Anticipatory balance control and dimension reduction

Abstract

AbstractA hallmark of many skilled motions is the anticipatory nature of the balance‐related adjustments that happen in preparation for the expected evolution of forces during the motion. This can shape simulated and animated motions in subtle but important ways, help lend physical credence to the motion, and help signal the character's intent. In this article, we investigate how center‐of‐mass reference trajectories (CMRTs) can be learned so as to achieve anticipatory balance control with a state‐of‐the‐art reactive balancing system. This enables the design of physics‐based motion simulations that involve fast pose transitions as well as force‐based interactions with the environment, such as punches, pushes, and catching heavy objects. We also show that generating CMRTs in a reduced space may result in faster computation times for similar task motions that deal with environmental interactions. We demonstrate the results on planar human models and show that CMRTs generalize well across parameterized versions of a motion. We illustrate that they are also effective at conveying a mismatch between a character's expectations and reality, for example, thinking that an object is heavier than it is.