Adaptive landing gear concept—feedback control validation

Abstract

The objective of this paper is to present an integrated feedback control concept for adaptive landing gears (ALG) and its experimental validation. Aeroplanes are subjected to high dynamic loads as a result of the impact during each landing. Classical landing gears, which are in common use, are designed in accordance with official regulations in a way that ensures the optimal energy dissipation for the critical (maximum) sink speed. The regulations were formulated in order to ensure the functional capability of the landing gears during an emergency landing. However, the landing gears, whose characteristics are optimized for these critical conditions, do not perform well under normal impact conditions. For that situation it is reasonable to introduce a system that would adapt the characteristics of the landing gears according to the sink speed of landing. The considered system assumes adaptation of the damping force generated by the landing gear, which would perform optimally in an emergency situation and would adapt itself for regular landings as well. This research covers the formulation and design of the control algorithms for an adaptive landing gear based on MR fluid, implementation of the algorithms on an FPGA platform and experimental verification on a lab-scale landing gear device. The main challenge of the research was to develop a control methodology that could operate effectively within 50 ms, which is assumed to be the total duration of the phenomenon. The control algorithm proposed in this research was able to control the energy dissipation process on the experimental stand.

The Recent Advances in Magnetorheological Fluids-Based Applications

“…mechanism [58]. Moreover, the MRF can be used as the pneumatic rotary actuator to control rotary motion and velocities [44,[59][60][61]74].…”

A European Association for the Control of Structures joint perspective. Recent studies in civil structural control across Europe

“…• MR fluid-based shock absorbers [72] • Piezo-valve based hydraulic/pneumatic shock absorbers [72,73] • adaptive Inflatable Structures AIS [71,72] • impactometer for online impact load identification [74] • various strategies of active flow control for pneumatic/hydraulic valves [73] • various strategies of active control for online pressure release in AIS systems (eg. adaptive airbags) [71,75] • systems based on multi-folding-snap-through effect [72,76] Promising fields of applications currently under investigation are the following:…”

Vibration Attenuation of Magnetorheological Landing Gear System with Human Simulated Intelligent Control

“…In this model, the landing object is treated as rigid body, which is slightly different to the actual case. The internal characteristics (stiffness and damping properties) are neglected in this study, although they are very important for the final landing scenario [7]. However, the simple model is sufficient to formulate the control strategy, and the model can describe main dynamic behaviors of a landing gear during touchdown.…”

“…Here is the lift factor and is chosen to be 0.667 [7]. describes the nonlinear spring force of a tire given by .…”

“…According to the energy balance, the optimal control force is calculated. The researches [4][5][6][7] indicate that the control method based on energy balance is simple and effective and easy to understand for the single degree of landing gear system. When higher degree dynamic landing gear system or practical case is applied, the control strategy may have difficulty in calculating the energy sometimes it is even impossible considering the many uncertainties and nonlinearity in a practical landing gear system.…”