Cooperative actuator fault accommodation in formation flight of unmanned vehicles using absolute measurements

Abstract

In this study, the problem of cooperative fault accommodation in formation flight of unmanned vehicles represented by linear time-invariant models that are subject to loss-of-effectiveness actuator faults is investigated through a hierarchical framework. Three hierarchical levels are envisaged, namely a low-level fault recovery (LLFR), a formation-level fault recovery and a high-level supervisor. In the LLFR module, a recovery controller is designed by using an estimate of the actuator fault. A performance monitoring module is then introduced at the high-level to identify a 'partially low-level recovered' vehicle because of inaccuracy in the fault severity estimate that results in violating the 'error specification' of the formation mission. The high-level supervisor then activates the formation-level fault recovery module to compensate for the resulting performance degradations of the partially low-level (LL) recovered vehicle at the expense of other healthy vehicles. The fault is accommodated by reconfiguring the formation structure through the novel notion of the weighted absolute measurement formation digraph, activating a robust controller for the partially LL recovered vehicle, and imposing a constraint on the desired input signals. Numerical simulations for a formation flight of five satellites in the planetary orbital environment are presented to confirm the validity and effectiveness of the proposed analytical work.

Robust adaptive hierarchical insensitive tracking control of a class of leader-follower agents

“…That means u j (t), x j (t), η j (t), andψ j (t), j ∈ {Ω 0 ∪ Ω 1 } are bounded signals based on the definitions of controllers (4) and (5), control gain functions (12) and (28), error functions (8) and (9), and adaptive laws (14), (15), (29), and (30). Then it can be concluded that the signalẋ j (t) is bounded from the description of agent (1). Thus, the closed-loop system model of the third layer agents can be constructed similarly to the second layer agents in (26).…”

“…[1,11,13,17,24,34]). In this kind of topology structure, agents can be divided into several layers based on information flow.…”

Networked Estimation of Multi‐Agent Systems Subject to Faults and Unreliable Information

“…In the remainder of the paper, we consider a general state space representation of an LTI system S as given by (5). In the following, the associated state dependency (SD) directed graph (digraph) of the linear multi-agent system (5) is introduced [14,23].…”

“…Procedure 1. Consider the LTI system associated with N multi-agent system that is governed by (5) with the corresponding state dependency (SD) digraph as specified by Definition 2. The sub-observer SO (i) is designed by choosing…”

“…From this perspective, our proposed networked estimation approach can be classified as an active and reconfigurable methodology as opposed to the conventional passive estimation techniques in the literature. This paper is a generalization of our previous work in [8] to the case of "multi-agent systems" subject to "faults", which requires a new formulation in the "networked" estimation framework (Definition 1 and Equations (1)- (5)), whereas in [8] a general state space model of linear time-invariant (LTI) systems was considered albeit through multi-agent and supervisory approaches. As compared to [8], in this paper the definition of a sub-observer (Definition 3) is revised and modified based on the notion of the "neighboring sets".…”