Obstacle avoidance refactoring

This commit is contained in:
Alexander Nozik 2023-04-23 11:01:08 +03:00
parent cdaa17a3b9
commit cac5841401
3 changed files with 614 additions and 547 deletions

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@ -5,531 +5,62 @@
package space.kscience.trajectory
import space.kscience.kmath.geometry.*
import space.kscience.kmath.geometry.Euclidean2DSpace.distanceTo
import space.kscience.kmath.geometry.Euclidean2DSpace.minus
import space.kscience.kmath.geometry.Euclidean2DSpace.norm
import space.kscience.kmath.geometry.Euclidean2DSpace.plus
import space.kscience.kmath.geometry.Euclidean2DSpace.times
import space.kscience.kmath.geometry.Euclidean2DSpace.vector
import space.kscience.kmath.misc.zipWithNextCircular
import space.kscience.kmath.operations.DoubleField.pow
import kotlin.math.*
internal data class Tangent(
val startCircle: Circle2D,
val endCircle: Circle2D,
val startObstacle: Obstacle,
val endObstacle: Obstacle,
val lineSegment: LineSegment2D,
val startDirection: Trajectory2D.Direction,
val endDirection: Trajectory2D.Direction = startDirection,
) : LineSegment2D by lineSegment
import space.kscience.kmath.geometry.Circle2D
import space.kscience.kmath.geometry.LineSegment2D
import space.kscience.kmath.geometry.Polygon
import space.kscience.kmath.geometry.Vector2D
private class LR<T>(val l: T, val r: T) {
operator fun get(direction: Trajectory2D.Direction) = when (direction) {
Trajectory2D.L -> l
Trajectory2D.R -> r
}
}
public interface Obstacle {
public val circles: List<Circle2D>
public val center: Vector2D<Double>
private class TangentPath(val tangents: List<Tangent>) {
fun last() = tangents.last()
}
public fun intersects(segment: LineSegment2D): Boolean
private fun TangentPath(vararg tangents: Tangent) = TangentPath(listOf(*tangents))
/**
* Create inner and outer tangents between two circles.
* This method returns a map of segments using [DubinsPath] connection type notation.
*/
internal fun tangentsBetweenCircles(
first: Circle2D,
second: Circle2D,
): Map<DubinsPath.Type, LineSegment2D> = with(Euclidean2DSpace) {
//return empty map for concentric circles
if (first.center.equalsVector(second.center)) return emptyMap()
// A line connecting centers
val line = LineSegment(first.center, second.center)
// Distance between centers
val distance = line.begin.distanceTo(line.end)
val angle1 = atan2(second.center.x - first.center.x, second.center.y - first.center.y)
var angle2: Double
return listOf(
DubinsPath.Type.RSR,
DubinsPath.Type.RSL,
DubinsPath.Type.LSR,
DubinsPath.Type.LSL
).associateWith { route ->
val r1 = when (route.first) {
Trajectory2D.L -> -first.radius
Trajectory2D.R -> first.radius
}
val r2 = when (route.third) {
Trajectory2D.L -> -second.radius
Trajectory2D.R -> second.radius
}
val r = if (r1.sign == r2.sign) {
r1.absoluteValue - r2.absoluteValue
} else {
r1.absoluteValue + r2.absoluteValue
}
if (distance * distance < r * r) error("Circles should not intersect")
val l = sqrt(distance * distance - r * r)
angle2 = if (r1.absoluteValue > r2.absoluteValue) {
angle1 + r1.sign * atan2(r.absoluteValue, l)
} else {
angle1 - r2.sign * atan2(r.absoluteValue, l)
}
val w = vector(-cos(angle2), sin(angle2))
LineSegment(
first.center + w * r1,
second.center + w * r2
)
}
}
internal class Obstacle(
public val circles: List<Circle2D>,
) {
public val center: Vector2D<Double> = vector(
circles.sumOf { it.center.x } / circles.size,
circles.sumOf { it.center.y } / circles.size
)
internal val tangents: List<LineSegment2D>
public val direction: Trajectory2D.Direction
init {
if (circles.size < 2) {
tangents = emptyList()
direction = Trajectory2D.R
} else {
val lslTangents = circles.zipWithNextCircular { a, b ->
tangentsBetweenCircles(a, b)[DubinsPath.Type.LSL]!!
public companion object {
public fun allPathsAvoiding(
start: DubinsPose2D,
finish: DubinsPose2D,
trajectoryRadius: Double,
vararg obstacles: Obstacle,
): List<CompositeTrajectory2D> {
val obstacleShells: List<ObstacleShell> = obstacles.map { polygon ->
ObstacleShell(polygon.circles)
}
val rsrTangents = circles.zipWithNextCircular { a, b ->
tangentsBetweenCircles(a, b)[DubinsPath.Type.RSR]!!
