Alan Rudnai, Ascendant Engineering Solutions
Creating a weapon shock simulator that accurately recreates the weapon shock experienced by an M4 class weapon to test electro optic and electronic accessories.
Using LabVIEW software and CompactDAQ hardware, we developed a system to simulate the mechanical impedance of the weapon/soldier and match the complex weapon shock time history and shock response spectrum for use as a replacement for live fire in testing M4 accessories per MIL-STD-810G.
Ascendant Engineering Solutions (AES) provides design and engineering services including systems, mechanical, electrical, and software engineering to customers across a wide range of industries. For this project, we were challenged to create a weapon shock simulator that accurately recreated the weapon shock experienced by an M4/M16/AR-15 class of weapon. The military initially requested the simulator for testing small arms accessories without having to use live fire. Weapons are increasingly transitioning to weapon systems that incorporate optics and electronics. Electronics can fail from weapon shocks with peak levels of several thousand Gs.
Conducting live fire tests is becoming increasingly expensive and more difficult. We estimate costs of $4–5 per round for live fire testing, which includes the cost of ammunition, labor, wear and tear on the equipment, and range time. To supply thermal optic scopes to the military, we required lot tests of 10,000 rounds per quarter. Conducting live fire measurements can be quite challenging due to variations in weather, temperature, ammunitions, and equipment. One scope supplier could no longer conduct the live fire tests in its state due to increasing costs.
We needed a simulator to test electro optic and electronic accessories, including thermal weapon sights, lasers pointers, and flashlights. To do this, the system needed to simulate the mechanical impedance of the weapon/soldier and match the complex weapon shock time history and shock response spectrum.
We used LabVIEW and CompactDAQ based on our previous experience in making synchronized multichannel shock measurements using accelerometers in other projects. We used an NI 9234 C Series dynamic signal acquisition module to acquire data from three Meggitt Endevco 7250A subminiature piezoelectric accelerometers mounted on the weapon simulator in three axes. We used two NI 9401 bidirectional digital input modules to communicate with a pneumatics controller integrated into a single case.
The pneumatics control system drives synchronized actuators to reproduce shocks from pyrotechnic and bolt carrier assembly actions of automatic weapons. The system duplicates reflected mass/inertia and stiffness at the weapon/sight interface by incorporating critical components of the actual weapons being simulated. The system only requires AC power and a simple shop air compressor to operate.
Using LabVIEW, we developed an integrated data collection, reporting, and analysis software system to display results in real time. We liked the close integration between the hardware and software, including the data export capability. This tight integration helped us automate the process to develop a high productivity, stand-alone test system. Using LabVIEW, we developed a simple user interface that was easy to operate.
Users have found the system increases efficiency significantly. While we designed the system to address the high cost of qualification, users found that when they make changes to the thermal optic scopes or other equipment under development to be placed on the weapon, they do not have to go to the firing range to verify performance. Instead they can run a complete 420 round combat test in less than two minutes to verify the design changes. AES and its defense customers have measured weapon shocks on a number of weapon systems in addition to the M4 and determined that the M4 has the most severe weapon shocks due to its low weight. We can essentially pre-verify weapon accessories verified on the Weapon Shock Simulator for many other weapon systems. Due to the significant efficiency improvements and close duplication to live fire, some users have incorporated the system in their end-of-line tests.
The Weapon Shock Simulator enables quick in-house testing and significantly reduces test cycle time and related costs. The government tested and approved the simulator for use as a replacement for live firing in testing M4 accessories. It is the only system the US government allows to replace live-fire testing.
Alan Rudnai
Ascendant Engineering Solutions
arudnai@aesaustin.com