Library · Signals, sensing & imaging

What State Estimation & Kalman Filtering got wrong, from 73 theses

Summary written by a model from the records below: Across these studies, Kalman filters and related state estimation algorithms frequently encounter divergence or performance degradation caused by severe nonlinearities, unmodeled physical dynamics, and degraded sensor observations. Practitioners also reject or abandon these filtering methods due to prohibitive computational demands, ensemble variance collapse, constraint violations, and underperformance relative to simpler baselines. These records come from graduate theses, 2021 to 2026, each labeled with its degree where the repository states it, and each links to its thesis. They were extracted by language models reading the full text, so treat each as a lead to read, not a verdict.

73
theses
21
institutions
82
failure records
7
failure modes

Plus 10 problems the authors left open, listed at the end.

Failure modes, by theses reporting them

Select a mode to jump to its records.

Linearization errors and severe nonlinearities cause filter divergence or degraded tracking accuracy
17
17 theses · 10 institutions · 18 records
High computational complexity and memory overhead prevent deployment on embedded or large-scale systems
15
15 theses · 10 institutions · 15 records
Sparse observations, uncompensated delays, and sensor noise destabilize state updates
13
13 theses · 8 institutions · 13 records
Kalman filters underperform simpler empirical smoothers, linear baselines, or raw measurements
11
11 theses · 9 institutions · 12 records
Ensemble Kalman filters suffer from ensemble collapse, variance loss, and spurious correlations
8
8 theses · 6 institutions · 9 records
Unmodeled physical forces and structural model misspecification induce persistent drift
9
9 theses · 5 institutions · 9 records
Unconstrained filtering violates physical boundaries, manifold geometry, and admissibility limits
6
6 theses · 4 institutions · 6 records

Linearization errors and severe nonlinearities cause filter divergence or degraded tracking accuracy

17 theses · 10 institutions

First-order Taylor series approximations and linear measurement updates fail when tracking highly nonlinear kinematics, yielding severe estimation errors or filter divergence. Propagating Gaussian approximations through complex nonlinear dynamics or multimodal distributions frequently produces unphysical values and loses spacecraft or vehicle tracking.

Tried and failed

extended Kalman filter for nonlinear depth estimation applied to visual feature depth tracking. Outcome: unstable. Reason: linearization breakdown under high measurement nonlinearity caused filter divergence and unphysical negative values

Spacecraft navigation and decision making in uncertain environments · UT Austin · PhD

Tried and failed

extended Kalman filter SLAM applied to robot localization with odometry noise. Outcome: did not converge. Reason: linearization errors from odometry uncertainty cause divergence in stationary counterexample scenarios

Onboard control, tracking and navigation for autonomous systems · UT Austin · PhD

Tried and failed

conventional extended Kalman filter state estimation applied to indirect wind velocity estimation. Outcome: did not converge. Reason: linearization errors during high-dynamic coordinated turning maneuvers caused filter divergence

An Invariant Extended Kalman Filter for Indirect Wind Estimation Using a Small, Fixed-Wing Uncrewed Aerial Vehicle · Virginia Tech · Doctorate

Tried and failed

particle filter with extended Kalman filter state estimation applied to jump-Markov state estimation. Outcome: worse than baseline. Reason: linearization errors in the extended Kalman filter reduced estimation accuracy

Advances in the Use of Finite-Set Statistics for Multitarget Tracking · Virginia Tech · Doctorate

Tried and failed

linear Kalman filtering on nonlinear kinematics applied to aircraft state and wind estimation. Outcome: did not converge. Reason: Maneuvering kinematics violated nominal equilibrium linearization assumptions, causing filter divergence

Identification of Unsteady Flight Dynamic Models and Model-based Wind Estimation with Flight Test Validation · Virginia Tech · Doctorate

Tried and failed

conventional extended Kalman filter applied to aerodynamic wind estimation from inertial data. Outcome: did not converge. Reason: linearization errors caused filter divergence during unaccelerated straight and level flight

An Invariant Extended Kalman Filter for Indirect Wind Estimation Using a Small, Fixed-Wing Uncrewed Aerial Vehicle · Virginia Tech · Doctorate

Tried and failed

extended Kalman filtering with kinematic motion models applied to trajectory prediction of maneuvering targets. Outcome: worse than baseline. Reason: linear kinematic assumptions cannot accurately capture complex nonlinear maneuvering dynamics

Data-driven Target Tracking and Hybrid Path Planning Methods for Autonomous Operation of UAV · Virginia Tech · Doctorate

Lost to a baseline

Classic Kalman filtering (1 GMM component) failed to resolve nonlinear/non-Gaussian parabolic joint dependencies between state variables during data assimilation compared to the GMM-DO filter.

