Allen, Brian F.Faloutsos, PetrosJehee Lee and Paul Kry2014-01-292014-01-292012978-3-905674-37-81727-5288https://doi.org/10.2312/SCA/SCA12/231-234In this paper, we address certain misconceptions that have been perpetuated in the animation practice and research for quite some time related to the proportional-derivative (PD) control of physics-based systems. Because in animation we often think in terms of targeting keyframes, we tend to forget that PD control, in its simple form, has a very specific asymptotic behavior that approaches zero (or an offset) with zero velocity as time approaches infinity. We pay particular attention to the issue of introducing a ''desired'' or ''end'' velocity term in the equation of a proportional-derivative controller, and discuss how this term should be interpreted and how it relates to feedforward control rather than an end derivative problem.I.3.7 [Computer Graphics]Three Dimensional Graphics and RealismAnimation