Design and implementation of a piezoelectric servo-flap actuation system for helicopter rotor individual blade control

A novel new actuator for helicopter rotor control, the X-Frame Actuator, was developed, demonstrating superior performance for applications requiring compact, fast acting, large stroke actuation. The detailed experimental characterization of this actuator is described, including bench-top output energy measurements and transverse shake test performance. A Mach scaled rotor blade utilizing the X-Frame actuator to power a trailing edge servo-flap near the tip was also designed, manufactured and tested. A description of the design and composite manufacturing of the rotor blade and servo-flap is presented. Preliminary bench tests of the active blade actuation system are also presented. The hover tests of the active blade provided transfer function identification of the performance of the actuator in producing flap deflections, and the response of the rotor from deflections of the servo-flap. At the highest field level of 60 V/mil P-P the actuation system produces 7.75 degrees of quasi-static peak-to-peak flap deflection in hover. The servo-flap produces significant control authority, especially near the 3/rev frequency that would be important for the CH-47. Scaled to a full-sized CH-47, the rotor can produce over 16,000 lb peak-to-peak thrust variation at 3/rev, which is 32% of the aircraft's gross weight. Closed-loop feedback control was experimentally applied to the model rotor system. Both single frequency and combined frequency controllers were successfully implemented on the rotor. Most significantly, simultaneous control of 1/rev, 3/rev, 4/rev, 5/rev, and 6/rev harmonic vibration has been successfully demonstrated. The peak vibrations were eliminated at each frequency, as well as the vibrations over a small bandwidth surrounding each peak. Experimental comparison of continuous time versus discrete time control has shown the former to be a more effective approach for vibration reduction.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2000

Author dc:creator

• Prechtl, Eric Frederick

Advisor dc:contributor.advisor

• Steven R. Hall.

• Aeronautics and Astronautics.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/9266

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/9266