Jonathan Rogers's research while affiliated with Georgia Institute of Technology and other places

Publications (98)

Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-2741.vid The private eVTOL/UAM market is rapidly expanding, with many companies and investors betting on the possibility of low-cost-to-operate and zero emissions air taxis and last-mile-delivery sUAS dominating the skies of cities in the near future. While fixed wing and rotary wing aircraft...
Article
This paper demonstrates the extension of the harmonic decomposition methodology, originally developed for rotorcraft applications, to the study of the nonlinear time-periodic dynamics of flapping-wing flight. A harmonic balance algorithm based on harmonic decomposition is applied to find the periodic equilibrium and approximate linear time-invarian...
Article
The public road setback distance is often an important factor that drives wind farm design. This paper outlines a methodology for assessing the risk imposed by blade throw at various road setbacks using a physics-based simulation approach. Given a road setback distance, Monte Carlo simulation is performed wherein blade throw parameters and vehicle...
Conference Paper
Full-text available
A novel trajectory generation and control architecture for fully autonomous autorotative flare is proposed that combines rapid path generation with model-based control. The trajectory generation component uses optical Tau theory to compute flare trajectories for both longitudinal and vertical vertical speed. These flare trajectories are tracked by...
Article
Motion primitive planning under parametric uncertainty may be modeled as a chance-constrained Markov Decision Process (CCMDP). Single-query solutions to CCMDPs can be obtained by searching the And/Or graph representing the state–action space of the system. The Risk-bounded AO* (RAO*) algorithm has been proposed as a solution method for this problem...
Article
This paper describes a novel approach to regime recognition based on the notion of motion primitives. Originally developed for path planning, motion primitives decompose a vehicle trajectory into maneuver and trim segments. In a regime recognition context, this decomposition can be used to improve component life tracking through separate classifica...
Article
Condition-based maintenance programs for modern helicopters rely on algorithmic techniques to estimate the useful life remaining for life-limited components. Regime-recognition-based condition-based maintenance programs involve a regime recognition step and a damage estimation step in which damage is calculated based on the identified regimes. Rece...
Article
Multi-unmanned aerial vehicle (UAV) cooperative lift systems use multiple UAVs to collectively lift and transport payloads. These systems have unique benefits over standard single-vehicle logistics paradigms in that they distribute lift capacity among several potentially inexpensive and man-portable aircraft, and furthermore provide redundancy to g...
Conference Paper
Full-text available
This paper demonstrates the extension of the harmonic decomposition methodology, originally developed for rotor-craft applications, to the study of the nonlinear time-periodic dynamics of flapping-wing flight. A harmonic balance algorithm based on harmonic decomposition is successfully applied to find the periodic equilibrium and approximate linear...
Conference Paper
Predicting the probability of dynamic component failure in aircraft is of interest to both civilian and military operators for safe and cost-effective component retirement. While aircraft OEM assumed usage spectra have been used throughout the years for fatigue forecasting and for creation of part replacement timelines, advancements in aircraft reg...
Article
The selection of model structure is an important step in system identification for nonlinear systems in cases where the model form is not known a priori. This process, sometimes called covariate selection or sparsity identification, involves the selection of terms in the dynamic model and is performed prior to parameter estimation. Previous work ha...
Article
Probabilistic inverse problems arise in a variety of scientific and engineering applications. A particular type of probabilistic inverse problem, termed a generalized aggregate data inverse problem, involves the specification of expected value targets and/or probabilistic constraints at discrete times or in a discrete set of transformed domains. Be...
Article
In this paper, a numerical method is proposed for determining the periodic state and control solutions of nonlinear time-periodic systems. Starting from an initial guess at the solution, the algorithm uses a harmonic balance technique to refine the solution through a gradient-based optimization approach. The algorithm introduces three major innovat...
Article
There is increasing demand for full or partial automation of autorotation maneuvers for next-generation helicopters, which may be optionally piloted or capable of fully autonomous flight. A key challenge in the development of autorotation controllers lies in the competing state constraints that often arise during the terminal, or flare, phase of th...
Conference Paper
Autorotation is a challenging flight maneuver that involves highly coordinated control actions and competing constraints. It is generally recognized that pilot performance in autorotation may benefit from additional cues that improve decision-making as well as timing and coordination of control inputs. This paper describes the development and simul...
Conference Paper
Full-text available
An alternative approach to regime recognition that is based on the notion of motion primitives is developed. The algorithm developed is non-causal and leverages the ideas of maneuvers and trims as defined in a motion primitive context. The algorithm functions in three major steps. Given a state and control input time history obtained from flight da...
Conference Paper
Full-text available
Modern flight vehicle development typically involves significant uncertainty in aerodynamic loads and vehicle control responses. In many cases, it may be necessary to consider this uncertainty in preliminary evaluations of stability, handling qualities (HQ), and performance. This paper introduces a novel methodology for computing these quantities i...
