klampt.model.multipath module

This module defines the MultiPath class, and methods for loading and saving multipaths from xml files.

class klampt.model.multipath.MultiPath

Bases: object

A sophisticated path representation that allows timed/untimed paths, attached velocity information, as well as making and breaking contact.

Primarily, a MultiPath consists of a list of Sections, each of which is a path or timed trajectory along a fixed stance.

A Section can either contain the Holds defining its stance, or its stance could be defined by indices into the holdSet member of MultiPath. If all Sections have the latter structure it is known as an “aggregated” MultiPath.

sections

the segments of the multipath, each operating over a fixed stance.

Type:

list of Sections

settings

an unstructured propery map ‘settings’ which can contain metadata about which robot this path applies to, how the path was created, etc.

Type:

dict mapping str to str

holdSet

a set of indexed Holds, which can be referred to inside Section objects.

Type:

dict mapping int to Hold

class Section

Bases: object

Contains a path or time-parameterized trajectory, as well as a list of holds and ik constraints

If the times member is set, this is time parameterized. Otherwise, it is just a path.

settings

an unstructured property map.

Type:

dict mapping str to str

configs

a list of N configurations along the path section.

Type:

list of lists of floats

velocities

a list of N joint velocities along the path section.

Type:

list of lists of floats, optional

times

along the path section.

Type:

list of floats, optional

holds

the set of Holds that this section is required to meet.

Type:

list of Holds, optional

holdIndices

the set of Holds that this section is required to meet, indexed into MultiPath.holdSet.

Type:

list of ints, optional

ikObjectives

the set of extra IKObjectives that this section is required to meet.

Type:

list of IKObjectives, optional

numSections()

Return type:

int

startConfig()

Return type:

Sequence[float]

endConfig()

Return type:

Sequence[float]

startTime()

Return type:

float

endTime()

Returns the final time parameter

Return type:

float

duration()

Return type:

float

hasTiming()

Returns true if the multipath is timed

Return type:

bool

checkValid()

Checks for validity of the path

isContinuous()

Returns true if all the sections are continuous (i.e., the last config of each section matches the start config of the next).

Return type:

bool

getSectionTiming(section)

Returns a pair (tstart,tend) giving the timing of the section

Return type:

Tuple[float, float]

getStance(section)

Returns the list of Holds that the section should satisfy

getIKProblem(section)

Returns the set of IKObjectives that the section should satisfy

aggregateHolds(holdSimilarityThreshold=None)

Aggregates holds from all sections to the global holdSet variable, and converts sections to use holdIndices. If holdSimilarityThreshold is not None, then sections’ holds that are the same within the given tolerance are combined into one hold.

deaggregateHolds()

De-aggregates holds from the global holdSet variable into the sections’ holds.

setConfig(section, configIndex, q, v=None, t=None, maintainContinuity=True)

Sets a configuration along the path, maintaining continuity if maintainContinuity is true. Equivalent to self.sections[section].configs[configIndex] = q except that adjacent sections’ configurations are also modified.

concat(path)

Appends the path, making sure times and holds are appropriately set

save(fn)

Saves this multipath to an xml file.

load(fn)

Loads this multipath from a multipath xml file.

saveXML()

Saves this multipath to a multipath xml tree (ElementTree)

loadXML(tree)

Loads a multipath from a multipath xml tree (ElementTree).

timeToSection(t)

Returns the section corresponding to the time parameter t

timeToSegment(t)

Returns a (section index,milestone index,param) tuple such that interpolation between the section’s milestone and its successor corresponds to time t.

eval(t)

Evaluates the MultiPath at time t.

setTrajectory(trajectory)

Set this MultiPath to a single-section trajectory. If trajectory is a HermiteTrajectory, velocities will be extracted.

getTrajectory(robot=None, eps=None)

Returns a trajectory representation of this MultiPath. If robot is provided, then a RobotTrajectory is returned. Otherwise, if velocity information is given, then a HermiteTrajectory is returned. Otherwise, a Trajectory is returned.

If robot and eps is given, then the IK constraints along the trajectory are solved and the path is discretized at resolution eps.

Return type:

Trajectory