Main Content

IMU

IMU simulation model

Since R2020a

  • IMU block

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

Description

The IMU Simulink® block models receiving data from an inertial measurement unit (IMU) composed of accelerometer, gyroscope, and magnetometer sensors. You can specify the reference frame of the block inputs as the NED (North-East-Down) or ENU (East-North-Up) frame by using the Reference Frame parameter.

Ports

Input

expand all

Acceleration of the IMU in the local navigation coordinate system, specified as an N-by-3 matrix of real scalars in meters per second squared. N is the number of samples in the current frame. Do not include the gravitational acceleration in this input since the sensor models gravitational acceleration by default.

To specify the orientation of the IMU sensor body frame with respect to the local navigation frame, use the Orientation input port.

Data Types: single | double

Angular velocity of the IMU sensor body frame in the local navigation coordinate system, specified as an N-by-3 matrix of scalars in radians per second. N is the number of samples in the current frame. To specify the orientation of the IMU sensor body frame with respect to the local navigation frame, use the Orientation input port.

Data Types: single | double

Orientation of the IMU sensor body frame with respect to the local navigation coordinate system, specified as an N-by-4 array of real scalars or a 3-by-3-by-N rotation matrix. Each row the of the N-by-4 array is assumed to be the four elements of a quaternion. N is the number of samples in the current frame.

Data Types: single | double

Temperature of IMU, specified as an N-by-1 vector of real scalars in degrees Celsius.

Dependencies

To enable this port, in the Parameters tab, select Specify temperature from input port.

Data Types: single | double

Magnetic field vector in the local navigation coordinate system, specified as an N-by-3 matrix of scalars in microteslas.

Dependencies

To enable this port, in the Parameters tab, select Specify magnetic field from input port.

Data Types: single | double

Output

expand all

Accelerometer measurement of the IMU in the sensor body coordinate system, returned as an N-by-3 matrix of real scalars in meters per second squared. N is the number of samples in the current frame.

Data Types: single | double

Gyroscope measurement of the IMU in the sensor body coordinate system, returned as an N-by-3 matrix of real scalars in radians per second. N is the number of samples in the current frame.

Data Types: single | double

Magnetometer measurement of the IMU in the sensor body coordinate system, returned as an N-by-3 matrix of real scalars in microtesla. N is the number of samples in the current frame.

Data Types: single | double

Parameters

expand all

Parameters

Navigation reference frame, specified as NED (North-East-Down) or ENU (East-North-Up).

Note

  • If you choose the NED reference frame, specify the sensor inputs in the NED reference frame. Additionally, the sensor models the gravitational acceleration as [0 0 9.81] m/s2.

  • If you choose the ENU reference frame, specify the sensor inputs in the ENU reference frame. Additionally, the sensor models the gravitational acceleration as [0 0 −9.81] m/s2.

Select this check box to enable the input of temperature by using the Temperature input port.

Operating temperature of the IMU in degrees Celsius, specified as a real scalar.

When the block calculates temperature scale factors and environmental drift noises, 25 oC is used as the nominal temperature.

Dependencies

To enable this parameter, unselect Specify temperature from input port.

Data Types: single | double

Select this check box to enable the input of magnetic field by using the Magnetic field input port.

Magnetic field vector expressed in the NED navigation frame, specified as a 1-by-3 vector of scalars.

The default magnetic field corresponds to the magnetic field at latitude zero, longitude zero, and altitude zero.

Dependencies

To enable this parameter, set Reference frame to NED and unselect Specify magnetic field from input port.

Data Types: single | double

Magnetic field vector expressed in the ENU navigation frame, specified as a 1-by-3 vector of scalars.

The default magnetic field corresponds to the magnetic field at latitude zero, longitude zero, and altitude zero.

Dependencies

To enable this parameter, set Reference frame to ENU and unselect Specify magnetic field from input port.

Data Types: single | double

Initial seed of a random number generator algorithm, specified as a nonnegative integer.

Data Types: single | double

  • Interpreted execution — Simulate the model using the MATLAB® interpreter. This option shortens startup time. In Interpreted execution mode, you can debug the source code of the block.

  • Code generation — Simulate the model using generated C code. The first time that you run a simulation, Simulink generates C code for the block. The C code is reused for subsequent simulations if the model does not change. This option requires additional startup time.

Accelerometer

Maximum sensor reading in m/s2, specified as a real positive scalar.

Data Types: single | double

Resolution of sensor measurements in (m/s2)/LSB, specified as a real nonnegative scalar.

Data Types: single | double

Constant sensor offset bias in m/s2, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Sensor axes skew in percentage, specified as a scalar, a 3-element row vector, or a 3-by-3 matrix. The diagonal elements of the matrix account for the misalignment effects for each axes. The off-diagonal elements account for the cross-axes misalignment effects. The measured state vmeasure is obtained from the true state vtrue via the misalignment matrix as:

vmeasure=1100Mvtrue=1100[m11m12m13m21m22m23m31m32m33]vtrue

  • If you specify the property as a scalar, then all the off-diagonal elements of the matrix take the value of the specified scalar and all the diagonal elements are 100.

