Analysis and Control of a Magnetorheological Landing Gear System for a Helicopter

• Published in: Journal of the American Helicopter Society Vol. 61; no. 3; pp. 1 - 8
• Main Authors: Choi, Young-Tai, Robinson, Ryan, Hu, Wei, Wereley, Norman M., Birchette, Terrence S., Bolukbasi, Akif O., Woodhouse, Jin
• Format: Journal Article
• Language: English
• Published: AHS International 01.07.2016
• ISSN: 2161-6027
• DOI: 10.4050/JAHS.61.032006

This study develops the design analysis and control of adaptive magnetorheological landing gear dampers (MRLGDs) to enable adaptive shock mitigation in a lightweight helicopter. MRLGDs were designed to achieve a desired stroking load of 4000 lb (17.8 kN) over a desired equivalent sink rate range of 6-12 ft/ s (1.83-3.65 m/s). The design analysis at low equivalent sink rates, vs < 10 ft/s (3.05 m/s), was experimentally validated using ramp displacement inputs on a servo-hydraulic testing machine at low speed. To validate the analysis at high equivalent sink rates, vs > 10 ft/s (3.05 m/s), single damper drop tests were performed. Two force feedback control algorithms were developed to achieve the desired constant stroking load over the desired sink rate range, that is, (1) bang-bang current control and (2) continuous current control. The effectiveness of control algorithms was evaluated using both single damper drop tests and an iron-bird test setup with a landing gear system having a pair of forward and aft MRLGDs.