Scientific Machine Learning for Dynamical Systems: Theory and Applications to Fluid Flow and Ocean Ecosystem Modeling · MIT · PhD

Lost to a baseline

In the Circular Restricted Three-Body Problem (CR3BP) northern halo orbit tracking test, the standard linear-update UKF diverges right before 3 TU (loses tracking of the spacecraft), losing to the higher-order quadratic and polynomial filters (QUKF, QACUKF-4, CACUKF-6).

Polynomial Kalman filter updates · Iowa State · Master's

Considered and rejected

Considered and rejected: Rejected standard iterative Taylor linearization / Extended Kalman Filtering because range and angle measurements are highly nonlinear and underdetermined, failing to maintain Gaussianity.

Blind as a bat: spatial perception without sight · EPFL · PhD

Considered and rejected

Considered and rejected: Rejected classical Extended Kalman Filter (EKF) and linear observers due to Jacobian linearization errors and inability to handle abrupt feed discontinuities

Advancing bioprocessing with ensemble kalman filter: from state estimation to knowledge transfer · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected using extended Kalman filter (EKF) linearizations because propagating first/second-order approximations caused large errors in highly non-linear arm dynamics

Efficient and Safe Robot Planning in Human-Robot Collaboration · University at Buffalo · PhD

Considered and rejected

Considered and rejected: Rejected Extended Kalman Filter (EKF) and Particle Filter in favor of Unscented Kalman Filter due to EKF instability on highly non-linear measurement equations and Particle Filter computational inefficiency.

Advances in passive acoustic detection, localization, and tracking applied to unmanned underwater vehicles · Woods Hole · PhD

Tried and failed

Gaussian companion filters for particle flow uncertainty propagation applied to highly nonlinear state estimation. Outcome: unstable. Reason: linearized or unscented covariance approximations lead to statistically inconsistent uncertainty estimates in severe nonlinearities

Adventures in Kalman filtering : exploring methods of expanding the uses of the Kalman filter · UT Austin · PhD

Tried and failed

extended and unscented Kalman filtering applied to nonlinear spacecraft relative navigation. Outcome: did not converge. Reason: point-wise unobservability and multimodal non-Gaussian posterior state distributions

Advancements in single- and multi-target filtering : using posterior estimates to update Gaussian mixture weights · UT Austin · PhD

Considered and rejected

Considered and rejected: Rejected the Extended Kalman Filter (EKF) in favor of the Unscented Kalman Filter (UKF) to avoid linearisation approximation errors from Taylor series expansion while keeping computational complexity low.

Identification of nonlinear and time-varying systems under dynamic and seismic excitation · Politecnico di Torino · PhD

Considered and rejected

Considered and rejected: Rejected Extended Kalman Filter (EKF) in favor of Unscented Kalman Filter (UKF) because the hydraulic model's non-Newtonian frictional pressure loss terms require numerical solutions without explicit analytical forms, making linearization impractical.

Autonomous steering and event detection : modeling, estimation, and control in drilling engineering · UT Austin · PhD

Tried and failed

Kalman filtering and particle filtering applied to nonlinear biological tissue state-space models. Outcome: did not converge. Reason: Nonlinear gating dynamics, latent variable insensitivity, and particle degeneracy in high dimensions.

Data analytics and mathematical modeling to advance cardiac care · Texas Tech · PhD

High computational complexity and memory overhead prevent deployment on embedded or large-scale systems

15 theses · 10 institutions

Inverting large covariance matrices, propagating ensembles, and executing iterative nonlinear updates require excessive runtime and computational resources. These processing demands frequently exceed microcontroller capacity and render complex filtering variants impractical compared to lighter alternatives.

