Kamesh Subbarao

The University of Texas at Arlington | UTA · Department of Mechanical and Aerospace Engineering

This paper introduces the application of Gaussian Process Regression (GPR), a probabilistic machine learning technique, to quantify uncertainty in dynamic systems and address limitations inherent in the techniques found in the literature. Although Monte Carlo (MC) methods are widely used for uncertainty quantification and propagation, they require...

The paper presents a cooperative docking approach for a micro Unmanned Aerial Vehicle (UAV) onto a Unmanned Ground Vehicle (UGV) employing an advanced Guidance, Navigation, and Control algorithm, with the Bitcraze Crazyflie quadrotor used as the platform for demonstrating the docking process onto a mobile autonomous rover. The system is divided int...

The performance of an uncrewed aerial system (UAS) operating nominally in an indoor/outdoor environment depends upon the available power, and how well the system reacts to disturbances and nonlinear dynamic effects. This paper focuses on development of approaches to compensate for nonlinear dynamic effects due to aerodynamics, gyroscopic coupling,...

We propose three time-to-go consensus protocols to effect the same-time position consensus of multiple agents (or vehicles) to a destination. We prove same-time position consensus to occur through the use of control generated using each of the three protocols viz max-time, min-time, and achievable-time protocols using a backstepping-inspired speed...

The problem of precisely estimating the position and orientation of multiple dipoles using synthetic EEG signals is considered in this paper. After determining a proper forward model, a nonlinear constrained optimization problem with regularization is solved, and the results are compared with a widely used research code, namely EEGLAB. A thorough s...

This work implements a non-linear programming method to synthesize edge weights of an adjacency matrix for a linear parameter varying multi-agent system using bilinear matrix inequalities, which suffer uncertainties. First, convex–concave decompositions are used on the bilinear matrix inequality constraints for nominal H∞synthesis. Then this method...

This paper analyzes the consensus problem in a group of networked agents with nonuniform time-varying delays communicating over an uncertain communication network. Time-varying delays are assumed to be associated with each link in a directed communication graph topology. The network topology for information exchange is modeled with communication li...

p>The problem of precise estimation of the position and orientation of multiple dipoles using synthetic EEG signals is considered in this paper. A nonlinear constrained optimization problem with regularization is solved and the results com-pared with popular research codes namely EEGLAB. A thorough sensitivity analysis of the estimation algorithm t...

p>The problem of precise estimation of the position and orientation of multiple dipoles using synthetic EEG signals is considered in this paper. A nonlinear constrained optimization problem with regularization is solved and the results com-pared with popular research codes namely EEGLAB. A thorough sensitivity analysis of the estimation algorithm t...

Objective Customization of the rate of drug delivered based on individual patient requirements is of paramount importance in the design of drug delivery devices. Advances in manufacturing may enable multilayer drug delivery devices with different initial drug distributions in each layer. However, a robust mathematical understanding of how to optimi...

This paper focuses on the computation of reachable sets for nonlinear dynam-ical systems. The hypersonic atmospheric re-entry problem is considered, and the time evolution of reachable sets is studied for the system subject to implicit controls that are nonlinear in the governing equations of motion. To provide background , the reachable set synthe...

Some of the final sets of corrections requested in the proof did not unfortunately make it to the final version in [1]. We would like to point those out in this document.

A novel data-driven conceptual framework using a moving platform was developed to accurately estimate the drift of objects in the marine environment in real time using a combination of a perception-based sensing technology and deep-learning algorithms. The framework for conducting field experiments to establish the drift properties of moving object...

View Video Presentation: https://doi.org/10.2514/6.2022-4076.vid The paper develops a complete flight dynamics model of a non-conventional airship that utilizes a pair of main rotors for thrust, and fins in the `+' configuration for pitch and yaw control. The roll authority is limited and is accomplished by differential thrust and differential fin...

In this paper, we propose a novel time and control effort optimal aggressive trajectory synthesis and control design methodology. The trajectory synthesis is a modified minimum snap design but with specific position and orientation constraints on a multi-copter, such as flying through tight spaces (windows) at specific orientations. The paper also...

This paper studies distributed edge weight synthesis of a cooperative system for a fixed topology to improve $H_{\infty}$ performance, considering that disturbances are injected at interconnection channels. This problem is cast into a linear matrix inequality problem by replacing original cooperative system with an equivalent ideal cooperative syst...

