A Review of Two Patents Relating to Novel Energy Harvesting Techniques to Provide Electrical Power On-Board Gun-Fired Projectiles

This is a review of two patents relating to electrical power generation on-board gun-fired munitions. The devices harvest mechanical energy from the motion of the projectile (e.g. the axial firing acceleration), and then convert the energy from mechanical to electrical using novel mechanisms and materials such as piezoelectric elements. The devices are particularly important for several reasons. Firstly, the devices are inherently safe because the root source of the electrical energy is the motion of the projectile; therefore no electrical energy can be produced until after the projectile is fired. Second, the devices have a much longer shelf-life than competing electrical power sources such as batteries. Finally, the devices are simple, rugged, and reliable making them ideal for the harsh environment on-board gun-fired projectiles. In addition to presenting the general approach, the logical framework of the patented embodiments is presented, especially with respect to the types of motion used for harvesting and the challenges presented by the varied magnitudes of those motions in different weapon platforms.