Considered and rejected

Considered and rejected: Rejected full-Jacobian all-pixel Extended Kalman Filter (EKF) covariance matrix tracking due to intractable O((2*N_pix)^3) matrix inversion complexity, restricting analysis to single-pixel EKF

Embedded Computing for Wavefront Control on Future Space Telescopes · MIT · PhD

Considered and rejected

Considered and rejected: Rejected running BPTT through the Kalman filter in a recurrent feedback hybrid architecture due to excessive compute and optimization instabilities.

Verfahren zur Zustandsschätzung im LKW-Trailer · Leibniz Universität Hannover · PhD

Tried and failed

Unscented Kalman Filter state estimation applied to nonlinear dynamic wind estimation. Outcome: worse than baseline. Reason: Higher computational overhead and tuning complexity yielded no significant improvement over Extended Kalman Filter.

Identification of Unsteady Flight Dynamic Models and Model-based Wind Estimation with Flight Test Validation · Virginia Tech · Doctorate

Considered and rejected

Considered and rejected: Rejected UKF and Sigma-Point Kalman filters in favor of EKF because they did not provide significant accuracy improvements relative to their added computational overhead

Cooperative Multi-Robot Systems for Aquatic Environmental Sensing · EPFL · PhD

Tried and failed

Extended Kalman filter with linearized observation model applied to sensor state estimation on microcontrollers. Outcome: too slow. Reason: linearizing piecewise nonlinear observation equations exceeded the microcontroller's computational capacity

Modular Robots Morphology Transformation And Task Execution · Penn · PhD

Tried and failed

uniform or manual particle filter initialization applied to target state estimation. Outcome: infeasible cost. Reason: uniform distribution wasted particles across state space while manual placement imposed excessive operator burden

Robust Online Trajectory Prediction for Non-cooperative Small Unmanned Aerial Vehicles · Virginia Tech · Master's

Considered and rejected

Considered and rejected: Rejected nonlinear filtering (unscented Kalman filter) and Bayesian parameter estimation due to prohibitive computational expense on big data.

Deep Time: Deep Learning Extensions to Time Series Factor Analysis with Applications to Uncertainty Quantification in Economic and Financial Modeling · Virginia Tech · Master's

Considered and rejected

Considered and rejected: Rejected Kalman filter for combining accelerometer and gyroscope data due to its high computational processing cost, choosing complementary filter instead

Implementación de un sistema no invasivo para la identificación del nivel de atención en personas · BUAP · PhD

Considered and rejected

Considered and rejected: Rejected using a single full 3-D Kalman filter with 6x6 matrices due to higher computing complexity and calculations, choosing two 2-D KFs with 4x4 matrices instead

SELECTIVE BEAMSTEERING AND 3-D TRACKING PHASED ARRAY RADAR WITH REDUCED DIMENSION KALMAN FILTERING · Naval Postgraduate School · Master's

Considered and rejected

Considered and rejected: Rejected particle filter (PF) state estimation in favor of iSAM2 nonlinear least-squares due to excessive computational cost

Adaptive AUV-assisted Diver Navigation for Loosely-Coupled Teaming in Undersea Operations · MIT · PhD

Considered and rejected

Considered and rejected: Rejected a full extended Kalman filter (AHRS) running real-time on the microcontroller due to high computational demand.

Sensor-based electronic monitoring of feeding and drinking activity of nursery pigs in swine farms · Iowa State · Master's

Considered and rejected

Considered and rejected: Rejected Extended Kalman Filter (EKF) in favor of standard Kalman Filter (KF) within IMM due to EKF's computational complexity and runtime for non-real-time offline data processing.

