The Balancing Cube: A Dynamic Sculpture As Test Bed for Distributed Estimation and Control

The balancing cube is a dynamic sculpture that can balance autonomously on any of its edges or corners (see Figures 14). When standing on a corner, the cube represents a three-dimensional (3-D) inverted pendulum with multiple actuation, sensing, and control units that are interconnected over a communication network. The main structural components are the cube body (a rigid aluminum structure with a cubic shape) and six identical rotating arms located on each of the cube's inner faces. The rotating arms are self-contained units carrying sensors, actuation, a computer, and a battery. Due to their modular design, these units are referred to as modules. As they rotate, they shift the overall center of mass of the system, exert forces on the cube structure, and can, as a result, influence the cube's motion. The modules constitute the agents in the distributed and networked control system; their joint objective is the stabilization of the cube. A video of the cube can be found on the project Web site [1].