Pyrotechnic Actuator Installation Robot
Sandia National Laboratories, Livermore, CA, USA
ID: GSP6
Relevant Skills: mechanical design, robotics, software
Pyrotechnic actuators are highly reliable, compact single shot devices that are used by industry to perform rapid mechanical work on components. Due to their inherent high reliability, actuators are often used where a failure would result in death or a substantial loss of property. Pyrotechnic actuators are initiated by a bridgewire which causes the pyrotechnic to rapidly deflagrate, thereby generating hot gas capable of performing work in a system. Pyrotechnic actuators, such as the PC-23, have many applications including; ejector seats, emergency oxygen flow on airplanes, fast-shear bolts, cable cutters, airbags, safe/arm units in missiles, fuel transfer and many others. The figure below shows a small cross-section of the devices that use pyrotechnic actuator driven components.
A bare actuator alone is not very useful; it must be installed into an assembly designed to function with rapidly expanding hot gas in order to accomplish work. The handling of bare pyrotechnic actuators during the installation process is hazardous, mainly due to the potential for stray currents to ignite the actuator before it is safely installed in the larger assembly. If a bare actuator ignites while being handled by an operator, serious injury, and in extreme cases, death can result.
The only known way to install actuators is by hand, a process that can potentially expose the operator to dangers associated with bare actuators. Due to the hazards, the safety procedures for installing actuators into assemblies can be quite arduous. In addition, Sandia strives to follow the cardinal rule of explosives; expose the minimum amount of personnel to the minimum amount of explosives for the minimum amount of time. If the actuator installation process was automated, Sandia would better serve the cardinal rule, personnel would be safer and the labs working with actuators would realize an increase in efficiency. Sandia uses many different actuators as part of the National Security Mission, but this problem statement will focus on one: the PC-23. More information on the PC-23 can be found at http://www.hstc.com/Products/OrdnanceProducts/PowCartSquibInit/PC23Series/
The task is as follows: Design a robot that locates PC-23 actuators in an open packing tray (much like a miniature egg carton) and installs them in a larger assembly. This will occur in a designated “explosives room” where power sources are very limited to minimize the potential for stray currents. Key features of the robot include:
- Minimize electrical power needs – any necessary electrical components must be intrinsically safe (explosion proof). Options to minimize the use of electrical components include pneumatics and hydraulics.
- The robot’s energy source must be self-contained and all components shall operate with as low voltages as possible. No connection to building electricity is allowed.
- The robot must be able to remove the PC-23 from the egg-crate-like container it is shipped in.
- The robot shall be able to install the PC-23 into a threaded hole and torque it to a pre-specified, adjustable torque.
- The robot shall not damage the PC-23 in any way, including cosmetic level scratches.
- Although complete automation is desired (push a single button to commence installation process), it is not necessary. The robot may be remote controlled and guided to the PC-23 in the crate and to the destination part by a human.
- Any remote control cannot be RF based and must be wired through shielded cables.
- The PC-23 shipping crate will be placed within 18 inches of the part into which the actuator must be installed.
- Parts of the robot that come into contact with the PC-23 shall be grounded to the building’s explosive system rated ground. The resistance between these parts and the building ground may be no more than 0.5 ohms.
- Initial budget is $3000.