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|id=Vol-3674/CPSS4Sus-paper2
|storemode=property
|title=
|pdfUrl=https://ceur-ws.org/Vol-3674/CPSS4Sus-paper2.pdf
|volume=Vol-3674
|authors=Carolina Lagartinho-Oliveira,Filipe Moutinho,Luis Gomes
|dblpUrl=https://dblp.org/rec/conf/rcis/Lagartinho-Oliveira24
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====
https://ceur-ws.org/Vol-3674/CPSS4Sus-paper2.pdf
A Cyber-Physical Social System Approach for User-Centric
Power Wheelchairs
Carolina Lagartinho-Oliveira* , Filipe Moutinho* and Luís Gomes*
NOVA School of Science and Technology, Centre of Technology and Systems (UNINOVA-CTS) and Associated Lab of Intelligent
Systems (LASI), NOVA University Lisbon, 2829-516 Caparica, Portugal
Abstract
Conventional power wheelchair models often prioritize basic navigation and comfort at the expense of user-centric
solutions. This overlooks the opportunity for solutions that can address specific challenges and promote user
empowerment towards a sustainable society. This article explores a cyber-physical social system (CPSS) approach
for power wheelchairs; a CPSS that brings together different stakeholders to promote better understanding,
customization, and assistance of wheelchairs. The aim is to enhance user experience and safety while contributing
to sustainability in the sector. To achieve this, this approach comprehends the use of digital twin (DT) technology
employing Petri net models. DT allows for the creation of a virtual replica of a power wheelchair (or part),
enabling iterative design through real-time simulations and remote control. Petri nets specify the DT within the
CPSS, facilitating formal analysis and automated implementation.
Keywords
Cyber-physical system, Digital twins, Petri nets, Real-time information, Remote monitoring and control
1. Introduction
A wheelchair is most effective when designed to meet the user’s needs. This may involve exploring
alternative control devices [1], sensor technologies [2], and training in simulated environments [3].
Clinicians can also make use of assessment tools to prescribe wheelchairs [4] or educate users about
their operation [5]. This user-centric attitude aligns with the rise of Industry 5.0 (I5.0) [6], wherein
cutting-edge technologies can transform the power wheelchair sector. I5.0 goes beyond the limits
of cyber-physical systems and acknowledges the interaction between humans, technology, and the
environment, encouraging for exploration within cyber-physical social systems (CPSSs). However, the
design of CPSSs is a complex task due to the heterogeneity of hardware, software, communication
networks, and human interactions; and this makes it challenging to ensure that all of these components
work seamlessly together and do not pose safety risks. Therefore, the proposed cyber-physical social
approach encompasses the use of digital twins modeled with Petri nets (PNs).
Petri nets are a graphical modeling formalism for describing system behavior [7]. They benefit from
rigorous mathematical analysis techniques to identify faults early on and verify whether systems meet
the desired requirements. This aspect is also advantageous for creating digital twins, which deeply
rely on behavioral modeling to ensure virtual entities accurately mirror their physical counterparts [8].
The benefit of creating and manipulating virtual copies lies in the ease of anticipating challenges,
detecting problems, and increasing efficiency of the systems. Ultimately, this will lead to various
possible end-user services within the proposed cyber-physical social approach. This means that the
digital twin is not intended for the resulting CPSS. Instead, its main application is to design new parts
to augment wheelchairs and support their use and maintenance, thus promoting user well-being and
environmental integrity. Three dimensions are explored as follows: the cyber dimension involves
the use of Input-Output Place-Transition Petri nets [9] and associated tools [10] for deploying digital
twins; the physical dimension includes tangible components of power wheelchairs, assistive devices,
microcontrollers, sensors, and interfaces; and the social dimension focus on addressing and meeting
Joint Proceedings of RCIS 2024 Workshops and Research Projects Track, May 14-17, 2024, Guimarães, Portugal
*
Corresponding author.
