  Shake tables provide a critical tool for simulating earthquake events and
testing the response of structures to seismic forces. However, existing shake
tables are either expensive or proprietary. This paper presents the design and
implementation of a low-cost, open-source shake table named Shakebot for
earthquake engineering research and education, built using Robot Operating
System (ROS) and robotic concepts. The Shakebot adapts affordable and
high-accuracy components from 3D printers, particularly a closed-loop stepper
motor for actuation and a toothed belt for transmission. The stepper motor
enables the bed to reach a maximum horizontal acceleration of 11.8 m/s^2 (1.2
g), and velocity of 0.5 m/s, with a 2 kg specimen. The Shakebot is equipped
with an accelerometer and a high frame-rate camera for bed motion estimation.
The low cost and easy use make the Shakebot accessible to a wide range of
users, including students, educators, and researchers in low-resource settings.
An important application of the Shakebot is to examine the dynamics of
precariously balanced rocks (PBRs), which are negative indicators of
earthquakes in nature. Our earlier research built a virtual shake robot in
simulation for the PBR study. The Shakebot provides an approach to validate the
simulation through physical experiments. The ROS-based perception and motion
software facilitates the code transition from our virtual shake robot to the
physical Shakebot. The reuse of the control programs ensures that the
implemented ground motions are consistent for both the simulation and physical
experiments, which is critical to validate our simulation experiments.

Robotics;Geophysics