1 /*
2 * Copyright (C) 2019 Alberto Irurueta Carro (alberto@irurueta.com)
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16 package com.irurueta.navigation.indoor.position;
17
18 import com.irurueta.geometry.Point2D;
19 import com.irurueta.navigation.LockedException;
20 import com.irurueta.navigation.indoor.RadioSource;
21 import com.irurueta.navigation.indoor.RadioSourceLocated;
22 import com.irurueta.navigation.indoor.RangingAndRssiFingerprint;
23 import com.irurueta.navigation.indoor.RangingAndRssiReading;
24 import com.irurueta.navigation.lateration.LMedSRobustLateration2DSolver;
25 import com.irurueta.numerical.robust.RobustEstimatorMethod;
26
27 import java.util.List;
28
29 /**
30 * Robustly estimates 2D position using located radio sources and their ranging+RSSI
31 * readings at unknown locations and using LMedS algorithm to discard outliers.
32 * This kind of estimator can be used to robustly determine the 2D position of a given
33 * device by getting ranging+RSSI readings at an unknown location of different radio
34 * sources whose 2D locations are known.
35 */
36 public class LMedSRobustRangingAndRssiPositionEstimator2D extends RobustRangingAndRssiPositionEstimator2D {
37
38 /**
39 * Constructor.
40 */
41 public LMedSRobustRangingAndRssiPositionEstimator2D() {
42 super();
43 init();
44 }
45
46 /**
47 * Constructor.
48 *
49 * @param sources located radio sources used for lateration.
50 * @throws IllegalArgumentException if provided sources is null or the number of
51 * provided sources is less than the required minimum.
52 */
53 public LMedSRobustRangingAndRssiPositionEstimator2D(final List<? extends RadioSourceLocated<Point2D>> sources) {
54 super();
55 init();
56 internalSetSources(sources);
57 }
58
59 /**
60 * Constructor.
61 *
62 * @param fingerprint fingerprint containing ranging+RSSI readings at an unknown
63 * location for provided located radio sources.
64 * @throws IllegalArgumentException if provided fingerprint is null.
65 */
66 public LMedSRobustRangingAndRssiPositionEstimator2D(
67 final RangingAndRssiFingerprint<? extends RadioSource, ? extends RangingAndRssiReading<? extends RadioSource>> fingerprint) {
68 super();
69 init();
70 internalSetFingerprint(fingerprint);
71 }
72
73 /**
74 * Constructor.
75 *
76 * @param sources located radio sources used for lateration.
77 * @param fingerprint fingerprint containing ranging+RSSI readings at an unknown
78 * location for provided located radio sources.
79 * @throws IllegalArgumentException if either provided sources or fingerprint is null
80 * or the number of provided sources is less than the required minimum.
81 */
82 public LMedSRobustRangingAndRssiPositionEstimator2D(
83 final List<? extends RadioSourceLocated<Point2D>> sources,
84 final RangingAndRssiFingerprint<? extends RadioSource, ? extends RangingAndRssiReading<? extends RadioSource>> fingerprint) {
85 super();
86 init();
87 internalSetSources(sources);
88 internalSetFingerprint(fingerprint);
89 }
90
91 /**
92 * Constructor.
93 *
94 * @param listener listener in charge of handling events.
95 */
96 public LMedSRobustRangingAndRssiPositionEstimator2D(
97 final RobustRangingAndRssiPositionEstimatorListener<Point2D> listener) {
98 super(listener);
99 init();
100 }
101
102 /**
103 * Constructor.
104 *
105 * @param sources located radio sources used for lateration.
106 * @param listener listener in charge of handling events.
107 * @throws IllegalArgumentException if provided sources is null or the number of
108 * provided sources is less than the required minimum.
109 */
110 public LMedSRobustRangingAndRssiPositionEstimator2D(
111 final List<? extends RadioSourceLocated<Point2D>> sources,
112 final RobustRangingAndRssiPositionEstimatorListener<Point2D> listener) {
113 super(listener);
114 init();
115 internalSetSources(sources);
116 }
117
118 /**
119 * Constructor.
120 *
121 * @param fingerprint fingerprint containing ranging+RSSI readings at an unknown
122 * location for provided location radio sources.
