Tetrobot: a modular system for hyper-redundant parallel robotics

A modular system for the design, implementation, and control of a class of highly redundant parallel robotic mechanisms is described. The Tetrobot system features a novel concentric multilink spherical (CMS) joint which allows an arbitrary number of links to share a common center of rotation. The CMS joint facilitates the construction of a wide variety of variable geometry truss mechanisms using an integrated control and computational framework. A distributed control algorithm is based on an iterative virtual force based solution which propagates the goal positions of target nodes to determine systematic adjustments of actuators. Capabilities of the Tetrobot system have been demonstrated by the construction of several configurations of up to 18 nodes, 48 links, and 15 actuators. Implementations of a double Stewart platform and a six-legged walker, constructed from the same set of parts, are described in this paper