Triple-Integral Control for Reduced-G Atmospheric Flight

Afman, Juan-Pablo; Féron, Éric; Hauser, John

doi:10.23919/acc.2018.8431251

Cited by 10 publications

(7 citation statements)

References 8 publications

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“…When ( 2) is linear time-invariant-equivalently, when k = 1-the system (2) is stable if and only if there exists a quadratic Lyapunov function for (2). This is, however, not true in the general setting of (2); indeed, there exists stable switched systems for which no quadratic Lyapunov function exists [1].…”

Section: Notation and Preliminariesmentioning

confidence: 99%

“…They are useful abstractions for studying systems with uncertain parameters, and they can be used to represent mode-switched systems when the switching scheme may be unknown. In all cases, computing stability margins is an important exercise, with practical benefits for safety critical systems [2]. In the following, we study both switched-linear and LTV systems in an equivalent manner and propose methods to compute upper and lower bounds on a system's stability margin.…”

Section: Introductionmentioning

confidence: 99%

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A Numerical Method to Compute Stability Margins of Switching Linear Systems

Klett¹,

Abate²,

Coogan³

et al. 2020

Preprint

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Stability margins for linear time-varying (LTV) and switched-linear systems are traditionally computed via quadratic Lyapunov functions, and these functions certify the stability of the system under study. In this work, we show how the more general class of homogeneous polynomial Lyapunov functions is used to compute stability margins with reduced conservatism, and we show how these Lyapunov functions aid in the search for periodic trajectories for marginally stable LTV systems. Our work is premised on the recent observation that the search for a homogeneous polynomial Lyapunov function for some LTV systems is easily encoded as the search for a quadratic Lyapunov function for a related LTV system, and our main contribution is an intuitive algorithm for generating upper and lower bounds on the system's stability margin. We show also how the worst-case switching scheme-which draws an LTV system closest to a periodic orbit-is generated.Three numerical examples are provided to aid the reader and demonstrate the theoretical contributions of the work.

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Section: Notation and Preliminariesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Numerical Method to Compute Stability Margins of Switching Linear Systems

Klett¹,

Abate²,

Coogan³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…However, a few applications exist for which these performance measures do not form part of the UAV design requirements. An example is the use of UAVs as research platforms to enable microgravity for an on-board payload [1,15,18,19]. For such UAVs, the main performance criterion is the ability to maintain a desired constant acceleration-free-fall-so that the payload experiences microgravity for a specified duration.…”

Section: Introductionmentioning

confidence: 99%

“…Flight tests producing reduced gravity using conventional quadrotors have been reported in Siddhardha [28], and using quadrotors with variable pitch propellers in Afman et al [1]. A conventional quadrotor with fixed-pitch propellers, however, cannot be used to produce microgravity in the descend part of the free-fall manoeuvre as it does not have reverse thrust producing capability which is required to maintain free-fall despite the drag forces acting on it.…”

Section: Introductionmentioning

confidence: 99%

“…A conventional quadrotor with fixed-pitch propellers, however, cannot be used to produce microgravity in the descend part of the free-fall manoeuvre as it does not have reverse thrust producing capability which is required to maintain free-fall despite the drag forces acting on it. In Afman et al [1], the authors proposed a proportional-integralquadratic-ramp control structure for their variable pitch quadrotor to achieve and maintain a constant experienced acceleration equal to Martian gravity for a small duration. Such a complex control structure was required, because their control design was based on a model blind approach; that is, they ignored the underlying rotor aerodynamic effect on thrust in axial flight conditions, and considered only drag among the factors that influence the vehicle's acceleration.…”

Section: Introductionmentioning

confidence: 99%

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Acceleration control of a multi-rotor UAV towards achieving microgravity

Kedarisetty

Manathara

2019

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In this paper, we present control and parameter estimation strategies with theoretical guarantees to turn a hex-rotor unmanned aerial vehicle (UAV) into a microgravity enabling platform. We make the UAV to maintain a constant acceleration equal to freefall acceleration for it and any payload on-board to experience microgravity. Towards this, we derive a feedback linearisationbased acceleration control law exploiting the differential flatness property of our system. The proposed control law requires the estimates of the system parameters. Therefore, ancillary to this control law, we propose a parameter estimation scheme and prove that the proposed control law along with the parameter estimation scheme ensures convergence of acceleration to the desired value under certain conditions. We also characterize these conditions that guarantee convergence. The flight tests that we have performed employing the proposed control and parameter estimation schemes gave microgravity levels of the order of 10 −3 g for 1.6 s. To our knowledge, our hex-rotor UAV is the first multi-rotor UAV to achieve microgravity, and the first UAV-fixed-wing or rotary-to attain and maintain such levels of microgravity.

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Performance Assessment Framework for Multirotor Unmanned Aerial Vehicle Microgravity Platforms

Kedarisetty,

George Manathara

2023

Microgravity Sci. Technol.

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Triple-Integral Control for Reduced-G Atmospheric Flight

Cited by 10 publications

References 8 publications

A Numerical Method to Compute Stability Margins of Switching Linear Systems

A Numerical Method to Compute Stability Margins of Switching Linear Systems

Acceleration control of a multi-rotor UAV towards achieving microgravity

Performance Assessment Framework for Multirotor Unmanned Aerial Vehicle Microgravity Platforms

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