneﬁts from them. Emerging paradigms

and technologies such as pervasive computing, au-

tonomous agents, augmented reality, virtual reality,

among others, tend to be exploited and integrated in

all sectors of the industry.

There is a sustained motivation to increasingly

venture on new technology solutions since the ex-

pected earnings are huge and the changes are fast.

Human-Machine Interfaces (HMIs) for manufactur-

ing process control are no different from other areas

and can greatly beneﬁt from the integration of various

technologies.

https://orcid.org/0000-0003-2681-147X

https://orcid.org/0000-0001-8371-0347

HMIs are used on a daily basis for a variety of

purposes, such as in: cars - to provide driver infor-

mation about the trip, motor parameters, and extras

such as air conditioning or radio; medical equipment

- to provide information about the patient and to allow

some action by the patient’s condition; in the industry

- to provide information about a manufacturing pro-

cess and to allow control thereon.

In the industrial context different manufacturing

processes have different needs from the control and

automation point of view. One of the main objectives

of HMIs in industrial contexts is to provide correct

information to the operator and to enable it to assist in

the normal operation of the processes or in situations

of failure (Holliﬁeld et al., 2008).

A well-designed HMI can lead to large beneﬁts,

for example in the case reported in (Errington et al.,

2005), where the redesign of an HMI resulted in an in-

crease of more than 5 times the number of anticipated

fault situations and an increase of 37% in success rate

Rodrigues, M., Pereira, J. and Moreira, P.

I-AM: Interface for Additive Manufacturing.

DOI: 10.5220/0007933406450652

In Proceedings of the 16th International Conference on Informatics in Control, Automation and Robotics (ICINCO 2019), pages 645-652

ISBN: 978-989-758-380-3

645

in the treatment of malfunctions.

The work reported here arises from an innovative

project that aims to investigate the process of addi-

tive manufacturing in an industrial environment using

thermoplastic materials for high temperature and re-

sistance applications, a process that has very speciﬁc

needs regarding the control of the equipment and pro-

cess monitoring.

Additive Manufacturing (AM), also known as

Addition of Material, is a manufacturing process

whereby a product can be directly manufactured from

a 3D model, allowing the production of a very wide

range of forms. The techniques of manufacture by

addition of material, in counterpoint with more tra-

ditional processes of subtraction, have several advan-

tages. It is the process used in most 3D printing de-

vices.

This work aimed to develop an HMI, based on

web technologies, customized for an additive manu-

facturing equipment. The HMI shall allow preview-

ing, monitoring and manipulation of its parameters

by providing the operator with a tool capable of pro-

viding in real time all the information concerning the

manufacturing process as well as the equipment itself

and shall allow the control through functions speciﬁ-

cally designed for that purpose.

2 RELATED WORK

A main goal of this work is to devise an easy to de-

velop and easy to deploy interface. The system should

be able to integrate easily, being able to convey infor-

mation from/to the myriad of computational devices

on an industrial plant. With this goal in mind, stan-

dard web technologies became a rational choice due

the cross platform / media support for the interfaces,

the large support of tools and languages and the easy

integration via services or APIs on top of reliable and

available internet protocols.

The following text on this section describes some

of the most relevant examples found in the literature

regarding the use of web technologies for the imple-

mentation of HMIs in industrial processes.

A case study, described by Kacur et al. (Ka

cur

et al., 2013), a PLC (Programmable Logic Controller)

was used as a web server and allowed to remotely

monitor a physical process. By taking advantage of

the capabilities of web technologies, monitoring can

be done remotely, anywhere on the planet, provided

they have access to the internet. In this case, two

physical processes were used for remote control: steel

coil winding and coal gasiﬁcation, in which both tem-

perature values were monitored.

Another noticeable implementation of a web-

based system for control and automation was pre-

sented by Bermudez-Ortega et al. (Bermudez-Ortega

et al., 2016). In this case, a system was devel-

oped based on web technologies for remote control

of PLCs from a control laboratory through a browser.

The system consists of a Beckhoff manufacturer’s

PLC with Twincat software, which allowed running

control experiments in a laboratory. As a webserver

they used Node.JS which has an implementation that

allows connectivity to Twincat and on the frontend

of web application with a dedicated library : Easy

Javascript Simulations (EjsS).

Another work that is relevant to the subject and

that relates to the previous case is described by Li

and Zhang (Li and Zhang, 2011) where a system is

described to carry out remote control experiments in

a PLC. The developed system included a pneumatic

manipulator as control object, connected to the PLC

(Siemens model S7-224 PLC). It contained a net-

work card and was ethernet-connected to a server with

Windows 2000 operating system and STEP7-Micro /

WIN32 software installed. This software is also from

the Siemens manufacturer and serves for the purpose

of developing automation projects. The server in turn

was connected to a network hub that allowed remote

access by clients on the internal network and on the

internet.

