SUMO - Simulation of Urban MObility
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MSCFModel.cpp
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1 /****************************************************************************/
11 // The car-following model abstraction
12 /****************************************************************************/
13 // SUMO, Simulation of Urban MObility; see http://sumo.sourceforge.net/
14 // Copyright (C) 2001-2013 DLR (http://www.dlr.de/) and contributors
15 /****************************************************************************/
16 //
17 // This file is part of SUMO.
18 // SUMO is free software: you can redistribute it and/or modify
19 // it under the terms of the GNU General Public License as published by
20 // the Free Software Foundation, either version 3 of the License, or
21 // (at your option) any later version.
22 //
23 /****************************************************************************/
24 
25 
26 // ===========================================================================
27 // included modules
28 // ===========================================================================
29 #ifdef _MSC_VER
30 #include <windows_config.h>
31 #else
32 #include <config.h>
33 #endif
34 
35 #include <math.h>
36 #include "MSCFModel.h"
37 #include "MSVehicleType.h"
38 #include "MSVehicle.h"
39 #include "MSLane.h"
41 
42 
43 // ===========================================================================
44 // method definitions
45 // ===========================================================================
46 MSCFModel::MSCFModel(const MSVehicleType* vtype, const SUMOReal accel,
47  const SUMOReal decel, const SUMOReal headwayTime)
48  : myType(vtype), myAccel(accel), myDecel(decel), myHeadwayTime(headwayTime) {
49 }
50 
51 
53 
54 
56 MSCFModel::moveHelper(MSVehicle* const veh, SUMOReal vPos) const {
57  const SUMOReal oldV = veh->getSpeed(); // save old v for optional acceleration computation
58  const SUMOReal vSafe = MIN2(vPos, veh->processNextStop(vPos)); // process stops
59  // we need the acceleration for emission computation;
60  // in this case, we neglect dawdling, nonetheless, using
61  // vSafe does not incorporate speed reduction due to interaction
62  // on lane changing
63  const SUMOReal vMin = getSpeedAfterMaxDecel(oldV);
64  const SUMOReal vMax = MIN3(veh->getLane()->getVehicleMaxSpeed(veh), maxNextSpeed(oldV, veh), vSafe);
65  assert(vMin <= vMax);
66  return veh->getLaneChangeModel().patchSpeed(vMin, vMax, vMax, *this);
67 }
68 
69 
71 MSCFModel::interactionGap(const MSVehicle* const veh, SUMOReal vL) const {
72  // Resolve the vsafe equation to gap. Assume predecessor has
73  // speed != 0 and that vsafe will be the current speed plus acceleration,
74  // i.e that with this gap there will be no interaction.
75  const SUMOReal vNext = MIN2(maxNextSpeed(veh->getSpeed(), veh), veh->getLane()->getVehicleMaxSpeed(veh));
76  const SUMOReal gap = (vNext - vL) *
77  ((veh->getSpeed() + vL) / (2.*myDecel) + myHeadwayTime) +
78  vL * myHeadwayTime;
79 
80  // Don't allow timeHeadWay < deltaT situations.
81  return MAX2(gap, SPEED2DIST(vNext));
82 }
83 
84 
85 void
86 MSCFModel::leftVehicleVsafe(const MSVehicle* const ego, const MSVehicle* const neigh, SUMOReal& vSafe) const {
87  if (neigh != 0 && neigh->getSpeed() > 60. / 3.6) {
88  SUMOReal mgap = MAX2((SUMOReal) 0, neigh->getPositionOnLane() - neigh->getVehicleType().getLength() - ego->getPositionOnLane() - ego->getVehicleType().getMinGap());
89  SUMOReal nVSafe = followSpeed(ego, ego->getSpeed(), mgap, neigh->getSpeed(), neigh->getCarFollowModel().getMaxDecel());
90  if (mgap - neigh->getSpeed() >= 0) {
91  vSafe = MIN2(vSafe, nVSafe);
92  }
93  }
94 }
95 
96 
98 MSCFModel::maxNextSpeed(SUMOReal speed, const MSVehicle* const /*veh*/) const {
99  return MIN2(speed + (SUMOReal) ACCEL2SPEED(getMaxAccel()), myType->getMaxSpeed());
100 }
101 
102 
103 SUMOReal
105  /* one possiblity to speed this up is to precalculate speedReduction * steps * (steps+1) / 2
106  for small values of steps (up to 10 maybe) and store them in an array */
107  const SUMOReal speedReduction = ACCEL2SPEED(getMaxDecel());
108  const int steps = int(speed / speedReduction);
109  return SPEED2DIST(steps * speed - speedReduction * steps * (steps + 1) / 2) + speed * myHeadwayTime;
110 }
111 
112 
113 SUMOReal
114 MSCFModel::freeSpeed(const MSVehicle* const veh, SUMOReal speed, SUMOReal seen, SUMOReal maxSpeed) const {
115  UNUSED_PARAMETER(veh);
116  // adapt speed to succeeding lane, no reaction time is involved
117  // when breaking for y steps the following distance g is covered
118  // (drive with v in the final step)
119  // g = (y^2 + y) * 0.5 * b + y * v
120  // y = ((((sqrt((b + 2.0*v)*(b + 2.0*v) + 8.0*b*g)) - b)*0.5 - v)/b)
121  const SUMOReal b = ACCEL2SPEED(myDecel);
122  const SUMOReal y = MAX2(0.0, ((sqrt((b + 2.0 * maxSpeed) * (b + 2.0 * maxSpeed) + 8.0 * b * seen) - b) * 0.5 - maxSpeed) / b);
123  const SUMOReal yFull = floor(y);
124  const SUMOReal exactGap = (yFull * yFull + yFull) * 0.5 * b + yFull * maxSpeed + (y > yFull ? maxSpeed : 0.0);
125  return MAX2((SUMOReal)0.0, seen - exactGap) / (yFull + 1) + yFull * myDecel + maxSpeed;
126 }
127 
128 /****************************************************************************/