Character Inverted Pendulum: Pogo-Sticks, Pole-Vaulting, and Dynamic Stepping

This article gives a practical overview of the popular biomechanically inspired, computationally efficient, algorithmically straightforward inverted pendulum technique for character-based systems. We explain the different flavours of inverted pendulum (e.g., springloaded and gravity compensated inverted pendulum), their viability for different situations (e.g., walking, running), simulation results, and practical step-by-step implementation details. We also discuss how the inverted pendulum model can be used for biped and multileg characters (e.g., humans and dogs) and any necessary engineering solutions that might be necessary to make the implementation a practical usable solution for real-time environments. While a basic introduction introduces the mathematics and principles behind the inverted pendulum they can brush over or neglect to mention numerical approximations and corrective engineering solutions necessary to make the inverted pendulum a usable tool for character based control (e.g., upright balanced walking). The inverted pendulum is a self-adapting low-dimensional controller that provides intelligent foot placement information for balancing and upright locomotion. CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional Graphics and Realism—Animation I.6.8 [Computer Graphics]: Animation—Types of Simulation–Animation