Statistical Modeling of Air Traffic: Development of Methods and Application through a Canadian Case Study · Carleton University · Master's

Considered and rejected

Considered and rejected: Decided against using the Unscented Kalman Filter in Chapter 5 in favor of the Extended Kalman Filter to reduce computation time during large simulation runs

Mission-driven Sensor Network Design for Space Domain Awareness · Virginia Tech · Doctorate

Tried and failed

full-state extended Kalman filter on discretized PDE applied to convection-diffusion bioreactor state estimation. Outcome: unstable. Reason: numerical instability caused by ill-conditioned covariance matrix inversion with high-dimensional discretized states

Digital Twin Design and Autonomous Control of Bioreactor Systems for Human Immune Cell Expansion · Georgia Tech · PhD

Considered and rejected

Considered and rejected: Rejected Unscented Kalman Filter (UKF) and Ensemble Kalman Filter (EnKF) in favor of EKF because they require multiple or ensemble model queries per update rather than a single differentiable forward pass.

An Approach for Rapid, Uncertainty-aware Damage Diagnosis of Rotating Machinery · Georgia Tech · PhD

Sparse observations, uncompensated delays, and sensor noise destabilize state updates

13 theses · 8 institutions

Filters diverge when measurement updates are infrequent, sensor delays remain uncorrected, or observation channels lose absolute reference information. In addition, high sensor noise, inadequate excitation, and mutual ranging correlations lead to covariance growth and corrupted state estimates.

Tried and failed

constant-acceleration Extended Kalman Filter applied to mobile emitter tracking with position error. Outcome: did not converge. Reason: diverged due to large relative position errors, performing worse than standard linear Kalman filter

Data-Driven Localization and Structure Learning in Reverberant Underwater Acoustic Environments · MIT · PhD

Tried and failed

extended Kalman filter with increased measurement noise covariance applied to indirect wind velocity estimation. Outcome: did not converge. Reason: state estimates diverged when measurement noise covariance was increased

An Invariant Extended Kalman Filter for Indirect Wind Estimation Using a Small, Fixed-Wing Uncrewed Aerial Vehicle · Virginia Tech · Doctorate

Tried and failed

unscented Kalman filter applied to orbit determination with sparse measurements. Outcome: did not converge. Reason: long propagation gaps between measurement updates caused divergence under nonlinear dynamics

Sequential Monte Carlo filtering with Gaussian mixture models for highly nonlinear systems · UT Austin · PhD

Tried and failed

Extended Kalman filter using sparse line-of-sight ranging applied to spacecraft orbit determination. Outcome: did not converge. Reason: measurement visibility below twenty percent caused unbounded filter divergence and extreme state estimation errors

Lunar Laser Ranging for Autonomous Cislunar Spacecraft Navigation · Virginia Tech · Master's

Tried and failed

Extended Kalman filter online parameter estimation applied to car-following model parameter identification. Outcome: did not converge. Reason: Persistent excitation order was insufficient to prevent divergence and high error covariance in linear parameter estimation

Vehicle Longitudinal Control under Autonomy, Connectivity, and Mixed-flow Traffic · Georgia Tech · PhD

Tried and failed

sensor exclusion during Kalman filter state estimation applied to satellite attitude and torque estimation. Outcome: unstable. Reason: loss of absolute attitude measurements causes immediate filter divergence

Modeling and Analysis of a Thermospheric Density Measurement System Based on Torque Estimation · Virginia Tech · Master's

Tried and failed

Kalman-filter-based motion tracking without appearance features applied to multi-object tracking under occlusions. Reason: Kalman filter error accumulates during occlusions, preventing re-identification upon target reappearance

Intelligent perception frameworks and algorithms for social good: food security and public safety · Iowa State · PhD

Tried and failed

late-stage Kalman filter multi-sensor fusion applied to collaborative multi-object tracking. Outcome: worse than baseline. Reason: noisy local sensor measurements corrupted precise communicated baseline data during fusion

Enhancing Perception Systems using V2V Sensor Fusion · Virginia Tech · Master's

Tried and failed

reducing sensor noise parameter below model accuracy threshold applied to Kalman filter state estimation. Outcome: worse than baseline. Reason: underlying reference model resolution limits dominated error when sensor noise was over-optimistically tuned

Lunar Surface Navigation Using Gravity and Star Tracker Measurements · Virginia Tech · Master's

Considered and rejected

Considered and rejected: Rejected standard Kalman filtering for post-intervention Stage II MoodZoom data due to high missingness (29%), using time-adjusted RMSSD (tRMSSD) instead

