Theo jansens sculpture in 3DS max. Using an invisible crank -"The digital model uses Inverse Kinematics and Bones in 3D Studio Max to create the connections needed for the machine. Essentially, each side of the model is rigged with Inverse Kinematic solvers and then parented to an invisible "Crank" in the middle. By rotating the center crank (named Crank1) around the Y-axis, the system begins to "walk" forwards or backwards depending on the rotation of the crank. Once the initial rig is created, it can be instanced to create the full system as shown in Mr. Jansens actual sculpture. " - http://www.liftarchitects.com/journal/?currentPage=3, Andrew Payne.