Comparative Analysis of Vision-Based Sensors for Human Monitoring in Care Robots: Exploring the Utility-Privacy Trade-off

Striking a balance between utility and privacy holds significant importance in systems that rely on sensor utilization, such as robots. This balance is even more vital in care robots, given the sensitivity of personal data and the necessity for privacy-preserving monitoring to ensure user comfort. This paper presents a comprehensive investigation into the utility-privacy trade-off concerning different vision-based sensors. Specifically, RGB cameras, color and mono-color thermal cameras, and depth sensors are compared, considering technical aspects and users’ perception of privacy. The technical analysis addresses human pose tracking, human presence detection, human vital sign monitoring, and human facial and emotion recognition. The quantitative examination of sensors in real-life scenarios highlights the mono-color thermal camera’s effectiveness for user monitoring. Particularly, this sensor excels in challenging human presence detection scenarios compared to RGB cameras. Furthermore, interview and survey studies, encompassing two different age groups were carried out to compare how sensors are perceived in terms of user privacy. The quantitative and qualitative assessments of users’ feedback in these studies reveal that apart from depth sensors, thermal mono-color, and thermal color sensors are perceived as better at preserving user privacy compared to RGB cameras. The analysis includes the influence of participant age on privacy perception, indicating non-significant effects. Considering both the technical assessment and user preferences, the mono-color thermal camera emerges as the optimal choice for human monitoring purposes.