return findAllPaths(start, trajectoryRadius, finish, trajectoryRadius, obstacleShells)
}
public fun allPathsAvoiding(
start: DubinsPose2D,
finish: DubinsPose2D,
trajectoryRadius: Double,
vararg obstacles: Polygon<Double>,
): List<CompositeTrajectory2D> {
val obstacleShells: List<ObstacleShell> = obstacles.map { polygon ->
ObstacleShell(polygon.points.map { Circle2D(it, trajectoryRadius) })
}
val center = vector(
circles.sumOf { it.center.x } / circles.size,
circles.sumOf { it.center.y } / circles.size
)
val lslToCenter =
lslTangents.sumOf { it.begin.distanceTo(center) } + lslTangents.sumOf { it.end.distanceTo(center) }
val rsrToCenter =
rsrTangents.sumOf { it.begin.distanceTo(center) } + rsrTangents.sumOf { it.end.distanceTo(center) }
if (rsrToCenter >= lslToCenter) {
this.tangents = rsrTangents
this.direction = Trajectory2D.R
} else {
this.tangents = lslTangents
this.direction = Trajectory2D.L
}
}
}
internal fun nextTangent(circle: Circle2D, direction: Trajectory2D.Direction): Tangent {
val circleIndex = circles.indexOf(circle)
if (circleIndex == -1) error("Circle does not belong to this tangent")
val nextCircleIndex = if (direction == this.direction) {
if (circleIndex == circles.lastIndex) 0 else circleIndex + 1
} else {
if (circleIndex == 0) circles.lastIndex else circleIndex - 1
return findAllPaths(start, trajectoryRadius, finish, trajectoryRadius, obstacleShells)
}
return Tangent(
circle,
circles[nextCircleIndex],
this,
this,
LineSegment(
tangents[nextCircleIndex].end,
tangents[nextCircleIndex].begin
),
direction
)
}
override fun equals(other: Any?): Boolean {
if (other == null || other !is Obstacle) return false
return circles == other.circles
}
override fun hashCode(): Int {
return circles.hashCode()
}
}
internal fun Obstacle(vararg circles: Circle2D): Obstacle = Obstacle(listOf(*circles))
public fun Obstacle(vararg circles: Circle2D): Obstacle = ObstacleShell(listOf(*circles))
private fun LineSegment2D.intersectsSegment(other: LineSegment2D): Boolean {
fun crossProduct(v1: DoubleVector2D, v2: DoubleVector2D): Double {
return v1.x * v2.y - v1.y * v2.x
}
return if (crossProduct(other.begin - begin, other.end - begin).sign ==
crossProduct(other.begin - end, other.end - end).sign
) {
false
} else {
crossProduct(begin - other.begin, end - other.begin).sign != crossProduct(
begin - other.end,
end - other.end
).sign
}
}
private fun LineSegment2D.intersectsCircle(circle: Circle2D): Boolean {
val a = (begin.x - end.x).pow(2.0) + (begin.y - end.y).pow(2.0)
val b = 2 * ((begin.x - end.x) * (end.x - circle.center.x) +
(begin.y - end.y) * (end.y - circle.center.y))
val c = (end.x - circle.center.x).pow(2.0) + (end.y - circle.center.y).pow(2.0) -
circle.radius.pow(2.0)
val d = b.pow(2.0) - 4 * a * c
if (d < 1e-6) {
return false
} else {
val t1 = (-b - d.pow(0.5)) * 0.5 / a
val t2 = (-b + d.pow(0.5)) * 0.5 / a
if (((0 < t1) and (t1 < 1)) or ((0 < t2) and (t2 < 1))) {
return true
}
}
return false
}
/**
* Check if segment has any intersections with an obstacle
*/
private fun LineSegment2D.intersectsObstacle(obstacle: Obstacle): Boolean =
obstacle.tangents.any { tangent -> intersectsSegment(tangent) }
|| obstacle.circles.any { circle -> intersectsCircle(circle) }
/**
* All tangents between two obstacles
*
* In general generates 4 paths.
* TODO check intersections.
