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| report:soa [2026/06/14 14:43] – [2.3 Research] team5 | report:soa [2026/06/14 15:33] (current) – team5 |
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| ==== 2.1 Introduction ==== | ==== 2.1 Introduction ==== |
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| This chapter presents the background research done to develop Connect. It covers: | This chapter presents the background research done to develop CONNECT and share. It covers: |
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| - **Interactive urban light installations:** Public art installations that respond to human presence in real time, where strangers collectively shape a shared visual | - **Interactive urban light installations:** Public art installations that respond to human presence in real time, where strangers collectively shape a shared visual |
| - **Participatory public art:** Research into design principles that create a sense of connection between strangers in shared spaces. | - **Participatory public art:** Research into design principles that create a sense of connection between strangers in shared spaces. |
| - **Research:** Academic studies and technical documentation covering loneliness in urban environments, velostat as a pressure-sensing material, the ESP32 microcontroller family, CAN bus communication and addressable LED components. | - **Research:** Academic studies and technical documentation covering loneliness in urban environments, velostat as a pressure-sensing material, the ESP32 microcontroller family, CAN bus communication and addressable LED components. |
| - **Comparative analysis:** A structured overview of the products, installations, and sources reviewed in this chapter, summarising their relevance to Connect. | - **Comparative analysis:** A structured overview of the products, installations, and sources reviewed in this chapter, summarising their relevance to CONNECT and share. |
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| ==== 2.2 Products ==== | ==== 2.2 Products ==== |
| == 2.3.1 Loneliness in public spaces == | == 2.3.1 Loneliness in public spaces == |
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| A central motivation behind Connect is the observation that people in dense urban environments such as metro carriages, often feel more disconnected from those around them, not less. This paradox is supported by the research article “Lonely in a crowd” [(Hammoud2021)], who investigated the real-time relationship between loneliness and the social environment, published in Scientific Reports. Using a smartphone-based assessment method, 756 participants across multiple countries reported their momentary feelings of loneliness up to three times daily over 14 days, alongside observations about their immediate environment [(Hammoud2021)]. | A central motivation behind CONNECT and share is the observation that people in dense urban environments such as metro carriages, often feel more disconnected from those around them, not less. This paradox is supported by the research article “Lonely in a crowd” [(Hammoud2021)], who investigated the real-time relationship between loneliness and the social environment, published in Scientific Reports. Using a smartphone-based assessment method, 756 participants across multiple countries reported their momentary feelings of loneliness up to three times daily over 14 days, alongside observations about their immediate environment [(Hammoud2021)]. |
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| The study found that perceived overcrowding was positively associated with loneliness (OR: 1.39), meaning that being surrounded by many people did not reduce feelings of isolation, it increased them. In contrast, perceived social inclusivity, defined as feeling welcome, feeling that others would help you, and sensing shared values with those nearby, was significantly associated with lower loneliness (OR: 0.79). Contact with nature similarly reduced loneliness (OR: 0.72), and the two effects amplified each other when combined [(Hammoud2021)]. | The study found that perceived overcrowding was positively associated with loneliness (OR: 1.39), meaning that being surrounded by many people did not reduce feelings of isolation, it increased them. In contrast, perceived social inclusivity, defined as feeling welcome, feeling that others would help you, and sensing shared values with those nearby, was significantly associated with lower loneliness (OR: 0.79). Contact with nature similarly reduced loneliness (OR: 0.72), and the two effects amplified each other when combined [(Hammoud2021)]. |
| It should be noted that the study has limitations. The sample was self-selected and the main participants was educated, middle-aged, Caucasian participants, which limits how broadly the findings can be generalized. Loneliness was also measured with a single survey item, and the study is observational, meaning the associations found do not establish causation. Still, the core finding, that overcrowding increases loneliness while perceived inclusivity reduces it, provides a meaningful theoretical basis for our project. | It should be noted that the study has limitations. The sample was self-selected and the main participants was educated, middle-aged, Caucasian participants, which limits how broadly the findings can be generalized. Loneliness was also measured with a single survey item, and the study is observational, meaning the associations found do not establish causation. Still, the core finding, that overcrowding increases loneliness while perceived inclusivity reduces it, provides a meaningful theoretical basis for our project. |