A Final example is the Eiger software (Mark-

forged, 2018) providing remarkable features as:

• Access through any device with a browser;

• Import of 3D models / drawings to be printed;

• Print layers preview;

• Able to edit some properties such as dimensions,

positioning, material, etc.

• Real-time print parameter monitoring;

• Store and preview previously printed parts;

• 3D and 2D part display;

3 PROPOSED ARCHITECTURE

3.1 Architecture

The proposed general architecture follows a multi-tier

architectural model. In the particular case we identify

5 fundamental layers.

Sensing/Actuation Layer

Composed by all the apparatus that compose the

additive manufacturing appliance, including sen-

sors and actuators;

ICINCO 2019 - 16th International Conference on Informatics in Control, Automation and Robotics

646

Connectivity Layer

Implementing the communications protocols and

network infrastructure (HTTP, MQTT, sockets,

etc.);

Data Integration Layer

This layer responsibility is concerned with data

integration from several sources, persistence and

data processing (e.g. time series)

Application Layer

The application layer implements the main logic

and data access and processing. Exposes data ac-

cess and functionality via RESTful services. Also

enables subscription to real time services using

web sockets that enable two way communication

between the application and presentation layer;

Presentation Layer

This layer comprises the front-end modules and

applications, intended to be executed by a web

browser. Web standard client side technologies

such as HTML5, CSS and JavaScript are the sup-

porting technologies, although front end frame-

works and libraries can be integrated. Presen-

tation is intended to be cross platform and re-

sponsive to several devices speciﬁc characteristics

(size, colors, etc.).

In our speciﬁc instance of the proposed architec-

ture, the interface is fetched by a web browser that

loads all the resources needed to start the HMI. In

addition to HTML (structure and content) the loaded

web page incorporates by reference CSS (presenta-

tion) and Javascript / Ember.js (communication, in-

teraction, and behavior) documents. Ember.js was the

front-end framework selected for creating web inter-

faces using Javascript.

Real time services are subscribed using Socket.IO

library which enables real-time, bidirectional and

event-based communication between the browser and

the server.

The web server was implemented in Node.js and

making use of the express.js frameworks and the

ADS.js module. The latter enables communication

with automation software via TCP/IP.

At the integration layer we opted to incorporate

the Twincat automation solution from Beckhoff man-

ufacturer, which enables you to develop automation

solutions as well as communicate with hardware de-

vices that are connected to the system, such as motor

drives, PLCs (Programmable Logic Controller or Pro-

grammable Logic Controller) , input/output channels,

etc. This software has a modular architecture that al-

lows to deal with each module (consisting of software

and possibly hardware device) as a stand-alone de-

vice. The messages between the modules are made

Figure 1: First Interface Prototype.

possible through an ADS (Automation Device Spec-

iﬁcation) interface that each module has and through

the ”ADS Router” in the software that manages and

can identify the recipients of the messages. This in

practice means that when a remote message arrives,

the ”ADS Router” can identify which module / device

this message is addressed to.

Finally, at the sensing/actuator layer there are sev-

eral different types of devices that can control and

monitor the physical process, such as servos, temper-

ature and pressure sensing devices, etc.

3.2 First Prototype

In order to validate the proposed architecture and

technologies, a ﬁrst functional prototype was imple-

mented, although not in the ﬁnal equipment, but in a

similar equipment in terms of functionality and char-

acteristics.

The developed prototype allowed to assess possi-

ble issues from the implementation and to validate the

architecture and the considered for the ﬁnal system

in a real equipment, thus giving us unidealized infor-

mation of its behavior, forms of communication, and

integration issues. It also allowed us to show a ﬁrst

approximation to the reality that would be put into

practice in the development of the ﬁnal system. With-

out hard concerns about usability or requirements re-

sponding to user needs, the main focus of the proto-

type was to develop a system using a set of selected

technologies, as well as to analyze its behavior.

This prototype has a set of functions that allow to

control and monitor the process equipment and pa-

rameters (see Figure 1), such as monitoring the state

of the machine (it can vary between on / off, pause,

auto or manual), set the axes to a certain position,

send a GCode program to the machine to interpret and

execute, pause the equipment, abort the execution of a

GCode program, view the GCode lines that are being

executed in real time, track position and view the 2D

and 3D models drawings (Figure 2).

