1 /*
2 * Copyright (C) 2020 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.inertial.calibration.noise;
17
18 import com.irurueta.navigation.inertial.calibration.AccelerationTriad;
19 import com.irurueta.navigation.inertial.calibration.AccelerometerNoiseRootPsdSource;
20 import com.irurueta.navigation.inertial.calibration.TimeIntervalEstimator;
21 import com.irurueta.units.Acceleration;
22 import com.irurueta.units.AccelerationConverter;
23 import com.irurueta.units.AccelerationUnit;
24
25 /**
26 * Estimates accumulated acceleration noise variances and PSD's (Power Spectral Densities)
27 * along with their average values.
28 * This estimator must be used when the body where the accelerometer is attached
29 * remains static on the same position with zero velocity while capturing data.
30 * To compute PSD's, this estimator assumes that measurement samples are obtained
31 * at a constant provided rate equal to {@link #getTimeInterval()} seconds.
32 * If not available, accelerometer sampling rate average can be estimated using
33 * {@link TimeIntervalEstimator}.
34 * This estimator does NOT require the knowledge of current location and body
35 * orientation.
36 * Because body location and orientation is not known, estimated average values
37 * cannot be used to determine biases. Only norm of noise estimations
38 * (variance or standard deviation) can be safely used.
39 * This estimator does NOT require the knowledge of current location and body
40 * orientation.
41 * This implementation of noise estimator will use the following units:
42 * - meters per squared second (m/s^2) for acceleration, average or standard deviation values.
43 * - (m^2/s^4) for acceleration variances.
44 * - (m^2 * s^-3) for accelerometer PSD (Power Spectral Density).
45 * - (m * s^-1.5) for accelerometer root PSD (Power Spectral Density).
46 */
47 public class AccumulatedAccelerationTriadNoiseEstimator extends
48 AccumulatedTriadNoiseEstimator<AccelerationUnit, Acceleration, AccelerationTriad,
49 AccumulatedAccelerationTriadNoiseEstimator, AccumulatedAccelerationTriadNoiseEstimatorListener>
50 implements AccelerometerNoiseRootPsdSource {
51
52 /**
53 * Constructor.
54 */
55 public AccumulatedAccelerationTriadNoiseEstimator() {
56 super();
57 }
58
59 /**
60 * Constructor.
61 *
62 * @param listener listener to handle events raised by this estimator.
63 */
64 public AccumulatedAccelerationTriadNoiseEstimator(
65 final AccumulatedAccelerationTriadNoiseEstimatorListener listener) {
66 super(listener);
67 }
68
69 /**
70 * Creates a triad with provided values and unit.
71 *
72 * @param valueX x coordinate value.
73 * @param valueY y coordinate value.
74 * @param valueZ z coordinate value.
75 * @param unit unit.
76 * @return created triad.
77 */
78 @Override
79 protected AccelerationTriad createTriad(
80 final double valueX, final double valueY, final double valueZ, final AccelerationUnit unit) {
81 return new AccelerationTriad(unit, valueX, valueY, valueZ);
82 }
83
84 /**
85 * Gets default unit for a measurement.
86 *
87 * @return default unit for a measurement.
88 */
89 @Override
90 protected AccelerationUnit getDefaultUnit() {
91 return AccelerationUnit.METERS_PER_SQUARED_SECOND;
92 }
93
94 /**
95 * Creates a measurement with provided value and unit.
96 *
97 * @param value value to be set.
98 * @param unit unit to be set.
99 * @return created measurement.
100 */
101 @Override
102 protected Acceleration createMeasurement(final double value, final AccelerationUnit unit) {
103 return new Acceleration(value, unit);
104 }
105
106 /**
107 * Converts provided value and unit into default unit.
108 *
109 * @param value measurement value to be converted.
110 * @param unit unit of measurement value to be converted.
111 * @return converted value.
112 */
113 @Override
114 protected double convertToDefaultUnit(final double value, final AccelerationUnit unit) {
115 return AccelerationConverter.convert(value, unit, getDefaultUnit());
116 }
117
118 /**
119 * Gets accelerometer base noise level root PSD (Power Spectral Density)
120 * expressed in (m * s^-1.5).
121 *
122 * @return accelerometer base noise level root PSD.
123 */
124 @Override
125 public double getAccelerometerBaseNoiseLevelRootPsd() {
126 return getNoiseRootPsdNorm();
127 }
128 }