Magnetorheological fluid damper feedback linearization control for helicopter rotor application

Abstract

This study explores the possible use of a magnetorheological (MR) damper with feedback linearization control law for helicopter lag damping applications. Since this control law is based on an assumed damper model, the helicopter may be susceptible to limit cycle instabilities in the presence of model errors due to uncertainties (even if the prescribed damping using feedback linearization control is greater than the system negative damping). For specified uncertainty bounds, a robust control law can be synthesized which will eliminate limit cycle instability by using a much larger value of prescribed damping ratio. The resulting periodic loads in forward flight, however, would be excessively high. To reduce these periodic loads a band-rejecting filter is introduced that eliminates the 1/rev component of velocity from the feedback control signal. By doing so, stability of perturbation motions can be ensured and periodic loads can be drastically reduced, even in the presence of MR damper model errors.

Modeling and identification of a small scale magnetorheological damper

“…These devices have small and large scale applications depending on their dimensions. Typically, Small MR damper forces range around 1000 N and have been used, among others, as shock absorbers for vehicle's and motorcycle's suspension Poynor (2001); Gravatt (2003), cars seat suspension Choi et al (2000), vibration control in helicopters rotors F. Gandhi and Xia (2001) and prosthetic limbs J.D. Carlson and Toscano (2001).…”

Vibration Analysis and Models of Adjacent Structures Controlled by Magnetorheological Dampers

“…The device uses the typical property of controllable magnetorheological fluids: when exposed to a magnetic field, it can change in milliseconds its characteristics from a linear viscous fluid to a semisolid state. The literature reports many applications of MR dampers in several engineering fields, including mechanics, aerospace and robotic [26], and also biomedical [27] and civil engineering [28]. The prototype of the MR damper is the RD-1005-3 model, produced by the Lord Corporation.…”

Force control of semi‐active valve lag dampers for vibration reduction in helicopters

“…Magnetorheological fluids consist of micro-sized, magnetically polarisable particles dispersed in a carrier medium such a silicon or mineral oil [10]. When a magnetic field is applied to the fluid, particle chains form and the fluid becomes semi-solid displaying viscoplastic behaviour.…”

“…When a magnetic field is applied to the fluid, particle chains form and the fluid becomes semi-solid displaying viscoplastic behaviour. Changes in the applied magnetic field leads to changes in the damper force hence improving the adaptability characteristics [10]. Laboratory work has shown that lag damper versions of MRFE dampers also have amplitude-and frequencydependent behaviour [13], [12].…”