Nailing and Pinning: Adding Constraints to Inverse Kinematics

Abstract

Inverse kinematics is commonly applied to compute the resulting movement of an avatar for a prescribed target pose. The motion path computed by inverse kinematics, however, often differs from the expected or desired result due to an underconstrained parameter space of the degrees-offreedom of all joints. In such cases, it is necessary to introduce additional constraints, for instance by locking a joint's position and / or rotation. We present a method to fix a joint in terms of position and explain how to incorporate these constraints into the inverse kinematics solution.