Preprint
Full-text available
For dynamical systems involving decision making, the success of the system greatly depends on its ability to make good decisions with incomplete and uncertain information. By leveraging the Koopman operator and its adjoint property, we introduce the Koopman Expectation, an efficient method for computing expectations as propagated through a dynamica...
Preprint
In this paper, we present an online adaptive robust control framework for underactuated brachiating robots traversing flexible cables. Since the dynamic model of a flexible body is unknown in practice, we propose an indirect adaptive estimation scheme to approximate the unknown dynamic effects of the flexible cable as an external force with paramet...
Preprint
Control of wire-borne underactuated brachiating robots requires a robust feedback control design that can deal with dynamic uncertainties, actuator constraints and unmeasurable states. In this paper, we develop a robust feedback control for brachiating on flexible cables, building on previous work on optimal trajectory generation and time-varying L...
Article
Autorotation maneuvers inherently offer little margin for error in execution and induce high pilot workload, particularly as the aircraft nears the ground in an autorotative flare. Control augmentation systems may potentially reduce pilot workload while simultaneously improving the likelihood of a successful landing by offering the pilot appropriat...
Article
Regime recognition (RR) is an important aspect of condition-based maintenance for modern helicopters. RR involves the postflight classification of flight data into regime categories. These classifications are then used to predict fatigue damage and vehicle usage spectra. Although several RR algorithms have been proposed to date, many suffer from an...
Article
Full-text available
Wind turbine curtailment is oftentimes required as a means to mitigate environmental impacts of a wind energy installation. For example, curtailment may be required to satisfy constraints on the occurrence of shadow flicker on nearby homes or to reduce wildlife fatalities below a certain limit. This paper introduces an optimal curtailment strategy,...
Article
High-altitude low-opening airdrop is a technique for aerial delivery that has unique operational advantages. The primary decisions that must be made in execution of these missions are the aircraft release heading, package release point, and altitude at which the package transitions from the drogue to the main ballistic parachute. Algorithms have re...
Conference Paper
Full-text available
This paper proposes a novel mathematical methodology for probabilistic handling qualities evaluation using the Koopman operator. The Koopman operator is used to quantify the impact of parametric uncertainty in a pilot model to specific pilot-vehicle system performance specifications and to perceived vehicle handling qualities. The considered specif...
Article
The use of motion primitives to plan trajectories has received significant attention in the robotics literature. This work considers the application of motion primitives to path planning and obstacle avoidance problems in which the system is subject to significant parametric and/or initial condition uncertainty. In problems involving parametric unc...
Article
Unmanned aerial vehicles are increasingly being tasked to connect to payload objects or docking stations for the purposes of package transport or recharging. However, autonomous docking creates challenges in that the air vehicle must precisely position itself with respect to the dock, oftentimes in the presence of uncertain winds and measurement er...
Article
Mission planning for ballistic airdrop requires the selection of optimal control inputs under uncertainty. While significant uncertainty usually exists in airdrop scenarios, current mission planning algorithms use only nominal parameters to compute a deterministic solution. This paper introduces an optimal control algorithm in which the Koopman ope...
Conference Paper
Regime recognition is a critical tool used for condition-based maintenance, fatigue life prediction, and creation of usage spectra for military and commercial rotorcraft. While a variety of regime recognition algorithms are currently in use, many current algorithms suffer from an over-reliance on training data or poor classification accuracy with r...
Article
Cooperative transportation of payloads by multiple unmanned air vehicles has received increasing interest due to unique operational advantages. These include the portability of the individual vehicles and the scalability of the lifting strategy in the presence of differing payloads. By rigidly attaching a set of unmanned air vehicles to a payload,...
Conference Paper
Autorotation to landing is a difficult manoeuvre to accomplish successfully in an emergency. During autorotation, it is critical to simultaneously maintain the desired flight path, decelerate the aircraft appropriately, all whilst locating and reaching a safe location to land. This significantly increases the pilot work load in the cockpit. Therefo...
Article
Weapon-target assignment is a multi-agent control problem in which each weapon is assigned to a target to minimize the expected survival value of the targets. In this work, a multi-objective version of the weapon-target assignment problem is considered in which the quality of an assignment is dependent on both the total effectiveness of the weapons...
Article
Parameter estimation and model order reduction (MOR) are important system identification techniques used in the development of models for mechanical systems. A variety of classical parameter estimation and MOR methods are available for nonlinear systems but performance generally suffers when little is known about the system model a priori. Recent a...
Article
Payload transportation via connected modular unmanned aerial vehicles is an emerging new area that offers unique advantages over other forms of aerial logistics. When considering rigidly attached, modular, vertical lift, unmanned aerial vehicles, differing payloads and vehicle attachment geometries have a significant effect on the composite aircraf...
