Shakebot: A Low-cost, Open-source Robotic Shake Table for Earthquake Research and Education
Shake tables serve as 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 \textit{Shakebot} for earthquake engineering research and education, built using Robot Operating System (ROS) and principles of robotics. 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 $\mathbf{g}$), 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 resource-constrained settings. The Shakebot, along with its digital twin--a virtual shake robot--has showcased significant potential in advancing ground motion research. Specifically, this study examines the dynamics of precariously balanced rocks. 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.