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.RangingFingerprint;
23 import com.irurueta.navigation.indoor.RangingReading;
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 readings
31 * 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 readings at an unknown location of different radio sources
34 * whose 2D locations are known.
35 */
36 public class LMedSRobustRangingPositionEstimator2D extends RobustRangingPositionEstimator2D {
37
38 /**
39 * Constructor.
40 */
41 public LMedSRobustRangingPositionEstimator2D() {
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 LMedSRobustRangingPositionEstimator2D(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 readings at an unknown location
63 * for provided located radio sources.
64 * @throws IllegalArgumentException if provided fingerprint is null.
65 */
66 public LMedSRobustRangingPositionEstimator2D(
67 final RangingFingerprint<? extends RadioSource, ? extends RangingReading<?
68 extends RadioSource>> fingerprint) {
69 super();
70 init();
71 internalSetFingerprint(fingerprint);
72 }
73
74 /**
75 * Constructor.
76 *
77 * @param sources located radio sources used for lateration.
78 * @param fingerprint fingerprint containing ranging readings at an unknown location
79 * for provided located radio sources.
80 * @throws IllegalArgumentException if either provided sources or fingerprint is null
81 * or the number of provided sources is less than the required minimum.
82 */
83 public LMedSRobustRangingPositionEstimator2D(
84 final List<? extends RadioSourceLocated<Point2D>> sources,
85 final RangingFingerprint<? extends RadioSource, ? extends RangingReading<?
86 extends RadioSource>> fingerprint) {
87 super();
88 init();
89 internalSetSources(sources);
90 internalSetFingerprint(fingerprint);
91 }
92
93 /**
94 * Constructor.
95 *
96 * @param listener listener in charge of handling events.
97 */
98 public LMedSRobustRangingPositionEstimator2D(final RobustRangingPositionEstimatorListener<Point2D> listener) {
99 super(listener);
100 init();
101 }
102
103 /**
104 * Constructor.
105 *
106 * @param sources located radio sources used for lateration.
107 * @param listener listener in charge of handling events.
108 * @throws IllegalArgumentException if provided sources is null or the number of
109 * provided sources is less than the required minimum.
110 */
111 public LMedSRobustRangingPositionEstimator2D(
112 final List<? extends RadioSourceLocated<Point2D>> sources,
113 final RobustRangingPositionEstimatorListener<Point2D> listener) {
114 super(listener);
115 init();
116 internalSetSources(sources);
117 }
118
119 /**
120 * Constructor.
121 *
122 * @param fingerprint fingerprint containing ranging readings at an unknown
123 * location for provided location radio sources.
124 * @param listener listener in charge of handling events.
125 * @throws IllegalArgumentException if provided fingerprint is null.
126 */
127 public LMedSRobustRangingPositionEstimator2D(
128 final RangingFingerprint<? extends RadioSource, ? extends RangingReading<?
129 extends RadioSource>> fingerprint,
130 final RobustRangingPositionEstimatorListener<Point2D> listener) {
131 super(listener);
132 init();
133 internalSetFingerprint(fingerprint);
134 }
135
136 /**
137 * Constructor.
138 *
139 * @param sources located radio sources used for lateration.
140 * @param fingerprint fingerprint containing readings at an unknown location for
141 * provided located radio sources.
142 * @param listener listener in charge of handling events.
143 * @throws IllegalArgumentException if either provided sources or fingerprint is
144 * null or the number of provided sources is less than the required minimum.
145 */
146 public LMedSRobustRangingPositionEstimator2D(
147 final List<? extends RadioSourceLocated<Point2D>> sources,
148 final RangingFingerprint<? extends RadioSource, ? extends RangingReading<?
149 extends RadioSource>> fingerprint,
150 final RobustRangingPositionEstimatorListener<Point2D> listener) {
151 super(listener);
152 init();
153 internalSetSources(sources);
154 internalSetFingerprint(fingerprint);
155 }
156
157 /**
158 * Returns threshold to be used to keep the algorithm iterating in case that
159 * best estimated threshold using median of residuals is not small enough.
160 * Once a solution is found that generates a threshold below this value, the
161 * algorithm will stop.
162 * The stop threshold can be used to prevent the LMedS algorithm to iterate
163 * too many times in cases where samples have a very similar accuracy.
164 * For instance, in cases where proportion of outliers is very small (close
165 * to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would
166 * iterate for a long time trying to find the best solution when indeed
167 * there is no need to do that if a reasonable threshold has already been
168 * reached.
169 * Because of this behaviour the stop threshold can be set to a value much
170 * lower than the one typically used in RANSAC, and yet the algorithm could
171 * still produce even smaller thresholds in estimated results.
172 *
173 * @return stop threshold to stop the algorithm prematurely when a certain
174 * accuracy has been reached.
175 */
176 public double getStopThreshold() {
177 return ((LMedSRobustLateration2DSolver) laterationSolver).getStopThreshold();
178 }
179
180 /**
181 * Sets threshold to be used to keep the algorithm iterating in case that
182 * best estimated threshold using median of residuals is not small enough.
183 * Once a solution is found that generates a threshold below this value,
184 * the algorithm will stop.
185 * The stop threshold can be used to prevent the LMedS algorithm to iterate
186 * too many times in cases where samples have a very similar accuracy.
187 * For instance, in cases where proportion of outliers is very small (close
188 * to 0%), and samples are very accurate (i.e. 1e-6), the algorithm would
189 * iterate for a long time trying to find the best solution when indeed
190 * there is no need to do that if a reasonable threshold has already been
191 * reached.
192 * Because of this behaviour the stop threshold can be set to a value much
193 * lower than the one typically used in RANSAC, and yet the algorithm could
194 * still produce even smaller thresholds in estimated results.
195 *
196 * @param stopThreshold stop threshold to stop the algorithm prematurely
197 * when a certain accuracy has been reached.
198 * @throws IllegalArgumentException if provided value is zero or negative.
199 * @throws LockedException if this solver is locked.
200 */
201 public void setStopThreshold(final double stopThreshold) throws LockedException {
202 ((LMedSRobustLateration2DSolver) laterationSolver).setStopThreshold(stopThreshold);
203 }
204
205 /**
206 * Returns method being used for robust estimation.
207 *
208 * @return method being used for robust estimation.
209 */
210 @Override
211 public RobustEstimatorMethod getMethod() {
212 return RobustEstimatorMethod.LMEDS;
213 }
214
215 /**
216 * Initializes robust lateration solver.
217 */
218 private void init() {
219 laterationSolver = new LMedSRobustLateration2DSolver(trilaterationSolverListener);
220 }
221 }