$ ci.oliveira@campus.fct.unl.pt (C. Lagartinho-Oliveira); fcm@fct.unl.pt (F. Moutinho); lugo@fct.unl.pt (L. Gomes)
0000-0002-5796-6653 (C. Lagartinho-Oliveira); 0000-0002-0930-7418 (F. Moutinho); 0000-0003-4299-8270 (L. Gomes)
© 2024 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
CEUR
ceur-ws.org
Workshop ISSN 1613-0073
Proceedings
1
drive
drive seat
change_2 change
1 1
left_motor_stop raise_down right_motor_stop
drive lie
G: y > - ( x ) G: y = - ( x ) G: y < - ( x ) G: y = - ( x ) G: y < - ( x ) G: y > x G: y = x G: y < x G: y = x G: y < x
go_forward_3 stop_3 go_backward_4 stop_4 go_backward_3 G: go_forward stop go_backward_2 stop_2 go_backward
change_5 change_4
G: y > - ( x )
go_forward_4 G: y > x
go_forward_2
left_motor_forward left_motor_backward lie_down right_motor_forward right_motor_backward
l = ( x + y ) / 2 when( y = 0 ) l = ( x + y ) / 2 when( y = 0 ) r = ( y - x ) / 2 when( y = 0 ) r = ( y - x ) / 2 when( y = 0 )
l = ( x + y ) when( y <> 0 AND ( -3 <= ( x + y ) <= 3 l)=) ( x + y ) when( y <> 0 AND ( -3 <= ( x + y ) <= 3 ) ) r = ( y - x ) when( y <> 0 AND ( -3 <= ( y - x ) <= 3 ) r) = ( y - x ) when( y <> 0 AND ( -3 <= ( y - x ) <= 3 ) )
l = -3 when( y <> 0 AND ( ( x + y ) < -3 ) ) l = -3 when( y <> 0 AND ( ( x + y ) < -3 ) ) raise r = -3 when( y <> 0 AND ( ( y - x ) < -3 ) ) r = -3 when( y <> 0 AND ( ( y - x ) < -3 ) )
l = 3 when( y <> 0 AND ( ( x + y ) > 3 ) ) l = 3 when( y <> 0 AND ( ( x + y ) > 3 ) ) r = 3 when( y <> 0 AND ( ( y - x ) > 3 ) ) r = 3 when( y <> 0 AND ( ( y - x ) > 3 ) )
G:
change_3
recline_motor_stop elevation_motor_stop leg_motor_stop
G: x = 0 AND ystop_4_2
go_forward_2_2 > G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_5 G:yx<=00) AND ygo_up
go_backward_2_2 < G:
0 x = 0 AND ystop_2_2
> G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_3_2 G:yx<=00) AND ygo_forward_3_2
go_down < G:
0 x = 0 AND ystop_6
> G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_7 G:yx<=00) AND y < 0
go_backward_3_2
recline_motor_backward recline_motor_forward elevation_motor_up elevation_motor_down leg_motor_forward leg_motor_backward
b = -1 b=1 s=1 s = -1 f=1 f = -1
mode seat - mode position lie - position y x r l s b f
drive - mode raise - position
Figure 1: A framework for a cyber-physical social approach to power wheelchairs.
the diverse needs of users and stakeholders. Section 2 presents the proposed cyber-physical social
approach; Section 3 provides some discussion around the proposal and work in progress; and Section 4
presents concluding thoughts and future work.
2. A Cyber-Physical Social Approach to Power Wheelchairs
Each dimension in a cyber-physical social approach contributes to a user-centric solution. Notable, in
this approach, stakeholders placed in the social dimension can rely on the cyber dimension for services
that can enhance their experience in the physical dimension. The proposal overview is in Fig. 1, with
detailed explanations in the following subsections, beginning with the assessment of essential system
requirements within the social dimension.
2.1. The Social Dimension: Stakeholder Interactions and Requirements
The social dimension of the CPSS in Fig. 1 includes users and caregivers using power wheelchairs, thera-
pists involved in rehabilitation, technicians responsible for selecting technology for power wheelchairs
and providing training and technical support, and engineers who can design innovative solutions within
that framework. The focus is precisely on collaboration among them (in social dimension) to optimize
users’ capabilities through seamless operation of wheelchairs and related services, ultimately promoting
sustainability in the context. This involves selecting features and functionalities to enhance user safety,
comfort, and handling, while reducing maintenance and repair expenses. To reach this goal and as part
of a user-centric strategy, an online questionnaire was used to gather insights from those with personal
or professional experience with power wheelchairs [11].
A total of 139 participants were informed about the study through a list of non-governmental
organizations for people with disabilities and companies specializing in wheelchairs. For users, the
survey delved into their disabilities, current power wheelchair details, control devices, past experiences,
and desired features. It also explored their maintenance history, preferences for remote services, and
their thoughts on integrating health monitoring. For others involved, the survey focused on their
preferred features, the services they wished users had access to, and how support for wheelchair users
could be improved. To end, the survey offered an opportunity for general feedback. The findings
underscored several key areas of interest for participants; highlighted here are obstacle navigation,
monitoring user health, tracking wheelchair condition and maintenance, and training.
