Author: ginaseo

This week, I completed the rapid prototyping of 4 pressure sensors and an LDR in Arduino IDE, with strong initial thresholds set for sensitivity. The pressure sensors are connected to GPIO pins (32, 33, 34, 35), and I’ve assigned names to each sensor for easy identification in the serial monitor. The system checks for pressure detection, and prints the sensor name and value when pressure is applied. For the light sensor, I used a TEMT6000 on GPIO 26, and set a threshold to detect changes in the light status. The sensor was sensitive enough to detect when my hand came closer to cover the circuit, simulating the fridge door closing, but it was not affected by the LED light. I’ve also connected an LED to GPIO 25 to indicate the light status — if the light is on, the LED lights up, and if the light is off, the LED is turned off. A demo video is shown here.

Additionally, Jess, Sarah and I completed the design report by Friday. I mainly focused on research and writing on hardware components, justifications, battery life, problem statement and solution overview, and system diagrams.

Overall, my team and I are making steady progress and are on schedule.

Some roadblocks included the late delivery of the LED, NFC tag, and NFC scanner, so we weren’t able to integrate everything over Spring break. However, I plan to integrate the LED system with Jess next week. Even further, with Jess’s progress on the Bluetooth (BLE) functionality and WiFi setup for the ESP32, I will be able to help put together our initial prototype + real LED strips with Wifi data transfer mechanism, which will be key for moving forward with the integration.

This week, I focused on finalizing our design slides and collaborated with Jess and Sarah to thoroughly review our hardware components for the presentation. We ensured that all elements were clearly documented and that our explanations were concise and well-supported. Additionally, after internal discussions and consulting with a Master’s-level Mechanical Engineer experienced in working with pressure and weight sensors in various projects, we decided to transition from force-sensitive resistors (FSRs) to weight sensors for greater accuracy and reliability. To support this shift, I began exploring different weight sensor options that align with our design needs. However, we are concurrently testing pressure sensors to validate our decision, as we have acquired square and small circle pressure sensors from the Ideate lab for evaluation.

Our decision to move away from pressure sensors stems from their inherent limitations in detecting stacked items. Pressure sensors measure force per unit area, meaning that if the added item distributes its weight over a large surface, the overall pressure change might be too minimal to register accurately. This could lead to unreliable or inconsistent readings. In contrast, a load cell strain gauge directly measures total force applied, making it far more effective at detecting subtle weight changes due to stacking. By using a load cell, we can ensure a much more precise and responsive detection system, which is crucial for our application.

In addition to refining our sensor choices, I addressed concerns regarding the fabrication of our electronics with FDA-safe silicone. On Thursday, I met with Cody from Ideate to discuss the scope of our project, our progress so far, and the feasibility of using food-safe silicone for the final product. We received great news—facilities are available to help us create silicone molds using FDA-compliant materials, as the Creative Soft Robotics class is currently working on similar projects involving silicone mold printing. Cody demonstrated how straightforward the process would be, as long as we finalize the sensor layout.

The decision to use a weight sensor aligns well with this fabrication plan, as we can calibrate it precisely to account for any pressure applied by the silicone casing. Additionally, Cody helped us select free acrylic sheets that I can laser cut (since I already have clearance for laser cutting) to create plates for sandwiching the strain gauge weight sensor. This setup will provide a stable and effective means of integrating the sensor into our final design.

Looking ahead, I plan to begin drafting the design report since the deadline is quickly approaching. Simultaneously, I will start assembling the prototype with the team to ensure we have a functional version before spring break. Having a physical build will give us a much clearer understanding of any potential integration challenges, allowing us to refine our design early in the process. We’re making steady progress, but accelerating our pace now will help us stay ahead of upcoming deadlines.

This week, I focused on refining our design and advancing our prototyping efforts. I worked on structuring and finalizing the implementation plan in our design slides and also conducted a final review of the components we need for our prototype with Jess, verifying specifications to ensure they align with our system requirements. I worked on detailed modifications on the testing, verification, and validation requirements by setting clear success criteria for evaluating the effectiveness of our hardware and software integration.

Using circuit components from the Physical Computing Lab in Ideate, I began assembling an initial hardware prototype, testing basic circuit configurations, and ensuring our force sensors, LEDs, and ESP32 communicate as expected. My hardware prototyping efforts will continue this weekend as I refine the first stage of our prototype, aiming to present a functional snippet during our design presentation.

Our progress remains on track with our project schedule. This weekend, I will help Sarah with practicing for our design presentation, ensuring we hit all the points. This coming week, we will expand our rapid prototyping efforts to include software-hardware communication by running ESP32-compatible software (Johnny-Five) alongside FastAPI to establish initial firmware interactions. I plan to finalize and test an early-stage hardware prototype with working LED indicators and force sensors early this week to begin integration testing to ensure firmware and hardware communication align with our expected use case. I will also continue refining our design presentation based on feedback after presenting.

This week, I focused on creating the Proposal Deck with my team. I refined the storytelling and flow of our presentation to ensure clarity and engagement, carefully structuring the slides to effectively communicate our project’s goals, requirements, and challenges. This meant delving deep into the root causes of the problem and identifying user pain points and drawing a direct connection to our proposed solution and the ways in which it can address them. Additionally, I practiced delivering the pitch to ensure a compelling and coherent narrative.

On the technical front, I conducted preliminary research to identify suitable hardware components, focusing on sensor accuracy, power efficiency, and feasibility within our design constraints. I am currently collecting components from the IDeATe Physical Computing Lab to build a mini MVP of our silicone pad. I plan to use an ESP32 microcontroller, a simple LED bulb, and pressure sensors to test the hardware and identify potential considerations before finalizing component selection.

Collaborating with team members, I dissected technical challenges, defined requirements, and strategized solutions. We addressed specific technical challenges and outlined requirements to ensure our solution is robust and effective. The positive feedback we received from peers and Professor Brumley well-reflected our efforts.

My progress is on track with the project schedule. Following the mini MVP testing, Jess and I will finalize a comprehensive list of components, ensuring each aligns with our system and performance goals. We will also incorporate feedback from Professor Brumley regarding our proposal presentation to refine our approach.

In the next week, I plan to finalize the list of components based on MVP testing outcomes, integrate Professor Brumley’s feedback into our project plan, and begin assembling the initial prototype with the selected components.