  To approach the level of advanced human players in table tennis with robots,
generating varied ball trajectories in a reproducible and controlled manner is
essential. Current ball launchers used in robot table tennis either do not
provide an interface for automatic control or are limited in their capabilities
to adapt speed, direction, and spin of the ball. For these reasons, we present
AIMY, a three-wheeled open-hardware and open-source table tennis ball launcher,
which can generate ball speeds and spins of up to 15.4 ms-1 and 192 s-1,
respectively, which are comparable to advanced human players. The wheel speeds,
launch orientation and time can be fully controlled via an open Ethernet or
Wi-Fi interface. We provide a detailed overview of the core design features, as
well as open source the software to encourage distribution and duplication
within and beyond the robot table tennis research community. We also
extensively evaluate the ball launcher's accuracy for different system settings
and learn to launch a ball to desired locations. With this ball launcher, we
enable long-duration training of robot table tennis approaches where the
complexity of the ball trajectory can be automatically adjusted, enabling
large-scale real-world online reinforcement learning for table tennis robots.
