  The mobile robotic testbed is an essential and critical support to verify the
effectiveness of mobile robotics research. This paper introduces a novel
multi-robot testbed, named Robopheus, which exploits the ideas of
virtual-physical modeling in digital-twin. Unlike most existing testbeds, the
developed Robopheus constructs a bridge that connects the traditional physical
hardware and virtual simulation testbeds, providing scalable, interactive, and
high-fidelity simulations-tests on both sides. Another salient feature of the
Robopheus is that it enables a new form to learn the actual models from the
physical environment dynamically and is compatible with heterogeneous robot
chassis and controllers. In turn, the virtual world's learned models are
further leveraged to approximate the robot dynamics online on the physical
side. Extensive experiments demonstrate the extraordinary performance of the
Robopheus. Significantly, the physical-virtual interaction design increases the
trajectory accuracy of a real robot by 300%, compared with that of not using
the interaction.
