IdmPlusOld.java
package org.opentrafficsim.road.gtu.lane.tactical.following;
import java.io.Serializable;
import org.djunits.unit.AccelerationUnit;
import org.djunits.unit.DurationUnit;
import org.djunits.unit.LengthUnit;
import org.djunits.unit.SpeedUnit;
import org.djunits.value.vdouble.scalar.Acceleration;
import org.djunits.value.vdouble.scalar.Duration;
import org.djunits.value.vdouble.scalar.Length;
import org.djunits.value.vdouble.scalar.Speed;
import org.opentrafficsim.base.parameters.ParameterException;
import org.opentrafficsim.base.parameters.Parameters;
import org.opentrafficsim.road.gtu.lane.perception.PerceptionIterable;
import org.opentrafficsim.road.gtu.lane.perception.headway.Headway;
import org.opentrafficsim.road.network.speed.SpeedLimitInfo;
import org.opentrafficsim.road.network.speed.SpeedLimitTypes;
/**
* IDMPlus implements the <i>Integrated Lane Change Model with Relaxation and Synchronization</i> as published by Wouter J.
* Schakel, Bart van Arem, Member, IEEE, and Bart D. Netten. 2012. <br>
* There are two nasty type setting errors in equation 7 in this published version of the paper. Both times an equals sign
* (<cite>=</cite>) after <cite>a<sub>gain</sub></cite> should <b>not</b> be there.
* <p>
* Copyright (c) 2013-2024 Delft University of Technology, PO Box 5, 2600 AA, Delft, the Netherlands. All rights reserved. <br>
* BSD-style license. See <a href="https://opentrafficsim.org/docs/license.html">OpenTrafficSim License</a>.
* </p>
* @author <a href="https://tudelft.nl/staff/p.knoppers-1">Peter Knoppers</a>
*/
public class IdmPlusOld extends AbstractGtuFollowingModelMobil implements Serializable
{
/** */
private static final long serialVersionUID = 20140704L;
/** Preferred net longitudinal distance when stopped [m]. */
private final Length s0;
/** Longitudinal acceleration [m/s^2]. */
private Acceleration a;
/** Longitudinal deceleration [m/s^2]. (Should be a positive value even though it is a <b>de</b>celeration.) */
private final Acceleration b;
/** Safe time headway. */
private Duration tSafe;
/**
* Mean speed limit adherence (1.0: mean free speed equals the speed limit; 1.1: mean free speed equals 110% of the speed
* limit, etc.).
*/
private double delta;
/**
* Default step size used by IDMPlus (not defined in the paper, but 0.5s is a reasonable trade-off between computational
* speed and accuracy).
*/
private static final Duration DEFAULT_STEP_SIZE = new Duration(0.5, DurationUnit.SECOND);
/**
* Construct a new IDM+ car following model with reasonable values (reasonable for passenger cars). <br>
* These values are from <b>Integrated Lane Change Model with Relaxation and Synchronization</b> by Wouter J. Schakel,
* Victor L. Knoop, and Bart van Arem, published in Transportation Research Record: Journal of the Transportation Research
* Board, No. 2316, Transportation Research Board of the National Academies, Washington, D.C., 2012, pp. 47–57.
*/
public IdmPlusOld()
{
this.a = new Acceleration(1.56, AccelerationUnit.METER_PER_SECOND_2);
this.b = new Acceleration(2.09, AccelerationUnit.METER_PER_SECOND_2);
this.s0 = new Length(3, LengthUnit.METER);
this.tSafe = new Duration(1.2, DurationUnit.SECOND);
this.delta = 1d;
}
/**
* Construct a new IDMPlus car following model.
* @param a Acceleration; the maximum acceleration of a stationary vehicle (normal value is 1 m/s/s)
* @param b Acceleration; the maximum deemed-safe deceleration (this is a positive value)
* @param s0 Length; the minimum stationary headway
* @param tSafe Duration; the minimum time-headway
* @param delta double; the speed limit adherence (1.0; mean free speed equals the speed limit; 1.1: mean free speed equals
* 110% of the speed limit; etc.)
*/
public IdmPlusOld(final Acceleration a, final Acceleration b, final Length s0, final Duration tSafe, final double delta)
{
this.a = a;
this.b = b;
this.s0 = s0;
this.tSafe = tSafe;
this.delta = delta;
}
/**
* Desired speed (taking into account the urge to drive a little faster or slower than the posted speed limit).
