ik

package
v0.55.0 Latest Latest
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 Go to latest Published: Dec 16, 2024 License: AGPL-3.0 Imports: 14 Imported by: 0

Documentation

Overview

Package ik contains tols for doing gradient-descent based inverse kinematics, allowing for the minimization of arbitrary metrics based on the output of calling `Transform` on the given frame.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func FSConfigurationDistance added in v0.54.0 

func FSConfigurationDistance(segment *SegmentFS) float64

FSConfigurationDistance is a fs metric which will sum the abs differences in each input from start to end.

func FSConfigurationL2Distance added in v0.54.0 

func FSConfigurationL2Distance(segment *SegmentFS) float64

FSConfigurationL2Distance is a fs metric which will sum the L2 norm differences in each input from start to end.

func JointMetric 

func JointMetric(segment *Segment) float64

JointMetric is a metric which will sum the squared differences in each input from start to end.

func L2InputMetric 

func L2InputMetric(segment *Segment) float64

L2InputMetric is a metric which will return a L2 norm of the StartConfiguration and EndConfiguration in an arc input.

func NewMetricMinFunc added in v0.48.1 

func NewMetricMinFunc(metric StateMetric, frame referenceframe.Frame, logger logging.Logger) func([]float64) float64

NewMetricMinFunc takes a metric and a frame, and converts to a function able to be minimized with Solve().

func NewPoseFlexOVMetricConstructor added in v0.10.0 

func NewPoseFlexOVMetricConstructor(alpha float64) func(spatial.Pose) StateMetric

NewPoseFlexOVMetricConstructor will provide a distance function which will converge on a pose with an OV within an arclength of `alpha` of the ov of the goal given.

func OrientDist 

func OrientDist(o1, o2 spatial.Orientation) float64

OrientDist returns the arclength between two orientations in degrees.

func OrientDistToRegion 

func OrientDistToRegion(goal spatial.Orientation, alpha float64) func(spatial.Orientation) float64

OrientDistToRegion will return a function which will tell you how far the unit sphere component of an orientation vector is from a region defined by a point and an arclength around it. The theta value of OV is disregarded. This is useful, for example, in defining the set of acceptable angles of attack for writing on a whiteboard.

func SolveMetric added in v0.48.1 

func SolveMetric(
	ctx context.Context,
	ik Solver,
	frame referenceframe.Frame,
	solutionChan chan<- *Solution,
	seed []referenceframe.Input,
	solveMetric StateMetric,
	rseed int,
	logger logging.Logger,
) error

SolveMetric is a wrapper for Metrics to be used easily with Solve for IK solvers.

func SquaredNormNoOrientSegmentMetric 

func SquaredNormNoOrientSegmentMetric(segment *Segment) float64

SquaredNormNoOrientSegmentMetric is a metric which will return the cartesian distance between the two positions.

func WeightedSquaredNormSegmentMetric added in v0.54.0 

func WeightedSquaredNormSegmentMetric(segment *Segment) float64

WeightedSquaredNormSegmentMetric is a distance function between two poses to be used for gradient descent. This changes the magnitude of the position delta used to be smaller and avoid numeric instability issues that happens with large floats. It also scales the orientation distance to give more weight to it.

Types

type Segment 

type Segment struct {
	StartPosition      spatial.Pose
	EndPosition        spatial.Pose
	StartConfiguration []referenceframe.Input
	EndConfiguration   []referenceframe.Input
	Frame              referenceframe.Frame
}

Segment is a referenceframe.Frame-specific contains all the information a constraint needs to determine validity for a movement. It contains the starting inputs, the ending inputs, corresponding poses, and the frame it refers to. Pose fields may be empty, and may be filled in by a constraint that needs them.

func (*Segment) String added in v0.26.0 

func (s *Segment) String() string

type SegmentFS added in v0.54.0 

type SegmentFS struct {
	StartConfiguration map[string][]referenceframe.Input
	EndConfiguration   map[string][]referenceframe.Input
	FS                 referenceframe.FrameSystem
}

SegmentFS is a referenceframe.FrameSystem-specific contains all the information a constraint needs to determine validity for a movement. It contains the starting inputs, the ending inputs, and the framesystem it refers to.

type SegmentFSMetric added in v0.54.0 

type SegmentFSMetric func(*SegmentFS) float64

SegmentFSMetric are functions which produce some score given an SegmentFS. Lower is better. This is used to sort produced IK solutions by goodness, for example.

type SegmentMetric 

type SegmentMetric func(*Segment) float64

SegmentMetric are functions which produce some score given an Segment. Lower is better. This is used to sort produced IK solutions by goodness, for example.

func NewSquaredNormSegmentMetric 

func NewSquaredNormSegmentMetric(orientationScaleFactor float64) SegmentMetric

NewSquaredNormSegmentMetric returns a metric which will return the cartesian distance between the two positions. It allows the caller to choose the scaling level of orientation.