*/
private fun outerTangents(first: Obstacle, second: Obstacle): Map<DubinsPath.Type, Tangent> = buildMap {
for (firstCircle in first.circles) {
for (secondCircle in second.circles) {
for ((pathType, segment) in tangentsBetweenCircles(firstCircle, secondCircle)) {
val tangent = Tangent(
firstCircle,
secondCircle,
first,
second,
segment,
pathType.first,
pathType.third
)
if (!(tangent.intersectsObstacle(first)) && !(tangent.intersectsObstacle(second))) {
put(
pathType,
tangent
)
}
}
}
}
}
private fun arcLength(
circle: Circle2D,
point1: DoubleVector2D,
point2: DoubleVector2D,
direction: Trajectory2D.Direction,
): Double {
val phi1 = atan2(point1.y - circle.center.y, point1.x - circle.center.x)
val phi2 = atan2(point2.y - circle.center.y, point2.x - circle.center.x)
var angle = 0.0
when (direction) {
Trajectory2D.L -> {
angle = if (phi2 >= phi1) {
phi2 - phi1
} else {
2 * PI + phi2 - phi1
}
}
Trajectory2D.R -> {
angle = if (phi2 >= phi1) {
2 * PI - (phi2 - phi1)
} else {
-(phi2 - phi1)
}
}
}
return circle.radius * angle
}
private fun normalVectors(v: DoubleVector2D, r: Double): Pair<DoubleVector2D, DoubleVector2D> {
return Pair(
r * vector(v.y / norm(v), -v.x / norm(v)),
r * vector(-v.y / norm(v), v.x / norm(v))
)
}
private fun constructTangentCircles(
point: DoubleVector2D,
direction: DoubleVector2D,
r: Double,
): LR<Circle2D> {
val center1 = point + normalVectors(direction, r).first
val center2 = point + normalVectors(direction, r).second
val p1 = center1 - point
return if (atan2(p1.y, p1.x) - atan2(direction.y, direction.x) in listOf(PI / 2, -3 * PI / 2)) {
LR(
Circle2D(center1, r),
Circle2D(center2, r)
)
} else {
LR(
Circle2D(center2, r),
Circle2D(center1, r)
)
}
}
private fun sortedObstacles(
currentObstacle: Obstacle,
obstacles: List<Obstacle>,
): List<Obstacle> {
return obstacles.sortedBy { norm(it.center - currentObstacle.center) }
}
private fun tangentsAlongTheObstacle(
initialCircle: Circle2D,
direction: Trajectory2D.Direction,
finalCircle: Circle2D,
obstacle: Obstacle,
): List<Tangent> {
val dubinsTangents = mutableListOf<Tangent>()
var tangent = obstacle.nextTangent(initialCircle, direction)
dubinsTangents.add(tangent)
while (tangent.endCircle != finalCircle) {
tangent = obstacle.nextTangent(tangent.endCircle, direction)
dubinsTangents.add(tangent)
}
return dubinsTangents
}
/**
* Check if all proposed paths have ended at [finalObstacle]
*/
private fun allFinished(
paths: List<TangentPath>,
finalObstacle: Obstacle,
): Boolean {
for (path in paths) {
if (path.last().endObstacle != finalObstacle) {
return false
}
}
return true
}
private fun LineSegment2D.toTrajectory() = StraightTrajectory2D(begin, end)
private fun TangentPath.toTrajectory(): CompositeTrajectory2D = CompositeTrajectory2D(
buildList {
tangents.zipWithNext().forEach { (left, right) ->
add(left.lineSegment.toTrajectory())
add(
CircleTrajectory2D.of(
right.startCircle.center,
left.lineSegment.end,
right.lineSegment.begin,
right.startDirection
)
)
}
add(tangents.last().lineSegment.toTrajectory())
}
)
internal fun findAllPaths(
start: DubinsPose2D,
startingRadius: Double,
finish: DubinsPose2D,
finalRadius: Double,
obstacles: List<Obstacle>,
): List<CompositeTrajectory2D> {
fun DubinsPose2D.direction() = vector(cos(bearing), sin(bearing))
// two circles for the initial point
val initialCircles = constructTangentCircles(
start,
start.direction(),
startingRadius
)
//two circles for the final point
val finalCircles = constructTangentCircles(
finish,
finish.direction(),
finalRadius
)
//all valid trajectories
val trajectories = mutableListOf<CompositeTrajectory2D>()
for (i in listOf(Trajectory2D.L, Trajectory2D.R)) {
for (j in listOf(Trajectory2D.L, Trajectory2D.R)) {
//Using obstacle to minimize code bloat
val finalObstacle = Obstacle(finalCircles[j])
var currentPaths: List<TangentPath> = listOf(
TangentPath(
//We need only the direction of the final segment from this
Tangent(
initialCircles[i],
initialCircles[i],
Obstacle(initialCircles[i]),
Obstacle(initialCircles[i]),
LineSegment(start, start),
i
)
)
)
while (!allFinished(currentPaths, finalObstacle)) {
// paths after next obstacle iteration
val newPaths = mutableListOf<TangentPath>()
// for each path propagate it one obstacle further
for (tangentPath: TangentPath in currentPaths) {
val currentCircle = tangentPath.last().endCircle
val currentDirection: Trajectory2D.Direction = tangentPath.last().endDirection
val currentObstacle = tangentPath.last().endObstacle
// If path is finished, ignore it
// TODO avoid returning to ignored obstacle on the next cycle
if (currentObstacle == finalObstacle) {
