  The single, double, and triple pendulum has served as an illustrative
experimental benchmark system for scientists to study dynamical behavior for
more than four centuries. The pendulum system exhibits a wide range of
interesting behaviors, from simple harmonic motion in the single pendulum to
chaotic dynamics in multi-arm pendulums. Under forcing, even the single
pendulum may exhibit chaos, providing a simple example of a damped-driven
system. All multi-armed pendulums are characterized by the existence of
index-one saddle points, which mediate the transport of trajectories in the
system, providing a simple mechanical analog of various complex transport
phenomena, from biolocomotion to transport within the solar system. Further,
pendulum systems have long been used to design and test both linear and
nonlinear control strategies, with the addition of more arms making the problem
more challenging. In this work, we provide extensive designs for the
construction and operation of a high-performance, multi-link pendulum on a cart
system. Although many experimental setups have been built to study the behavior
of pendulum systems, such an extensive documentation on the design,
construction, and operation is missing from the literature. The resulting
experimental system is highly flexible, enabling a wide range of benchmark
problems in dynamical systems modeling, system identification and learning, and
control. To promote reproducible research, we have made our entire system
open-source, including 3D CAD drawings, basic tutorial code, and data.
Moreover, we discuss the possibility of extending our system capability to be
operated remotely to enable researchers all around the world to use it, thus
increasing access.
