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.AngularSpeedTriad;
19 import com.irurueta.navigation.inertial.calibration.GyroscopeNoiseRootPsdSource;
20 import com.irurueta.navigation.inertial.calibration.TimeIntervalEstimator;
21 import com.irurueta.units.AngularSpeed;
22 import com.irurueta.units.AngularSpeedUnit;
23
24 /**
25 * Estimates angular speed noise variances and PSD's (Power Spectral Densities)
26 * along with the gyroscope average values for a windowed amount of samples.
27 * This estimator must be used when the body where the gyroscope is attached
28 * remains static on the same position with zero velocity while capturing data.
29 * To compute PSD's, this estimator assumes that gyroscope samples are
30 * obtained at a constant provided rate equal to {@link #getTimeInterval()} seconds.
31 * If not available, gyroscope sampling rate average can be estimated using
32 * {@link TimeIntervalEstimator}.
33 * This estimator does NOT require the knowledge of current location and body
34 * orientation.
35 * Because body location and orientation is not known, estimated average values
36 * cannot be used to determine biases. Only norm of noise estimations can be
37 * safely used as an indication of variation of overall rotation rate (which is
38 * indicated by norm of estimated average).
39 * Notice that if there are less than {@link #getWindowSize()} processed
40 * samples in the window, this estimator will assume that the remaining ones
41 * until the window is completed have zero values.
42 * This implementation of noise estimator will use the following units:
43 * - radians per second (rad/s) for angular speed, average or standard deviation values.
44 * - (rad^2/s^2) fr angular speed variances.
45 * - (rad^2/s) for gyroscope PSD (Power Spectral Density).
46 * - (rad * s^-0.5) for gyroscope root PSD (Power Spectral Density).
47 */
48 public class WindowedAngularSpeedTriadNoiseEstimator extends
49 WindowedTriadNoiseEstimator<AngularSpeedUnit, AngularSpeed, AngularSpeedTriad,
50 WindowedAngularSpeedTriadNoiseEstimator, WindowedAngularSpeedTriadNoiseEstimatorListener>
51 implements GyroscopeNoiseRootPsdSource {
52
53 /**
54 * Constructor.
55 */
56 public WindowedAngularSpeedTriadNoiseEstimator() {
57 super();
58 }
59
60 /**
61 * Constructor.
62 *
63 * @param listener listener to handle events raised by this estimator.
64 */
65 public WindowedAngularSpeedTriadNoiseEstimator(final WindowedAngularSpeedTriadNoiseEstimatorListener listener) {
66 super(listener);
67 }
68
69 /**
70 * Creates a copy of a triad.
71 *
72 * @param input triad to be copied.
73 * @return copy of a triad.
74 */
75 @Override
76 protected AngularSpeedTriad copyTriad(final AngularSpeedTriad input) {
77 return new AngularSpeedTriad(input);
78 }
79
80 /**
81 * Creates a triad with provided values and unit.
82 *
83 * @param valueX x coordinate value.
84 * @param valueY y coordinate value.
85 * @param valueZ z coordinate value.
86 * @param unit unit.
87 * @return created triad.
88 */
89 @Override
90 protected AngularSpeedTriad createTriad(
91 final double valueX, final double valueY, final double valueZ, final AngularSpeedUnit unit) {
92 return new AngularSpeedTriad(unit, valueX, valueY, valueZ);
93 }
94
95 /**
96 * Creates a triad with provided values.
97 *
98 * @param valueX x coordinate value.
99 * @param valueY y coordinate value.
100 * @param valueZ z coordinate value.
101 * @return created triad.
102 */
103 @Override
104 protected AngularSpeedTriad createTriad(
105 final AngularSpeed valueX, final AngularSpeed valueY, final AngularSpeed valueZ) {
106 return new AngularSpeedTriad(valueX, valueY, valueZ);
107 }
108
109 /**
110 * Gets default unit for a measurement.
111 *
112 * @return default unit for a measurement.
113 */
114 @Override
115 protected AngularSpeedUnit getDefaultUnit() {
116 return AngularSpeedUnit.RADIANS_PER_SECOND;
117 }
118
119 /**
120 * Creates a measurement with provided value and unit.
121 *
122 * @param value value to be set.
123 * @param unit unit to be set.
124 * @return created measurement.
125 */
126 @Override
127 protected AngularSpeed createMeasurement(final double value, final AngularSpeedUnit unit) {
128 return new AngularSpeed(value, unit);
129 }
130
131 /**
132 * Gets gyroscope base noise level root PSD (Power Spectral Density)
133 * expressed in (rad * s^-0.5)
134 *
135 * @return gyroscope base noise level root PSD.
136 */
137 @Override
138 public double getGyroscopeBaseNoiseLevelRootPsd() {
139 return getNoiseRootPsdNorm();
140 }
141 }