newPaths.add(tangentPath)
} else {
val tangentToFinal: Tangent = outerTangents(currentObstacle, finalObstacle)[DubinsPath.Type(
currentDirection,
Trajectory2D.S,
j
)] ?: TODO("Intersecting obstacles are not supported")
// searching for the nearest obstacle that intersects with the direct path
val nextObstacle = sortedObstacles(currentObstacle, obstacles).find { obstacle ->
tangentToFinal.intersectsObstacle(obstacle)
} ?: finalObstacle
//TODO add break check for end of path
// All valid tangents from current obstacle to the next one
val nextTangents: Collection<Tangent> = outerTangents(
currentObstacle,
nextObstacle
).filter { (key, tangent) ->
obstacles.none { obstacle -> tangent.intersectsObstacle(obstacle) } && // does not intersect other obstacles
key.first == currentDirection && // initial direction is the same as end of previous segment direction
(nextObstacle != finalObstacle || key.third == j) // if it is the last, it should be the same as the one we are searching for
}.values
for (tangent in nextTangents) {
val tangentsAlong = if (tangent.startCircle == tangentPath.last().endCircle) {
//if the previous segment last circle is the same as first circle of the next segment
//If obstacle consists of single circle, do not walk around
if (tangent.startObstacle.circles.size < 2){
emptyList()
} else {
val lengthMaxPossible = arcLength(
tangent.startCircle,
tangentPath.last().lineSegment.end,
tangent.startObstacle.nextTangent(
tangent.startCircle,
currentDirection
).lineSegment.begin,
currentDirection
)
val lengthCalculated = arcLength(
tangent.startCircle,
tangentPath.last().lineSegment.end,
tangent.lineSegment.begin,
currentDirection
)
// ensure that path does not go inside the obstacle
if (lengthCalculated > lengthMaxPossible) {
tangentsAlongTheObstacle(
currentCircle,
currentDirection,
tangent.startCircle,
currentObstacle
)
} else {
emptyList()
}
}
} else {
tangentsAlongTheObstacle(
currentCircle,
currentDirection,
tangent.startCircle,
currentObstacle
)
}
newPaths.add(TangentPath(tangentPath.tangents + tangentsAlong + tangent))
}
}
}
currentPaths = newPaths
}
trajectories += currentPaths.map { tangentPath ->
val lastDirection: Trajectory2D.Direction = tangentPath.last().endDirection
val end = finalCircles[j]
TangentPath(
tangentPath.tangents +
Tangent(
end,
end,
Obstacle(end),
Obstacle(end),
LineSegment(finish, finish),
startDirection = lastDirection,
endDirection = j
)
)
}.map { it.toTrajectory() }
}
}
return trajectories
}
public object Obstacles {
public fun allPathsAvoiding(
start: DubinsPose2D,
finish: DubinsPose2D,
trajectoryRadius: Double,
obstaclePolygons: List<Polygon<Double>>,
): List<CompositeTrajectory2D> {
val obstacles: List<Obstacle> = obstaclePolygons.map { polygon ->
Obstacle(polygon.points.map { point -> Circle2D(point, trajectoryRadius) })
}
return findAllPaths(start, trajectoryRadius, finish, trajectoryRadius, obstacles)
}
}
//public fun Trajectory2D.intersects(
// polygon: Polygon<Double>,
// radius: Double,
//): Boolean {
// val obstacle = Obstacle(polygon.points.map { point -> Circle2D(point, radius) })
// return when (this) {
// is CircleTrajectory2D -> {
// val nearestCircle = obstacle.circles.minBy { it.center.distanceTo(circle.center) }
//
// }
// is StraightTrajectory2D -> obstacle.intersects(this)
// is CompositeTrajectory2D -> segments.any { it.intersects(polygon, radius) }
// }
//}

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package space.kscience.trajectory
import space.kscience.kmath.geometry.*
import space.kscience.kmath.geometry.Euclidean2DSpace.distanceTo
import space.kscience.kmath.geometry.Euclidean2DSpace.minus
import space.kscience.kmath.geometry.Euclidean2DSpace.plus
import space.kscience.kmath.geometry.Euclidean2DSpace.times
import space.kscience.kmath.misc.zipWithNextCircular
import space.kscience.kmath.operations.DoubleField.pow
import kotlin.math.*
internal data class Tangent(
val startCircle: Circle2D,
val endCircle: Circle2D,
val startObstacle: ObstacleShell,
val endObstacle: ObstacleShell,
val lineSegment: LineSegment2D,
val startDirection: Trajectory2D.Direction,
val endDirection: Trajectory2D.Direction = startDirection,
) : LineSegment2D by lineSegment
private class LR<T>(val l: T, val r: T) {
operator fun get(direction: Trajectory2D.Direction) = when (direction) {
Trajectory2D.L -> l
Trajectory2D.R -> r
}
}
private class TangentPath(val tangents: List<Tangent>) {
fun last() = tangents.last()
}
private fun TangentPath(vararg tangents: Tangent) = TangentPath(listOf(*tangents))
/**
* Create inner and outer tangents between two circles.
