artisynth.core.mechmodels

Class KinematicTree

java.lang.Object

artisynth.core.mechmodels.KinematicTree

public class KinematicTree
extends java.lang.Object

Models an articulated structure as a bipartite tree consisting of body and joint nodes, with a body node as the root. Body nodes have joint nodes as their parents and children and joint nodes have body nodes as their parents and children.

Each body node corresponds to a single ConnectableBody which is also a cut vertex of a graph in which the bodies are vertices and the constrainers connecting them are edges. Each joint node corresponds to the sub-graph of bodies and constrainers separated by the body nodes (i.e., cut vertices). This arrangement means that setting coordinates values for the joints within a joint node can be done independently of the constrainers in the other joint nodes, which allows the setting of coordinate values for different joints in the tree to be done in a computationally efficient way.

In the simplest case, a joint node contains a single joint or constraint and will then have a single child node and connect the two bodies associated with its parent and child nodes. The joint's coordinates, if present, will uniquely determine the pose of the child body relative to the parent. In more complex cases, a joint node may contain multiple joints and/or constraints and joint coordinates within the node may not be independent. An iterative solve procedure must then be used to determine the coordinate values that result from setting one or more coordinates within the node. This procedure will also determine the poses of the child bodies with respect to the parent.

Where appropriate, the tree's root node is set to represent the structures least mobile body. This will be ground if the structure is actually connected to ground; otherwise, other rules are used to determined the root node as specified in the documentation for findRootNode(java.util.List<artisynth.core.mechmodels.KinematicTree.JointNode>, java.util.HashMap<artisynth.core.mechmodels.ConnectableBody, artisynth.core.mechmodels.KinematicTree.BodyInfo>).

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	debug
static RigidBody	Ground Special rigid body instance representing ground.

Constructor Summary

Constructors

Constructor and Description
KinematicTree() Create an empty kinematic tree.
KinematicTree(artisynth.core.mechmodels.KinematicTree.BodyNode root) Create a tree based on a specific root node.

Method Summary

Modifier and Type	Method and Description
static KinematicTree	findTree(BodyConnector bcon, java.util.Collection<? extends Constrainer> extraConstrainers) Finds the kinematic tree associated with a given body connector.
static KinematicTree	findTree(ConnectableBody body, java.util.Collection<? extends Constrainer> extraConstrainers) Finds the kinematic tree associated with a given body.
static java.util.List<KinematicTree>	findTreesForBodies(java.util.Collection<? extends ConnectableBody> bodies, java.util.Collection<ConstrainerBase> extraConstrainers) Finds all the kinematic trees associated with a set of bodies.
java.util.ArrayList<ConnectableBody>	getBodies() Get a list of all the bodies in this tree.
artisynth.core.mechmodels.KinematicTree.BodyNode	getRoot() Queries the root node of this tree.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

Ground

public static final RigidBody Ground

Special rigid body instance representing ground.

debug

public static boolean debug

Constructor Detail

KinematicTree

public KinematicTree()

Create an empty kinematic tree.

KinematicTree

public KinematicTree(artisynth.core.mechmodels.KinematicTree.BodyNode root)

Create a tree based on a specific root node.

Method Detail

getRoot

public artisynth.core.mechmodels.KinematicTree.BodyNode getRoot()

Queries the root node of this tree.

getBodies

public java.util.ArrayList<ConnectableBody> getBodies()

Get a list of all the bodies in this tree.

findTree

public static KinematicTree findTree(ConnectableBody body,
                                     java.util.Collection<? extends Constrainer> extraConstrainers)

Finds the kinematic tree associated with a given body. This is formed from all the bodies that it is connected to via both body connectors and extra constrainers.

findTree

public static KinematicTree findTree(BodyConnector bcon,
                                     java.util.Collection<? extends Constrainer> extraConstrainers)

Finds the kinematic tree associated with a given body connector. This is formed from all the bodies that it is connected to via both body connectors and extra constrainers.

findTreesForBodies

public static java.util.List<KinematicTree> findTreesForBodies(java.util.Collection<? extends ConnectableBody> bodies,
                                                               java.util.Collection<ConstrainerBase> extraConstrainers)

Finds all the kinematic trees associated with a set of bodies.