ROBOCRANE AND EMMA APPLIED TO WASTE STORAGE TANK REMEDIATION

AbstractThe RoboCrane is a revolutionary concept in crane automation. The RoboCrane, based on the Stewart platform parallel link manipulator design, consists of cables as the parallel links and winches as the actuators. The result is a work platform that can maneuver tools and/or manipulators with full six degree-of-freedom control. EMMA, a serpentine manipulator, is currently being developed for sev-eral applications, including the delivery and orien-tation of end-effectors throughout nuclear waste storage tanks. The combination of Robo- Crane and EMMA can provide an adaptable and highly effective means for waste storage tank remedia-tion.Keywords: RoboCrane, EMMA, parallel link manipulator, Stewart platform devices, cable-based robots, cranes. 1.0 RoboCrane Since the late 1980's, the National Institute of Standards and Technology (NIST) has been work-ing on the RoboCrane ® . The RoboCrane is a cable driven, multi-purpose manipulator based on the Stewart platform parallel link manipulator [1]. It provides full six degree-of-freedom (6 DoF) load control via tele-operative, semi-autonomous and autonomous control modes. Originally, the RoboCrane was developed under a Defense Advanced Research Project Agency (DARPA) contract to stabilize crane loads [2]. Currently, the configuration has advanced to include air-lifted, land, sea, and space applications. It can be designed for high lift-to-weight ratio, stable gantry configurations, flexibility, precise maneuverability, and mobility over a variety of surfaces including very rough terrain. As part of the NIST mission, the Intelligent Sys-tems Division (ISD) provides "... research in, develops methods for, and applies intelligent sys-tems technology to improve U.S. industry compet-itiveness.” The RoboCrane provides an intelligent machine enhancement to current large scale manu-facturing methods. It also provides a means for manipulating tools and equipment, such as long-range manipulators and end-effectors, into waste storage tanks for inspection and remediation.Multiple RoboCrane prototypes have been devel-oped to study a variety of applications. A 6 m octa-hedral system (see FIGURE 1) has performed heavy load maneuverability, sawing, grinding, gripping, welding, and assembly tasks under tele-operative, preprogrammed, off-line, and/or hybrid control modes. The 6 m RoboCrane prototype has been subjected to a variety of performance measurements and computer simulations [3]. Experimental tests were conducted to verify its functional work volume, static loading capability, and load positioning accuracy. These experimental results compared favorably to associated computer analysis. Posi-tioning uncertainty of this 6 m prototype has been measured at up to 1 mm in translation and angular precision of approximately 0.5° throughout a min-imum 100 m