forked from ymjdz/MATLAB-Codes
-
Notifications
You must be signed in to change notification settings - Fork 0
/
GNSS_Least_Squares.m
214 lines (183 loc) · 7.63 KB
/
GNSS_Least_Squares.m
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
function [out_profile,out_errors,out_clock] = GNSS_Least_Squares(in_profile,...
no_epochs,GNSS_config)
%GNSS_Least_Squares - Simulates stand-alone GNSS using a least-squares
%positioning algorithm
%
% Software for use with "Principles of GNSS, Inertial, and Multisensor
% Integrated Navigation Systems," Second Edition.
%
% This function created 11/4/2012 by Paul Groves
%
% Inputs:
% in_profile True motion profile array
% no_epochs Number of epochs of profile data
% GNSS_config
% .epoch_interval Interval between GNSS epochs (s)
% .init_est_r_ea_e Initial estimated position (m; ECEF)
% .no_sat Number of satellites in constellation
% .r_os Orbital radius of satellites (m)
% .inclination Inclination angle of satellites (deg)
% .const_delta_lambda Longitude offset of constellation (deg)
% .const_delta_t Timing offset of constellation (s)
% .mask_angle Mask angle (deg)
% .SIS_err_SD Signal in space error SD (m)
% .zenith_iono_err_SD Zenith ionosphere error SD (m)
% .zenith_trop_err_SD Zenith troposphere error SD (m)
% .code_track_err_SD Code tracking error SD (m)
% .rate_track_err_SD Range rate tracking error SD (m/s)
% .rx_clock_offset Receiver clock offset at time=0 (m)
% .rx_clock_drift Receiver clock drift at time=0 (m/s)
%
% Outputs:
% out_profile Navigation solution as a motion profile array
% out_errors Navigation solution error array
% out_clock Receiver clock estimate array
%
% Format of motion profiles:
% Column 1: time (sec)
% Column 2: latitude (rad)
% Column 3: longitude (rad)
% 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 error (m/s)
% Column 6: east velocity error (m/s)
% Column 7: down velocity error (m/s)
% Column 8: NOT USED (attitude error about north (rad))
% Column 9: NOT USED (attitude error about east (rad))
% Column 10: NOT USED (attitude error about down = heading error (rad))
%
% Format of receiver clock array:
% Column 1: time (sec)
% Column 2: estimated clock offset (m)
% Column 3: estimated clock drift (m/s)
% Copyright 2012, Paul Groves
% License: BSD; see license.txt for details
% Begins
% Initialize true navigation solution
old_time = in_profile(1,1);
true_L_b = in_profile(1,2);
true_lambda_b = in_profile(1,3);
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)';
[true_r_eb_e,true_v_eb_e] =...
pv_NED_to_ECEF(true_L_b,true_lambda_b,true_h_b,true_v_eb_n);
time_last_GNSS = old_time;
GNSS_epoch = 1;
% Determine satellite positions and velocities
[sat_r_es_e,sat_v_es_e] = Satellite_positions_and_velocities(old_time,...
GNSS_config);
% Initialize the GNSS biases. Note that these are assumed constant throughout
% the simulation and are based on the initial elevation angles. Therefore,
% this function is unsuited to simulations longer than about 30 min.
GNSS_biases = Initialize_GNSS_biases(sat_r_es_e,true_r_eb_e,true_L_b,...
true_lambda_b,GNSS_config);
% Generate GNSS measurements
[GNSS_measurements,no_GNSS_meas] = Generate_GNSS_measurements(old_time,...
sat_r_es_e,sat_v_es_e,true_r_eb_e,true_L_b,true_lambda_b,true_v_eb_e,...
GNSS_biases,GNSS_config);
% Determine GNSS position solution
[est_r_eb_e,est_v_eb_e,est_clock] = GNSS_LS_position_velocity(...
GNSS_measurements,no_GNSS_meas,GNSS_config.init_est_r_ea_e,[0;0;0]);
est_C_b_n = true_C_b_n; % This sets the attitude errors to zero
[est_L_b,est_lambda_b,est_h_b,est_v_eb_n] =...
pv_ECEF_to_NED(est_r_eb_e,est_v_eb_e);
% Generate output profile record
out_profile(1,1) = old_time;
out_profile(1,2) = est_L_b;
out_profile(1,3) = est_lambda_b;
out_profile(1,4) = est_h_b;
out_profile(1,5:7) = est_v_eb_n';
out_profile(1,8:10) = 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(1,1) = old_time;
out_errors(1,2:4) = delta_r_eb_n';
out_errors(1,5:7) = delta_v_eb_n';
out_errors(1,8:10) = [0;0;0];
% Generate clock output record
out_clock(1,1) = old_time;
out_clock(1,2:3) = est_clock(1:2);
% Progress bar
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
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 time from motion profile
time = in_profile(epoch,1);
% Determine whether to update GNSS simulation
if (time - time_last_GNSS) >= GNSS_config.epoch_interval
GNSS_epoch = GNSS_epoch + 1;
time_last_GNSS = time;
% Input data from motion profile
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] =...
pv_NED_to_ECEF(true_L_b,true_lambda_b,true_h_b,true_v_eb_n);
% Determine satellite positions and velocities
[sat_r_es_e,sat_v_es_e] = Satellite_positions_and_velocities(time,...
GNSS_config);
% Generate GNSS measurements
[GNSS_measurements,no_GNSS_meas] = Generate_GNSS_measurements(...
time,sat_r_es_e,sat_v_es_e,true_r_eb_e,true_L_b,true_lambda_b,...
true_v_eb_e,GNSS_biases,GNSS_config);
% Determine GNSS position solution
[est_r_eb_e,est_v_eb_e,est_clock] = GNSS_LS_position_velocity(...
GNSS_measurements,no_GNSS_meas,est_r_eb_e,est_v_eb_e);
[est_L_b,est_lambda_b,est_h_b,est_v_eb_n] =...
pv_ECEF_to_NED(est_r_eb_e,est_v_eb_e);
est_C_b_n = true_C_b_n; % This sets the attitude errors to zero
% Generate output profile record
out_profile(GNSS_epoch,1) = time;
out_profile(GNSS_epoch,2) = est_L_b;
out_profile(GNSS_epoch,3) = est_lambda_b;
out_profile(GNSS_epoch,4) = est_h_b;
out_profile(GNSS_epoch,5:7) = est_v_eb_n';
out_profile(GNSS_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(GNSS_epoch,1) = time;
out_errors(GNSS_epoch,2:4) = delta_r_eb_n';
out_errors(GNSS_epoch,5:7) = delta_v_eb_n';
out_errors(GNSS_epoch,8:10) = [0;0;0];
% Generate clock output record
out_clock(GNSS_epoch,1) = time;
out_clock(GNSS_epoch,2:3) = est_clock(1:2);
% Reset old values
old_time = time;
end % if time
end %epoch
% Complete progress bar
fprintf(strcat(rewind,bars,'\n'));
% Ends