Building and debugging robotic programs is known to be difficult. The robotic
community has produced numerous tools, APIs and middlewares to help debug and
trace the construction and execution of robotic behaviors. However, most of
available debugging tools are text and log-oriented, leading to a tedious and
ad-hoc debugging activity. In this paper we fully describe VizRob, a tool to
debug robotic behaviors using logs and execution time. VizRob produces
interactive visualizations built from log traces within a state machine model,
that is, the visual representation of the behavior. VizRob is founded on
deficiencies we empirically found from semi-structured interviews and a
revision of tutorial materials. A small case study received an initial feedback
of VizRob in a robotic software engineering team. Our case study shows: (i)
VizRob helps engineers solve intricate debugging scenarios and (ii) engineers
perceive VizRob as filling a relevant gap within the current tools for building
robotic behavior.