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Inertial_navigation_ECI.m
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Inertial_navigation_ECI.m
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function [out_profile,out_errors] = Inertial_navigation_ECI(in_profile,...
no_epochs,initialization_errors,IMU_errors)
%Inertial_navigation_ECI - Simulates inertial navigation using ECI
% navigation equations and kinematic model
%
% Software for use with "Principles of GNSS, Inertial, and Multisensor
% Integrated Navigation Systems," Second Edition.
%
% This function created 3/4/2012 by Paul Groves
%
% Inputs:
% in_profile True motion profile array
% no_epochs Number of epochs of profile data
% initialization_errors
% .delta_r_eb_n position error resolved along NED (m)
% .delta_v_eb_n velocity error resolved along NED (m/s)
% .delta_eul_nb_n attitude error as NED Euler angles (rad)
% IMU_errors
% .delta_r_eb_n position error resolved along NED (m)
% .b_a Accelerometer biases (m/s^2)
% .b_g Gyro biases (rad/s)
% .M_a Accelerometer scale factor and cross coupling errors
% .M_g Gyro scale factor and cross coupling errors
% .G_g Gyro g-dependent biases (rad-sec/m)
% .accel_noise_root_PSD Accelerometer noise root PSD (m s^-1.5)
% .gyro_noise_root_PSD Gyro noise root PSD (rad s^-0.5)
% .accel_quant_level Accelerometer quantization level (m/s^2)
% .gyro_quant_level Gyro quantization level (rad/s)
%
% Outputs:
% out_profile Navigation solution as a motion profile array
% out_errors Navigation solution error array
%
% Format of motion profiles:
% Column 1: time (sec)
% Column 2: latitude (rad)纬度
% Column 3: longitude (rad)经度
% Column 4: height (m)
% Column 5: north velocity (m/s)
% Column 6: east velocity (m/s)
% Column 7: down velocity (m/s)
% Column 8: roll angle of body w.r.t NED (rad)
% Column 9: pitch angle of body w.r.t NED (rad)
% Column 10: yaw angle of body w.r.t NED (rad)
%
% Format of error array:
% Column 1: time (sec)
% Column 2: north position error (m)
% Column 3: east position error (m)
% Column 4: down position error (m)
% Column 5: north velocity (m/s)
% Column 6: east velocity (m/s)
% Column 7: down velocity (m/s)
% Column 8: attitude error about north (rad)
% Column 9: attitude error about east (rad)
% Column 10: attitude error about down = heading error (rad)
% Copyright 2012, Paul Groves
% License: BSD; see license.txt for details
% Begins
% Initialize true navigation solution 初始化，输入读取到的参数，使用第一个历元
old_time = in_profile(1,1);
true_L_b = in_profile(1,2);%纬度
true_lambda_b = in_profile(1,3);%经度
true_h_b = in_profile(1,4);
true_v_eb_n = in_profile(1,5:7)';
true_eul_nb = in_profile(1,8:10)';
true_C_b_n = Euler_to_CTM(true_eul_nb)';%坐标转换矩阵
[true_r_eb_e,true_v_eb_e,true_C_b_e] =...
NED_to_ECEF(true_L_b,true_lambda_b,true_h_b,true_v_eb_n,true_C_b_n);
[old_true_r_ib_i,old_true_v_ib_i,old_true_C_b_i] =...
ECEF_to_ECI(old_time,true_r_eb_e,true_v_eb_e,true_C_b_e);
% Initialize estimated navigation solution
[old_est_L_b,old_est_lambda_b,old_est_h_b,old_est_v_eb_n,old_est_C_b_n] =...
Initialize_NED(true_L_b,true_lambda_b,true_h_b,true_v_eb_n,true_C_b_n,...
initialization_errors);
% Initialize output profile record and errors record
out_profile = zeros(no_epochs,10);
out_errors = zeros(no_epochs,10);
% Generate output profile record
out_profile(1,1) = old_time;
out_profile(1,2) = old_est_L_b;
out_profile(1,3) = old_est_lambda_b;
out_profile(1,4) = old_est_h_b;
out_profile(1,5:7) = old_est_v_eb_n';
out_profile(1,8:10) = CTM_to_Euler(old_est_C_b_n')';
out_errors(1,1) = old_time;
out_errors(1,2:4) = initialization_errors.delta_r_eb_n';
out_errors(1,5:7) = initialization_errors.delta_v_eb_n';
out_errors(1,8:10) = initialization_errors.delta_eul_nb_n';
[old_est_r_eb_e,old_est_v_eb_e,old_est_C_b_e] = NED_to_ECEF(old_est_L_b,...
old_est_lambda_b,old_est_h_b,old_est_v_eb_n,old_est_C_b_n);
[old_est_r_ib_i,old_est_v_ib_i,old_est_C_b_i] =...