Power wheelchairs pose practical challenges due to their bulkiness, obstructive seating, and lack of
visibility aids, making navigation difficult in tight spaces. Respondents suggested incorporating mirrors,
cameras, and/or sensors. Additionally, therapists and caregivers are concerned about users’ prolonged
sitting and pressure points on cushions leading to ulcers. Regarding users’ health, they may also face
respiratory issues, digestive problems, sleep disorders, and so forth. Therefore, respondents expressed
interest in obtaining posture duration, comprehensive health data, and medication intake details.
Technicians are also worried about users’ misconception that wheelchairs do not need maintenance,
leading to problems being addressed only after they arise. However, for users, maintenance also drives a
demand for regular, fast, and affordable services. A systematic approach is required, with both preventive
and corrective measures. Finally, there is a growing concern about the lack of user training, highlighting
the need for improved education on power wheelchair usage. These insights lay the groundwork for
the proposed CPSS, wherein the digital twin application (in cyber-physical dimensions) can address
these issues by improve wheelchair design, operation, and maintenance. Also, by integrating users’
health factors, it can significantly enhance the overall user experience and quality of life.
2.2. The Cyber Dimension: Petri Nets and Digital Twins
In the cyber dimension, Input-Output Place-Transition Petri nets (IOPT-nets) model digital twins. IOPT-
nets are a class of non-autonomous Petri nets in which behavioral models can be conditioned through
input and output signals or events. This makes them useful for specifying the interaction between
systems and the external world, also suitable for creating a digital twin. In a digital twin, there is an
automatic and two-way data flow from a physical entity (PE) - such as a wheelchair or its components -
to the virtual twin (VE). The entities are dynamically updated and adjusted based on data, with changes
in one leading to corresponding changes in the other. Thus, the creation of a digital twin relies on
precise physical-digital mapping and the data flow between the entities that make it up. While other
models can be considered, behavioral modeling stands out because it can explicitly specify how a PE
behaves, interacts, and reacts to external stimuli. Moreover, it is ideal to simultaneously design both PE
and VE with the same characteristics, properties, functions, and models.
For this reason, this approach proposes using IOPT-nets to model the behavior of both the PE and
VE in DT. In particular, using the same IOPT-net model can ensure that PE and VE evolve and align
as intended, maintaining the consistency of the DT over its lifecycle. On the PE side, the model can
effectively satisfy numerous functional and safety requirements. The net can model the behavior of
the power wheelchair and its augmentations with sensors, actuators, user input devices, and other
features that may need to be added. On the VE side, the same model can be used to monitor and
control the PE after deployment. The design of the model and implementation of PE are facilitated by
the IOPT-Tools framework [10]. IOPT-Tools is an online framework meant for developing controllers
specified with IOPT-nets. The provided tools include a graphical IOPT-net model editor, a simulator [12],
a state-space generator [13], an automatic code generator [14], and a remote debugger [15]. The editor
is used for model specification; the simulator and state-space generator verify and validate the desired
requirements for PE/VE; and the automatic code generator converts the IOPT-net model into software
code for microcontrollers or hardware descriptions for FPGAs. Afterward, the VE and its connection to
PE are placed using the IOPT-tools remote debugger (refer to Fig. 2).
The PE-VE connection within the DT primarily serves to enable the VE to oversee and potentially
influence the PE. For the VE, the aim is not only to observe and predict PE actions, but also to exert control
over the physical dimension as needed. This enhances the VE’s ability for remote intervention, such as
adjusting the speed of drive motors based on sensor-detected obstacles. This underscores the importance
of interacting with PE related elements in the physical dimension, specifically sensors and actuators.
Sensors provide input signals to the PE, conveying instructions to the model or monitoring real-world
conditions; actuators translate the model’s output signals into actions in the environment. The IOPT-
nets enable this particular feature through their inputs and outputs, with each signal potentially being
mapped to a GPIO for deployment purposes. During implementation, the code generator maps IOPT-net
signals to platform pins, enabling interaction for the PE. This way, the PE, e.g. a wheelchair, can gather
sensor data, receive input from joysticks, buttons, or switches; or issue commands to actuators, and
manage displays/LEDs for user communication.
