tpspace

Documentation

Overview

Package tpspace defines an assortment of precomputable trajectories which can be used to plan nonholonomic 2d motion

Index

• func NewPTGFrameFromKinematicOptions(name string, logger golog.Logger, ...) (referenceframe.Frame, error)
• func NewPTGFrameFromPTGFrame(frame referenceframe.Frame, refDist float64) (referenceframe.Frame, error)
• type PTG
  • func NewCCPTG(maxMMPS, maxRPS float64) PTG
  • func NewCCSPTG(maxMMPS, maxRPS float64) PTG
  • func NewCSPTG(maxMMPS, maxRPS float64) PTG
  • func NewCirclePTG(maxMMPS, maxRPS float64) PTG
  • func NewDiffDrivePTG(maxMMPS, maxRPS float64) PTG
  • func NewSideSOverturnPTG(maxMMPS, maxRPS float64) PTG
  • func NewSideSPTG(maxMMPS, maxRPS float64) PTG
• type PTGProvider
• type PTGSolver
  • func NewPTGGridSim(simPTG PTG, arcs uint, simDist float64, endsOnly bool) (PTGSolver, error)
  • func NewPTGIK(simPTG PTG, logger golog.Logger, refDist float64, randSeed int) (PTGSolver, error)
• type TrajNode
  • func ComputePTG(simPTG PTG, alpha, dist, diffT float64) ([]*TrajNode, error)

Functions

func NewPTGFrameFromKinematicOptions

func NewPTGFrameFromKinematicOptions(
	name string,
	logger golog.Logger,
	velocityMMps, angVelocityDegps, turnRadMeters, refDist float64,
	geoms []spatialmath.Geometry,
	diffDriveOnly bool,
) (referenceframe.Frame, error)

NewPTGFrameFromKinematicOptions will create a new Frame which is also a PTGProvider. It will precompute the default set of trajectories out to a given distance, or a default distance if the given distance is <= 0.

func NewPTGFrameFromPTGFrame

func NewPTGFrameFromPTGFrame(frame referenceframe.Frame, refDist float64) (referenceframe.Frame, error)

NewPTGFrameFromPTGFrame will create a new Frame from a preexisting ptgGroupFrame, allowing the adjustment of `refDist` while keeping other params the same. This may be expanded to allow altering turning radius, geometries, etc.

Types

type PTG

type PTG interface {
	// Velocities returns the linear and angular velocity at a specific point along a trajectory
	Velocities(alpha, dist float64) (float64, float64, error)
	Transform([]referenceframe.Input) (spatialmath.Pose, error)
}

PTG is a Parameterized Trajectory Generator, which defines how to map back and forth from cartesian space to TP-space PTG coordinates are specified in polar coordinates (alpha, d) One of these is needed for each sort of motion that can be done.

func NewCCPTG

func NewCCPTG(maxMMPS, maxRPS float64) PTG

NewCCPTG creates a new PTG of type ptgCC.

func NewCCSPTG

func NewCCSPTG(maxMMPS, maxRPS float64) PTG

NewCCSPTG creates a new PTG of type ptgCCS.

func NewCSPTG

func NewCSPTG(maxMMPS, maxRPS float64) PTG

NewCSPTG creates a new PTG of type ptgCS.

func NewCirclePTG

func NewCirclePTG(maxMMPS, maxRPS float64) PTG

NewCirclePTG creates a new PTG of type ptgC.

func NewDiffDrivePTG

func NewDiffDrivePTG(maxMMPS, maxRPS float64) PTG

NewDiffDrivePTG creates a new PTG of type ptgDiffDrive.

func NewSideSOverturnPTG

func NewSideSOverturnPTG(maxMMPS, maxRPS float64) PTG

NewSideSOverturnPTG creates a new PTG of type ptgSideS which overturns. It turns X amount in one direction, then countersteers X*countersteerFactor in the other direction.

func NewSideSPTG

func NewSideSPTG(maxMMPS, maxRPS float64) PTG

NewSideSPTG creates a new PTG of type ptgSideS.

type PTGProvider

type PTGProvider interface {
	// PTGs returns the list of PTGs associated with this provider
	PTGSolvers() []PTGSolver
}

PTGProvider is something able to provide a set of PTGs associsated with it. For example, a frame which precomputes a number of PTGs.

type PTGSolver

type PTGSolver interface {
	// Solve will return the (alpha, dist) TP-space coordinates whose corresponding relative pose minimizes the given function
	ik.InverseKinematics
	PTG

	// MaxDistance returns the maximum distance that a single trajectory may travel
	MaxDistance() float64

	// Returns the set of trajectory nodes along the given trajectory, out to the requested distance
	Trajectory(alpha, dist float64) ([]*TrajNode, error)
}

PTGSolver wraps a PTG with the ability to perform Inverse Kinematics.

func NewPTGGridSim

func NewPTGGridSim(simPTG PTG, arcs uint, simDist float64, endsOnly bool) (PTGSolver, error)

NewPTGGridSim creates a new PTG by simulating a PTG for some distance, then cacheing the results in a grid for fast lookup.

func NewPTGIK

func NewPTGIK(simPTG PTG, logger golog.Logger, refDist float64, randSeed int) (PTGSolver, error)

NewPTGIK creates a new ptgIK, which creates a frame using the provided PTG, and wraps it providing functions to fill the PTG interface, allowing inverse kinematics queries to be run against it.

type TrajNode

type TrajNode struct {
	// TODO: cache pose point and orientation so that we don't recompute every time we need it
	Pose       spatialmath.Pose // for 2d, we only use x, y, and OV theta
	Time       float64          // elapsed time on trajectory
	Dist       float64          // distance travelled down trajectory
	Alpha      float64          // alpha k-value at this node
	LinVelMMPS float64          // linvel in millimeters per second at this node
	AngVelRPS  float64          // angvel in radians per second at this node
}

TrajNode is a snapshot of a single point in time along a PTG trajectory, including the distance along that trajectory, the elapsed time along the trajectory, and the linear and angular velocity at that point.

func ComputePTG

func ComputePTG(simPTG PTG, alpha, dist, diffT float64) ([]*TrajNode, error)

ComputePTG will compute all nodes of simPTG at the requested alpha, out to the requested distance, at the specified diffT resolution.