View Video Presentation: https://doi.org/10.2514/6.2022-0961.vid This paper investigates the distributed model predictive control for unmanned cooperative systems subject to stochastic uncertainties in the parameters. Framework of generalized polynomial chaos expansion is utilized to propagate the stochastic uncertainties through the system model a...

View Video Presentation: https://doi.org/10.2514/6.2022-0755.vid This paper studies the consensus problem of high-order linear multi-agent systems subject to non-uniform time-varying delays. We design a distributed control protocol for the agents in directed graph topology and provide an equivalent stability problem to be solved that guarantees the...

View Video Presentation: https://doi.org/10.2514/6.2022-0959.vid This paper provides a framework to characterize the stability margins of a linear time-invariant multi-agent system where the interaction topology is described by a graph with a directed spanning tree. The stability analysis of the multi-agent system, which is based on the generalized...

View Video Presentation: https://doi.org/10.2514/6.2022-1845.vid This paper proposes a same-time consensus framework for a planar engagement between multiple pursuers and a target. For the pursuers and the target modeled using nonlinear kinematics, guidance laws are developed for both stationary as well as maneuvering targets. For the case of a man...

Accurate detection of oscillatory electrical signals emitted from remote sources is necessary in many applications but poses several challenges. The major challenge is attributed to the source voltage and conductivity of the medium through which signals must transmit before they can be sensed by the receiving electrodes/sensors. This study introduc...

In this paper, a momentum-preserving integration scheme is implemented for the simulation of single and cooperative multi-rotors with a flexible-cable suspended payload by employing a Lie group based variational integrator (VI), which provides the preservation of the configuration manifold and geometrical constraints. Due to the desired properties...

The importance of determining the sidereal rotation period of an astronomical object on future investigations pertaining to said object has been well documented in the literature. Researchers, however, have differed in their techniques used to estimate and model objects in the space catalog. In this paper, several period-estimation methods will be...

This article presents a rigorous formulation for the pursuit‐evasion (PE) game when velocity constraints are imposed on agents of the game or players. The game is formulated as an infinite‐horizon problem using a non‐quadratic functional, then sufficient conditions are derived to prove capture in a finite‐time. A novel tracking Hamilton–Jacobi–Isaa...

The temperature distribution in the battery significantly impacts the short-term and long-term performance of battery systems. Therefore, efficient, safe, and reliable battery system operation requires an accurate estimation of the temperature field. The current industry standard for sensors to battery cell ratio is quite frugal. Thus, the problem...

A framework for a systematic design of robust controllers to guarantee desired output performance for an interconnected group of multi-input–multi-output dynamic systems is presented. The framework enables design of a robust linear parameter varying (LPV) controller for all individual vehicles as well as the interconnected group to account for unce...

In this technical note, a recursive {set-membership} filtering algorithm for discrete-time nonlinear dynamical systems subject to unknown but bounded process and measurement noises is proposed. The nonlinear dynamics is represented in a pseudo-linear form using the state dependent coefficient (SDC) parameterization. Matrix Taylor expansions are uti...

In this paper, a hybrid missile guidance algorithm is proposed for planar engagement scenarios. The method combines nonlinear model predictive control (NMPC) with a collision cone approach, and enables the guidance algorithm to achieve interception, while ensuring that the impact angle lies in a predefined range. The guidance scheme comprises two c...

The temperature distribution in the battery significantly impacts the short-term and long-term performance of battery systems. Therefore, efficient, safe, and reliable battery system operation requires an accurate estimation of the temperature field. The current industry standard for sensors to battery cell ratio is quite frugal. Thus, the problem...

We propose two perturbation-based extremum seeking control (ESC) schemes for general single input single output nonlinear dynamical systems, having structures similar to that of the classical ESC scheme. We propose novel adaptation laws for the excitation signal amplitudes in each scheme that drive the amplitudes to zero. The rates of decay for bot...

In this paper, a generalized polynomial chaos (gPC) expansion-based framework for designing controllers for continuous-time linear multi-agent systems with probabilistic parameters and uncertain initial conditions is presented. Minimum expectation optimal trajectories are obtained by synthesizing optimal stabilizing controllers for both single-agen...

