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This document presents the implementation details of the Extended Kalman Filter (EKF) state update process, focusing on the linearization of the system using MATLAB equations. The state update incorporates a Taylor-Heun approximation, effectively integrating the dynamics and corrections for measurements. The relevant equations outline the state transition model, error covariance propagation, and measurement integration steps. Key concepts include the initialization of state matrices, the prediction phase, and the update mechanism that refines estimates based on new measurements while accounting for uncertainties.
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, then Let: Problem Setup ,
State Update A(:,:,i)=linearize(qk_km1(:,i)); = F(:,i)=[qk_km1(2,i) (-2*qk_km1(4,i)*qk_km1(3,i)*qk_km1(2,i)-(qk_km1(1,i)*qk_km1(3,i)^2)+ARF(i)) 0 0]';
qk_km1(:,i) = M(:,:,i)*F(:,i)*intdt + qk_km1(:,i); P_dot = A(:,:,i)*Pk_k(:,:,i) + Pk_k(:,:,i)*A(:,:,i)' + Q; Pk_k(:,:,i) = Pk_k(:,:,i) + (intdt)*M(:,:,i)*P_dot*M(:,:,i)'; State Update, cont. Taylor-Heun Approximation: (Mazzoni 2007, courtesy of Muhel & Vivek) M(:,:,i) = inv(eye(4) - A(:,:,i)*intdt/(2));
K(:,i) = Pk_k(:,:,i)*H'*(1/(Pk_k(1,1,i)+R)); qk_k(:,i) = qk_km1(:,i) + K(:,i)*(ytrue(i)-qk_km1(1,i)); Pk_k(:,:,i) = (eye(4) - K(:,i)*H)*Pk_k(:,:,i); Measurement Update