Digital phenotyping and interventions for sleep & circadian rhythms in borderline personality disorder · Oxford · PhD

Tried and failed

Kalman filtering without sensor delay compensation applied to fast dynamic robot state estimation. Outcome: unstable. Reason: ignoring uncorrected sensor latencies caused large error accumulation during rapid transient phases

Estimation and Planning for Dynamic Robot Behaviors · Harvard · PhD

Tried and failed

unscented quaternion state estimation filter applied to rigid body attitude tracking with bias. Outcome: did not converge. Reason: residual sensor biases and disturbance torques prevented convergence to high accuracy

Computational Methods to Improve Satellite Attitude Determination and Control with a Focus on Autonomy, Generalizability, and Underactuation · MIT · PhD

Tried and failed

online Kalman filtering for multi-rate sensor fusion applied to longitudinal acceleration estimation. Outcome: unstable. Reason: non-systematic measurement noise from low-frequency observation sources degraded state tracking

Crowd-sourced Road Geometry and Accurate Vehicle State Estimation Using Mobile Devices · University at Buffalo · PhD

Kalman filters underperform simpler empirical smoothers, linear baselines, or raw measurements

11 theses · 9 institutions

Complex Kalman filters and smoothers often deliver worse accuracy or higher estimation error than simple moving averages, linear regressions, or raw sensor data. Several advanced filter formulations also lose to basic observers or non-filtering baselines during transient jumps and benign operational conditions.

Lost to a baseline

Kalman Filter was outperformed by the Levant Observer and Luenberger Observer in relative velocity estimation accuracy under noisy position measurements.

Guidance and Navigation Algorithms for Spacecraft Low-Thrust Proximity Operations: Formation Flight in Circular Relative Orbit · Politecnico di Torino · PhD

Lost to a baseline

Variance-scaled Kalman filtering (KFSA/KFSB) exhibited larger parameter estimation biases and variance than variance-scaled Gaussian (GS) and negative binomial (NB) estimators under high noise (q_p, q_m = 2).

Enhancing methods for modeling and estimation of complex socio-technical systems · MIT · PhD

Lost to a baseline

Kalman Filter and Moving Average smoothing produced higher TTC MAE (0.81 s and 0.86 s) compared to raw UWB measurements (0.62 s excluding 20 m).

Utilization of Wireless Sensors for Pedestrian Safety Studies · Carleton University · PhD

Lost to a baseline

Kalman with GCV hyperparameter optimization performed worse than Savitzky-Golay gridsearched optima on several benchmark systems.

Open-Source Dynamical Systems Research, with a Side of (Francis) Bacon · University of Washington · PhD

Tried and failed

unscented Kalman filter for motion state estimation applied to pedestrian multi-object tracking. Outcome: worse than baseline. Reason: nonlinear filtering degraded tracking accuracy compared to standard linear Kalman filter models

Improved 2D Camera-Based Multi-Object Tracking for Autonomous Vehicles · Virginia Tech · Master's

Tried and failed

Kalman filtering with signal quality indices applied to physiological time series denoising. Outcome: worse than baseline. Reason: Denoising removed motion and noise patterns that were informative and correlated with the target event

Self-Aware Machine Learning for Chronic Pathology Monitoring on Wearable Devices · EPFL · PhD

Lost to a baseline

Kalman filter prediction method (185 m/year average RMSE) was beaten by simple linear regression rate extrapolation (128 m/year average RMSE).

Coastal Erosion Hazard in Bangladesh: Space-time pattern analysis and empirical forecasting, impacts on land use/cover, and human risk perception · Virginia Tech · Doctorate

Lost to a baseline

Baseline Linear Kalman Filter slightly achieved higher Sharpe ratios than the non-linear UKF across cutoff levels.

Topics in Bayesian machine learning for finance · Oxford · PhD

Lost to a baseline

Kalman smoothing with GCV hyperparameter optimization was outperformed by gridsearched Kalman smoothing and gridsearched Savitzky-Golay across multiple benchmark ODEs.

Open-Source Dynamical Systems Research, with a Side of (Francis) Bacon · University of Washington · PhD

Lost to a baseline

Standard FairMOT and Faster R-CNN/YOLOv8 outperformed standard Kalman filtering in tracking and speed estimation accuracy in video processing.

