title: Contactless on-bed activity sensing using first-reflection echolocation.
abstract: A novel system capable of detecting on-bed activity during sleep using first-reflection ultrasonic echolocation is described herein. As is employed in many existing solutions, such activity detection may be utilized in the assessment of sleep quality. Compared to current approaches using either wearable devices or sensors collocated on the surface of the bed, the proposed architecture greatly enhances convenience for the end-user by providing minimal disruptions to his or her standard sleep routine. A series of experiments were conducted in order to investigate the capacity of the system to detect activity during sleep. System performance was benchmarked against both a wrist-worn accelerometer as well as a smartphone application placed adjacent to the subject on the bed. Analysis demonstrates a statistically significant correlation between features computed from the system's output and the filtered activity data produced by the application, with maximum p values on the order of 10-3. Comparison with activity estimates formulated from the wrist-worn accelerometer output suggests stronger agreement, as indicated by increased correlation coefficient values.
authors.forename: Henry
authors.initials: H
authors.lastname: Griffith
authors.lastname: Yan Shi
authors.forename: Subir
authors.initials: S
authors.lastname: Biswas
mesh_terms: D061725:Accelerometry; D056044:Actigraphy / Q000379:methods*; D006801:Humans; D008954:Models, Biological; D008991:Monitoring, Physiologic / Q000379:methods*; D012890:Sleep / Q000502:physiology; D014465:Ultrasonics / Q000379:methods*; D014953:Wrist / Q000502:physiology