As conclusion, we conﬁrmed that the set of se-

lected technologies was suitable for the development

I-AM: Interface for Additive Manufacturing

647

Figure 2: 2D and 3D views of the part being manufactured.

and was used as a reference in the development of the

ﬁnal system.

4 DESIGN OF THE FINAL HMI

4.1 Requirements Elicitation

Requirements elicitation is a crucial phase in the life

cycle of each project because an erroneous, incom-

plete or non-existent requirement usually means seri-

ous design problems.

The main objectives of the requirements analysis

can be summarized in understanding the problem and

identifying the needs of the project and, as a result of

the analysis, the deﬁnition of a set of requirements

as speciﬁcations to be implemented, describing the

behaviors, properties and the expected attributes that

reﬂect the needs of stakeholders in the project (Fer-

reira, 2010, p.25). A survey of requirements was car-

ried out with a group of HMI users (see Table 1) that

were categorized into three large groups, ”Informa-

tive”, ”Functional”, and ” Complementary”.

4.2 Interface Prototype

The next step was to develop a ﬁrst version of the

HMI. The strategy was to develop a mockup that man-

ifest the list of requirements collected from users.

The development of mockups facilitates the un-

derstanding of the requirements between all the par-

ties involved, presenting concepts and functionali-

ties of the software. There are several approaches

to develop mockups, that is, they may be low ﬁ-

delity, with no screen interaction, but they allow for

quick adjustments or changes depending on feedback

collected, as well as complex and interactive mock-

ups that more closely represent the software to be

Table 1: Requirements from the operators.

Function Details Category

View Axis

Axis X

Axis Y

Axis Z

Axis B

Axis C

Informative

View Speeds

Operation

Polymer Extrusion

Fiber Extrusion

Informative

View Temperatures

(current / target)

Chamber

Chiller

Table / Platform

Extruder

Motors

Informative

Control Heating System

(set / on / off)

Chamber

Table / Platform

Extruder

Functional

Control Ventilation

(set / on / off)

Chamber

Table / Platform

Extruder

Functional

Set Operation Mode

Automatic

Manual

MDI mode

Functional

GCode Program Execution

Import

Start

Pause

Stop

General Homing

Axis Homing

Functional

GCode Manual Commands

Execute Command

Pause

Stop

Functional

Set Conﬁguration Parameters

Operation Speed

Polymer Extrusion

Fiber Extrusion

Functional

History View Log Informative

Manual Control

(On / Off)

Global

Heating

Ventilation

Motors

Functional

Illumination

(On / Off)

Chamber Complementary

developed , but whose counterpart is the fact that

the necessary changes or adjustments are more time-

consuming to make.

The approach followed was to, in the ﬁrst phase,

create mockups that visually had a representation as

close as possible to the ﬁnal HMI, but which were

static. A web tool specializing in the creation of static

mockups was used (https://moqups.com/).

The design of the ﬁrst mockups was intended to

conduct an observation and analysis on how the in-

formation would be organized and made available to

the users in the interface, as well as all to check the

fullness of the functionality available to the user. To

this end, it was a crucial to discuss with the potential

users of the interface operators of the AM equipment

in order to understand the priorities in the organiza-

tion of information and functionalities.

From that discussion, it resulted the ﬁrst drawing

of the mockup illustrated in Figure 3, where it can be

observed that in the upper area of the screen there are

three groups of information that is being updated in

real time, relative to the position of the axes, the op-

erating speeds and temperatures measured at several

places.

ICINCO 2019 - 16th International Conference on Informatics in Control, Automation and Robotics

648

Figure 3: First static HMI prototype.

This was indicated as the most critical informa-

tion set and consequently should be placed to enable

a quick understanding for the user. Below there are

user interaction zones, namely the Automatic, Man-

ual and MDI modes.

In the Automatic mode it is allowed to execute and

control the execution of a G code ﬁle, in Manual mode

it is allowed to control and operate each axis manually

and individually and in the MDI mode it is allowed to

execute a G code command.

Finally, in the lower part of the screen it can be

seen a set of tabs that allow to control some parame-

ters related to the additive manufacturing process and

also to the equipment itself. The ﬁrst tab: Heating, al-

lows you to control parameters related to the heating

system of the equipment, such as heating the cham-

ber, the platform (tray) or the extruder, as well as sim-

ply making variations in the temperatures of the same.

The Ventilation tab allows you to control the air sup-

ply of the camera. The Parameters tab allows you to

adjust the feed speeds, polymer extrusion and ﬁber

extrusion. The Other tab allows you to run a table ad-

justment function and control camera lighting. The

last tab allows you to turn off equipment components

such as motors, the heating system, the chamber heat-

ing and all equipment.