New modelling approaches to analyse unsafe traffic conditions in real-time · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected low-pass filters and Kalman filters for prediction output post-processing in favor of EMA filter due to superior smoothing and stability

Investigation of Future Voluntary Movement Prediction for Pathological Tremor-Alleviating Exoskeletons · Virginia Tech · Master's

Lost to a baseline

robust Kalman Filter was beaten by the Certainty Equivalent Kalman Filter on benign simulations by up to 1.64x mean squared error

Statistical Learning For System Identification, Estimation, And Control · Penn · PhD

Ensemble Kalman filters suffer from ensemble collapse, variance loss, and spurious correlations

8 theses · 6 institutions

Diminishing ensemble spread and unmodeled spatial correlations trigger posterior variance collapse and filter divergence in high dimensions. Non-Gaussian fields, chaotic flow stretching, and static process noise assumptions further distort forecasts and smear sharp physical boundaries.

Tried and failed

ensemble Kalman filter with high update frequency applied to hydrodynamic state estimation. Outcome: unstable. Reason: diminishing ensemble spread caused filter divergence, leading to ignored observations

Integrated numerical modeling and data-driven techniques for thermal effluent simulation in coastal waters · Imperial · PhD

Tried and failed

multilevel ensemble Kalman filtering applied to quasigeostrophic fluid dynamics data assimilation. Outcome: did not converge. Reason: lack of forecast corrections, mean corrections, and spatial covariance localization caused filter divergence

Combining Data-driven and Theory-guided Models in Ensemble Data Assimilation · Virginia Tech · Doctorate

Considered and rejected

Considered and rejected: Rejected evaluating linear warming trends using the Paleoclimate Data Assimilation (PDA) ensemble mean due to Kalman filter variance loss and time-dependent proxy network dropouts.

Decadal to centennial-scale climate interactions across the Indo-Pacific region · MIT · PhD

Tried and failed

ensemble Kalman filter applied to Lagrangian data assimilation in chaotic flows. Outcome: unstable. Reason: assimilation intervals exceed the Lagrangian autocorrelation timescale causing filter divergence from chaotic hyperbolic stretching

High-Dimensional Optimal Path Planning and Multi-Timescale Lagrangian Data Assimilation in Stochastic Dynamical Ocean Environments · MIT · PhD

Tried and failed

ensemble Kalman filter without covariance localization applied to large-scale high-dimensional data assimilation. Outcome: unstable. Reason: spurious correlations caused posterior variance collapse in high dimensions

Ensemble Kalman filtering and conditional normalizing flows for seismic monitoring via data assimilation · Georgia Tech · PhD

Tried and failed

ensemble Kalman filter on non-Gaussian spatial fields applied to subsurface permeability parameter estimation. Outcome: worse than baseline. Reason: violation of Gaussian assumptions smeared sharp facies boundaries and distorted production forecasts

Rule-based and machine learning hybrid reservoir modeling for improved forecasting · UT Austin · PhD

Tried and failed

ensemble Kalman filter with static process noise applied to state estimation of zero-concentration components. Reason: constant noise covariance induced artificial fluctuations when true physical state was strictly zero

Advancing bioprocessing with ensemble kalman filter: from state estimation to knowledge transfer · Imperial · PhD

Tried and failed

ensemble Kalman filter data assimilation applied to bioreactor kinetic state estimation. Outcome: unstable. Reason: unmodeled time delays and discrete kinetic switching caused filter instability, forcing state exclusion

Advancing bioprocessing with ensemble kalman filter: from state estimation to knowledge transfer · Imperial · PhD

Considered and rejected

Considered and rejected: Rejected recursive data assimilation / iterative Ensemble Kalman Filtering in EnsCGP to avoid over-conditioning, bias accumulation, and ensemble collapse.

Physics-based and data-driven inversion of magnetotelluric data for subsurface imaging · Woods Hole · PhD

Unmodeled physical forces and structural model misspecification induce persistent drift

9 theses · 5 institutions

Filters drift or diverge when internal models omit friction, aerodynamic thrust, structural elasticity, or true input disturbance terms. Adaptive covariance schemes and gain predictors fail to compensate for these missing dynamics, leading to accumulated errors and closed-loop instability.

