Steerable Adaptive Bullet Flight Control Mechanism Design

Abstract

The paper begins with an historical overview of automated guidance systems in general, then early aerospace systems, finally wrapping up the introduction with a summary of several adaptive bullet and cannon shell programs. This paper describes a novel type of piezoelectrically driven flight control actuators for use in guided bullets and cannon shells. US Pat. 7,898,153 was issued in March 2011. This patent describes the overall layout of the actuators, how they are mounted, laminated, energized and used to control the flight of several different families of devices; accordingly, this part of the paper is a lay-technologist companion to the Patent. One of the key features of this class of actuator is the use of a Low Net Passive Stiffness (LNPS) actuator configuration. A subset of LNPS actuators use axial forces applied to the ends of an actively bending beam to reduce the passive stiffness of the element. As the passive stiffness approaches the null point, deflections increase to the point that they become so large that the actuator can tear itself apart. The other key component of the patent is a novel mechanism to allow actuators of this class to maintain structural integrity at these high deflection levels. Experimental data on this class of actuator shows deflection magnification levels in excess of 300% with no degradation in blocked moments. The paper concludes with short summary of progress to date and implications for future hard-launch munition designs.