ECEF_to_ECI(old_time,old_est_r_eb_e,old_est_v_eb_e,old_est_C_b_e);
% Initialize IMU quantization residuals
quant_residuals = [0;0;0;0;0;0];
% Progress bar 进度条，可以不要
dots = '....................';
bars = '||||||||||||||||||||';
rewind = '\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b';
fprintf(strcat('Processing: ',dots));
progress_mark = 0;
progress_epoch = 0;
% Main loop
for epoch = 2:no_epochs
% Update progress bar 更新进度条，没用
if (epoch - progress_epoch) > (no_epochs/20)
progress_mark = progress_mark + 1;
progress_epoch = epoch;
fprintf(strcat(rewind,bars(1:progress_mark),...
dots(1:(20 - progress_mark))));
end % if epoch
% Input data from motion profile
time = in_profile(epoch,1);
true_L_b = in_profile(epoch,2);
true_lambda_b = in_profile(epoch,3);
true_h_b = in_profile(epoch,4);
true_v_eb_n = in_profile(epoch,5:7)';
true_eul_nb = in_profile(epoch,8:10)';
true_C_b_n = Euler_to_CTM(true_eul_nb)';
[true_r_eb_e,true_v_eb_e,true_C_b_e] =...
NED_to_ECEF(true_L_b,true_lambda_b,true_h_b,true_v_eb_n,true_C_b_n);
[true_r_ib_i,true_v_ib_i,true_C_b_i] =...
ECEF_to_ECI(time,true_r_eb_e,true_v_eb_e,true_C_b_e);
% Time interval
tor_i = time - old_time;
% Calculate specific force and angular rate
[true_f_ib_b,true_omega_ib_b] = Kinematics_ECI(tor_i,true_C_b_i,...
old_true_C_b_i,true_v_ib_i,old_true_v_ib_i,old_true_r_ib_i);
% Simulate IMU errors
[meas_f_ib_b,meas_omega_ib_b,quant_residuals] = IMU_model(tor_i,...
true_f_ib_b,true_omega_ib_b,IMU_errors,quant_residuals);
% Update estimated navigation solution
[est_r_ib_i,est_v_ib_i,est_C_b_i] = Nav_equations_ECI(tor_i,...
old_est_r_ib_i,old_est_v_ib_i,old_est_C_b_i,meas_f_ib_b,...
meas_omega_ib_b);
[est_r_eb_e,est_v_eb_e,est_C_b_e] =...
ECI_to_ECEF(time,est_r_ib_i,est_v_ib_i,est_C_b_i);
[est_L_b,est_lambda_b,est_h_b,est_v_eb_n,est_C_b_n] =...
ECEF_to_NED(est_r_eb_e,est_v_eb_e,est_C_b_e);
% Generate output profile record
out_profile(epoch,1) = time;
out_profile(epoch,2) = est_L_b;
out_profile(epoch,3) = est_lambda_b;
out_profile(epoch,4) = est_h_b;
out_profile(epoch,5:7) = est_v_eb_n';
out_profile(epoch,8:10) = CTM_to_Euler(est_C_b_n')';
% Determine errors and generate output record
[delta_r_eb_n,delta_v_eb_n,delta_eul_nb_n] = Calculate_errors_NED(...
est_L_b,est_lambda_b,est_h_b,est_v_eb_n,est_C_b_n,true_L_b,...
true_lambda_b,true_h_b,true_v_eb_n,true_C_b_n);
out_errors(epoch,1) = time;
out_errors(epoch,2:4) = delta_r_eb_n';
out_errors(epoch,5:7) = delta_v_eb_n';
out_errors(epoch,8:10) = delta_eul_nb_n';
% Reset old values
old_time = time;
old_true_r_ib_i = true_r_ib_i;
old_true_v_ib_i = true_v_ib_i;
old_true_C_b_i = true_C_b_i;
old_est_r_ib_i = est_r_ib_i;
old_est_v_ib_i = est_v_ib_i;
old_est_C_b_i = est_C_b_i;
end %epoch
% Complete progress bar
fprintf(strcat(rewind,bars,'\n'));
% Ends