Linear quadratic Gaussian/loop transfer recovery design for a helicopter in low-speed flight

Abstract

A control law for a helicopter in low-speed flight is designed using the linear quadratic Gaussian/loop transfer recovery method. The specifications are adapted from a subset of the U.S. Army helicopter handling qualities requirements. The design model consists of the rigid-body dynamics linearized about the 30 kt forward flight condition, together with a simplified, low-order representation of actuator and rotor dynamics. Evaluation is performed using higher-order models, obtained by linearization about several different points in the flight envelope, covering the speed range from 10 to 50 kt. These models contain more accurate representations of the high-frequency actuator and rotor modes. The final selection of the numerical values of the linear quadratic parameters is made by numerical optimization of the loop shape. It is found that the specifications considered can be satisfied for all of the evaluation models without gain scheduling.

Robust multi-mode flight control design for an unmanned helicopter based on multi-loop structure

“…However it does not provide a systematic way to consider uncertainties, disturbance, input saturation and cross-couplings among channels, [8]. Thereafter, researchers used multivariable techniques for design of stability augmentation and guidance systems for helicopter, such as Eigenstructure Assignment [9], LQG/LQG [10], µ -synthesis [11], H 2 [12], and H ∞ [13][14][15][16]. Among MIMO approaches, H ∞ theory is the most widely used in recent decade as it provides robust stability for systems subject to uncertainty and disturbance.…”

“…Control design for unmanned helicopter has been considered as a challenge in aeronautical field over decades [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The main difficulties, in designing controllers for UAH, can be generally characterized as underactuated, cross-coupled, large uncertainties, openloop instabilities and highly nonlinear dynamics, [2,3,5].…”

“…In spite of all these challenges, a number of researchers have worked on designing UAHs and wide set of design techniques, from classical control to neuralbased adaptive control, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], have been reported. Among early control technique, one-loop-at-a-time control design methods, based on classical single input single output (SISO) techniques with a proportionalplus-integral (PI) configuration are the most widely used [5][6][7][8].…”

A novel MOGA-based method of flight control law design for a helicopter and its application

“…At present, many modern control theories such as eigenstructure assignment (EA) [1][2], H ∞ robust control [3][4], quantitative feedback theory (QFT) [5][6], dynamic inversion and linear quadratic gauss (LQG) [7][8][9] have been successfully applied to flight control laws design for specified helicopters (see [1][2][3][4][5][6][7][8][9]). Besides, the classical full-flight-envelop method is still widely used in engineering projects due to its simplicity and mature.…”

Stability Analysis of a Helicopter with an External Slung Load System

“…The control problem has been tackled using different approaches ranging from linear quadratic control [6], eigenstructure assignment [7], classical SISO techniques [8], to sliding mode control [9]. Apart from the methods emphasised above there are many other techniques which are reported for complex modern control system design ranging from quantitative feedback theory to singular perturbation method [10].…”