Tried and failed

augmented Extended Kalman Filter parameter estimation applied to structurally misspecified dynamic systems. Outcome: did not converge. Reason: missing model dynamics terms cause parameter estimates to diverge or converge to incorrect values

Online Information-Aware Motion Planning with Model Improvement for Uncertain Mobile Robotics · MIT · PhD

Tried and failed

extended Kalman filter wheel odometry fusion applied to mobile robot track navigation. Outcome: unstable. Reason: unmodeled variable frictional slip between drive wheels and contact surfaces degraded state estimation

A novel railway maintenance robot for inspection and repair · Cranfield · PhD

Lost to a baseline

Misspecified linear Kalman filter yielded higher correlations but worse relative standard deviations in non-linear state space setups compared to the partial information filter.

ESSAYS ON MACRO FINANCE · Penn · PhD

Considered and rejected

Considered and rejected: Rejected the standard uncorrected Extended Kalman Predictor (EKP) for position states because ignorable coordinates with non-zero equilibrium velocity (e.g., X, Y, Z, psi) accumulate an uncompensated drift/bias shift over the delay horizon.

Time Delay Mitigation in Aerial Telerobotic Operations Using Predictors and Predictive Displays · Virginia Tech · Doctorate

Tried and failed

Kalman state estimation with underestimated stiffness parameter applied to compliant parallel robot state estimation. Outcome: unstable. Reason: Underestimating the stiffness matrix in the filter introduced lag and oscillation, destabilizing closed-loop whole-body control

Design and Control of a Structurally Elastic Humanoid Robot · Virginia Tech · Doctorate

Tried and failed

adaptive extended Kalman filter under dynamics mismatch applied to multi-agent state estimation during propagation. Outcome: did not generalise. Reason: adaptive covariance estimation failed to compensate for severe structural model mismatch, increasing cumulative uncertainty

Enhancing Teamwork in Multi-Robot Systems: Embodied Intelligence via Model- and Data-Driven Approaches · Georgia Tech · PhD

Tried and failed

finite input covariance filter for joint estimation applied to nonlinear dynamic structural state estimation. Outcome: unstable. Reason: incorrect initial input covariance causes severe low-frequency drift and underestimates residual state displacements

Input-State Estimation of Inelastic Structural Systems: Theoretical Framework and Experimental Validation · Georgia Tech · PhD

Tried and failed

neural network prediction of Kalman filter gains applied to multi-sensor state estimation. Outcome: did not generalise. Reason: Model assumption dependency, noise sensitivity, and failure to adapt to unmodeled environmental and sensor anomalies.

ML-Enhanced Visual Inertial Navigation System for UAVs · Cranfield · PhD

Tried and failed

Orthogonal function modeling with Kalman filter estimation applied to unsteady vehicle aerodynamic dynamics. Outcome: did not generalise. Reason: Omission of dynamic thrust modeling and accumulated state estimation errors under severe environmental disturbances.

Identification of Unsteady Flight Dynamic Models and Model-based Wind Estimation with Flight Test Validation · Virginia Tech · Doctorate

Unconstrained filtering violates physical boundaries, manifold geometry, and admissibility limits

6 theses · 4 institutions

Standard unconstrained state updates allow estimated quantities to violate physical boundaries, resulting in numerical model crashes and invalid negative values. Similarly, neglecting quaternion unit-norm constraints or contact manifolds introduces singularities, heading oscillations, and biased state estimates.

Considered and rejected

Considered and rejected: Additive Extended Kalman Filter (AEKF) was rejected because quaternion norm constraints are violated, covariance singularities occur, and error quaternions cannot form valid covariance representations.

Attitude Determination using Asynchronous MultiSensor Fusion · York University · Master's

Considered and rejected

Considered and rejected: Rejected standard additive Kalman filtering for quaternion states due to non-unit norm drift and renormalization inaccuracies, adopting MEKF error vectors instead

Modeling and Analysis of a Thermospheric Density Measurement System Based on Torque Estimation · Virginia Tech · Master's

Considered and rejected

Considered and rejected: Rejected model reduction for enforcing Kalman filter state constraints due to loss of physical state meaning and lack of general tractability across complex or time-varying constraints.

