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Published byHope Curtis Modified over 9 years ago
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Slam is a State Estimation Problem
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Predicted belief corrected belief
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Bayes Filter Reminder
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Gaussians
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Standard deviation Covariance matrix
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Gaussians in one and two dimensions One standard deviation two standard deviations
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Gaussians in three dimensions Multivariate probability
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Properties of Gaussians for Univariate case Linear system Standard deviation on output of linear system Mean on output of linear system For two-dimensional system:
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Properties of Gaussians Properties of Gaussians for Multivariate case From previous slide
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Properties of Gaussians Important Property of all these methods
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Discrete Kalman Filters
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Kalman Filter background 1.Kalman Filter is a Bayes Filter 2.Kalman Filter uses Gaussians 3.Estimator for the linear Gaussian case 4.Optimal solution for linear models and Gaussian distributions 5.Developed in late 1950’s 6.Most relevant Bayes filter variant in practice 7.Applications in econcomics, weather forecasting, satellite navigations, GPS, robotics, robot vision and many other 8.Kalman filter is just few matrix operations such as multiplication.
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Discrete Kalman Filter
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Components of a Kalman Filter
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Example of Example of Kalman Filter Updates in one dimension Kalman Filter calculates a weighted mean value!
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Kalman Filter Updates in 1D: PREDICTION Single dimension Matrices in multi-dimensions Again generalization to many dimensions here
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CORRECTION Kalman Filter Updates in 1D: CORRECTION Variant single variable Generalization: Generalization: Variant of multiple variables matrix
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Kalman Filter Updates
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Linear Gaussian Systems
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Initialization Linear Gaussian Systems: Initialization Initial belief has a normal distribution:
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Dynamics Linear Gaussian Systems: Dynamics Gaussian
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Linear Gaussian Systems: Dynamics From previous slide Linear, gaussian
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Linear Gaussian Systems: Observations R = correction
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Linear Gaussian Systems: Observations
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: Marginalization and Conditioning Properties: Marginalization and Conditioning Notation for Gaussians All are Gaussian
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Kalman Filter assumes linearity Zero-mean Gaussian Noise
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Linear Motion Model We want to calculate this probability variable
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Theorem 1
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We want to calculate this probability variable
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Theorem 2
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the belief is Gaussian! Everything stays Gaussian: the belief is Gaussian! Probabilistic Robotics Proofs of these theorems and properties are not trivial and can be found in the book by ‘three Germans” called Probabilistic Robotics. Theorem 3
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Kalman Filter Algorithm
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The Kalman Filter Assumptions are: 1.Gaussian distributions 2.Gaussian noise 3.Linear motion 4.Linear observation model Discuss later
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Calculates multi- dimensional mean and covariance matrix Prediction phase Correction phase R for motion Q for measurement Prediction of multi-dimensional mean Prediction of multi-dimensional covariance matrix Calculates corrected multi- dimensional mean and covariance matrix Kalman
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Kalman Filter Algorithm Different notation to previous slide Measurement noise
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Kalman Filter Algorithm: navigation using odometry and measurement to landmark Predicted and corrected position of the ship
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The Prediction-Correction-Cycle The phase of Prediction
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The Prediction-Correction-Cycle The phase of Correction
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The Prediction-Correction-Cycle
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The general Optimal State Estimation Problem
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Diagram of general State Estimation 123123 2 or 3 !
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Discrete Kalman Filter This is what we discussed
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Linear-Optimal State Estimation Compare with this Change with time derivative
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Linear-Optimal State Estimation (Kalman-Bucy Filter) Similar to before Kalman
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Estimation Gain for the Kalman-Bucy Filter Same equations as those that define control gain, except – solution matrix, P, propagated forward in time – Matrices and matrix sequences are different
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Second-Order Example of Kalman- Bucy Filter
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Kalman-Bucy Filter with Two Measurements
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State Estimate with Angle Measurement Only
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Kalman Filter Summary
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Non-Linear Dynamic Systems
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Sources Wolfram Burgard Cyrill Stachniss, Maren Bennewitz Kal Arras
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