  In the context of Intelligent Transportation Systems and the delivery of
goods, new technology approaches need to be developed in order to cope with
certain challenges that last mile delivery entails, such as navigation in an
urban environment. Autonomous delivery robots can help overcome these
challenges. We propose a method for performing mixed reality (MR) simulation
with ROS-based robots using Unity, which synchronizes the real and virtual
environment, and simultaneously uses the sensor information of the real robots
to locate themselves and project them into the virtual environment, so that
they can use their virtual doppelganger to perceive the virtual world. Using
this method, real and virtual robots can perceive each other and the
environment in which the other party is located, thereby enabling the exchange
of information between virtual and real objects. Through this approach a more
realistic and reliable simulation can be obtained. Results of the demonstrated
use-cases verified the feasibility and efficiency as well as the stability of
implementing MR using Unity for ROS-based robots.
