PuppetMaster: robotic animation of marionettes

We present a computational framework for robotic animation of real-world string puppets. Also known as marionettes, these articulated figures are typically brought to life by human puppeteers. The puppeteer manipulates rigid handles that are attached to the puppet from above via strings. The motions of the marionette are therefore governed largely by gravity, the pull forces exerted by the strings, and the internal forces arising from mechanical articulation constraints. This seemingly simple setup conceals a very challenging and nuanced control problem, as marionettes are, in fact, complex coupled pendulum systems. Despite this, in the hands of a master puppeteer, marionette animation can be nothing short of mesmerizing. Our goal is to enable autonomous robots to animate marionettes with a level of skill that approaches that of human puppeteers. To this end, we devise a predictive control model that accounts for the dynamics of the marionette and kinematics of the robot puppeteer. The input to our system consists of a string puppet design and a target motion, and our trajectory planning algorithm computes robot control actions that lead to the marionette moving as desired. We validate our methodology through a series of experiments conducted on an array of marionette designs and target motions. These experiments are performed both in simulation and using a physical robot, the human-sized, dual arm ABB YuMi^® IRB 14000.