Parallel Kinematic Machine Research at NIST: Past, Present, and Future

Unchained from the confines of controller limitations, the industrial application of parallel kinematic machines in manufacturing is beginning to emerge. The launch of commercially available hexapod machine tools at the 1994 International Manufacturing Technology Show in Chicago represented the first radical departure in machine tool design since the introduction of numerical controls. The parallel actuator technology promises to offer manufacturers a number of advantages relative to conventional machine tools, such as a higher stiffness-to-mass ratio, higher speeds, higher accuracy, reduced installation requirements, and mechanical simplicity. Several machine tool makers in the U.S. and around the world are pursuing parallel actuator technology, while their prospective customers—manufacturers—are beginning to contemplate what the novel multi-axis machining technology might mean for their operations. As part of the Manufacturing Engineering Laboratory's National Advanced Manufacturing Testbed (NAMT), NIST researchers and collaborators from industry and universities are studying the new tools' unique capabilities. The work includes extensive tests on an octahedral hexapod machine tool that was installed at NIST in May 1995. Research areas include machine metrology, performance characterization test methods and standards, performance enhancement methods, simulation and remote experimentation tools, and open architecture controller interfaces. This paper will give an overview of history and current status of research in parallel kinematic machines at NIST. The merits and key challenges of parallel kinematic machine tools will also be addressed, and directions for future research will be identified.