After the creation of the ﬁrst static version of the

models, a second version was created. This version

allowed interactivity, that is, it was possible to navi-

gate between screens and tabs of the HMI, in order to

simulate the execution of all the tasks. Also note that

these respected the size of the touch screen that will be

used in the actual additive manufacturing equipment

and were created using a web tool (https://proto.io/)

that allowed exporting a prototype in HTML, making

it possible the execution of the same in the browser

Figure 4: HMI - Fully Interactive Mockup.

and the consequent navigation between screens. An

example of this model can be seen in Figure 4.

4.3 Interface Assessment

Since the interface is the most visible part of the

whole system and enables the interaction between op-

erators and the additive manufacturing equipment, it

has become fundamental to carry out an evaluation of

the interface as well as its usability.

Usability tests are processes that aim to evaluate

the ease of use of a product (system, interface, etc.),

preferably with the participation of groups of poten-

tial users, allowing to improve and bring constructive

criticism about its usability. In an ideal scenario, the

test participants will be real users and will perform

real tasks, creating a scenario very similar to the re-

ality that the product will be subject to when it is

launched. The test results will be obtained from the

observation and measurement of the interaction be-

tween the participants and the interface (Afonso et al.,

2013).

In order to perform the usability tests, two strate-

gies were used to evaluate the system, together with

a group of four users and the functional model exe-

cuted on the device’s touch screen. Considering that

the solution to be developed would be for a speciﬁc

equipment, that is, oriented to Additive Manufactur-

ing, it became more difﬁcult to select users with sufﬁ-

cient knowledge to perform usability tests. However,

according to several studies ((Virzi, 1992), (Sauro,

2010), (Nielsen, 2000) and (Molich, 2010)) a group

of four to ﬁve users may be sufﬁcient to obtain value

results and cover approximately 80-90% of existing

usability problems.

The ﬁrst evaluation strategy was based on the Sys-

tem Usability Scale (SUS) (Brooke, 1996) survey,

which allows us to measure the usability of a sys-

tem through a set of ten questions, and where re-

sponses are recorded on a Likert scale and should

ranging from 1 (Strongly Disagree) to 5 (Strongly

Agree) (Brooke, 1995). This tool allows to evalu-

ate a wide range of products or services and has the

I-AM: Interface for Additive Manufacturing

649

Table 2: SUS Survey Results.

Item User 1 User 2 User 3 User 4

I think that I would like to use this system frequently 4 4 4 5

I found the system unnecessarily complex 1 1 1 1

I thought the system was easy to use 5 4 5 4

I think that I would need the support of a technical person to be

able to use this system

3 2 2 2

I found the various functions in this system were well integrated 5 3 4 4

I thought there was too much inconsistency in this system 1 1 1 1

I would imagine that most people would learn to use this system

very quickly

5 4 5 4

I found the system very cumbersome to use 1 1 1 1

I felt very conﬁdent using the system 5 5 4 5

I needed to learn a lot of things before I could get going with this

system

2 1 1 1

SUS Score = 88,125

Figure 5: Home Screen of the Final HMI Design.

main advantages of being able to easily differentiate

between usable and non-usable systems, to be quite

easy to apply and to compare since it is widely used

(Brooke, 2013).

In the table 2 the results of the SUS are made

available, per question and per operator, and a calcu-

lation method speciﬁc to the tool is used to calculate

the ”SUS Score” per user. used the arithmetic mean

of all calculated ”SUS Score”. The ﬁnal result was

88,125 in a maximum of 100, which indicates a high

degree of user satisfaction about the usability of the

system.

Notice that, complimentary to the SUS survey, we

have used observation instruments and open question-

naires that allowed us to gather additional information

about speciﬁc issues that operators pointed out that

could be improved or corrected in subsequent itera-

tions of the HMI design.

4.4 Final Design

The developed system is made available to the user

through a web interface, which is executable through

a browser. In addition to this layer of graphical inter-

face, the system also has a backend layer developed

using NodeJS technology and a document database,

RethinkDB, which in turn are connected to the Twin-

cat automation solution . Thus, the initial screen made

available to the user is that of Figure 5.

