factorIMUBiasPrior

Prior factor for IMU bias

Since R2022a

Description

The factorIMUBiasPrior object is a factor that has prior information for an IMU bias for a factorGraph object.

Creation

Syntax

F = factorIMUBiasPrior(nodeID)

F = factorIMUBiasPrior(nodeID,Name=Value)

Description

F = factorIMUBiasPrior(nodeID) creates a factorIMUBiasPrior object, F, with the node identification numbers property NodeID set to nodeID

F = factorIMUBiasPrior(nodeID,Name=Value) specifies properties using one or more name-value arguments. For example, factorIMUBiasPrior(1,Measurement=[1 2 3 1 2 3]) sets the Measurement property of the factorIMUBiasPrior object to [1 2 3 1 2 3].

Properties

NodeID — Node ID numbers

Read-only: N-element column vector of nonnegative integers

This property is read-only.

Node ID numbers, specified as an N-element vector of nonnegative integers, where N is the total number of desired factors. Each element represents a factor that connects to a node of type IMU_BIAS in the factor graph using the specified node ID.

If a factor in the factorIMUBiasPrior object specifies ID that does not correspond to a node in the factor graph, the factor graph automatically creates an IMU_BIAS 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.

Measurement — Measured prior IMU bias

zeros(N,6) (default) | N-by-6 matrix

Measured prior IMU bias, specified as an N-by-6 matrix where each row is in the form [GyroBias, AccelBias]. N is the total number of factors, and GyroBias and AccelBias are three-element row vectors of the gyroscope bias and acceleration bias in radians per second and meters per second, respectively.

Information — Information matrices associated with measurements

eye(6) (default) | 6-by-6 matrix | 6-by-6-by-N array

Information matrices associated with the measurements, specified as a 6-by-6 matrix or a 6-by-6-by-N array. N is the total number of factors specified by the factorIMUBiasPrior object. Each information matrix corresponds to the measurements of the corresponding node in NodeID.

If you specify this property as a 6-by-6 matrix when NodeID contains more than one element, the information matrix corresponds to all measurements in Measurement.

Object Functions

nodeType

Get node type of node in factor graph

Examples

Add factorIMUBiasPrior Object to Factor Graph

Create an IMU bias prior factor with a node ID of 1.

f = factorIMUBiasPrior(1);

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

R2023a: Specify multiple factors

The NodeID, Measurement, and Information properties now accept additional rows to specify multiple factors.