# 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

example

````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

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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.

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 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

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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);```