“…The second category of techniques for explicitly estimating availability leverages a person's demeanor, focusing on immediate social cues of availability. Social cues, such as eye contact, are largely task-independent, and as a result, models based on social cues are more easily generalizable across a wider set of applications: in robotics, the methods have been used to estimate related measures of a person's "intent-to-engage" and awareness of the robot in applications ranging from companion robots [13,42], shopping mall assistants [9,31,57,59], receptionists [7], and bartenders [21]. Some prior work has relied on external sensors such as motion capture systems, ground-mounted LIDAR, and ceiling cameras [9,31,57,59], which can be expensive and difficult to deploy in support of mobile robots traversing a large space.…”