1 package org.opentrafficsim.road.gtu.lane.perception;
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) 2013-2015 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 /** @return whether this object is a GTU or not. */
50 public boolean isGtu()
51 {
52 return this.equals(GTU);
53 }
54
55 /** @return whether this object is a GTU or not. */
56 public boolean isTrafficLight()
57 {
58 return this.equals(TRAFFICLIGHT);
59 }
60
61 /** @return whether this object is an object or not. */
62 public boolean isObject()
63 {
64 return this.equals(OBJECT);
65 }
66
67 /** @return whether no object was observed and only a distance was stored. */
68 public boolean isDistanceOnly()
69 {
70 return this.equals(DISTANCEONLY);
71 }
72 }
73
74 /**
75 * @return String; the id of the other object for comparison purposes, cannot be null.
76 */
77 String getId();
78
79 /**
80 * @return Speed; the (perceived) speed of the other object; can be null if unknown.
81 */
82 Speed getSpeed();
83
84 /**
85 * Retrieve the strongly typed distance to the other object.
86 * @return Length; the distance to the object, return value null indicates that the other object is parallel to the
87 * reference object
88 */
89 Length getDistance();
90
91 /**
92 * @return Length; the (perceived) object Type, can be null if no object type unknown.
93 */
94 ObjectType getObjectType();
95
96 /**
97 * @return Acceleration; acceleration the (perceived) acceleration of the other object; can be null if unknown.
98 */
99 Acceleration getAcceleration();
100
101 /**
102 * Return the (perceived) front overlap to the other object. This value should be null if there is no overlap. In the figure
103 * for two GTUs below, it is distance c, positive for GTU1, negative for GTU2.
104 *
105 * <pre>
106 * ----------
107 * | GTU 1 | ----->
108 * ----------
109 * ---------------
110 * | GTU 2 | ----->
111 * ---------------
112 * | a | b | c |
113 * </pre>
114 * @return Length; the (perceived) front overlap to the other object or null if there is no overlap.
115 */
116 Length getOverlapFront();
117
118 /**
119 * Return the (perceived) rear overlap to the other object. This value should be null if there is no overlap.In the figure
120 * below for two GTUs, it is distance a, positive for GTU1, negative for GTU2.
121 *
122 * <pre>
123 * ----------
124 * | GTU 1 | ----->
125 * ----------
126 * ---------------
127 * | GTU 2 | ----->
128 * ---------------
129 * | a | b | c |
130 * </pre>
131 * @return Length; the (perceived) rear overlap to the other object or null if there is no overlap.
132 */
133 Length getOverlapRear();
134
135 /**
136 * Return the (perceived) overlap with the other object. This value should be null if there is no overlap. In the figure
137 * below for two GTUs, it is distance b, positive for GTU1 and GTU2.
138 *
139 * <pre>
140 * ----------
141 * | GTU 1 | ----->
142 * ----------
143 * ---------------
144 * | GTU 2 | ----->
145 * ---------------
146 * | a | b | c |
147 * </pre>
148 * @return Length, the (perceived) overlap with the other object or null if there is no overlap.
149 */
150 Length getOverlap();
151
152 /**
153 * @return whether the other object is in front of the reference object.
154 */
155 boolean isAhead();
156
157 /**
158 * @return whether the other object is behind the reference object.
159 */
160 boolean isBehind();
161
162 /**
163 * @return whether the other object is behind the reference object.
164 */
165 boolean isParallel();
166
167 /** {@inheritDoc} */
168 @Override
169 default int compareTo(Headway headway)
170 {
171 return getDistance().compareTo(headway.getDistance());
172 }
173 }