Our project is the result of a cross-border collaboration between six students from diverse European academic backgrounds. By merging technical precision with creative design, we aim to bridge the gap between human interaction and digital innovation. This multidisciplinary fusion, present in Table 1, is essential for building a solution that is not only sustainable and inclusive but also deeply engaging for the public.

We chose digital art from the list because initially, we had difficulty finding shared interests within the group. At first, we mainly discussed healthcare and well-being, but those conversations felt repetitive and didn’t spark much excitement. When someone mentioned digital art, however, the group immediately became more engaged. It appealed to both the more creative, artistic members and the technologically inclined computer science enthusiasts, since it combines artistic expression with digital innovation. Very quickly, we decided we wanted to create an interactive installation that not only showcases art but also creates a memorable experience for people.

Despite being physically crowded, modern public transit, specifically the metro systemhas become a space of profound social isolation. This “digital bubble” effect is driven by two primary factors:

Passive Consumption: Passengers use smartphones as a defense mechanism against the discomfort of a crowded environment, leading to a “heads-down” culture. This transforms a potentially shared journey into a repetitive, solitary experience.

The Anonymity of the Commute: The metro is often viewed as a “non-place”, a functional void to be endured rather than experienced. Current transit environments lack stimuli that encourage presence or spontaneous human interaction, resulting in a missed opportunity for community building and mental well-being.

Our project addresses this lack of meaningful physical engagement by challenging the habitual reliance on personal screens through an immersive, shared environment.

Our core mission is to transform the metro from a transition point into a participatory destination. We aim to:

Disrupt Digital Isolation: Incentivize passengers to put down their devices in favor of tactile, real-world stimuli.

Humanize the Journey: Turn a passive, anonymous ride into a sensory, human-centered experience from the moment of boarding.

Foster Collective Agency: Use interactive light and sound to show passengers that their presence and physical touch contribute to a larger, beautiful “shared journey.”

Promote Presence: Encourage mindfulness and “being in the moment” so passengers leave with a story rather than just a completed commute.

To ensure the project adheres to essential Regulatory and Standard Requirements, the following EU Directives and guidelines must be observed:

• Electromagnetic Compatibility Directive (EMCD)
• Low Voltage Directive (LVD)
• Machinery Directive (MD)
• Radio Equipment Directive (RED)
• Restriction of Hazardous Substances in Electrical and Electronic Equipment Directive (ROHS)
• Mandatory adoption and use of the International System of Units
• Use open-source software and technologies.
• Functional & Experiential Requirements

Location & Accessibility: The solution must be designed for public locations, specifically focusing on the metro. The design must be universally inclusive and accessible, requiring no specific language skills or instructions to use.

• Human-Centered Design: The project must deliver a human-centered, participatory experience that encourages presence in the moment.
• Social Impact: The system must actively discourage smartphone distraction and isolation by fostering physical and social connection between strangers.
• Interactive Journey: The solution must transform the passive commute into an interactive physical space, creating an immediate impact starting at boarding.
• Digital Storytelling: The system must allow users to leave with stories. This includes implementing a Quick Response (QR) code system near exit doors that directs passengers to a platform where they can either record a short voice message or listen to a memo from a previous passenger.
• Sustainability: The design must incorporate sustainability as a core focus point.

Technical & Hardware Requirements

• System Architecture: The technological artwork must be built using a power supply, a microcontroller, input sensors, and output components.
• Sensor Integration: The system must use physical actions (like gripping handles) as direct inputs, utilizing sensors such as pressure, light, and heart-rate sensors.
• Sensory Output: The system must provide immediate visual (light/color) and auditory (sound) feedback based on human interaction.
• Interactive Handrails: The metro handrails must be modified into tubes containing sensors and lights.
• Visual Light Propagation: When a passenger touches the pole, that specific spot must light up in a unique color, which then visibly travels through the pole to the metro ceiling, blending with the colors of other interacting passengers.

The goal of this project is to create a working prototype of a Distributed Smart Lighting System for public transportation. This system enhances the passenger experience by providing interactive visual feedback through addressable LEDs, triggered by touch-sensitive poles equipped with Velostat sensors. By utilizing a CAN Bus network, the system ensures high-reliability communication across the metro car, even in environments with high electromagnetic interference.

The primary objective of this project is to deliver a functional and robust prototype. To guarantee its performance and safety in a railway-simulated environment, several tests must be conducted. Each test is outlined below, including the specific Evaluation Methodology used to verify the results.