* This method returns a map of segments using [DubinsPath] connection type notation.
*/
internal fun tangentsBetweenCircles(
first: Circle2D,
second: Circle2D,
): Map<DubinsPath.Type, LineSegment2D> = with(Euclidean2DSpace) {
// Distance between centers
val distanceBetweenCenters: Double = first.center.distanceTo(second.center)
// return empty map if one circle is inside another
val minRadius = min(first.radius, second.radius)
val maxRadius = max(first.radius, second.radius)
val listOfTangents = when {
// one circle inside another, no tangents
distanceBetweenCenters + minRadius <= maxRadius -> return emptyMap()
// circles intersect, only outer tangents
distanceBetweenCenters - minRadius <= maxRadius -> listOf(DubinsPath.Type.RSR, DubinsPath.Type.LSL)
// no intersections all tangents
else -> listOf(DubinsPath.Type.RSR, DubinsPath.Type.RSL, DubinsPath.Type.LSR, DubinsPath.Type.LSL)
}
val angle1 = atan2(second.center.x - first.center.x, second.center.y - first.center.y)
return listOfTangents.associateWith { route ->
val r1 = when (route.first) {
Trajectory2D.L -> -first.radius
Trajectory2D.R -> first.radius
}
val r2 = when (route.third) {
Trajectory2D.L -> -second.radius
Trajectory2D.R -> second.radius
}
val r = if (r1.sign == r2.sign) {
r1.absoluteValue - r2.absoluteValue
} else {
r1.absoluteValue + r2.absoluteValue
}
val l = sqrt(distanceBetweenCenters * distanceBetweenCenters - r * r)
val angle2 = if (r1.absoluteValue > r2.absoluteValue) {
angle1 + r1.sign * atan2(r.absoluteValue, l)
} else {
angle1 - r2.sign * atan2(r.absoluteValue, l)
}
val w = vector(-cos(angle2), sin(angle2))
LineSegment(
first.center + w * r1,
second.center + w * r2
)
}
}
private fun Circle2D.isInside(other: Circle2D): Boolean {
return center.distanceTo(other.center) + radius <= other.radius
}
internal class ObstacleShell(
nodes: List<Circle2D>,
) : Obstacle {
override val circles: List<Circle2D>
override val center: Vector2D<Double>
private val shell: List<LineSegment2D>
private val shellDirection: Trajectory2D.Direction
init {
this.center = Euclidean2DSpace.vector(
nodes.sumOf { it.center.x } / nodes.size,
nodes.sumOf { it.center.y } / nodes.size
)
// this.circles = nodes.filter { node ->
// //filter nodes inside other nodes
// nodes.none{ node !== it && node.isInside(it) }
// }
this.circles = nodes.distinct()
if (nodes.size < 2) {
shell = emptyList()
shellDirection = Trajectory2D.R
} else {
//ignore cases when one circle is inside another one
val lslTangents = circles.zipWithNextCircular { a, b ->
tangentsBetweenCircles(a, b)[DubinsPath.Type.LSL] ?: error("Intersecting circles")
}
val rsrTangents = circles.zipWithNextCircular { a, b ->
tangentsBetweenCircles(a, b)[DubinsPath.Type.RSR] ?: error("Intersecting circles")
}
val lslToCenter = lslTangents.sumOf { it.begin.distanceTo(center) } +
lslTangents.sumOf { it.end.distanceTo(center) }
val rsrToCenter = rsrTangents.sumOf { it.begin.distanceTo(center) } +
rsrTangents.sumOf { it.end.distanceTo(center) }
if (rsrToCenter >= lslToCenter) {
this.shell = rsrTangents
this.shellDirection = Trajectory2D.R
} else {
this.shell = lslTangents
this.shellDirection = Trajectory2D.L
}
}
}
/**
* Check if segment has any intersections with this obstacle
*/
override fun intersects(segment: LineSegment2D): Boolean =
shell.any { tangent -> segment.intersectsSegment(tangent) }
|| circles.any { circle -> segment.intersectsCircle(circle) }
fun nextTangent(circle: Circle2D, direction: Trajectory2D.Direction): Tangent {
val circleIndex = circles.indexOf(circle)
if (circleIndex == -1) error("Circle does not belong to this tangent")
val nextCircleIndex = if (direction == this.shellDirection) {
if (circleIndex == circles.lastIndex) 0 else circleIndex + 1
} else {
if (circleIndex == 0) circles.lastIndex else circleIndex - 1
}
return Tangent(
circle,
