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factorIMU

Convert IMU readings to factor

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Description

The factorIMU object converts raw IMU readings into constraints between poses, velocities, and IMU biases for a factorGraph object.

Creation

Syntax

F = factorIMU(nodeID,GyroscopeBiasNoise,AccelerometerBiasNoise,GyroscopeNoise,AccelerometerNoise,GyroscopeReadings,AccelerometerReadings)
F = factorIMU(___,ReferenceFrame="NED")

Description

example

F = factorIMU(nodeID,GyroscopeBiasNoise,AccelerometerBiasNoise,GyroscopeNoise,AccelerometerNoise,GyroscopeReadings,AccelerometerReadings) creates a factorIMU object, F, with the specified node identification numbers property NodeID set to nodeID, and with a sample rate, gyroscope bias noise, accelerometer bias noise, gyroscope noise, accelerometer noise, gyroscope readings, and accelerometer readings set to their corresponding values.

F = factorIMU(___,ReferenceFrame="NED") specifies the reference frame for the local coordinate system as north-east-down (NED) instead of east-north-up (ENU), in addition to all input arguments from the previous syntax.

Properties

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This property is read-only.

Node ID numbers, specified as a six-element row vector. The factorIMU object factor connects to these nodes in the factor graph.

If there are no nodes in the factor graph with the specified ID, nodes with the specified IDs are automatically created and added to the factor graph when this factor is added to the factor graph.

You must specify this property at object creation.

Data Types: int

This property is read-only.

IMU sampling rate, in Hz, specified as a positive scalar greater than 100.

You must specify this property at object creation.

Data Types: double

This property is read-only.

Gyroscope bias noise covariance, specified as a 3-by-3 matrix.

You must specify this property at object creation.

Data Types: double

This property is read-only.

Accelerometer bias noise covariance, specified as a 3-by-3 matrix.

You must specify this property at object creation.

Data Types: double

This property is read-only.

Gyroscope measurement noise covariance, specified as a 3-by-3 matrix.

You must specify this property at object creation.

Data Types: double

This property is read-only.

Accelerometer measurement noise covariance, specified as a 3-by-3 matrix.

You must specify this property at object creation.

Data Types: double

This property is read-only.

Gyroscope readings,, specified as an N-by-3 matrix, where N is the number of readings. The specified gyroscope readings are preintegrated into the factor. GyroscopeReadings and AccelerometerReadings must have the same size.

You must specify this property at object creation.

Data Types: double

This property is read-only.

Accelerometer readings, specified as an N-by-3 matrix, where N is the number of readings. The specified accelerometer readings are preintegrated into the factor. GyroscopeReadings and AccelerometerReadings must have the same size.

You must specify this property at object creation.

Data Types: double

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

Data Types: string | char

Object Functions

nodeTypeGet node type of node in factor graph
predictPredict pose and velocity of factor

Examples

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Open Live Script

Set up parameters such as the connected node IDs, sample rate, noise, and readings. Then create an IMU factor with these parameters as arguments.

nodeID = [1,2,3,4,5,6];
sampleRate = 400; % Hz
gyroBiasNoise = 1.5e-9 * eye(3);
accelBiasNoise = diag([9.62e-9, 9.62e-9, 2.17e-8]);
gyroNoise = 6.93e-5 * eye(3);
accelNoise = 2.9e-6 * eye(3); 
gyroReadings = [ -0.0151    0.0299    0.0027
                -0.0079    0.0370   -0.0014
                -0.0320    0.0306    0.0035
                -0.0043    0.0340   -0.0066
                -0.0033    0.0331   -0.0011];
accelReadings = [   1.0666    0.0802    9.9586
                   1.1002    0.0199    9.6650
                   1.0287    0.3071   10.1864
                   0.9077   -0.2239   10.2989
                   1.2322    0.0174    9.8411];
  
f = factorIMU(nodeID, sampleRate, gyroBiasNoise, accelBiasNoise, ...
             gyroNoise, accelNoise, gyroReadings, accelReadings, ReferenceFrame="NED");

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

g = factorGraph;
addFactor(g,f);

References

[1] Forster, Christian, Luca Carlone, Frank Dellaert, and Davide Scaramuzza. “On-Manifold Preintegration for Real-Time Visual--Inertial Odometry.” IEEE Transactions on Robotics 33, no. 1 (February 2017): 1–21. https://doi.org/10.1109/TRO.2016.2597321.

Extended Capabilities

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

Version History

Introduced in R2022a

See Also

Objects

Topics