When the VE aims to control the PE, it does so by modifying inputs and outputs, overriding real
1
drive
drive seat
change_2 change
1 1
left_motor_stop raise_down right_motor_stop
drive lie
G: y > - ( x ) G: y = - ( x ) G: y < - ( x ) G: y = - ( x ) G: y < - ( x ) G: y > x G: y = x G: y < x G: y = x G: y < x
go_forward_3 stop_3 go_backward_4 stop_4 go_backward_3 G: go_forward stop go_backward_2 stop_2 go_backward
change_5 change_4
G: y > - ( x )
go_forward_4 G: y > x
go_forward_2
left_motor_forward left_motor_backward lie_down right_motor_forward right_motor_backward
l = ( x + y ) / 2 when( y = 0 ) l = ( x + y ) / 2 when( y = 0 ) r = ( y - x ) / 2 when( y = 0 ) r = ( y - x ) / 2 when( y = 0 )
l = ( x + y ) when( y <> 0 AND ( -3 <= ( x + y ) <= 3 l)=) ( x + y ) when( y <> 0 AND ( -3 <= ( x + y ) <= 3 ) ) r = ( y - x ) when( y <> 0 AND ( -3 <= ( y - x ) <= 3 ) r) = ( y - x ) when( y <> 0 AND ( -3 <= ( y - x ) <= 3 ) )
l = -3 when( y <> 0 AND ( ( x + y ) < -3 ) ) l = -3 when( y <> 0 AND ( ( x + y ) < -3 ) ) raise r = -3 when( y <> 0 AND ( ( y - x ) < -3 ) ) r = -3 when( y <> 0 AND ( ( y - x ) < -3 ) )
l = 3 when( y <> 0 AND ( ( x + y ) > 3 ) ) l = 3 when( y <> 0 AND ( ( x + y ) > 3 ) ) r = 3 when( y <> 0 AND ( ( y - x ) > 3 ) ) r = 3 when( y <> 0 AND ( ( y - x ) > 3 ) )
G:
change_3
recline_motor_stop elevation_motor_stop leg_motor_stop
G: x = 0 AND ystop_4_2
go_forward_2_2 > G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_5 G:yx<=00) AND ygo_up
go_backward_2_2 < G:
0 x = 0 AND ystop_2_2
> G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_3_2 G:yx<=00) AND ygo_forward_3_2
go_down < G:
0 x = 0 AND ystop_6
> G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_7 G:yx<=00) AND y < 0
go_backward_3_2
recline_motor_backward recline_motor_forward elevation_motor_up elevation_motor_down leg_motor_forward leg_motor_backward
b = -1 b=1 s=1 s = -1 f=1 f = -1
mode seat - mode position lie - position y x r l s b f
drive - mode raise - position
Figure 2: An IOPT-net model used to specify a PE and a VE within a digital twin, and their connectivity across
cyber-physical dimensions.
values on GPIO pins; and the PE evolves towards the desired behavior. This points out the need for
seamless data exchange between PE and VE that bridges cyber-physical dimensions. In this sense, the
IOPT-tools remote debugger facilitates the connection between the VE and PE. This feature proves
particularly beneficial when models are running on devices that are not easily accessible, extending
remote operation capabilities to the DT. For instance, this is advantageous for customers residing in
remote areas with limited access to service providers and healthcare professionals – who can start
offering remote assistance. The code generated for the PE incorporates an HTTP server definition
intended to establish a connection with the remote debugger, where the VE is running (refer to Fig. 2).
This enables the VE to promptly receive notifications regarding any alterations in the PE’s state, and to
transmit commands. By monitoring PE changes, the VE visually mirrors its state in the IOPT-net model.
The remote debugger also includes tracing for step-by-step execution, breakpoint setting, and remote
PE state control via VE. Finally, the remote debugger incorporates a history recording feature, saving
the evolution of the net. This recorded history can be replayed later through the simulator, facilitating
a thorough analysis of PE conditions.
2.3. The Physical Dimension: Power Wheelchairs, Sensors, and Interfaces
Within the physical dimension power wheelchairs are the core. Customizing and ensuring their
regulatory compliance is costly and difficult to address. Therefore, the use of a digital twin with low-
cost add-on devices presents a good alternative to high-end equipment. Namely, wheelchairs equipped
with obstacle and proximity sensors can address concerns around navigation and maneuverability.
These sensors, along with motion sensors and floor/edge detectors, create a comprehensive awareness
system. They help users navigate by detecting objects in their path, including blind spots, tracking
their movement, and identifying changes in terrain. Through features like audible alerts and vibration
feedback, these sensors can educate, train, and ultimately empower users, particularly those with visual
impairments, to move safely and confidently in their environment.