circles[nextCircleIndex],
this,
this,
LineSegment(
shell[nextCircleIndex].end,
shell[nextCircleIndex].begin
),
direction
)
}
internal fun tangentsAlong(
initialCircle: Circle2D,
direction: Trajectory2D.Direction,
finalCircle: Circle2D,
): List<Tangent> {
val dubinsTangents = mutableListOf<Tangent>()
var tangent = nextTangent(initialCircle, direction)
dubinsTangents.add(tangent)
while (tangent.endCircle != finalCircle) {
tangent = nextTangent(tangent.endCircle, direction)
dubinsTangents.add(tangent)
}
return dubinsTangents
}
override fun equals(other: Any?): Boolean {
if (other == null || other !is ObstacleShell) return false
return circles == other.circles
}
override fun hashCode(): Int {
return circles.hashCode()
}
}
internal fun ObstacleShell(vararg circles: Circle2D): ObstacleShell = ObstacleShell(listOf(*circles))
private fun LineSegment2D.intersectsSegment(other: LineSegment2D): Boolean {
fun crossProduct(v1: DoubleVector2D, v2: DoubleVector2D): Double {
return v1.x * v2.y - v1.y * v2.x
}
return if (crossProduct(other.begin - begin, other.end - begin).sign ==
crossProduct(other.begin - end, other.end - end).sign
) {
false
} else {
crossProduct(begin - other.begin, end - other.begin).sign != crossProduct(
begin - other.end,
end - other.end
).sign
}
}
private fun LineSegment2D.intersectsCircle(circle: Circle2D): Boolean {
val a = (begin.x - end.x).pow(2.0) + (begin.y - end.y).pow(2.0)
val b = 2 * ((begin.x - end.x) * (end.x - circle.center.x) +
(begin.y - end.y) * (end.y - circle.center.y))
val c = (end.x - circle.center.x).pow(2.0) + (end.y - circle.center.y).pow(2.0) -
circle.radius.pow(2.0)
val d = b.pow(2.0) - 4 * a * c
if (d < 1e-6) {
return false
} else {
val t1 = (-b - d.pow(0.5)) * 0.5 / a
val t2 = (-b + d.pow(0.5)) * 0.5 / a
if (((0 < t1) and (t1 < 1)) or ((0 < t2) and (t2 < 1))) {
return true
}
}
return false
}
/**
* All tangents between two obstacles
*
* In general generates 4 paths.
* TODO check intersections.
*/
private fun outerTangents(first: ObstacleShell, second: ObstacleShell): Map<DubinsPath.Type, Tangent> = buildMap {
for (firstCircle in first.circles) {
for (secondCircle in second.circles) {
for ((pathType, segment) in tangentsBetweenCircles(firstCircle, secondCircle)) {
val tangent = Tangent(
firstCircle,
secondCircle,
first,
second,
segment,
pathType.first,
pathType.third
)
if (!(first.intersects(tangent)) && !(second.intersects(tangent))) {
put(
pathType,
tangent
)
}
}
}
}
}
private fun arcLength(
circle: Circle2D,
point1: DoubleVector2D,
point2: DoubleVector2D,
direction: Trajectory2D.Direction,
): Double {
val phi1 = atan2(point1.y - circle.center.y, point1.x - circle.center.x)
val phi2 = atan2(point2.y - circle.center.y, point2.x - circle.center.x)
var angle = 0.0
when (direction) {
Trajectory2D.L -> {
angle = if (phi2 >= phi1) {
phi2 - phi1
} else {
2 * PI + phi2 - phi1
}
}
Trajectory2D.R -> {
angle = if (phi2 >= phi1) {
2 * PI - (phi2 - phi1)
} else {
-(phi2 - phi1)
}
}
}
return circle.radius * angle
}
private fun normalVectors(v: DoubleVector2D, r: Double): Pair<DoubleVector2D, DoubleVector2D> {
return Pair(
r * Euclidean2DSpace.vector(v.y / Euclidean2DSpace.norm(v), -v.x / Euclidean2DSpace.norm(v)),
r * Euclidean2DSpace.vector(-v.y / Euclidean2DSpace.norm(v), v.x / Euclidean2DSpace.norm(v))
)
}
private fun constructTangentCircles(
point: DoubleVector2D,
direction: DoubleVector2D,
r: Double,
): LR<Circle2D> {
val center1 = point + normalVectors(direction, r).first
val center2 = point + normalVectors(direction, r).second
val p1 = center1 - point
return if (atan2(p1.y, p1.x) - atan2(direction.y, direction.x) in listOf(PI / 2, -3 * PI / 2)) {
LR(
Circle2D(center1, r),
Circle2D(center2, r)
)
} else {
LR(
Circle2D(center2, r),
Circle2D(center1, r)
)
}
}
private fun sortedObstacles(
currentObstacle: ObstacleShell,