Attitude Estimation Algorithms and Comprehensive Error Analysis in the Generic Multi-sensor Integration Strategy · York University · PhD

Tried and failed

unscented Kalman filter applied to systems with contact constraints. Reason: sampled sigma points fell into infeasible regions, biasing state estimates away from the contact manifold

Estimation and Planning for Dynamic Robot Behaviors · Harvard · PhD

Tried and failed

unconstrained extended Kalman filter with geometric error measurements applied to vehicle heading and pose estimation. Outcome: unstable. Reason: large initial heading errors caused non-unique cross-track error solutions leading to continuous heading oscillations

Autonomous Vehicle Pose Estimation in GNSS-Denied Areas Using Cross-Track Error Measurements · Virginia Tech · Master's

Tried and failed

unconstrained Kalman filtering variants applied to nonlinear physical state estimation. Outcome: unstable. Reason: estimates violated physical admissibility bounds, causing numerical instability and process model crashes

On traffic state estimation and control in the world of connected vehicles · UT Austin · PhD

Left open by the authors

Problems the authors named and did not get to.

Left open

Develop a principled residual uncertainty tracking method for low-rank Kalman filters to prevent overconfidence without heuristic covariance inflation. Blocker: Lacks a concrete mathematical formulation or specific algorithmic mechanism for tracking truncated residual uncertainty.

Probabilistic Inference for Spatiotemporal Dynamics · Tübingen · PhD

Left open

Extend the Maximum Correntropy Criterion Extended Kalman Filter to secure distributed vehicle-to-vehicle state estimation in multi-robot systems. Blocker: None

Correntropy: Answer to non-Gaussian noise in modern SLAM applications? · University of Nevada, Reno · PhD

Left open

Integrate an Extended Kalman Filter with realistic navigation sensor models into the docking MPC simulation to reduce trajectory bouncing. Blocker: None

Application of model predictive control for the autonomous rendezvous and docking of small satellites · Georgia Tech · PhD

Left open

Implement bias-aware sequential Kalman filters to simultaneously estimate orbital state and systematic along-track biases from deep space TLE pseudo-observations. Blocker: None

Mitigation of deep space two-line element set biases with pseudo-orbit determination and data-driven models · Imperial · Doctorate

Left open

Implement an Extended Kalman Filter using a CTRV motion model for tracklet reconnection in subviral particle tracking. Blocker: None

Motion patterns of subviral particles: Digital tracking, image data processing and analysis Bewegungsmuster subviraler Partikel: Digitales Tracking, Bilddatenverarbeitung und -anal · University of Marburg · PhD

Left open

Develop multifidelity square root filters, specifically extending the linear control variates ensemble Kalman filtering framework to a multifidelity LETKF. Blocker: None

Combining Data-driven and Theory-guided Models in Ensemble Data Assimilation · Virginia Tech · Doctorate

Left open

Derive theoretical convergence rates for extended Kalman, unscented Kalman, and particle ODE filters. Blocker: None

Uncertainty-Aware Numerical Solutions of ODEs by Bayesian Filtering · Tübingen · PhD

Left open

Estimate full posterior state distribution uncertainty beyond Gaussian linear approximations for multi-modal vision-based state estimation. Blocker: No concrete approach, target benchmark, or formulation specified for non-Gaussian posterior estimation

Methods for Vision-Based State Estimation and Online Motion Model Adaptation Using Multi-Modal Measurements and Motion Constraints · Tübingen · PhD

Left open

Incorporate multimodal belief distributions over contact modes into contact-constrained Kalman filtering to prevent filter divergence in simulation. Blocker: None

Estimation and Planning for Dynamic Robot Behaviors · Harvard · PhD

Left open

Incorporate Kalman filtering or Bayesian tracking into the PEB-annealed 3D UAV path planner to combine noisy localization measurements over time. Blocker: None

Management and Analysis of Localization Information in Uncrewed Aerial Systems · Virginia Tech · Master's

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