Our Jack software supports the importation and graphical manipulation of externally-designed CAD models as a virtual world into which one or more anthropometrically valid human figures may be placed and animated. Jack supports the definition, positioning, animation, and human factors performance analysis of simulated human figures on Silicon Graphics workstations. Such figures can be used for human factors analysis of reach, view, fit, comfort, and motion. From modeling reasonable body size and shape, through control of the highly redundant body linkage, to simulation of plausible motions, human figures offer numerous computational problems and constraints. Enhanced interactive control is provided by a set of natural behaviors such as multiple constraints, looking, reaching, balancing, collision avoiding, lifting, stepping, walking, grasping, and so on. Besides interactive specification through mouse, menu, and keyboard, Jack allows external control through direct sensing of the user's body position. Jack may also be controlled through command files, network sockets, or a simulation system which provides a convenient temporal and spatial parallel ``programming language'' for behaviors.
Some advanced features of Jack include: