On the Beat! Timing and Tension for Dynamic Characters

Abstract

Dynamic simulation is a promising complement to kinematic motion synthesis, particularly in cases where simulated characters need to respond to unpredictable interactions. Moving beyond simple rag-doll effects, though, requires dynamic control. The main issue with dynamic control is that there are no standardized techniques that allow an animator to precisely specify the timing of the motion while still providing natural response to external disturbances. The few proposed techniques that address this problem are based on heuristically or manually tuning proportional-derivative (PD) control parameters and do not generalize easily. We propose an approach to dynamic character control that is able to honor timing constraints, to provide naturallooking motion and to allow for realistic response to perturbations. Our approach uses traditional PD control to interpolate between key-frames. The key innovation is that the parameters of the PD controllers are computed for each joint analytically. By continuously updating these parameters over time, the controller is able to respond naturally to both external perturbations and changes in the state of the character