IMU Filter

Estimate orientation using IMU Filter

Since R2023b

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Libraries:
Navigation Toolbox / Multisensor Positioning / Navigation Filters
Sensor Fusion and Tracking Toolbox / Multisensor Positioning / Navigation Filters

Description

The IMU Filter Simulink^® block fuses accelerometer and gyroscope sensor data to estimate device orientation.

Examples

Compute Orientation from Recorded IMU Data

Load the rpy_9axis file into the workspace. The file contains recorded accelerometer, gyroscope, and magnetometer sensor data from a device oscillating in pitch (around the y-axis), then yaw (around the z-axis), and then roll (around the x-axis). The file also contains the sample rate of the recording.

(Navigation Toolbox)

Ports

Input

Accel — Accelerometer readings in sensor body coordinate system (m/s²)

matrix

Accelerometer readings in the sensor body coordinate system in m/s², specified as an N-by-3 matrix of real numbers. N is the number of samples, and each row is of the form [x y z].

Data Types: single | double

Gyro — Gyroscope readings in sensor body coordinate system (rad/s)

matrix

Gyroscope readings in the sensor body coordinate system in rad/s, specified as an N-by-3 matrix of real numbers. N is the number of samples, and each row is of the form [x y z].

Data Types: single | double

Output

Orientation — Orientation of sensor body frame relative to navigation frame

matrix | array

Orientation of the sensor body frame relative to the navigation frame, returned as an M-by-4 matrix of real numbers or a 3-by-3-by-M array. Each row of the M-by-4 matrix represents the four components of a quaternion. Each page of the 3-by-3-by-M array represents a 3-by-3 rotation matrix.

The number of input samples N and the Decimation factor (Navigation Toolbox) parameter determine the output size M.

The output format depends on the value of the Orientation format (Navigation Toolbox) parameter.

Data Types: single | double

Angular Velocity — Angular velocity in sensor body coordinate system (rad/s)

matrix

Angular velocity, with gyroscope bias removed, in the sensor body coordinate system in rad/s, returned as an M-by-3 matrix of real numbers.

The number of input samples N and the Decimation factor parameter determine the output size M.

Data Types: single | double

Parameters

Reference frame — Navigation reference frame

NED (default) | ENU

Specify the navigation reference frame as NED (North-East-Down) or ENU (East-North-Up).

Orientation format — Orientation output format

quaternion (default) | Rotation Matrix

Specify the format in which to output Orientation as quaternion or Rotation matrix.

• quaternion — Orientation outputs an M-by-4 matrix of real numbers. Each row of the matrix represents the four components of a quaternion.

• Rotation matrix — Orientation outputs a 3-by-3-by-M array, in which each page of the array is a 3-by-3 rotation matrix.

The number of input samples N and the Decimation factor parameter determine the output size M.

Decimation factor — Decimation factor

1 (default) | positive integer

Specify the decimation factor by which to reduce the input sensor data rate as a positive integer.

The number of rows of the Accel (Navigation Toolbox) and Gyro (Navigation Toolbox) inputs must be a multiple of the decimation factor.

Initial process noise — Initial process noise

imufilter.defaultProcessNoise (default) | 9-by-9 matrix of real numbers

Specify the initial process noise as a 9-by-9 matrix of real numbers. The imufilter.defaultProcessNoise variable contains the default value.

Accelerometer noise ((m/s²)²) — Variance of accelerometer signal noise (m/s²)²

0.0001924722 (default) | positive real scalar

Specify the variance of the accelerometer signal noise in (m/s²)² as a positive real scalar.

Gyroscope noise ((rad/s)²) — Variance of gyroscope signal noise (rad/s)²

9.1385e-5 (default) | positive real scalar

Specify the variance of the gyroscope signal noise in (rad/s)² as a positive real scalar.

Gyroscope drift noise ((rad/s)²) — Variance of gyroscope offset drift (rad/s)²

3.0462e-13 (default) | positive real scalar

Specify the variance of the gyroscope offset drift in (rad/s)² as a positive real scalar.

Linear acceleration noise ((m/s²)²) — Variance of linear acceleration noise (m/s²)²

0.0096236100000000012 (default) | positive real scalar

Specify the variance of linear acceleration noise in (m/s²)² as a positive real scalar. The block models linear acceleration as a lowpass-filtered white noise process.

Linear acceleration decay factor — Decay factor for linear acceleration drift

0.5 (default) | scalar in the range [0 1)

Specify the decay factor for linear acceleration drift as a scalar in the range [0 1). If linear acceleration changes quickly, set this parameter to a lower value. If linear acceleration changes slowly, set this parameter to a higher value. The block models linear acceleration drift as a lowpass-filtered white noise process.

Simulate using — Type of simulation to run

Interpreted execution (default) | Code generation

Select the type of simulation to run from these options:

• Interpreted execution — Simulate the model using the MATLAB^® interpreter. This option reduces startup time, but has a slower simulation speed than Code generation. In this mode, you can debug the source code of the block.

• Code generation — Simulate the model using generated C code. The first time you run a simulation in this mode, Simulink generates C code for the block. Simulink reuses the C code for subsequent simulations, as long as the model does not change. This option requires additional startup time for the initial run, but increases the speed of subsequent simulations relative to Interpreted execution.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

Usage notes and limitations:

• This block also supports strict single-precision code generation.

Version History

Introduced in R2023b