While here the main focus of the digital twin is on developing new features for a power wheelchair,
its application has the potential to extend and integrate into various applications via APIs, thereby
enhancing the overall end-user experience. Addressing some of user’s concerns may simply involve a
solution similar to healthcare apps, which offer real-time tracking, proactive notifications, and user
engagement. These apps give users the ability to establish plans, set goals, and schedule reminders.
Improving healthcare for wheelchair users may involve using an application for logging health records
and setting timely alerts, granting users autonomy over when and with whom to share their health
information, enabling a personalized and flexible approach to disclosure. This type of application
encourages user engagement for customization based on individual needs and preferences; and can
be used to help power wheelchair users monitor details of medication intake, stay hydrated, manage
(rehabilitation) activities and sitting positions, and ensure adequate rest, all through personalized
notifications. An accelerometer and a gyroscope can track users’ sitting positions, providing insights
into the time spent in a specific posture; and coupled with personalized plans, users can heighten
awareness of their sitting habits, reducing the risk of skin injuries and promoting better posture.
Ultimately, such a tool can provide insights into users’ habits and help those who face challenges in
maintaining a consistent routine.
This user-centric strategy can also facilitate users’ adherence to wheelchair maintenance practices
assisted by someone capable of checking tire pressure, tightening screws, cleaning, etc. An application
for users’ adherence to wheelchair maintenance practices can be a way to raise awareness about
self-regular checks and help identify issues early on, preventing unexpected breakdowns; users can
also be alerted through timely notifications to schedule necessary maintenance tasks with technicians.
But if on the one hand, there is a need to educate users about the maintenance of their wheelchairs,
on the other hand, technicians need a way to keep detailed records of the support and maintenance
procedures they carry out. This includes documenting the repair and modification history, reporting
the procedures performed, along with dates, requested parts, quotations, and other relevant information
readily available to track the wheelchair’s condition over time. Ultimately, supporting preventive
maintenance practices through this strategy can result in long-term cost savings.
3. Discussion and Overview of Work in Progress
Around 16% of people worldwide face a higher risk of discrimination, poverty, and abuse due to
disabilities [16]. Assistive technologies can greatly improve their independence and overall well-being,
while reducing the need for healthcare. Yet, 90% of these individuals lack access to these essential
products [17], hindering their participation in society equitably. Although many challenges faced are
not tech-related (e.g. wheelchair accessibility barriers), investing in technological advances helps to
meet users’ diverse needs so they can seize their rights and opportunities. In this way, it is possible
to tap into varied talents and contributions, leading to increased stability, balance, and sustainability
for everyone. On the other hand, it is important to involve people with disabilities in decision-making
processes to ensure that assistance is built into solutions from the design phase, rather than being an
afterthought. The WHO’s GATE initiative aims to improve access to high-quality affordable assistive
products through a person-centred approach [18]. It collaborates with multiple stakeholders, including
users, to strengthen policies, ensure reliable supply chains, and improve services and workforce capacity.
In light of this, advocating for a cyber-physical social approach is paramount. The first steps of the
approach described above have already been taken. In addition to conducting a stakeholder inquiry
survey, an IOPT-net model was designed to deploy a digital twin for a power wheelchair. IOPT-nets and
IOPT-Tools have proven successful in achieving this goal. The model specifies the behavior required for
the wheelchair to move and adjust seating positions as needed, serving as basis for further development.
The model showed in Fig. 3 is accessible under the name "CPSS4Sus2024.pnml" within the IOPT-Tools
environment [19] (user: models, pass: models). Part A outlines the inputs and outputs necessary for
cognition/control in the DT; submodels B and C control the wheelchair’s drive motors, enabling actions
of stopping, moving forward, and backward; submodels D, E, and F similarly adjust the positions of
the backrest, seat, and footrest for user comfort; and submodel G manages the operational mode of the
wheelchair, ensuring the joystick functions differently based on the selected mode (driving or seating),
which prevents unintended seat adjustments during driving. The IOPT-Tools simulator verified the
behavior of the model ensuring it functioned as expected and confirmed it was deadlock-free. Following
this, it was generated C code for the model; and this code ran on a Raspberry Pi, which communicated
with a remote debugger. This allowed to remotely monitor and control the state of the physical
wheelchair prototype. The future work using this CPSS approach will involve incorporating user
feedback and preferences into this model, making the wheelchair meeting the presented requirements.
