factorGPS

Factor for GPS measurement

Since R2022a

Description

The factorGPS object adds a constraint to a node in a factorGraph by using a GPS position measurement.

Creation

Syntax

F = factorGPS(NodeID)

F = factorGPS(NodeID,Name=Value)

Description

F = factorGPS(NodeID) returns a factorGPS object, F, with the node identification number set to NodeID. The GPS factor adds a constraint to the corresponding factor graph node by using a GPS position measurement.

F = factorGPS(NodeID,Name=Value) specifies properties using one or more name-value arguments. For example, factorGPS(1,VDOP=1) sets the VDOP property of the factorGPS object to 1.

Properties

NodeID — Node ID numbers

Read-only: nonnegative integer

This property is read-only.

Node ID number, specified as a nonnegative integer. The factorGPS object factor connects to a node of type POSE_SE3 in the factor graph using the specified node ID.

If a factor in the factorGPS object specifies ID that does not correspond to a node in the factor graph, the factor graph automatically creates an POSE_SE3 type node with that ID and adds it to the factor graph when adding the factor to the factor graph.

You must specify this property at object creation.

For more information about the expected node types of all supported factors, see Expected Node Types of Factor Objects.

Location — Geodetic position measurement

[0 0 0] (default) | three-element row vector

Geodetic position measurement, specified as a three-element row vector of geodetic coordinates in the form (latitude longitude altitude). Latitude and longitude are in degrees and altitude is in meters.

HDOP — Horizontal dilution of precision

1 (default) | positive scalar

Horizontal dilution of precision, specified as a positive scalar.

VDOP — Vertical dilution of precision

2 (default) | positive scalar

Vertical dilution of precision, specified as a positive scalar.

ReferenceLocation — Origin of local coordinate system

[0 0 0] (default) | 3-element row vector

Origin of the local coordinate system, specified as a three-element row vector of geodetic coordinates in the form (latitude longitude altitude). Latitude and longitude are in degrees and altitude is in meters.

Altitude is the height above the reference ellipsoid mode, WGS84.

ReferenceFrame — Reference frame for local coordinate system

"ENU" (default) | "NED"

Reference frame for the local coordinate system, specified as "ENU" (east-north-up) or "NED" (north-east-down).

Data Types: string | char

Object Functions

nodeType

Get node type of node in factor graph

Examples

Add factorGPS Object to Factor Graph

Set up parameters such as the connected node ID, and reference location. Then create a GPS factor with these parameters as arguments, and set the reference frame to "NED".

id = 1;
loc = [5 5 1000];
hdop = 1.5;
vdop = 2.4;
refloc = [0 0 100];
f = factorGPS(id,Location=loc,HDOP=hdop,VDOP=vdop,ReferenceLocation=refloc,ReferenceFrame="NED");

Create a default factor graph and add the factor to the graph using the addFactor function.

g = factorGraph;
addFactor(g,f);

More About

Expected Node Types of Factor Objects

The NodeID property of each factor object specifies and connects to these node types.:

Factor Object	Expected Node Types of Specified Node IDs
factorGPS	["POSE_SE3"]
factorIMU	["POSE_SE3","VEL3","IMU_BIAS","POSE_SE3","VEL3","IMU_BIAS"]
factorCameraSE3AndPointXYZ	["POSE_SE3","POINT_XYZ"] or ["POSE_SE3","POINT_XYZ","TRANSFORM_SE3"]
factorPoseSE2AndPointXY	["POSE_SE2","POINT_XY"]
factorPoseSE3AndPointXYZ	["POSE_SE3","POINT_XYZ"]
factorTwoPoseSE2	["POSE_SE2","POSE_SE2"]
factorTwoPoseSE3	["POSE_SE3","POSE_SE3"]
factorTwoPoseSIM3	["POSE_SE3","POSE_SE3_SCALE","POSE_SE3","POSE_SE3_SCALE"]
factorIMUBiasPrior	["IMU_BIAS"]
factorPoseSE3Prior	["POSE_SE3"]
factorVelocity3Prior	["VEL_3"]

For example, factorPoseSE2AndPointXY([1 2]) creates a 2-D landmark factor connecting to node IDs 1 and 2. If you try to add that factor to a factor graph that already contains nodes with the IDs 1 and 2, the factor expects nodes 1 and 2 to be of types "POSE_SE2" and "POINT_XY", respectively.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

Version History

Introduced in R2022a