“…This paper conducts literature searches based on thematic words, including search titles, abstracts, author keywords, and additional keywords, to find papers highly relevant to research on optical sensor-based user behavior recognition in smart homes. The search criteria for thematic words are as follows: (1) With smart homes as the primary research context and considering their characteristics and usage environments, the first-level search theme revolves around three categories-"intelligence", "home", and "product". The related thematic word collection includes "smart, intelligen*, automat*"; "home*, household, house, domestic, room, kitchen, toilet, basement, garden"; "product, supplies, item, appliance", searching for papers containing two or more of these thematic words.…”