Automating the Demilitarization of Retired Munitions
by Walter Wapman
Sandia National Laboratories
The US Army is responsible for coordinating munition demilitarization for all the Services. More than 300,000 tons of rounds are currently in stockpile waiting to be demilled, some dating back to World War II. This amount is increasing by about 70,000 to 100,000 tons per year. Currently, these munitions are disassembled by personnel, which places them in potentially hazardous situations.
When Jim Wheeler, Director of the Defense Ammunition Center, decided to insert flexible automation systems into their conventional demil operations, they turned to Sandia's robotic expertise for guidance. Having already successfully solved a similar problem for DOE with its Automated Gas Generator Disassembly System (AGGDIS) work cell, Sandia was able to quickly adapt its technology and system integration capability to create a prototype system for the Army that would disassemble 40mm fixed-round munitions. Within 9 months, Sandia designed, developed, delivered, and demonstrated a complex prototype system at the McAlester Army Ammunition Plant in Oklahoma.
The task is completed by using an off-the-shelf articulated robot arm, force control, machine vision, custom tooling, and an operator-driven graphical user interface (GUI) to disassemble the round and separate out the component piece parts for reclamation. Safety features and reliability were designed into the work cell to maximize the system effectiveness. Sandia's work cell approach seamlessly integrated many processes into a highly complex disassembly operation.
Using robots to automate the process removes people from a potentially hazardous work environment. In addition, it appears that automation will provide a tremendous operational cost savings.
Sandia is now in the preliminary stages of designing a flexible automated pilot plant. A simulation has been created of the pilot plant disassembly process that is useful to perform timing studies, observe layouts, and to help estimate project costs. In this flexible automation pilot plant, robots will be used to open and remove munitions from containers. Part-to-part container variation resulting from transportation and handling damage, and the inherent difficulty in accessing and removing munitions from containers, requires vision and dexterous manipulation sensor driven systems. Dexterous manipulation combines the modeled physical characteristics of a tool within its environment with force feedback electrical signals to control robot articulation for performing nontrivial tasks. The range of problems that will be encountered in the flexible automation pilot plant requires the intelligence encapsulated within these sophisticated technologies since "standard" robotics system technologies would be inadequate for these tasks. The pilot plant is expected to be operational in 3 to 4 years. Preliminary studies show that it will process one million rounds in one year working two 8-hour shifts per day.
Long-term flexibility is built in to the system; once all 40mm fixed-round munitions have been disassembled (approximately 3 million are currently in stockpile), the system can be modified to handle other munitions by reusing the same equipment. With minor tooling and the software changes, the system will be able to handle the disassembly of 30mm to 120mm fixed round munitions.