123 * @param listener listener in charge of handling events.
124 * @throws IllegalArgumentException if provided fingerprint is null.
125 */
126 public LMedSRobustRangingAndRssiPositionEstimator2D(
127 final RangingAndRssiFingerprint<? extends RadioSource, ? extends RangingAndRssiReading<?
128 extends RadioSource>> fingerprint,
129 final RobustRangingAndRssiPositionEstimatorListener<Point2D> listener) {
130 super(listener);
131 init();
132 internalSetFingerprint(fingerprint);
133 }
134
135 /**
136 * Constructor.
137 *
138 * @param sources located radio sources used for lateration.
139 * @param fingerprint fingerprint containing ranging+RSSI readings at an unknown
140 * location for provided located radio sources.
141 * @param listener listener in charge of handling events.
142 * @throws IllegalArgumentException if either provided sources or fingerprint is
143 * null or the number of provided sources is less than the required minimum.
144 */
145 public LMedSRobustRangingAndRssiPositionEstimator2D(
146 final List<? extends RadioSourceLocated<Point2D>> sources,
147 final RangingAndRssiFingerprint<? extends RadioSource, ? extends RangingAndRssiReading<?
148 extends RadioSource>> fingerprint,
149 final RobustRangingAndRssiPositionEstimatorListener<Point2D> listener) {
150 super(listener);
151 init();
152 internalSetSources(sources);
153 internalSetFingerprint(fingerprint);
154 }
155
156 /**
157 * Returns threshold to be used to keep the algorithm iterating in case that
158 * best estimated threshold using median of residuals is not small enough.
159 * Once a solution is found that generates a threshold below this value, the
160 * algorithm will stop.
161 * The stop threshold can be used to prevent the LMedS algorithm to iterate
162 * too many times in cases where samples have a very similar accuracy.
163 * For instance, in cases where proportion of outliers is very small (close
164 * to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would
165 * iterate for a long time trying to find the best solution when indeed
166 * there is no need to do that if a reasonable threshold has already been
167 * reached.
168 * Because of this behaviour the stop threshold can be set to a value much
169 * lower than the one typically used in RANSAC, and yet the algorithm could
170 * still produce even smaller thresholds in estimated results.
171 *
172 * @return stop threshold to stop the algorithm prematurely when a certain
173 * accuracy has been reached.
174 */
175 public double getStopThreshold() {
176 return ((LMedSRobustLateration2DSolver) laterationSolver).getStopThreshold();
177 }
178
179 /**
180 * Sets threshold to be used to keep the algorithm iterating in case that
181 * best estimated threshold using median of residuals is not small enough.
182 * Once a solution is found that generates a threshold below this value,
183 * the algorithm will stop.
184 * The stop threshold can be used to prevent the LMedS algorithm to iterate
185 * too many times in cases where samples have a very similar accuracy.
186 * For instance, in cases where proportion of outliers is very small (close
187 * to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would
188 * iterate for a long time trying to find the best solution when indeed
189 * there is no need to do that if a reasonable threshold has already been
190 * reached.
191 * Because of this behaviour the stop threshold can be set to a value much
192 * lower than the one typically used in RANSAC, and yet the algorithm could
193 * still produce even smaller thresholds in estimated results.
194 *
195 * @param stopThreshold stop threshold to stop the algorithm prematurely
196 * when a certain accuracy has been reached.
197 * @throws IllegalArgumentException if provided value is zero or negative.
198 * @throws LockedException if this solver is locked.
199 */
200 public void setStopThreshold(final double stopThreshold) throws LockedException {
201 ((LMedSRobustLateration2DSolver) laterationSolver).setStopThreshold(stopThreshold);
202 }
203
204 /**
205 * Returns method being used for robust estimation.
206 *
207 * @return method being used for robust estimation.
208 */
209 @Override
210 public RobustEstimatorMethod getMethod() {
211 return RobustEstimatorMethod.LMEDS;
212 }
213
214 /**
215 * Initializes robust lateration solver.
216 */
217 private void init() {
218 laterationSolver = new LMedSRobustLateration2DSolver(trilaterationSolverListener);
219 }
220 }