type Solution 

type Solution struct {
	Configuration []float64
	Score         float64
	Exact         bool
}

Solution is the struct returned from an IK solver. It contains the solution configuration, the score of the solution, and a flag indicating whether that configuration and score met the solution criteria requested by the caller.

type Solver added in v0.48.1 

type Solver interface {
	referenceframe.Limited
	// Solve receives a context, a channel to which solutions will be provided, a function whose output should be minimized, and a
	// number of iterations to run.
	Solve(context.Context, chan<- *Solution, []float64, func([]float64) float64, int) error
}

Solver defines an interface which, provided with seed inputs and a function to minimize to zero, will output all found solutions to the provided channel until cancelled or otherwise completes.

func CreateCombinedIKSolver 

func CreateCombinedIKSolver(
	limits []referenceframe.Limit,
	logger logging.Logger,
	nCPU int,
	goalThreshold float64,
) (Solver, error)

CreateCombinedIKSolver creates a combined parallel IK solver that operates on a frame with a number of nlopt solvers equal to the nCPU passed in. Each will be given a different random seed. When asked to solve, all solvers will be run in parallel and the first valid found solution will be returned.

func CreateNloptSolver added in v0.48.1 

func CreateNloptSolver(
	limits []referenceframe.Limit,
	logger logging.Logger,
	iter int,
	exact, useRelTol bool,
) (Solver, error)

CreateNloptSolver creates an nloptIK object that can perform gradient descent on functions. The parameters are the limits of the solver, a logger, and the number of iterations to run. If the iteration count is less than 1, it will be set to the default of 5000.

type State 

type State struct {
	Position      spatial.Pose
	Configuration []referenceframe.Input
	Frame         referenceframe.Frame
}

State contains all the information a constraint needs to determine validity for a particular state or configuration. It contains inputs, the corresponding poses, and the frame it refers to. Pose field may be empty, and may be filled in by a constraint that needs it.

type StateFS added in v0.54.0 

type StateFS struct {
	Configuration map[string][]referenceframe.Input
	FS            referenceframe.FrameSystem
}

StateFS contains all the information a constraint needs to determine validity for a particular state or configuration of an entire framesystem. It contains inputs, the corresponding poses, and the frame it refers to. Pose field may be empty, and may be filled in by a constraint that needs it.

type StateFSMetric added in v0.54.0 

type StateFSMetric func(*StateFS) float64

StateFSMetric are functions which, given a StateFS, produces some score. Lower is better. This is used for gradient descent to converge upon a goal pose, for example.

func CombineFSMetrics added in v0.54.0 

func CombineFSMetrics(metrics ...StateFSMetric) StateFSMetric

CombineFSMetrics will take a variable number of StateFSMetrics and return a new StateFSMetric which will combine all given metrics into one, summing their distances.

func NewZeroFSMetric added in v0.54.0 

func NewZeroFSMetric() StateFSMetric

NewZeroFSMetric always returns zero as the distance.

type StateMetric 

type StateMetric func(*State) float64

StateMetric are functions which, given a State, produces some score. Lower is better. This is used for gradient descent to converge upon a goal pose, for example.

func CombineMetrics 

func CombineMetrics(metrics ...StateMetric) StateMetric

CombineMetrics will take a variable number of Metrics and return a new Metric which will combine all given metrics into one, summing their distances.

func NewPosWeightSquaredNormMetric added in v0.17.0 

func NewPosWeightSquaredNormMetric(goal spatial.Pose) StateMetric

NewPosWeightSquaredNormMetric is a distance function between two poses to be used for gradient descent. This changes the magnitude of the position delta used to be smaller and avoid numeric instability issues that happens with large floats. TODO: RSDK-6053 this should probably be done more flexibly.

func NewPositionOnlyMetric 

func NewPositionOnlyMetric(goal spatial.Pose) StateMetric

NewPositionOnlyMetric returns a Metric that reports the point-wise distance between two poses without regard for orientation. This is useful for scenarios where there are not enough DOF to control orientation, but arbitrary spatial points may still be arrived at.

func NewScaledSquaredNormMetric added in v0.31.0 

func NewScaledSquaredNormMetric(goal spatial.Pose, orientationDistanceScale float64) StateMetric

NewScaledSquaredNormMetric is a distance function between two poses. It allows the user to scale the contribution of orientation.

func NewSquaredNormMetric 

func NewSquaredNormMetric(goal spatial.Pose) StateMetric

NewSquaredNormMetric is the default distance function between two poses to be used for gradient descent.

func NewZeroMetric 

func NewZeroMetric() StateMetric

NewZeroMetric always returns zero as the distance.

Source Files

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