higher harmonic control
Also found in: Acronyms.
higher harmonic control[¦hī·ər här′män·ik kən‚trōl]
An active control concept for reducing helicopter vibration levels, in which the control system senses vibrations originating with aerodynamic forces acting on the rotor blades, and applies high-frequency pitch motion to the rotor blades at very small angles to suppress this aerodynamic excitation.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.