In this paper, we focus on ellipsoidal estimates of reachable sets for discrete-time nonlinear dynamical systems based on ellipsoidal set-membership techniques. To this end, we implement a set-membership filter that utilizes state dependent coefficient parameterization of the nonlinear dynamics. The set-membership filter has a correction-prediction...

In this paper, a set-membership filter-based pure proportional navigation (PPN) law for missile guidance is proposed. A recursive set-membership filter for nonlinear dynamical systems subject to unknown but bounded process and measurement noises is constructed using the state dependent coefficient parameterization of the nonlinear dynamics. At ever...

In this paper, a study on the application of modern robust control design techniques on a tailless Unmanned Air Vehicle is presented. A nonlinear mathematical model for the aircraft is constructed and linear control laws are synthesized following mu-synthesis approach. An ad-hoc controller scheduling method is implemented, and an optimization based...

In this paper, a set-membership filtering-based leader-follower synchronization protocol for discrete-time linear multi-agent systems is proposed wherein the aim is to make the agents synchronize with a leader. The agents, governed by identical high-order discrete-time linear dynamics, are subjected to unknown-but-bounded input disturbances. In ter...

In this paper, analytical expressions for cycle-averaged aerodynamic forces generated by flapping wings are derived using a force model and flapping kinematics suitable for the forward flight of avian creatures. A strip theory-based formulation is proposed and the analytical expressions are found as functions of the amplitude of twist profile, mean...

This paper is concerned with the consensus problem for multi-agent systems subject to communication delays between the neighboring agents. We consider a scenario where each agent is characterized by a general high-order linear system and the communication delays between the agents are non-uniform and time-varying. We design a distributed control pr...

In this paper, a set-membership filtering-based leader-follower synchronization protocol for discrete-time linear multi-agent systems is proposed wherein the aim is to make the agents synchronize with a leader. The agents, governed by identical high-order discrete-time linear dynamics, are subject to unknown-but-bounded input disturbances. In terms...

We propose two perturbation-based extremum seeking control (ESC) schemes for general single input single output nonlinear dynamical systems, having structures similar to that of the classical ESC scheme. We propose novel adaptation laws for the excitation signal amplitudes in each scheme that drive the amplitudes to zero. The rates of decay for bot...

Re-entry into the atmosphere exposes a space vehicle to several potential dangers such as combustion and mechanical failure and requires precise control of its entry trajectory. The atmospheric arc on Earth plays a pivotal role in reducing the kinetic energy by friction with the atmosphere. This paper presents the use of trajectory control methods...

In this study, the authors propose a backstepping-based, distributed formation control method that is stable independent of time delays in communication among multiple unmanned aerial vehicles (UAVs). Centralised formation control of UAVs requires each agent to maintain a separation distance from other agents, which burdens the communication networ...

This paper provides a framework to characterize the gain margin, phase margin, and maximum input delay margin of a linear time-invariant multi-agent system where the interaction topology is described by a graph with a directed spanning tree. The stability analysis of the multi-agent system based on the generalized Nyquist theorem is converted to fi...

In this technical note, a recursive set membership filtering algorithm for discrete-time nonlinear dynamical systems subject to unknown but bounded process and measurement noise is proposed. The nonlinear dynamics is represented in a pseudo-linear form using the state dependent coefficient (SDC) parameterization. Matrix Taylor expansions are utiliz...

Light curve inversion (LCI) has proven valuable in using photometric measurements to optimize various physical parameters of a resident space object (RSO) such as rotational period about its own spin axis, pole orientation and others. Other characteristics such as shape and size are dependent on the surface brightness. LCI has been developed signif...

This paper considers uncertainty quantification in systems perturbed by stochastic disturbances, in particular, Gaussian white noise. The main focus of this work is on describing the time evolution of statistical moments of certain invariants (for instance total energy and magnitude of angular momentum) for such systems. A first case study for the...

This paper focuses on the mathematical modeling and control of an unmanned aerial system (UAS) with a payload suspended using a cable. The motion of the payload induces disturbances on the aerial platform and needs to be mitigated for stable operation. The solution to this control problem is presented through the implementation of a passivity based...

