Multi-objective Design and Performance Analysis of Incremental Control Allocation-based Flight Control Laws

Abstract

The functional architecture of a flight control system (FCS) is driven by multiple objectives related to the aircraft’s operational mission and in-service performance targets. Control allocation (CA) is a common method to ensure adequate use of the available effector architecture once the number of control effectors linked to the FCS increases and the control problem becomes overdetermined. A primary CA design objective is to ensure that high-level motion control demands are met. However, the additional degrees of freedom offered by the control effector suite can also be exploited to perform secondary control tasks. In this light, this article focuses on the Incremental Control Allocation (INCA) framework in the context of in-flight optimization of arbitrary secondary flight control design objectives. An extension to the existing INCA concept is formulated that isolates this secondary control task from generating primary control demands. Moreover, an alternative, but closely related design method based on optimal control principles is proposed that extents the role of the control allocator to active control of the system dynamics. Design examples are demonstrated for least-squares minimization of total drag and control activity. These are analyzed in linear and nonlinear simulation scenarios based on an open-source General Dynamics F-16 simulation model.