A system for determining the pose of an articulated model of a virtual subject in carrying out a task within a vehicle occupant packaging design is described. The system uses an initial posture of the articulated model prior to the virtual subject carrying out the task as a starting point. The system determines pose throughout the carrying out of the task by the virtual subject. The pose is determined based on the parameters of the virtual subject, the design, the task to be completed, and a set of constraints restricting the motion of the virtual subject. The pose can be analyzed to determine the feasibility of a design for a human subject, without the need for live subject testing. The method is analytically derived and results in a kinematically and dynamically consistent posture in real-time without requiring iterative optimization.