obstacles: List<ObstacleShell>,
): List<ObstacleShell> {
return obstacles.sortedBy { Euclidean2DSpace.norm(it.center - currentObstacle.center) }
}
/**
* Check if all proposed paths have ended at [finalObstacle]
*/
private fun allFinished(
paths: List<TangentPath>,
finalObstacle: Obstacle,
): Boolean {
for (path in paths) {
if (path.last().endObstacle != finalObstacle) {
return false
}
}
return true
}
private fun LineSegment2D.toTrajectory() = StraightTrajectory2D(begin, end)
private fun TangentPath.toTrajectory(): CompositeTrajectory2D = CompositeTrajectory2D(
buildList {
tangents.zipWithNext().forEach { (left, right) ->
add(left.lineSegment.toTrajectory())
add(
CircleTrajectory2D.of(
right.startCircle.center,
left.lineSegment.end,
right.lineSegment.begin,
right.startDirection
)
)
}
add(tangents.last().lineSegment.toTrajectory())
}
)
internal fun findAllPaths(
start: DubinsPose2D,
startingRadius: Double,
finish: DubinsPose2D,
finalRadius: Double,
obstacles: List<ObstacleShell>,
): List<CompositeTrajectory2D> {
fun DubinsPose2D.direction() =
Euclidean2DSpace.vector(space.kscience.kmath.geometry.cos(bearing), space.kscience.kmath.geometry.sin(bearing))
// two circles for the initial point
val initialCircles = constructTangentCircles(
start,
start.direction(),
startingRadius
)
//two circles for the final point
val finalCircles = constructTangentCircles(
finish,
finish.direction(),
finalRadius
)
//all valid trajectories
val trajectories = mutableListOf<CompositeTrajectory2D>()
for (i in listOf(Trajectory2D.L, Trajectory2D.R)) {
for (j in listOf(Trajectory2D.L, Trajectory2D.R)) {
//Using obstacle to minimize code bloat
val finalObstacle = ObstacleShell(finalCircles[j])
var currentPaths: List<TangentPath> = listOf(
TangentPath(
//We need only the direction of the final segment from this
Tangent(
initialCircles[i],
initialCircles[i],
ObstacleShell(initialCircles[i]),
ObstacleShell(initialCircles[i]),
LineSegment(start, start),
i
)
)
)
while (!allFinished(currentPaths, finalObstacle)) {
// paths after next obstacle iteration
val newPaths = mutableListOf<TangentPath>()
// for each path propagate it one obstacle further
for (tangentPath: TangentPath in currentPaths) {
val currentCircle = tangentPath.last().endCircle
val currentDirection: Trajectory2D.Direction = tangentPath.last().endDirection
val currentObstacle = tangentPath.last().endObstacle
// If path is finished, ignore it
// TODO avoid returning to ignored obstacle on the next cycle
if (currentObstacle == finalObstacle) {
newPaths.add(tangentPath)
} else {
val tangentToFinal: Tangent = outerTangents(currentObstacle, finalObstacle)[DubinsPath.Type(
currentDirection,
Trajectory2D.S,
j
)] ?: break
// searching for the nearest obstacle that intersects with the direct path
val nextObstacle = sortedObstacles(currentObstacle, obstacles).find { obstacle ->
obstacle.intersects(tangentToFinal)
} ?: finalObstacle
//TODO add break check for end of path
// All valid tangents from current obstacle to the next one
val nextTangents: Collection<Tangent> = outerTangents(
currentObstacle,
nextObstacle
).filter { (key, tangent) ->
obstacles.none { obstacle -> obstacle.intersects(tangent) } && // does not intersect other obstacles
key.first == currentDirection && // initial direction is the same as end of previous segment direction
(nextObstacle != finalObstacle || key.third == j) // if it is the last, it should be the same as the one we are searching for
}.values
for (tangent in nextTangents) {
val tangentsAlong = if (tangent.startCircle == tangentPath.last().endCircle) {
//if the previous segment last circle is the same as first circle of the next segment
//If obstacle consists of single circle, do not walk around
if (tangent.startObstacle.circles.size < 2) {
emptyList()
} else {
val lengthMaxPossible = arcLength(
