Here's a simple MATLAB example to get you started:
% Measurement update z = y(:, i); K = P_pred*H'*inv(H*P_pred*H' + R); x_est(:, i) = x_pred + K*(z - H*x_pred); P_est(:, :, i) = P_pred - K*H*P_pred; end end
% --- True trajectory (unknown to the filter) --- true_velocity = 10; % m/s true_position = 0:dt:true_velocity*(T-1); true_state = [true_position; true_velocity * ones(1,T)]; kalman filter for beginners with matlab examples download
: This repository provides sample code for the book Kalman Filter for Beginners: With MATLAB Examples . It covers many topics from simple averaging filters to advanced Extended and Unscented Kalman Filters.
It looks at both the prediction and the measurement, calculates which one is more trustworthy at that exact moment, and finds the optimal "middle ground" estimate. How it Works: The 2-Step Cycle The Kalman Filter runs in a loop with two main phases: 1. Predict The filter projects the current state forward in time. Here's a simple MATLAB example to get you
% Define the system parameters dt = 0.1; % time step A = [1 dt; 0 1]; % transition model H = [1 0]; % measurement model Q = [0.01 0; 0 0.01]; % process noise R = [0.1]; % measurement noise
Pk−=APk−1AT+Qcap P sub k raised to the negative power equals cap A cap P sub k minus 1 end-sub cap A to the cap T-th power plus cap Q x̂k−x hat sub k raised to the negative power How it Works: The 2-Step Cycle The Kalman
% Kalman Filter For Beginners: 1D Constant Velocity Tracking % Based on examples in "Kalman Filter for Beginners" by Phil Kim clear all; close all; clc; % 1. Simulation Parameters N = 100; % Number of time steps dt = 1; % Time step % 2. True System Definition (Constant Velocity) true_pos = 0:dt:(N-1)*dt; % Actual position noise = 5 * randn(1, N); % Sensor noise measurements = true_pos + noise; % Noisy measurements % 3. Kalman Filter Matrices F = [1 dt; 0 1]; % State transition matrix (Pos = Pos + Vel*dt, Vel = Vel) H = [1 0]; % Measurement matrix (We only measure position) Q = [0.1 0; 0 0.1]; % Process noise covariance R = 25; % Measurement noise covariance (Variance of the noise) % 4. Initial Guesses x = [0; 0]; % Initial state: [position; velocity] P = [10 0; 0 10]; % Initial error covariance (high uncertainty) % 5. Kalman Filter Loop estimated_pos = zeros(1, N); for k = 1:N % --- PREDICT --- x_pred = F * x; P_pred = F * P * F' + Q; % --- UPDATE --- z = measurements(k); % Current measurement y = z - H * x_pred; % Innovation (measurement residual) S = H * P_pred * H' + R; % Innovation covariance K = P_pred * H' / S; % Kalman gain x = x_pred + K * y; % New state estimate P = (eye(2) - K * H) * P_pred; % New error covariance estimated_pos(k) = x(1); end % 6. Plot Results figure; plot(1:N, measurements, 'k.', 'MarkerSize', 10); hold on; plot(1:N, true_pos, 'b-', 'LineWidth', 2); plot(1:N, estimated_pos, 'r-', 'LineWidth', 2); legend('Noisy Measurement', 'True Position', 'Kalman Filter Estimate'); xlabel('Time Step'); ylabel('Position'); title('1D Kalman Filter Tracking'); grid on; Use code with caution. 2. How to Run Copy the code above. Open MATLAB .
x_est = x_pred + K * y; % new state estimate P_est = (eye(2) - K * H) * P_pred; % new covariance
The difference between the prediction and the measurement is called the .
The Kalman filter is a recursive algorithm that uses a combination of prediction and measurement updates to estimate the state of a system. It's a powerful tool for estimating the state of a system from noisy measurements, and it's particularly useful when the system is subject to uncertainty and noise.