Conference Paper
Parameter estimation and model order reduction (MOR) are important techniques used in the development of mechanical system models. A variety of classical parameter estimation and MOR methods are available for nonlinear systems but performance generally suffers when little is known about the system model a priori. Recent advancements in information...
Article
Regime recognition is an important tool in the creation of usage spectra and component lifetime prediction. During development of regime recognition codes, it is necessary to establish baseline performance using scripted flight-test data. Various problems arise when using scripted flight data for verification and validation that may be mitigated by...
Article
A probabilistic algorithm for the optimization of drogue-to-main parachute transition altitude is proposed for high-altitude, low-opening ballistic airdrop. In light of the significant effects of wind and model uncertainty on impact-point dispersion, the algorithm makes use of explicit nonlinear uncertainty propagation techniques to provide a proba...
Article
Microspoiler actuators have been established as a viable control mechanism for gun-launched guided projectiles. Although the geometric configuration of the microspoilers is known to have a large impact on control authority, these geometrical dependencies have previously not been well characterized. This work seeks to derive an optimal microspoiler...
Article
Actively controlled gun launched projectiles require a means of modifying the projectile flight trajectory. While numerous potential mechanisms exist, microspoiler devices have been shown to be a promising control actuator for fin-stabilized projectiles in supersonic flight. These devices induce a trim force and moment generated by the boundary-lay...
Conference Paper
Full-text available
This paper details the design and limited flight testing of a preliminary system for visual pilot cueing during autorotation maneuvers. The cueing system is based on a fully-autonomous, multi-phase autorotation control law that has been shown to successfully achieve autonomous autorotation landing in unmanned helicopters. To transition this control...
Article
Honeypots derive much of their value from their ability to fool attackers into believing they're authentic machines. Current cyber-physical system (CPS) honeypots fail to sufficiently capture and simulate behavior that's necessary to project this authenticity. In response, the HoneyPhy framework was developed for CPS honeypots that takes into accou...
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Full-text available
Parameter estimation is an important topic in the field of system identification. This paper explores the role of a new information theory measure of data dependency in parameter estimation problems. Causation entropy is a recently proposed information-theoretic measure of influence between components of multivariate time series data. Because causa...
Article
Weapon-target assignment is a combinatorial optimization problem in which a set of weapons must selectively engage a set of targets. In its decentralized form, it is also an important problem in autonomous multi-agent robotics. In this work, decentralized methods are explored for a modified weapon-target assignment problem in which weapons seek to...
Article
Successful navigation of small, unmanned aerial vehicles (UAVs) in cluttered environments is a challenging task, especially in the presence of turbulent winds and state estimation uncertainty. This paper proposes a probabilistic path planner for UAVs operating in cluttered environments. Unlike previous sampling-based approaches which select robust...
Article
The k-vector search technique is a method designed to perform extremely fast range searching of large databases at computational cost independent of the size of the database. k-vector search algorithms have historically found application in satellite star-tracker navigation systems which index very large star catalogues repeatedly in the process of...
Article
Performance optimization of guided, gun-launched projectiles is a difficult task due to nonlinear flight behavior, complex aerodynamic interactions, and unique engineering constraints. Historically, the design process for many smart weapons has been iterative in which a series of design improvements are made until performance requirements have been...
Article
A probabilistic approach to unguided airdrop mission planning is proposed. The algorithm proceeds in four stages, beginning with specification of the desired impact dispersion pattern in the form of a probability density function (PDF). This PDF is propagated backwards in time using the Stochastic Liouville Equation, an explicit method for nonlinea...
Article
This paper presents the development of a 12-degree-of-freedom flight dynamics model for a small-scale unmanned helicopter in both hovering and forward flight. The helicopter was fully instrumented and flight-tested for this modeling work. The development of this detailed model, appropriate for the design of a high-bandwidth control system, for such...
Article
Control of autonomous systems subject to stochastic uncertainty is a challenging task. In guided airdrop applications, random wind disturbances play a crucial role in determining landing accuracy and terrain avoidance. This paper describes a stochastic parafoil guidance system which couples uncertainty propagation with optimal control to protect ag...
Article
An algorithm for simultaneous tracking of multiple ground targetsbyan unmanned aerial vehicleis presented. The algorithm isspecifically tailored toward multirotor vehicles, and itconsistsofa particle filtertopredict target motion, a reference trajectory generator, and a finite-horizon model predictive controller for trajectory tracking. Two version...
Article
Small-diameter gun-launched projectiles pose a challenging platform on which to implement closed-loop guidance and control. This paper presents a novel imager-based guidance and control algorithm for small-diameter spin-stabilized projectiles. The control law is specifically formulated to rely on feedback only from a strapdown detector and roll ang...