The purpose of this paper is to present a new path-planning algorithm for planetary exploration rovers that will guide the vehicle safely to a reachable state. In particular, this work will make use of a special class of artificial potential functions called navigation functions which are guaranteed to be free of local minimum. The construction of...

This paper demonstrates the use of generalized polynomial chaos expansion for the propagation of uncertainties present in various dynamical models. Specifically, a sampling based non-intrusive approach using pseudospectral stochastic collocation is employed to obtain the coefficients required for the generalized polynomial chaos expansion. Various...

The range and endurance of an unmanned aerial system operating nominally in an outdoor environment depends upon the available power and environmental factors like the magnitude and direction of the prevailing wind. This paper focuses on the development of semi-analytical approaches to computing the range and endurance of battery-powered multi-copte...

This paper deals with the observability and sensitivity analysis of the lightcurve measurement for use in the estimation of instantaneous pose (orientation) and shape geometry. Since several reflectance models exist that are typically used in obtaining a synthetic lightcurve measurement, they are compared to assess the observability or/and ‘sensiti...

This article puts forth a framework using model-based techniques for path planning and guidance for an autonomous mobile robot in a constrained environment. The path plan is synthesized using a numerical navigation function algorithm that will form its potential contour levels based on the “minimum control effort.” Then, an improved nonlinear model...

Using tools from artificial intelligence, mainly artificial neural networks, this paper presents an walking-engine for humanoid robots. This engine uses dynamic neural networks with feedback for gait generation, a modified Zhang neural network for a singularity-robust inverse kinematics solver, and feedforward neural networks for neuro-adaptive con...

This paper develops a framework for propagation of uncertainties, governed by different probability distribution functions in a stochastic dynamical system. More specifically, it deals with nonlinear dynamical systems, wherein both the initial state and parametric uncertainty have been taken into consideration and their effects studied in the model...

A robust method for the estimation of Sidereal rotation period of Resident Space Objects (RSOs) in orbit using Periodogram analysis is presented. This can be applied to non-uniformly sampled light curves (a measurement of the object's brightness over time), typically used in astronomical data collection. Most ground-based photometric observations a...

The purpose of this paper is to present a methodology (theory with experimental verification) for control of a wheeled rover vehicle using a cyber-physical system architecture, nonlinear control, and a novel optimal trajectory design. An optimal trajectory with an acceleration limit is used to generate a reference for the rover to follow. A nonline...

Queuing models provide an attractive and highly-efficient alternative to simulation for quantifying traffic flow efficiency. Stationary Markovian queuing models in which both inter-arrival times and service times are exponentially distributed have been studied by the National Airspace System (NAS). However, stationary queues cannot account for peak...

This paper considers the problem of achieving attitude consensus in spacecraft formations with bounded, time-varying communication delays between spacecraft connected as specified by a strongly connected topology. A state feedback con- troller is proposed and investigated using a time domain approach (via LMIs) and a frequency domain approach (via...

This paper discusses the derivation and implementation of a nonlinear model predictive control law for tracking reference trajectories and constrained control of a quadrotor platform. The approach uses the state-dependent coefficient form to capture the system nonlinearities into a pseudo-linear system matrix. The state-dependent coefficient form i...

A Dynamic Neural Network (DNN), comprising of a Recurrent Neural Network (RNN) and two Feedforward Neural Networks (FFNN), is detailed in this paper. This neuro-dynamic system is used to adaptively solve the problem of trajectory generation; planning a path connecting a locus of points as a function of time. The RNN is designed to exhibit a desired...

This paper presents a framework for designing an autonomous carrier landing system for the A/V-8B Harrier like UAV using gain-scheduled autopilots. A non-linear high fidelity model of the aircraft is trimmed and linearized at a number of flight conditions following which feedback gains are determined using Linear Quadratic optimal control technique...

This work presents a case wherein the selection of models when producing synthetic light curves affects the estimation of the size of unresolved space objects. Through this case, “inverse crime” (using the same model for the generation of synthetic data and data inversion), is illustrated. This is done by using two models to produce the synthetic l...

The duality of estimation and control problems is a well known fact in control theory literature. Simultaneous parameter estimation while maintaining closed loop stability is a very difficult proposition and more so for unstable systems, even for linear systems. This typically motivates system identification to be performed only in offline experime...