Variable Geometry Truss Manipulator

The Variable Geometry Truss (VGT) Manipulator was developed to reduce the deflection for a manipulator designed to reach 16 feet from its base and lift a 2150-pound payload.

Pacific Northwest National Laboratory (PNNL) developed a concept using the Double Octahedral VGT concept pioneered by National Aeronautics and Space Administration (NASA) Langley Research Center, and NASA completed the detail design and fabrication. PNNL staff developed the control systems that were implemented on the actual robot. The VGT Manipulator that was developed performed well in the high payload task, and was able to position a 1000-pound load anywhere in its workspace with only 1/8th inch of deflection. A comparable traditional manipulator also was developed, and its deflection was approximately 2 inches under the same loading conditions.

The VGT Manipulator gets its strength from the parallel manipulator structure, which means that each component of the robot carries only a portion of the overall load. In a traditional robot, each joint in the manipulator has to carry the whole load, and therefore the deflection in each joint is added to the previous joints, making the overall deflection much more. In a parallel manipulator, the deflections of each joint are less, because they share the load with all other joints in the robot.

Project Contact: J. Tucker