LQ Optimal Control Models with Incomplete Information

Indefinite LQ Optimal Control for Systems with Multiplicative Noises: The Incomplete Information Case

Advances in Computer Science, Intelligent System and Environment - Advances in Intelligent and Soft Computing ◽

10.1007/978-3-642-23777-5_60 ◽

2011 ◽

pp. 363-370

Author(s):

Guojing Xing ◽

Chenghui Zhang ◽

Peng Cui ◽

Huihong Zhao

Keyword(s):

Optimal Control ◽

Incomplete Information ◽

Multiplicative Noises ◽

Lq Optimal Control

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An LQ Approach to Active Control of Vibrations in Helicopters

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.2801171 ◽

1996 ◽

Vol 118 (3) ◽

pp. 482-488 ◽

Cited By ~ 24

Author(s):

Sergio Bittanti ◽

Fabrizio Lorito ◽

Silvia Strada

Keyword(s):

Optimal Control ◽

Active Control ◽

Linear Quadratic ◽

Control Effort ◽

Vibration Effect ◽

Suitable Definition ◽

Lq Optimal Control ◽

The One ◽

Definition Of ◽

And Control

In this paper, Linear Quadratic (LQ) optimal control concepts are applied for the active control of vibrations in helicopters. The study is based on an identified dynamic model of the rotor. The vibration effect is captured by suitably augmenting the state vector of the rotor model. Then, Kalman filtering concepts can be used to obtain a real-time estimate of the vibration, which is then fed back to form a suitable compensation signal. This design rationale is derived here starting from a rigorous problem position in an optimal control context. Among other things, this calls for a suitable definition of the performance index, of nonstandard type. The application of these ideas to a test helicopter, by means of computer simulations, shows good performances both in terms of disturbance rejection effectiveness and control effort limitation. The performance of the obtained controller is compared with the one achievable by the so called Higher Harmonic Control (HHC) approach, well known within the helicopter community.

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Suppression of ground resonance in rotorcraft using active landing gear

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/09544100211023008 ◽

2021 ◽

pp. 095441002110230

Author(s):

Arjun Krishnan ◽

Ashwin Krishnan ◽

Mark Costello

Keyword(s):

Optimal Control ◽

Control Mechanism ◽

Landing Gear ◽

Superior Performance ◽

Physical Parameters ◽

Mechanical Instability ◽

Ground Resonance ◽

Excited Oscillation ◽

Lq Optimal Control ◽

Lag Dampers

This article examines the fundamental aspects of controlling ground resonance in rotorcraft equipped with actively controlled landing gear. Ground resonance is a mechanical instability affecting rotorcraft on the ground. It occurs at certain rotor speeds, where the lead–lag motion of the rotor couples with the motion of fuselage creating a self-excited oscillation. Typically, passive or semi-active lag dampers are used to avoid instability; however, these are undesirable from a design and maintenance perspective. Innovations in active landing gear for rotorcraft, such as articulated robotic legs, have provided an alternate approach to avoid the instability, eliminating the need for lag dampers with respect to ground resonance. This article extends classic ground resonance to include movable landing gear and identifies key physical parameters affecting dynamic behavior. Applying LQ optimal control to this model, it is shown that ground resonance instability can be eliminated using active landing gear as the control mechanism, even when there is no lag damping present in the rotor. In addition, while superior performance is achieved when landing gear movement can occur both longitudinally and laterally, it is still possible to stabilize ground resonance with inputs in a single direction, albeit with reduced performance.

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