Damage Mitigating Control of Rotorcraft

This paper investigates the feasibility and potential benefits of damage mitigating control (DMC) for rotorcraft. Minimization of damage rate is included in the control optimization. The design is formulated using linear parameter varying control, in which damage reduction and airspeed are included as parameters. The method is applied to control the vertical, yaw, and rotor RPM axes of a military helicopter, with the objective of minimizing damage to the main transmission while meeting level 1 handling qualities requirements over a range of flight conditions. The damage is represented by the length of a crack in the main bevel pinion of the transmission. The results of nonlinear simulations over a range of airspeeds validate the concept. Evaluation of handling qualities using the ADS-33E specification show that significant reduction in damage rate can be achieved with minimal reduction in handling qualities.