Functionality Tests:

• (FT-01)Velostat Touch Detection: Connect the sensor node to a PC and monitor the ADC output via the Serial Plotter. Apply varying hand pressures to ensure the signal changes linearly and triggers the intended software threshold.
• (FT-02)CAN Bus Communication: Implement a packet-counter script where the Pole Node sends 1,000 sequential messages. The Ceiling Node will log received IDs to calculate the Packet Delivery Ratio (PDR), with a target of $>99.9\%$.
• (FT-03)LED Visual Response: Trigger the sensor and visually inspect the LED strip for color accuracy ($RGB$ values), ensuring no “dead pixels” or flickering occur during the animation cycle.
• (FT-04)Sensitivity Calibration: Manually rotate the onboard potentiometer while applying a constant light touch. The test is successful if the trigger threshold can be adjusted to ignore vibrations while still detecting a deliberate touch.
• (FT-05)Power Management: Use a high-voltage laboratory power supply set to $72\text{V}$ and $110\text{V}$ DC. Use a multimeter to verify that the Buck Converter output remains at a stable $5.0\text{V } (\pm 0.1\text{V})$ under full LED load.

Performance Tests:

• (PT-01)System Response Time: Record the interaction using a high-speed camera ($240\text{ FPS}$). Count the frames between the initial hand-to-sensor contact and the first LED illumination to calculate total latency (Target: $<100\text{ms}$).
• (PT-02)EMI Noise Resistance: Operate a brushed DC motor (simulating metro traction noise) within $10\text{ cm}$ of the CAN wiring and Velostat sensor. Monitor the system for “ghost triggers” or communication resets.
• (PT-03)Thermal PerformanceMethodology: Activate the LEDs at $80\%$ brightness for $4\text{ hours}$ in a non-ventilated environment. Use an infrared thermometer to measure the enclosure surface temperature every $30\text{ minutes}$ (Target: $<50\text{°C}$).
• (PT-04)Voltage DropMethodology: With the strip at full white brightness, measure the voltage at the $VCC$ pin of the very last LED using a multimeter. Ensure it remains above $4.7\text{V}$ to prevent color distortion.
• (PT-05)Long-term Durability: Use an automated mechanical actuator (or repeated manual cycles) to trigger the sensor 1,000 times. Inspect the Velostat “sandwich” for delamination or loss of electrical sensitivity.

Software & Simulation Tests:

• (ST-01)Components Integration Simulation: Import $3D$ models of the PCBs and converters into a CAD environment (e.g., Fusion 360). Check for mechanical interferences and ensure a minimum $5\text{ mm}$ clearance between high-voltage and low-voltage traces.
• (ST-02)CAN Bus Logic Simulation: Use a network simulator or a dual-MCU breadboard setup to force “data collisions” by sending messages from two nodes simultaneously. Verify that hardware arbitration correctly prioritizes the higher-priority ID.
• (ST-03)Animation Algorithm: Run the LED code in a simulator (e.g., Wokwi) for $24\text{ hours}$ to check for memory leaks or buffer overflows that could lead to software hanging.
• (ST-04)Fault Detection: Physically disconnect the $CANH$ wire during operation. The software must detect a “Heartbeat Timeout” within $500\text{ ms}$ and switch the LEDs to a static “Safety White” mode.

Safety Tests:

• (SF-01)Electrical Safety: Perform a continuity test between the aluminum enclosure and the system $GND$ using a multimeter. Resistance must be $<0.1\text{ }\Omega$ to ensure proper earthing.
• (SF-02)Mechanical Safety: Conduct a tactile sweep test. Run a gloved hand over all surfaces and seams of the enclosure to ensure no sharp edges or protruding screws are present.
• (SF-03)Fire Safety: Review the manufacturer datasheets for all cables and $3D$ filaments used. Verify they carry a $V-0$ (UL94) flammability rating or $LSHF$ (Low Smoke Halogen Free) certification.
• (SF-04)Vandalism Resistance: Attempt to peel the sensor off the pole using fingers. Apply a $5\text{ kg}$ impact to the sensor area and verify that the electrical housing remains intact and functional.
• (SF-05)Ingress Protection (IP): Lightly spray the enclosure with a fine mist of water (simulating cleaning fluids). Open the box after $5\text{ minutes}$ to inspect for any moisture ingress near the electronic components.

User Acceptance Testing (UAT):

• (UAT-01)Trigger Intuitiveness: Observe 5 non-technical users. Ask them to “activate the interaction” without explaining where the sensor is. More than $>80\%$ of users need to identify the pole sensor as the interaction point within 5 seconds.
• (UAT-02)Visual Comfort (Glare Test): Users sit in a “metro seat” 1 meter away from the LEDs. Cycle through all colors at max brightness. Users report no eye strain or “dazzle” effect (blinding light).
• (UAT-03)Feedback Clarity: Ask users what the light animations signify (e.g., “What does the pulsing blue mean to you?”). Users correctly associate the animation with “System Active” or “Input Received”.
• (UAT-04)Ergonomics (Touch Height/Force): Test with users of different heights and hand strengths. All users can comfortably trigger the system regardless of their physical stature.

The testing framework defined in this chapter ensures the transition of the System from a concept to a robust prototype. By addressing EMI, thermal management, and passenger safety, these protocols guarantee that the CAN Bus architecture and Velostat sensing are reliable, scalable, and ready for real-world deployment in public transportation.

Below we can find in Table 2 the main structure of the report and a short description of every chapter.