Real-time gait control for partially immersed bipeds

Physics-based animation is an increasingly studied subject of computer animation because it allows natural interactions with the virtual environment. Though some existing motion controllers can handle the simulation of interactions between a character and a liquid, only few methods focus on the simulation of the locomotion of immersed bipeds. In this paper, we present a control strategy capable of simulating partially immersed gaits. The impact of the liquid on the character's motion is modeled through simple hydrodynamics. To produce natural looking animations, we design a controller allowing the combination of multiple gait styles, the conservation of balance through intelligent foot placement and precise control of the character's speed. We determine the optimal parameters for the controller by using an optimization process. This optimization is repeated for several scenarios where the character has to walk across a volume of liquid parametrized by its height. Our controller produces natural looking gaits while being capable of online adaptation to the variation of liquid height, to the modification of the liquid density and viscosity and to the variation of the required character's speed.