0x0426 - SetLocalLoiter

Description

This message is used to command the vehicle to loiter about a desired position in the local reference frame. Note that in some applications, particularly air and undersea, position may be a mix of local coordinates for XY position and absolute coordinates for Z/altitude/depth. This only applies if the Z axis for the vehicle coordinate frame is aligned with a vertical axis, e.g. a vector orthogonal to the ground plane. In all other cases, implementations must use Zlocal reporting only. For example, a UUV launched from a USV may need to navigate using local X/Y coordinates based on its launch point (using dead reckoning from its IMU) but rely on direct readings that do not suffer from drift for its Depth and/or Altitude ASF. All times are in Coordinated Universal Time (UTC).

Structure

SetLocalLoiter
 LocalLoiterSpecification
   LocalLoiterRec
   Loiter
     HoverRec
     PolygonRec
     RaceTrackRec

LocalLoiterSpecification

Type: Sequence

Field #	Field Name	Type	Optional	Interpretation
1	LocalLoiterRec	LocalLoiterRec	false
2	Loiter	Loiter	false

LocalLoiterRec

Type: Record

Field #	Field Name	Type	Optional
1	PresenceVector	uint8
2	X		false
3	Y		false
4	ZPosition		true

Loiter

Type: Variant

Index	Type
0	HoverRec
1	PolygonRec
2	RaceTrackRec

HoverRec

Type: Record

Field #	Field Name	Type	Units	Optional
1	HoverPreference	uint8	one	false
2	XYTolerance	uint32	meter	false
3	ZTolerance	uint32	meter	false

PolygonRec

Type: Record

Field #	Field Name	Type	Units	Optional	Interpretation
1	NumberLoiterVertices	uint8	one	false	Number of vertices in loiter convex, regular polygon 0 and 1 are a circular loiter; 2 forms a linear loiter
2	XYExtent	uint32	meter	false	Distance from loiter reference position to polygon vertices
3	LoiterDirection	uint8	one	false
4	LoiterBearing	uint16	radian	false	Angular offset from the X-axis in a right-hand sense about Z-axis from the loiter point to the first vertex of the polygon; a value of zero for a 4-vertex polygon would create a diamond while a value of PI/4 would create a square with respect to the local coordinate system.

RaceTrackRec

Type: Record

Field #	Field Name	Type	Units	Optional	Interpretation
1	LoiterType	uint8	one	false
2	LoiterRadius	uint32	meter	false	Width (smaller distance) of racetrack or figure 8
3	LoiterLength	uint32	meter	false	Length (larger distance) of racetrack or figure 8
4	LoiterDirection	uint8	one	false
5	LoiterBearing	uint16	radian	false	Angular offset of the length axis from the X-axis in a right-hand sense about Z-axis; a value of zero would align the “LoiterLength” with the X-axis while a value of PI/2 would align it with the Y-axis.