Actuation development and evaluation for INSTAR: inertially stabilized rifle

Abstract

In the use of piezoelectric actuators, it is a clear choice to use stack (or d 33 mode) architectures when very high force is required or bender (or d 31 mode) architectures when very high displacements are needed. However, the choice isn't as clear for applications that need simultaneously moderate to high force and displacement. This paper presents one such application, INSTAR, which is posed with this dilemma. INSTAR is a novel rifle system that has an inertially stabilized barrel via an active suspension based on piezoelectric actuation. While the frequency required for this application was low (~10Hz), the displacement (± 200 to 400 microns) and the force (22-45 N) are moderate. Two very different actuation approaches were developed, modeled, fabricated and experimentally validated within the INSTAR demonstration platform: 1) a d 31 approach based on the Recurve architecture with focus on generating higher forces than is common for d 31 actuators and 2) a d 33 approach based upon a compliant mechanism designed using topology optimization with focus on providing more amplified strain than is common for d 33 actuators. Both approaches were successful in meeting the INSTAR requirements, but each had its own advantages and disadvantages.

Compliant Mechanical Amplifier Design using Multiple Optimally Placed Actuators

“…In order to demonstrate the effectiveness of the method described above, an example problem is solved and compared with a single actuator problem. This problem has been taken from the authors' previous work, which had been described in detail in Frecker (2002, 2004) and Brei et al (2003). A brief overview of the problem definition is now given.…”