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| Despite these limitations, the finding by Hammoud et al. that perceived overcrowding increases loneliness (OR: 1.39) while inclusivity reduces it (OR: 0.79) directly shaped Connect’s output design. We operationalized this by projecting color across the shared ceiling rather than limiting feedback to a single pole, ensuring each passenger's presence is visible to the entire carriage. | Despite these limitations, the finding by Hammoud et al. that perceived overcrowding increases loneliness (OR: 1.39) while inclusivity reduces it (OR: 0.79) directly shaped CONNECT and share’s output design. We operationalized this by projecting color across the shared ceiling rather than limiting feedback to a single pole, ensuring each passenger's presence is visible to the entire carriage. |
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| The decision to use a microcontroller from the ESP32 family is supported by a comparative analysis of microcontroller platforms for the Internet of Things (IoT) and embedded systems [(maier2017)]. The study evaluates the ESP32 against comparable boards and concludes that its combination of low cost, low power consumption, and compatibility with the Arduino development environment makes it well suited for sensor-driven embedded applications. | The decision to use a microcontroller from the ESP32 family is supported by a comparative analysis of microcontroller platforms for the Internet of Things (IoT) and embedded systems [(maier2017)]. The study evaluates the ESP32 against comparable boards and concludes that its combination of low cost, low power consumption, and compatibility with the Arduino development environment makes it well suited for sensor-driven embedded applications. |
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| In Connect, the system is distributed across two types of nodes: sensor nodes embedded in each handrail pole, and a central ceiling node that drives the LED strip. Each node handles one task: either reading pressure input from the velostat sensor, or sending colour signals to the LED strip. A single-core microcontroller is sufficient for this, as no parallel processing is required at the node level. The ESP32 microcontroller can handle multiple tasks simultaneously [(maier2017)], which is not necessary for our project. Therefore we use the WEMOS mini, a development board based on the ESP32-C3 is used for this. It is a single-core RISC-V variant in the ESP32 family. This was chosen due to its compact form factor and lower power consumption compared to the dual-core original [(ESPRESSIF_C3_DATASHEET)]. | In CONNECT and share, the system is distributed across two types of nodes: sensor nodes embedded in each handrail pole, and a central ceiling node that drives the LED strip. Each node handles one task: either reading pressure input from the velostat sensor, or sending colour signals to the LED strip. A single-core microcontroller is sufficient for this, as no parallel processing is required at the node level. The ESP32 microcontroller can handle multiple tasks simultaneously [(maier2017)], which is not necessary for our project. Therefore we use the WEMOS mini, a development board based on the ESP32-C3 is used for this. It is a single-core RISC-V variant in the ESP32 family. This was chosen due to its compact form factor and lower power consumption compared to the dual-core original [(ESPRESSIF_C3_DATASHEET)]. |
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| The Arduino-compatible development environment shared across the ESP32 family is a practical advantage for our multidisciplinary student team, as it is «beginner-friendly» and have several libraries for both sensor input and LED control [(maier2017)]. | The Arduino-compatible development environment shared across the ESP32 family is a practical advantage for our multidisciplinary student team, as it is «beginner-friendly» and have several libraries for both sensor input and LED control [(maier2017)]. |
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| Maier et al. confirmed that the ESP32-C3 offers sufficient processing capacity for single-task embedded nodes at low power. In Connect, each Sensor Node performs only ADC polling and CAN transmission, while the Central Node only processes incoming CAN frames and drives LED output. No parallel processing is required at either node, making the single-core WEMOS C3 Mini the appropriate and cost-effective choice. | Maier et al. confirmed that the ESP32-C3 offers sufficient processing capacity for single-task embedded nodes at low power. In CONNECT and share, each Sensor Node performs only ADC polling and CAN transmission, while the Central Node only processes incoming CAN frames and drives LED output. No parallel processing is required at either node, making the single-core WEMOS C3 Mini the appropriate and cost-effective choice. |
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| == 2.3.3 Velostat sheet == | == 2.3.3 Velostat sheet == |
