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Introduction To Kalman Filters

John Edwards - Watch Now - DSP Online Conference 2025 - Duration: 50:56

Introduction To Kalman Filters
John Edwards

Kalman filters are powerful recursive estimation algorithms widely used in control systems, signal processing, and navigation. They provide an efficient means to estimate the internal state of a dynamic system in the presence of noise and uncertainty, making them indispensable in applications such as target tracking, sensor fusion, robotics, and communications.

This presentation introduces the foundations and practical implementation of Kalman filters in an accessible manner. We begin with the motivation for state estimation, reviewing the limitations of direct measurement in noisy environments. The mathematical framework of the Kalman filter is then presented, highlighting the state-space model, prediction and update steps, and the role of covariance in quantifying uncertainty. Emphasis is placed on the recursive nature of the algorithm, which enables real-time operation with minimal computational complexity.

Practical examples illustrate how the filter balances model predictions with noisy observations to achieve optimal estimates. By the end of the presentation, attendees will understand both the theoretical foundations and practical benefits of Kalman filtering, equipping them to apply the method to a wide range of engineering and signal processing problems. This presentation will include example code and walk throughs.

This guide was created with the help of AI, based on the presentation's transcript. Its goal is to give you useful context and background so you can get the most out of the session.

What this presentation is about and why it matters

This talk is an accessible, code-backed introduction to the linear Kalman filter — a recursive estimator used to infer hidden state (for example, position and velocity) from noisy sensor data. For engineers working in signal processing, control, navigation, robotics or sensor fusion, Kalman filters are a staple: they give an optimal (minimum mean-square error) estimate for linear systems with Gaussian noise, run in real time with modest computation, and scale from simple 1D examples to multi-dimensional tracking problems.

John Edwards frames the Kalman filter as a practical, top-down tool: how to form a state-space model, predict forward, and correct using measurements. The talk emphasizes intuition (the role of the Kalman gain as a confidence weight), implementation (a short Python demo), and limitations (linear + Gaussian assumptions and extensions such as EKF/UKF). Watching this presentation will help you move from the idea of smoothing noisy signals to actually building a real-time estimator that performs well in practice.

Who will benefit the most from this presentation

  • DSP engineers and students who want a clear, practical introduction to Kalman filtering with code examples.
  • Control and robotics engineers who need to combine noisy sensor outputs (GPS, IMU, range sensors) into a single reliable state estimate.
  • Signal processing practitioners looking to understand trade-offs between model confidence and sensor confidence (how to tune covariances).
  • Anyone preparing to move on to nonlinear estimation (EKF/UKF) who needs a solid linear foundation first.

What you need to know

This talk is intentionally introductory but assumes familiarity with a few basic concepts. If you know the following, you will get the most from the presentation:

  • Discrete-time state-space models: the idea that a dynamic system can be written with a state vector that updates in time using a state transition matrix and optionally a control input.
  • Basic linear algebra: vectors, matrices, matrix transpose and matrix multiplication—these are used directly in the Kalman equations.
  • Probability basics: mean, variance and covariance; what it means for noise to be Gaussian (normal distribution).
  • Difference equations and simple one-pole filters: an intuition for feedback and weighting of past estimates versus new measurements helps understanding the Kalman gain.

If you like equations, the core Kalman steps you will see are (in standard notation):

  • Prediction (a priori state and covariance): $\hat{x}_{k|k-1} = A\hat{x}_{k-1|k-1} + B u_k$ and $P_{k|k-1} = A P_{k-1|k-1} A^{T} + Q$
  • Update (measurement correction): $K_k = P_{k|k-1} C^{T}(C P_{k|k-1} C^{T} + R)^{-1}$,
  • then $\hat{x}_{k|k} = \hat{x}_{k|k-1} + K_k(y_k - C\hat{x}_{k|k-1})$ and $P_{k|k} = (I - K_k C) P_{k|k-1}$.

These equations show the two-loop structure: predict forward using your model, then correct using the measurement and a gain computed from the predicted uncertainty and sensor noise.

Glossary

  • State vector — the set of variables describing the system at a time instant (e.g., position and velocity).
  • State transition matrix (A) — maps the previous state to the predicted next state (model dynamics).
  • Observation matrix (C) — maps the state to the measurement space (how the sensor sees the state).
  • Process noise (Q) — covariance that models uncertainty in the system evolution (unmodeled inputs, disturbances).
  • Measurement noise (R) — covariance that models sensor noise and measurement inaccuracy.
  • Estimation covariance (P) — matrix capturing the uncertainty (variance and covariance) of the state estimate.
  • Kalman gain (K) — matrix that weights measurement versus prediction; larger K means more trust in the measurement.
  • Predict (a priori) step — propagate state and covariance forward using the model before seeing the new measurement.
  • Update (correction) step — incorporate the new measurement to correct the predicted state and reduce uncertainty.
  • Extended/Unscented Kalman Filters (EKF/UKF) — nonlinear extensions: EKF linearizes the model, UKF uses deterministic sampling (unscented transform).

Why you should watch

John Edwards delivers a practical, engineer-friendly overview that balances intuition, equations and runnable code. The talk cuts through common confusion about what the Kalman filter actually does (it balances model prediction and noisy measurements using covariance), shows a minimal Python demo that you can reproduce quickly, and calls out real limitations and standard nonlinear extensions. If you want a clear path from concept to working estimator — and a friendly, top-down explanation that emphasizes implementation—this presentation will save you time and give you confidence to experiment with Kalman filters in your own projects.

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jekain314
Score: 0 | 1 week ago | 1 reply

Most "SIGNAL PROCESSING" texts dont even give the KF an honorable mention. Why do you think that is?

john.edwardsSpeaker
Score: 0 | 1 week ago | no reply

I think it's very misunderstood.

Leonard
Score: 0 | 1 week ago | 1 reply

is the code provided?

Stephane.Boucher
Score: 0 | 1 week ago | 1 reply

It's now available under 'Files Provided by the Speaker(s)'.

Leonard
Score: 0 | 1 week ago | 1 reply

Nice , Thank you John, btw I enjoyed the presentation.

john.edwardsSpeaker
Score: 0 | 1 week ago | no reply

Thank you, Leonard, much appreciated.
Best regards,
John