tangent.startCircle,
tangentPath.last().lineSegment.end,
tangent.startObstacle.nextTangent(
tangent.startCircle,
currentDirection
).lineSegment.begin,
currentDirection
)
val lengthCalculated = arcLength(
tangent.startCircle,
tangentPath.last().lineSegment.end,
tangent.lineSegment.begin,
currentDirection
)
// ensure that path does not go inside the obstacle
if (lengthCalculated > lengthMaxPossible) {
currentObstacle.tangentsAlong(
currentCircle,
currentDirection,
tangent.startCircle,
)
} else {
emptyList()
}
}
} else {
currentObstacle.tangentsAlong(
currentCircle,
currentDirection,
tangent.startCircle,
)
}
newPaths.add(TangentPath(tangentPath.tangents + tangentsAlong + tangent))
}
}
}
currentPaths = newPaths
}
trajectories += currentPaths.map { tangentPath ->
val lastDirection: Trajectory2D.Direction = tangentPath.last().endDirection
val end = finalCircles[j]
TangentPath(
tangentPath.tangents +
Tangent(
end,
end,
ObstacleShell(end),
ObstacleShell(end),
LineSegment(finish, finish),
startDirection = lastDirection,
endDirection = j
)
)
}.map { it.toTrajectory() }
}
}
return trajectories
}

View File

@ -18,18 +18,12 @@ class ObstacleTest {
val startRadius = 0.5
val finalPoint = vector(20.0, 4.0)
val finalDirection = vector(1.0, -1.0)
val finalRadius = 0.5
val obstacles = listOf(
Obstacle(Circle2D(vector(7.0, 1.0), 5.0))
)
val outputTangents = findAllPaths(
val outputTangents = Obstacle.allPathsAvoiding(
DubinsPose2D.of(startPoint, startDirection),
startRadius,
DubinsPose2D.of(finalPoint, finalDirection),
finalRadius,
obstacles
startRadius,
Obstacle(Circle2D(vector(7.0, 1.0), 5.0))
)
val length = outputTangents.minOf { it.length }
assertEquals(27.2113183, length, 1e-6)
@ -39,46 +33,62 @@ class ObstacleTest {
fun secondPath() {
val startPoint = vector(-5.0, -1.0)
val startDirection = vector(1.0, 1.0)
val startRadius = 0.5
val radius = 0.5
val finalPoint = vector(20.0, 4.0)
val finalDirection = vector(1.0, -1.0)
val finalRadius = 0.5
val obstacles = listOf(
Obstacle(
listOf(
Circle2D(vector(1.0, 6.5), 0.5),
Circle2D(vector(2.0, 1.0), 0.5),
Circle2D(vector(6.0, 0.0), 0.5),
Circle2D(vector(5.0, 5.0), 0.5)
)
), Obstacle(
listOf(
Circle2D(vector(10.0, 1.0), 0.5),
Circle2D(vector(16.0, 0.0), 0.5),
Circle2D(vector(14.0, 6.0), 0.5),
Circle2D(vector(9.0, 4.0), 0.5)
)
)
)
val paths = findAllPaths(
val paths = Obstacle.allPathsAvoiding(
DubinsPose2D.of(startPoint, startDirection),
startRadius,
DubinsPose2D.of(finalPoint, finalDirection),
finalRadius,
obstacles
radius,
Obstacle(
Circle2D(vector(1.0, 6.5), 0.5),
Circle2D(vector(2.0, 1.0), 0.5),
Circle2D(vector(6.0, 0.0), 0.5),
Circle2D(vector(5.0, 5.0), 0.5)
), Obstacle(
Circle2D(vector(10.0, 1.0), 0.5),
Circle2D(vector(16.0, 0.0), 0.5),
Circle2D(vector(14.0, 6.0), 0.5),
Circle2D(vector(9.0, 4.0), 0.5)
)
)
val length = paths.minOf { it.length }
assertEquals(28.9678224, length, 1e-6)
}
@Test
fun nearPoints() {
val startPoint = vector(-1.0, 0.0)
val startDirection = vector(0.0, 1.0)
val startRadius = 1.0
val finalPoint = vector(0, -1)
val finalDirection = vector(1.0, 0)
val paths = Obstacle.allPathsAvoiding(
DubinsPose2D.of(startPoint, startDirection),
DubinsPose2D.of(finalPoint, finalDirection),
startRadius,
Obstacle(
Circle2D(vector(0.0, 0.0), 1.0),
Circle2D(vector(0.0, 1.0), 1.0),
Circle2D(vector(1.0, 1.0), 1.0),
Circle2D(vector(1.0, 0.0), 1.0)
)
)
val length = paths.minOf { it.length }
println(length)
//assertEquals(28.9678224, length, 1e-6)
}
@Test
fun equalObstacles() {
val circle1 = Circle2D(vector(1.0, 6.5), 0.5)
val circle2 = Circle2D(vector(1.0, 6.5), 0.5)
assertEquals(circle1, circle2)
val obstacle1 = Obstacle(listOf(circle1))
val obstacle2 = Obstacle(listOf(circle2))
val obstacle1 = ObstacleShell(listOf(circle1))
val obstacle2 = ObstacleShell(listOf(circle2))
assertEquals(obstacle1, obstacle2)
}
}