  Evaluating human-robot social interactions in a rigorous manner is
notoriously difficult: studies are either conducted in labs with constrained
protocols to allow for robust measurements and a degree of replicability, but
at the cost of ecological validity; or in the wild, which leads to superior
experimental realism, but often with limited replicability and at the expense
of rigorous interaction metrics.
  We introduce a novel interaction paradigm, designed to elicit rich and varied
social interactions while having desirable scientific properties
(replicability, clear metrics, possibility of either autonomous or Wizard-of-Oz
robot behaviours). This paradigm focuses on child-robot interactions, and
builds on a sandboxed free-play environment. We present the rationale and
design of the interaction paradigm, its methodological and technical aspects
(including the open-source implementation of the software platform), as well as
two large open datasets acquired with this paradigm, and meant to act as
experimental baselines for future research.
