In the context of an aging population, technological tools such as socially assistive robots (SARs) have made their appearance as tools to assist the work practices of care teams in contact with the elderly. We want to show the contribution of user tests in a Living Lab in the process of co-designing such tools. These tests allow both technical problems to be highlighted and Human-Robot Interactions (HRI) to be studied in an iterative way. We conducted tests with elderly users as well as teenagers, to analyze the strategies used by users of the system. This also allowed us to observe the first emotional reaction and the first interaction modality (tactile or vocal) provoked by robot. Based on these observations, we propose perspectives for a better HRI.