  Interacting with humans is one of the main challenges for mobile robots in a
human inhabited environment. To enable adaptive behavior, a robot needs to
recognize touch gestures and/or the proximity to interacting individuals.
Moreover, a robot interacting with two or more humans usually needs to
distinguish between them. However, this remains both a configuration and cost
intensive task. In this paper we utilize inexpensive Bluetooth Low Energy (BLE)
devices and propose an easy and configurable technique to enhance the robot's
capabilities to interact with surrounding people. In a noisy laboratory
setting, a mobile spherical robot is utilized in three proof-of-concept
experiments of the proposed system architecture. Firstly, we enhance the robot
with proximity information about the individuals in the surrounding
environment. Secondly, we exploit BLE to utilize it as a touch sensor. And
lastly, we use BLE to distinguish between interacting individuals. Results show
that observing the raw received signal strength (RSS) between BLE devices
already enhances the robot's interaction capabilities and that the provided
infrastructure can be facilitated to enable adaptive behavior in the future. We
show one and the same sensor system can be used to detect different types of
information relevant in human-robot interaction (HRI) experiments.