Conference Paper
An algorithm for autonomous multirotor tracking of an arbitrary number of ground targets is formulated and evaluated through simulation. The algorithm consists of a particle filter to predict target motion, trajectory generator, and model predictive controller operating over a finite time horizon. Furthermore, a target selection algorithm is includ...
Conference Paper
It is well-known that the dynamics of spinning artillery projectiles are highly nonlinear, and that nonlinear effects can induce instability in some projectiles given certain flight conditions. In this paper, a new simplified nonlinear formulation of the angle of attack dynamics for gun-launched projectiles is formulated. Analysis of this reduced-o...
Chapter
Monte Carlo simulation is an important method of uncertainty quantification in a variety of scientific and engineering disciplines. Computational scalability is a critical problem in Monte Carlo implementation for many dynamical systems. However, new high-throughput computing architectures such as GPU’s are enabling realizations of Monte Carlo that...
Article
This paper describes a new metric for characterizing conflict between belief assignments. The new metric, specifically designed to quantify conflict on orderable sets, uses a Hausdorff-based measure to account for the distance between focal elements. This results in a distance metric that can accurately measure conflict between belief assignments w...
Article
It is well known that projectiles equipped with liquid payloads experience large destabilizing moments induced by internal motion of the fluid. For some configurations, these moments may lead to catastrophic flight instabilities. This paper explores how payload geometry, fluid spin-up rate, and the magnitude of launch perturbations affect the fligh...
Article
Terminal guidance of autonomous parafoils is a difficult problem in which wind uncertainty and system underactuation are major challenges. Existing strategies almost exclusively use impact error as the criterion for optimality. Practical airdrop systems, however, must also include other criteria that may be even more important than impact error for...
Conference Paper
Existing precision airdrop strategies almost exclusively use impact error in a flat target plane as the criterion for optimality. Practical airdrop systems must also include other criteria such as constraints imposed by terrain and challenging drop zones. Designing robust guidance strategies for drop zones with complex terrain is further complicate...
Conference Paper
Autonomous parafoil terminal guidance plays a critical role in landing accuracy but is inherently difficult due to underactuation and path disturbances caused by winds. Terminal path planners must generate flight paths that deliver the parafoil as close as possible to the destination while landing into the wind. This paper presents a novel path-pla...
Conference Paper
Autorotation maneuvers are required to perform a safe landing in single-engine helicopters in cases of engine loss and transmission or tail rotor malfunction. The rise of autonomous helicopter technology, and the pilot skill required to manually perform an autorotation, motivate the need for new autonomous autorotation control laws. Previous approa...
Article
An orientation state estimator is proposed for smart weapons applications using feedback from wide field-of-view thermal sensors and magnetometers. The state estimation system possesses several key advantages over current designs in that it maintains low cost, lacks moving parts, and is free from reliance on GPS or other state feedback. In order to...
Article
Setback distances established by regulatory authorities to minimize the probability of blade fragment impact with roads, structures and infrastructure can often have a significant impact on wind farm development. However, these minimum distance requirements typically rely on arbitrary rules of thumb and are not based on a physical or probabilistic...
Article
The use of magnetometers for orientation estimation on rapidly-spinning flight bodies is analyzed. Specifically, the effect of spin-induced magnetic field distortion is discussed, with particular attention to its impli-cations for magnetometer-based orientation estimation. First, the nature of spin-induced field distortion is described and it is sh...
Article
Full-text available
Monte Carlo trajectory simulation is a key element in the design and evaluation process for smart weapons development. Graphics processing units (GPU's) are powerful massively parallel computing devices that are increasingly being used for general purpose computing. This paper explores the use of graphics processing units for Monte Carlo trajectory...
Conference Paper
Smart projectile state estimation is a challenging task due to highly nonlinear vehicle dynamic behavior and unreliable or noisy sensor feedback. While Kalman filter-based algorithms are currently the primary means of sensor fusion and state estimation for smart weapons applications, they are limited in estimation accuracy, their ability to combine...
Article
This report documents the theory and use of the BOOM computer program. BOOM is an exterior ballistics simulation program specifically designed to predict atmospheric flight of smart projectiles. The software contains a projectile dynamic model coupled to an open structure flight control system. The code can be run on PC, Unix, or Mac systems.
Article
The use of inexpensive, commercially available thermopiles sensors for roll orientation estimation of spinning bodies is explored. The sensors convert observed thermal gradients into an electrical signal well suited for onboard data acquisition and real-time signal processing. An environmental model emulating sensor stimulus for a six-degree-of-fre...
Article
The design of a canard-controlled mortar projectile using a bank-to-turn concept is presented. A unique feature of this smart mortar configuration is that it is equipped with a set of two reciprocating fixed-angle maneuver canards and a set of two reciprocating fixed-angle roll canards. An active control system is designed such that the roll canard...