Real-Time Moment Rate Constrained Control Allocation for Aircraft with a Multiply-Redundant Control Suite

The problem of aircraft control allocation is that of finding a combination of control positions that cause the resulting aircraft moments to most closely satisfy a given desired moment vector. The problem is easily solved for the case of an aircraft having three control surfaces, each of which primarily imparts moments in each of the three aircraft axes. In this simple case, the solution to the control allocation problem is uniquely determined. However, many current and future aircraft designs employ a larger set of control effectors, resulting in a control redundancy in the sense that more than one combination of control positions can produce the same desired moment. When taking into account both the position and rate constraints of the control effectors, the problem is significantly more complex. Constrained moment-rate control allocation guarantees a control solution that can achieve every possible moment that is physically realizable by the aircraft. Addressed here is the real-time performance of moment-rate constrained control allocation as tested on a desktop simulation. Issues that were deemed interesting or potentially problematic in earlier batch simulation, such as control chattering due to restoring and apparent control wind-up, are investigated and an evaluation is made of the overall feasibility of these algorithms. The purpose of the research is to confirm that the results obtained from batch simulation testing are also valid using maneuvers representative of real-time flight and representative simulation frame sizes, and to uncover potential problems not observed in batch simulation.

NOTE: An updated copy of this ETD was added on 05/29/2013.