A Multi-Objective Flight Control Approach for Performance Adaptive Aeroelastic Wing

Abstract

As aircraft wings become much more flexible due to the use of lightweight composites material, adverse aerodynamics at off-design performance can result from changes in wing shapes due to aeroelastic deflections. Increased drag, hence more fuel burn, is a potential consequence. Without means for aeroelastic compensation, the benefit of weight reduction from the use of lightweight material could be negated by less optimal aerodynamic performance at off-design. Performance Adaptive Aeroelastic Wing (PAAW) technology can potentially address these technical challenges for future flexible wing transports. PAAW technology leverages multidisciplinary solutions to maximize the aerodynamic performance payoff of future adaptive wing design, while addressing simultaneously operational constraints that can prevent the aerodynamic performance from being realized. These operational constraints include reduced aeroelastic stability margins, increased airframe responses to gust and maneuver loads, pilot handling qualities, and ride qualities. All of these constraints while seeking the maximum aerodynamic performance present themselves as a multi-objective flight control solution. The paper presents a multi-objective flight control approach based on a drag-cognizant optimal control method. A concept of virtual control, which was previously introduced, is implemented to address the pair-wise flap motion constraints imposed by the elastomer material. This method is shown to be able to satisfy the constraints. Real-time drag minimization control is considered to be an important consideration for PAAW technology. Drag minimization control has many technical challenges such as sensing and control. An initial outline of a real-time drag minimization control is proposed and will be further investigated in the future. A simulation study of a multi-objective flight control for a flight path angle command with aeroelastic mode suppression and drag minimization demonstrates the effectiveness of the proposed solution.

Performance Optimizing Gust Load Alleviation Control of Flexible Wing Aircraft

“…The resulting forces are coupled to both the aircraft flight dynamics and aeroelasticity leading to the gust-disturbed equations of motion given in Eqs. 1and (2). A more detailed description of this process is provided in Ref.…”

“…The multi-objective optimal control approach used here for the GLA controller has been previously used to facilitate other performance-enhancing aircraft control designs. [1][2][3][4] In particular the technique has been show to be effective for both drag minimization 1,2 and maneuver load alleviation. 3 However, these implementations relied on all quantities required for control formulation being known.…”

Adaptive Maneuver Load Alleviation for Flexible Wing Aircraft with Nonminimum Phase Zeros

“…The VCCTEF can be used to exploit the increased flexibility of the wing by aeroelastically shaping the structure to facilitate performance goals such a drag minimization and load alleviation. [17][18][19] For simplicity, however, the VCCTEF segments are actuated as a single unit here. The GTM model consists of the coupled rigid body and elastic dynamics.…”

Gust Load Alleviation and Ride Quality Improvement with Incremental Nonlinear Dynamic Inversion

“…In order to find a balance between load alleviation and command tracking performance, a multi-objective cost function is needed. 3 The system is augmented with the integration of the tracking error x e = ∫ t…”

“…Linearizing the coupled EQM on preselected trimming points, and applying the linear control methods is a common practice, [2][3][4] which however, requires the gain scheduling technique when multiple operation points are considered. The parameter tuning and interpolation process of gain scheduling method can be tedious.…”