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| The decision to use velostat sheets for touch detection in the handrails of Connect is grounded in established research on flexible piezoresistive materials. Velostat is a polyethylene-carbon composite material that changes its electrical resistance in response to applied pressure. When compressed, the resistance decreases, producing a measurable electrical signal [(polym12122905)] | The decision to use velostat sheets for touch detection in the handrails of CONNECT and share is grounded in established research on flexible piezoresistive materials. Velostat is a polyethylene-carbon composite material that changes its electrical resistance in response to applied pressure. When compressed, the resistance decreases, producing a measurable electrical signal [(polym12122905)] |
| Dzedzickis et al. evaluated the mechanical and electrical characteristics of velostat as a tactile sensor material, testing it under static, long-term, and cyclic load conditions. | Dzedzickis et al. evaluated the mechanical and electrical characteristics of velostat as a tactile sensor material, testing it under static, long-term, and cyclic load conditions. |
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| The results confirm that velostat produces consistent, repeatable signals across multiple loading cycles, and that it can be implemented using a simple electrode pair [(polym12122905)]. These properties make it well suited for Connect, where the sensor must reliably detect the pressure of a passenger gripping a handrail and produce a signal the ESP32 can read. | The results confirm that velostat produces consistent, repeatable signals across multiple loading cycles, and that it can be implemented using a simple electrode pair [(polym12122905)]. These properties make it well suited for CONNECT and share, where the sensor must reliably detect the pressure of a passenger gripping a handrail and produce a signal the ESP32 can read. |
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| A practical advantage of velostat for this application is its flexibility. The material is thin and can conform to curved surfaces such as a handrail without requiring rigid mounting. One limitation noted in the research is that velostat's response is not perfectly linear and may drift slightly under repeated use [(polym12122905)]. To account for this, the sensor node includes a 10 kΩ potentiometer that allows the sensitivity to be manually adjusted during prototyping until reliable detection is achieved. | A practical advantage of velostat for this application is its flexibility. The material is thin and can conform to curved surfaces such as a handrail without requiring rigid mounting. One limitation noted in the research is that velostat's response is not perfectly linear and may drift slightly under repeated use [(polym12122905)]. To account for this, the sensor node includes a 10 kΩ potentiometer that allows the sensitivity to be manually adjusted during prototyping until reliable detection is achieved. |
| == 2.3.4 CAN Bus and MCP2551 transceiver == | == 2.3.4 CAN Bus and MCP2551 transceiver == |
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| Connect uses a distributed node architecture: each handrail pole contains an independent sensor node, and a central node at the ceiling receives their signals and controls the LED strip. Coordinating these nodes requires a communication protocol that can handle multiple transmitters on a shared line and remain reliable in an electrically noisy environment. | CONNECT and share uses a distributed node architecture: each handrail pole contains an independent sensor node, and a central node at the ceiling receives their signals and controls the LED strip. Coordinating these nodes requires a communication protocol that can handle multiple transmitters on a shared line and remain reliable in an electrically noisy environment. |
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| CAN (Controller Area Network) is a serial communication protocol originally developed for automotive applications, where multiple electronic control units must communicate reliably despite high levels of electrical interference [(BOZDAL)]. It is standardised under ISO 11898 and is widely used in embedded systems beyond the automotive industry, including industrial and building automation contexts [(ISO11898)]. Of particular relevance to Connect is CAN’s use of differential signalling: the bus carries each signal across two lines with opposite voltages, so interference affects both lines equally and is cancelled out at the receiver [(BOZDAL)]. This makes CAN significantly more robust against electromagnetic noise than single-ended alternatives, which is important in the context of a metro carriage. | CAN (Controller Area Network) is a serial communication protocol originally developed for automotive applications, where multiple electronic control units must communicate reliably despite high levels of electrical interference [(BOZDAL)]. It is standardised under ISO 11898 and is widely used in embedded systems beyond the automotive industry, including industrial and building automation contexts [(ISO11898)]. Of particular relevance to Connect is CAN’s use of differential signalling: the bus carries each signal across two lines with opposite voltages, so interference affects both lines equally and is cancelled out at the receiver [(BOZDAL)]. This makes CAN significantly more robust against electromagnetic noise than single-ended alternatives, which is important in the context of a metro carriage. |