  • If you specify the property as a vector [a b c], then m21 = m31 = a, m12 = m32 = b, and m13 = m23 = c. All the diagonal elements are 100.

Data Types: single | double

Velocity random walk in (m/s2/√Hz), specified as a real scalar or 3-element row vector. This property corresponds to the power spectral density of sensor noise. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Instability of the bias offset in m/s2, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Bias instability filter numerator coefficients, specified as a real-valued row vector. To specify coefficients for fractal noise, use the fractalcoef function.

Data Types: single | double

Bias instability filter denominator coefficients, specified as a real-valued row vector. To specify coefficients for fractal noise, use the fractalcoef function.

Data Types: single | double

Acceleration random walk of sensor in (m/s2)(√Hz), specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Select the type of random noise as:

  • double-sided — Random noise coefficients have a scale factor of 2.

  • single-sided — Random noise coefficients have a scale factor of 1.

Data Types: single | double

Sensor bias from temperature in (m/s2)/℃, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Scale factor error from temperature in %/℃, specified as a real scalar or real 3-element row vector with values ranging from 0 to 100. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Gyroscope

Maximum sensor reading in rad/s, specified as a real positive scalar.

Data Types: single | double

Resolution of sensor measurements in (rad/s)/LSB, specified as a real nonnegative scalar.

Data Types: single | double

Constant sensor offset bias in rad/s, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Sensor axes skew in percentage, specified as a scalar, a 3-element row vector, or a 3-by-3 matrix. The diagonal elements of the matrix account for the misalignment effects for each axes. The off-diagonal elements account for the cross-axes misalignment effects. The measured state vmeasure is obtained from the true state vtrue via the misalignment matrix as:

vmeasure=1100Mvtrue=1100[m11m12m13m21m22m23m31m32m33]vtrue

  • If you specify the property as a scalar, then all the off-diagonal elements of the matrix take the value of the specified scalar and all the diagonal elements are 100.

  • If you specify the property as a vector [a b c], then m21 = m31 = a, m12 = m32 = b, and m13 = m23 = c. All the diagonal elements are 100.

Data Types: single | double

Sensor bias from linear acceleration in (rad/s)/(m/s2), specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Angle random walk of sensor in (rad/s)/(√Hz), specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Instability of the bias offset in rad/s, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Bias instability filter numerator coefficients, specified as a real-valued row vector. To specify coefficients for fractal noise, use the fractalcoef function.

Data Types: single | double

Bias instability filter denominator coefficients, specified as a real-valued row vector. To specify coefficients for fractal noise, use the fractalcoef function.

Data Types: single | double

Select the type of random noise as:

  • double-sided — Random noise coefficients have a scale factor of 2.

  • single-sided — Random noise coefficients have a scale factor of 1.

Data Types: single | double

Integrated white noise of sensor in (rad/s)(√Hz), specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Sensor bias from temperature in (rad/s)/℃, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Scale factor error from temperature in %/℃, specified as a real scalar or real 3-element row vector with values ranging from 0 to 100. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Magnetometer

Maximum sensor reading in μT, specified as a real positive scalar.

Data Types: single | double

Resolution of sensor measurements in (μT)/LSB, specified as a real nonnegative scalar.

Data Types: single | double

Constant sensor offset bias in μT, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Sensor axes skew in percentage, specified as a scalar, a 3-element row vector, or a 3-by-3 matrix. The diagonal elements of the matrix account for the misalignment effects for each axes. The off-diagonal elements account for the cross-axes misalignment effects. The measured state vmeasure is obtained from the true state vtrue via the misalignment matrix as:

vmeasure=1100Mvtrue=1100[m11m12m13m21m22m23m31m32m33]vtrue

  • If you specify the property as a scalar, then all the off-diagonal elements of the matrix take the value of the specified scalar and all the diagonal elements are 100.

  • If you specify the property as a vector [a b c], then m21 = m31 = a, m12 = m32 = b, and m13 = m23 = c. All the diagonal elements are 100.

Power spectral density of sensor noise in μT/√Hz, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Instability of the bias offset in μT, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Bias instability filter numerator coefficients, specified as a real-valued row vector. To specify coefficients for fractal noise, use the fractalcoef function.

Data Types: single | double

Bias instability filter denominator coefficients, specified as a real-valued row vector. To specify coefficients for fractal noise, use the fractalcoef function.

Data Types: single | double

Select the type of random noise as:

  • double-sided — Random noise coefficients have a scale factor of 2.

  • single-sided — Random noise coefficients have a scale factor of 1.

Data Types: single | double

Integrated white noise of sensor in (μT)*√Hz, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Sensor bias from temperature in μT/℃, specified as a real scalar or 3-element row vector. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Scale factor error from temperature in %/℃, specified as a real scalar or real 3-element row vector with values ranging from 0 to 100. Any scalar input is converted into a real 3-element row vector where each element has the input scalar value.

Data Types: single | double

Algorithms

expand all

Extended Capabilities

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

Version History

Introduced in R2020a