1 package org.opentrafficsim.road.gtu.lane.perception.headway;
2
3 import org.djunits.value.vdouble.scalar.Acceleration;
4 import org.djunits.value.vdouble.scalar.Length;
5 import org.djunits.value.vdouble.scalar.Speed;
6 import org.opentrafficsim.core.perception.PerceivedObject;
7
8 /**
9 * Interface for a reference to information about a (lane based) GTU and a headway. The Headway can store information about GTUs
10 * or objects ahead of the reference GTU, behind the reference GTU, or (partially) parallel to the reference GTU. In addition to
11 * the (perceived) headway, several other pieces of information can be stored, such as (perceived) speed, (perceived)
12 * acceleration, (perceived) turn indicators, and (perceived) braking lights. <br>
13 * Special care must be taken in curves when perceiving headway of a GTU or object on an adjacent lane.The question is whether
14 * we perceive the parallel or ahead/behind based on a line perpendicular to the front/back of the GTU (rectangular), or
15 * perpendicular to the center line of the lane (wedge-shaped in case of a curve). The difficulty of a wedge-shaped situation is
16 * that reciprocity might be violated: in case of a clothoid, for instance, it is not sure that the point on the center line
17 * when projected from lane 1 to lane 2 is the same as the projection from lane 2 to lane 1. The same holds for shapes with
18 * sharp bends. Therefore, algorithms implementing headway should only project the <i>reference point</i> of the reference GTU
19 * on the center line of the adjacent lane, and then calculate the forward position and backward position on the adjacent lane
20 * based on the reference point. Still, our human perception of what is parallel and what not, is not reflected by fractional
21 * positions. See examples in <a href=
22 * "http://simulation.tudelft.nl:8085/browse/OTS-113">http://simulation.tudelft.nl:8085/browse/OTS-113</a>.
23 * <p>
24 * Copyright (c) 2013-2016 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
25 * BSD-style license. See <a href="http://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
26 * <p>
27 * @version $Revision: 1368 $, $LastChangedDate: 2015-09-02 00:20:20 +0200 (Wed, 02 Sep 2015) $, by $Author: averbraeck $,
28 * initial version 11 feb. 2015 <br>
29 * @author <a href="http://www.tbm.tudelft.nl/averbraeck">Alexander Verbraeck</a>
30 * @author <a href="http://www.tudelft.nl/pknoppers">Peter Knoppers</a>
31 */
32 public interface Headway extends PerceivedObject, Comparable<Headway>
33 {
34 /** the object types that can be distinguished for headway. */
35 enum ObjectType
36 {
37 /** the observed object for headway is a GTU. */
38 GTU,
39
40 /** the observed object for headway is a traffic light. */
41 TRAFFICLIGHT,
42
43 /** the observed object for headway is a generic object. */
44 OBJECT,
45
46 /** there is no observed object, just a distance. */
47 DISTANCEONLY,
48
49 /** intersection conflict. */
50 CONFLICT,
51
52 /** stop line. */
53 STOPLINE,
54
55 /** bus stop. */
56 BUSSTOP;
57
58 /** @return whether this object is a GTU or not. */
59 public boolean isGtu()
60 {
61 return this.equals(GTU);
62 }
63
64 /** @return whether this object is a GTU or not. */
65 public boolean isTrafficLight()
66 {
67 return this.equals(TRAFFICLIGHT);
68 }
69
70 /** @return whether this object is an object or not. */
71 public boolean isObject()
72 {
73 return this.equals(OBJECT);
74 }
75
76 /** @return whether no object was observed and only a distance was stored. */
77 public boolean isDistanceOnly()
78 {
79 return this.equals(DISTANCEONLY);
80 }
81
82 /** @return whether this object is a conflict or not. */
83 public boolean isConflict()
84 {
85 return this.equals(CONFLICT);
86 }
87
88 /** @return whether this object is a stop line or not. */
89 public boolean isStopLine()
90 {
91 return this.equals(STOPLINE);
92 }
93
94 /** @return whether this object is a bus stop or not. */
95 public boolean isBusStop()
96 {
97 return this.equals(BUSSTOP);
98 }
99
100 }
101
102 /**
103 * @return String; the id of the other object for comparison purposes, cannot be null.
104 */
105 String getId();
106
107 /**
108 * @return Length; the length of the other object; can be null if unknown.
109 */
110 Length getLength();
111
112 /**
113 * @return Speed; the (perceived) speed of the other object; can be null if unknown.
114 */
115 Speed getSpeed();
116
117 /**
118 * Retrieve the strongly typed distance to the other object.
119 * @return Length; the distance to the object, return value null indicates that the other object is parallel to the
120 * reference object
121 */
122 Length getDistance();
123
124 /**
125 * @return Length; the (perceived) object Type, can be null if no object type unknown.
126 */
127 ObjectType getObjectType();
128
129 /**
130 * @return Acceleration; acceleration the (perceived) acceleration of the other object; can be null if unknown.
131 */
132 Acceleration getAcceleration();
133
134 /**
135 * Return the (perceived) front overlap to the other object. This value should be null if there is no overlap. In the figure
136 * for two GTUs below, it is distance c, positive for GTU1, negative for GTU2.
137 *
138 * <pre>
139 * ----------
140 * | GTU 1 | ----->
141 * ----------
142 * ---------------
143 * | GTU 2 | ----->
144 * ---------------
145 * | a | b | c |
146 * </pre>
147 * @return Length; the (perceived) front overlap to the other object or null if there is no overlap.
148 */
149 Length getOverlapFront();
150
151 /**
152 * Return the (perceived) rear overlap to the other object. This value should be null if there is no overlap.In the figure
153 * below for two GTUs, it is distance a, positive for GTU1, negative for GTU2.
154 *
155 * <pre>
156 * ----------
157 * | GTU 1 | ----->
158 * ----------
159 * ---------------
160 * | GTU 2 | ----->
161 * ---------------
162 * | a | b | c |
163 * </pre>
164 * @return Length; the (perceived) rear overlap to the other object or null if there is no overlap.
165 */
166 Length getOverlapRear();
167
168 /**
169 * Return the (perceived) overlap with the other object. This value should be null if there is no overlap. In the figure
170 * below for two GTUs, it is distance b, positive for GTU1 and GTU2.
171 *
172 * <pre>
173 * ----------
174 * | GTU 1 | ----->
175 * ----------
176 * ---------------
177 * | GTU 2 | ----->
178 * ---------------
179 * | a | b | c |
180 * </pre>
181 * @return Length, the (perceived) overlap with the other object or null if there is no overlap.
182 */
183 Length getOverlap();
184
185 /**
186 * @return whether the other object is in front of the reference object.
187 */
188 boolean isAhead();
189
190 /**
191 * @return whether the other object is behind the reference object.
192 */
193 boolean isBehind();
194
195 /**
196 * @return whether the other object is parallel the reference object.
197 */
198 boolean isParallel();
199
200 /** {@inheritDoc} */
201 @Override
202 default int compareTo(Headway headway)
203 {
204 if (getDistance() == null && headway.getDistance() == null)
205 {
206 return getOverlapFront().compareTo(headway.getOverlapFront());
207 }
208 else if (getDistance() == null)
209 {
210 return -1;
211 }
212 else if (headway.getDistance() == null)
213 {
214 return 1;
215 }
216 return getDistance().compareTo(headway.getDistance());
217 }
218 }