Abstract
This thesis portfolio looks at how safety systems can better protect individuals from preventable injuries in everyday situations. Injuries from machines like lawnmowers and automobiles still happen often, even though the technology to prevent and minimize these risks already exists. In many cases, the issue is not whether the technology exists but how it’s designed, implemented, and adopted over time. Some safety solutions fail because they aren't integrated effectively into real-world use, while others are delayed due to cost, regulation, or other external factors. Because of this, people are sometimes left unprotected and at higher risk of injury even when solutions are available. These gaps show that safety isn’t only a technical problem but also one that is influenced by human decisions, financial constraints, and policy choices. As technology continues to improve and advance, the challenge becomes making sure these improvements are applied in ways that truly reach and protect everyone equally. This portfolio includes both a technical project and an STS research paper that approaches this issue from two different perspectives. The technical project focuses on designing a system to directly prevent injury, while the STS research examines how delays in safety regulations, specifically in the automotive industry, can lead to unequal protection across different socioeconomic groups.
The technical project is the design and development of a Radar-Actuated Lawnmower Protective Housing (RALPH), which is meant to reduce accidents caused by contact with the lawnmower blades of riding lawnmowers. Lawnmower injuries are common and can be severe, such as lacerations and amputations, especially when users come too close to active blades, or bystanders are not seen and run over. The safety system uses a millimeter wave radar sensor and an inertial measurement unit (IMU) to detect human presence and movement near the mower. These integrated sensors send the data collected to an ESP32 microcontroller, where it processes this data and decides whether a hazard is present. When an approaching person is detected, the microcontroller activates a relay that releases a latch, deploying a physical guard that acts as an extension of the mower skirt, blocking access underneath the skirt while also cutting power to the mower and the blades. A stepper motor and lead screw mechanism are used to reset the system once the hazard is cleared by manually pressing a Bluetooth button. The design focuses on fast response time, reliability, and minimizing false positives by combining and integrating multiple sensors. Testing showed that the system can detect approaching individuals and deploy the guard in a short time frame. The system shows that it could function as a practical safety solution for consumer lawn equipment. Overall, this project shows how real-time detection and automated response can help prevent accidents before they occur.
The STS research paper investigates whether delayed federal mandates for automotive safety technologies contribute to disparities in injury outcomes across income groups. Using airbags and backup cameras as case studies, the research analyzes the regulatory timelines, safety effectiveness, and socioeconomic differences in access to these technologies. The findings show that safety features are often introduced as optional technologies in higher-end vehicles before eventually being mandated, creating prolonged periods where only higher-income consumers benefit from improved protection. This results in unequal access, where lower-income consumers are more likely to rely on older vehicles that are not equipped with these safety features. The research also shows that vehicles with more safety technologies have lower fatality rates and that lower-income groups experience higher injury and crash severity rates. Drawing on Winner’s theory of technological politics, the paper argues that these regulatory delays are not neutral but reflect political and economic decisions that shape how protection is distributed. As a result, regulatory timing plays a significant role in deciding who benefits first and who remains at risk, showing that safety is not only a technical issue but a social one.
Together, these two projects show how important timing is in safety systems. The technical project focuses on preventing injury in the moment by detecting hazards and responding right away, while the STS research shows how regulatory delays of safety technologies can leave certain groups at higher risk over longer periods of time. Both projects suggest that improving safety isn’t only about developing better technology, but also about how and when that technology is available to everyone. By looking at both the technical and sociotechnical side of safety, this portfolio shows that reducing injury risk requires both better design and better decisions about how safety technologies are introduced and applied.
Notes
School of Engineering and Applied Science
Bachelor of Science in Mechanical Engineering
Technical Advisor: Jason Forman
STS Advisor: Kent Wayland
Technical Team Members: Jackson Berry, Mia Bonutti, Vincent Hu, Jimmy Sejas, Cole Smith, Averell Stith, Richard Townsley