G 1
drive
drive seat
change_2 change
B C
1 1
left_motor_stop raise_down right_motor_stop
drive lie
G: y > - ( x ) G: y = - ( x ) G: y < - ( x ) G: y = - ( x ) G: y < - ( x ) G: y > x G: y = x G: y < x G: y = x G: y < x
go_forward_3 stop_3 go_backward_4 stop_4 go_backward_3 G: go_forward stop go_backward_2 stop_2 go_backward
change_5 change_4
G: y > - ( x )
go_forward_4 G: y > x
go_forward_2
left_motor_forward left_motor_backward lie_down right_motor_forward right_motor_backward
l = ( x + y ) / 2 when( y = 0 ) l = ( x + y ) / 2 when( y = 0 ) r = ( y - x ) / 2 when( y = 0 ) r = ( y - x ) / 2 when( y = 0 )
l = ( x + y ) when( y <> 0 AND ( -3 <= ( x + y ) <= 3 l)=) ( x + y ) when( y <> 0 AND ( -3 <= ( x + y ) <= 3 ) ) r = ( y - x ) when( y <> 0 AND ( -3 <= ( y - x ) <= 3 ) r) = ( y - x ) when( y <> 0 AND ( -3 <= ( y - x ) <= 3 ) )
l = -3 when( y <> 0 AND ( ( x + y ) < -3 ) ) l = -3 when( y <> 0 AND ( ( x + y ) < -3 ) ) raise r = -3 when( y <> 0 AND ( ( y - x ) < -3 ) ) r = -3 when( y <> 0 AND ( ( y - x ) < -3 ) )
l = 3 when( y <> 0 AND ( ( x + y ) > 3 ) ) l = 3 when( y <> 0 AND ( ( x + y ) > 3 ) ) r = 3 when( y <> 0 AND ( ( y - x ) > 3 ) ) r = 3 when( y <> 0 AND ( ( y - x ) > 3 ) )
G:
change_3
D E F
recline_motor_stop elevation_motor_stop leg_motor_stop
G: x = 0 AND ystop_4_2
go_forward_2_2 > G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_5 G:yx<=00) AND ygo_up
go_backward_2_2 < G:
0 x = 0 AND ystop_2_2
> G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_3_2 G:yx<=00) AND ygo_forward_3_2
go_down < G:
0 x = 0 AND ystop_6
> G:
0 NOT( x = 0 AND y > 0 ) G: NOT( x = 0 AND
stop_7 G:yx<=00) AND y < 0
go_backward_3_2
recline_motor_backward recline_motor_forward elevation_motor_up elevation_motor_down leg_motor_forward leg_motor_backward
b = -1 b=1 s=1 s = -1 f=1 f = -1
mode seat - mode position lie - position y x r l s b f
A
drive - mode raise - position
Figure 3: CPSS4Sus2024.pnml: IOPT-net model of a digital twin for a power wheelchair.
4. Conclusion and Future Work
Power wheelchairs have the potential to significantly increase the independence of people with mobility
impairments in their daily lives. However, many market offerings fail to fully meet user needs. Just
like other industries, the power wheelchairs sector must also adopt new technologies and user-centric
strategies to empower users and contribute to a more inclusive and sustainable society. The framework
presented here offers a significant advancement in the design and implementation of user-centric
power wheelchairs through a cyber-physical social approach. This approach not only can address the
limitations of conventional models but also sets a precedent for inclusive design and collaboration
among stakeholders. Through the integration of social aspects, technology, and the environment, power
wheelchairs can be enhanced to better meet diverse user needs while ensuring safety and reliability.
The use of IOPT-net-based digital twin serves as a cornerstone in this proposal. Digital replicas of
power wheelchair, or specific components, enable iterative design, real-time simulations, and remote
control, thus facilitating the development of innovative and personalized solutions in the sector. Further-
more, IOPT-Tools proved to be instrumental in modeling and validating the behavior of both physical
and virtual entities within the cyber dimension; as well as in deploying a prototype at the physical
dimension. Looking ahead, the approach future application, using a real Invacare Fox wheelchair [20],
will provide valuable insights into its practical benefits and applications for mobility solutions.
Acknowledgments
This work had the support of the Portuguese Agency FCT ("Fundação para a Ciência e a Tecnologia"),
in the framework of project UIDB/00066/2020, and through the PhD scholarship with the DOI https:
//doi.org/10.54499/2020.08462.BD.
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