Investigation of Optimal Control Allocation for Gust Load Alleviation in Flight Control

Abstract

Advances in sensors and avionics computation power suggest real-time structural load measurements could be used in flight control systems for improved safety and performance. A conventional transport flight control system determines the moments necessary to meet the pilot's command, while rejecting disturbances and maintaining stability of the aircraft. Control allocation is the problem of converting these desired moments into control effector commands. In this paper, a framework is proposed to incorporate real-time structural load feedback and structural load constraints in the control allocator. Constrained optimal control allocation can be used to achieve desired moments without exceeding specified limits on monitored load points. Minimization of structural loads by the control allocator is used to alleviate gust loads. The framework to incorporate structural loads in the flight control system and an optimal control allocation algorithm will be described and then demonstrated on a nonlinear simulation of a generic transport aircraft with flight dynamics and static structural loads.

Active Gust Load Alleviation of High-Aspect Ratio Flexible Wing Aircraft

“…In previous research, [21][22][23][24] the wing root bending moment M y and the rigid-body x r and elastic state x e responses have been selected as the main performance metrics to consider. Consequently, the performance metrics relating to these variables (1, 2, and 5) will be considered to be of most importance.…”

Modelling and Control of an Urban Air Mobility Vehicle Subject to Empirically-Developed Urban Airflow Disturbances

“…The oncoming gust can be sensed using, Doppler LIDAR [20,21], angle of attack sensors [22], or aircraft mounted accelerometers [23]. The gust information gathered by these sensor systems can be used with active control techniques to actuate lifting surfaces [20,24] or flow control devices [23,25] which reduce the change in aircraft lift coefficient and wing bending moments. Passive control techniques have also been demonstrated, which accomplish the same goal of alleviating gust loading to the aircraft [26].…”

Advanced Gust Load Alleviation using Dynamic Control Allocation

“…In case of over-actuation, saturation effects may also be avoided by redistributing the demanded control power in real-time using dynamic control allocation [12]. For example, [13] implements a control allocation system for primary flight control which considers structural load constraints as a secondary objective. A similar approach is followed in [14], where the control allocation problem is formulated in terms of a quadratic program instead of a linear program.…”