* @param speedLimit Speed; the speed limit
* @param followerMaximumSpeed Speed; the maximum speed that the follower can drive
* @return DoubleScalarRel<SpeedUnit>; the desired speed
*/
private Speed vDes(final Speed speedLimit, final Speed followerMaximumSpeed)
{
return new Speed(Math.min(this.delta * speedLimit.getSI(), followerMaximumSpeed.getSI()), SpeedUnit.SI);
}
/** {@inheritDoc} */
@Override
public final Acceleration computeAcceleration(final Speed followerSpeed, final Speed followerMaximumSpeed,
final Speed leaderSpeed, final Length headway, final Speed speedLimit)
{
return computeAcceleration(followerSpeed, followerMaximumSpeed, leaderSpeed, headway, speedLimit, DEFAULT_STEP_SIZE);
}
/** {@inheritDoc} */
@Override
public final Acceleration computeAcceleration(final Speed followerSpeed, final Speed followerMaximumSpeed,
final Speed leaderSpeed, final Length headway, final Speed speedLimit, final Duration stepSize)
{
// TODO maxDistance
double leftComponent = 1 - Math.pow(followerSpeed.getSI() / vDes(speedLimit, followerMaximumSpeed).getSI(), 4);
if (Double.isNaN(leftComponent))
{
leftComponent = 0;
}
// limit deceleration for free term (= leftComponent)
if (leftComponent * this.a.si < -0.5)
{
leftComponent = -0.5 / this.a.si;
}
Acceleration logWeightedAccelerationTimes2 =
new Acceleration(Math.sqrt(this.a.getSI() * this.b.getSI()), AccelerationUnit.SI).times(2);
// don't forget the times 2
Speed dV = followerSpeed.minus(leaderSpeed);
Length sStar = this.s0.plus(followerSpeed.times(this.tSafe))
.plus(dV.times(followerSpeed.divide(logWeightedAccelerationTimes2)));
/*-
this.s0.plus(Calc.speedTimesTime(followerSpeed, this.tSafe)).plus(
Calc.speedTimesTime(dV, Calc.speedDividedByAcceleration(followerSpeed, logWeightedAccelerationTimes2)));
*/
if (sStar.getSI() < 0)
{
// Negative value should be treated as 0? This is NOT in the LMRS paper
// Without this "fix" a higher speed of the leader may cause a lower acceleration (which is crazy)
sStar = new Length(0, LengthUnit.SI);
}
double rightComponent = 1 - Math.pow(sStar.getSI() / headway.getSI(), 2);
Acceleration newAcceleration = new Acceleration(this.a).times(Math.min(leftComponent, rightComponent));
if (newAcceleration.getSI() * stepSize.getSI() + followerSpeed.getSI() < 0)
{
newAcceleration = new Acceleration(-followerSpeed.getSI() / stepSize.getSI(), AccelerationUnit.SI);
}
return newAcceleration;
}
/** {@inheritDoc} */
@Override
public final Duration getStepSize()
{
return DEFAULT_STEP_SIZE;
}
/** {@inheritDoc} */
@Override
public final Acceleration getMaximumSafeDeceleration()
{
return this.b;
}
/** {@inheritDoc} */
@Override
public final String getName()
{
return "IDM+";
}
/** {@inheritDoc} */
@Override
public final String getLongName()
{
return String.format("%s (a=%.1fm/s\u00b2, b=%.1fm/s\u00b2, s0=%.1fm, tSafe=%.1fs, delta=%.2f)", getName(),
this.a.getSI(), this.b.getSI(), this.s0.getSI(), this.tSafe.getSI(), this.delta);
}
/** {@inheritDoc} */
@Override
public final void setA(final Acceleration a)
{
this.a = a;
}
/** {@inheritDoc} */
@Override
public final void setT(final Duration t)
{
this.tSafe = t;
}
/** {@inheritDoc} */
@Override
public final void setFspeed(final double fSpeed)
{
this.delta = fSpeed;
}
// The following is inherited from CarFollowingModel
/** {@inheritDoc} */
@Override
public final Speed desiredSpeed(final Parameters parameters, final SpeedLimitInfo speedInfo) throws ParameterException
{
throw new UnsupportedOperationException("Old car-following model does not support desired speed.");
}
/** {@inheritDoc} */
@Override
public final Length desiredHeadway(final Parameters parameters, final Speed speed) throws ParameterException
{
throw new UnsupportedOperationException("Old car-following model does not support desired headway.");
}
/** {@inheritDoc} */
@Override
public final Acceleration followingAcceleration(final Parameters parameters, final Speed speed,
final SpeedLimitInfo speedInfo, final PerceptionIterable<? extends Headway> leaders) throws ParameterException
{
Length headway;
Speed leaderSpeed;
if (leaders.isEmpty())
{
headway = new Length(Double.MAX_VALUE, LengthUnit.SI);
leaderSpeed = speed;
}
else
{
Headway leader = leaders.first();
headway = leader.getDistance();
leaderSpeed = leader.getSpeed();
}
return this.computeAcceleration(speed, speedInfo.getSpeedInfo(SpeedLimitTypes.MAX_VEHICLE_SPEED), leaderSpeed, headway,
speedInfo.getSpeedInfo(SpeedLimitTypes.FIXED_SIGN));
}
/** {@inheritDoc} */
@Override
public final String toString()
{
return "IDMPlusOld [s0=" + this.s0 + ", a=" + this.a + ", b=" + this.b + ", tSafe=" + this.tSafe + ", delta="
+ this.delta + ", stepSize=" + DEFAULT_STEP_SIZE + "]";
}
}