Active Twist Control of Smart Helicopter Rotor - A Survey

Abstract

Helicopter vibration and blade-vortex interaction (BVI) noise are major problems restricting the wider use of helicopters in civil and military applications. Traditional methods based on vibration isolators and absorbers and passive designs of the rotor blade to reduce BVI noise have reached the point of diminishing returns and are increasingly unable to meet the stringent requirements of next generation helicopters. The advent of smart materials such as piezoceramics, has opened the possibility of actively twisting the rotor blade using control algorithms in a manner such that new higher harmonic forcing is developed which cancels the existing unsteady higher harmonic aerodynamic forces that are the main sources of vibration and noise on the rotor. Since the main rotor of a helicopter is the principal source of vehicle vibration, active twist control offers possibility of a low vibration helicopter. This paper reviews the literature in active twist rotor control using smart materials.