As it can be seen, the interface can be divided

into three main groups of use. The upper group con-

tains process control information, that is, it allows the

user to monitor in real time the position of the axes,

Figure 6: Working version of the I-AM HMI.

speeds and temperatures. The position of the axes is

made available in millimeters and is accompanied by

a graphic object representing the axis. In the case of

X, Y and Z axes, the graphic object is a progress bar

for each. The B axis, which in the actual equipment

corresponds to the inclination of the tray where the

printing takes place, is represented by a ﬁxed gray

horizontal bar and a blue (dynamic) bar that demon-

strates the inclination of the table (as if the tray were

seen in proﬁle ), corresponding to a certain angle in

degrees celsius. Finally, axis C, which in real equip-

ment corresponds to the rotation of the tray on itself,

is represented by a circumference and a red dot with

a blue line (dynamic) from the center of the circum-

ference for viewing the rotation angle (as if the board

was viewed from above). The system is also log a set

of parameters and displays them in the form of time

series. The working version of the developed HMI

alongside the 3D printer used in this work is depicted

in Figure 6

5 RESULTS

The developed system basically consists of a web in-

terface supported by a backend layer that, in turn, es-

tablishes and manages the communication with the

automation layer, and as such, it has become essen-

tial to close the cycle of this work to carry out tests

to the developed HMI which is connected to the ﬁnal

additive manufacturing equipment.

These tests were possible to run with the group

of four users who participated in the interface val-

idation inquiries, however, since part printing has a

cost to the material that is used, only one part can be

printed. In the remaining tests the same procedure

was performed with the only difference that although

the axes of the equipment made the same movements,

the pieces were not printed and the remaining data

were simulated. This difference was explicit through

an attribute in the content of the G code and there-

fore, in the perspective of the HMI the functionality

ICINCO 2019 - 16th International Conference on Informatics in Control, Automation and Robotics

650

Figure 7: Sample part manufactured during the user tests.

would be exactly the same because it only guaranteed

the upload of the ﬁle selected by the user and gave the

order to the controller to begin its execution.

Since the equipment is not yet ﬁnished from an

automation point of view, some of its functionality is

not yet implemented.

After the tests were carried out, a new SUS survey

was made to the users in order to obtain new feed-

back about the usability of the HMI. The ﬁnal result

was 89,375 in a maximum of 100, which indicates a

high degree of satisfaction in the usability of the sys-

tem. This value, compared to the value of the eval-

uations made to the models, was increased, since the

result had been 88,125. These results indicate that, in

general, users are satisﬁed with the developed HMI

and that it met their expectations. More relevant than

the quantitative assessment, the issues pointed out by

the operators were improved or corrected in the ﬁnal

version of the HMI.

During the tests with the equipment que HMI was

used to control the manufacturing of sample pieces as

the illustrated in Figure 7

6 CONCLUSIONS

The work carried out allowed to verify that, although

there are already some approaches similar to the pro-

posal presented here, there is still a great margin of

evolution in order to take advantage of all the exist-

ing potential in the technological areas and direct it

to areas of applicability in the industry, especially if

consider the area of Additive Manufacturing.

The methodology used involved users throughout

the process. In a ﬁrst phase, requirements were cre-

ated that allowed the creation of visual mockups and

obtaining ﬁrst user feedback through surveys, includ-

ing usability studies, which in turn validated the pro-

posed solution and ensured in advance that necessary

adjustments were recorded. Based on the results, the

ﬁnal solution was developed, and tests were carried

out on the actual equipment that resulted in the print-

ing of a part using the Additive Manufacturing as the

manufacturing process.

The development methodology of the interface,

centered on the operator needs, with validation and

evaluation by means of prototypes and user tests, re-

garding its usability, proved to be fundamental to

reach the aimed set of objectives. The ﬁnal solution

proved to ﬁt the users needs. The outcome of users

tests were a usability assessment close to the ”excel-

lent” according to the evaluation tool used (Bangor

et al., 2009). These results allowed us to validate the

usefulness and usability of the developed solution.

As future work, and in addition to the implemen-

tation of the features that are listed as requirements

but which have not yet been developed due to lack

of instrumentation or development in the project au-

tomation layer, the integration of an Augmented Re-

ality module with in order to visualize the part to be

printed in three dimensions and also to obtain infor-

mation on the process of printing it in real time, in

order to prove the feasibility and above all the con-

siderable value that this technology can contribute to

industrial processes.

An avenue to future developments is to general-

ize the proposed architecture towards a framework en-

abling the development of web based, cross-platform,

interactive and responsive interfaces for industrial

processes / appliances.

ACKNOWLEDGEMENTS

Parts of the presented work were supported by

project POCI-01-0145-FEDER-016414, co-funded

by Programa Operacional Competitividade e

Internacionalizac¸

ao and Programa Operacional

Regional de Lisboa, by means of Fundo Europeu de

Desenvolvimento Regional (FEDER) and national

funds from FCT – Fundac¸

ao para a Ci

encia e Tec-

nologia. Parts of the presented work were conducted

under the scope of project Maintenance 4.0 - FEDER

02/SAICT/2016 23725.

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