Inertial Sensor

Measure orientation, acceleration, and angular rate

Since R2021a

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Add-On Required: This feature requires the Simulink Coder Support Package for VEX EDR V5 Robot Brain add-on.

  • Inertial Sensor block

Libraries:
Simulink Coder Support Package for VEX EDR V5 Robot Brain / Sensors

Description

The Inertial Sensor block reads data from the Inertial sensor that is connected to the VEX® V5 Brain.

By default, the block outputs yaw, pitch, and roll (as Euler angles following the 3-2-1 convention). The block also outputs the quaternion, angular rate, and acceleration. The block returns the angular rate and acceleration as 3-by-1 double vector in x-y-z order and quaternion is returned as 4-by-1 double.

The VEX V5 inertial sensor auto-detects and adjusts for the mounting position. This allows the sensor to output the same orientation (Euler angles) even when the sensor is mounted upside down. For more information, see Using the V5 Inertial Sensor.

The sensor takes about 2 seconds for calibration when you start a program. Ensure that the inertial sensor is kept steady on a level surface while starting the program.

Note

When the sensor is placed on a level surface and if the pitch or roll angles show errors (of more than 1 degree), then you might need to calibrate the accelerometer.

Ports

Output

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This port represents rotation around the vertical z-axis.

Dependencies

To enable this port select the Euler angles (deg) parameter.

Data Types: double

This port represents the angle between x-axis and the horizontal plane.

Dependencies

To enable this port select the Euler angles (deg) parameter.

Data Types: double

This port represents rotation around the longitudinal axis (x-axis) of the sensor.

Dependencies

To enable this port select the Euler angles (deg) parameter.

Data Types: double

The Quat port outputs the orientation along the w-, x-, y-, and z- axes of the sensor as a 4-by-1 vector. The orientation is measured in quaternion. For more information on a quaternion, see Quaternion

Dependencies

The Quat port is available only when you select the Quaternion parameter.

The Ang rate port outputs the angle of rotation per second about the x-, y-, and z- axes of the sensor as a 3-by-1 vector. The angular rate is measured in deg/s.

Dependencies

To enable this port select the Angular rate (deg/s) parameter.

Data Types: double

The Accel port outputs acceleration along the x, y, and z axes of the sensor as a 3-by-1 vector. The Acceleration is measured in m/s2 and also includes acceleration due to gravity.

Dependencies

To enable this port select the Acceleration (m/s^2) parameter.

Data Types: double

The Status port outputs the calibration status. The port outputs the status as a boolean value. The status remains 0 until the calibration is complete. The sensor takes 2 seconds to complete calibration.

This table shows what each element values in the vector indicate about the sensor calibration status.

ValueCalibration Status
0Uncalibrated
1Calibrated

Dependencies

To enable this port select the Calibration Status parameter.

Data Types: Boolean

Parameters

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Select the smart port on the V5 robot to which the VEX V5 inertial sensor is connected. There are 21 smart ports on the V5 robot.

Assign a unique smart port for each block in the model. If you use multiple Inertial Sensor blocks with the same port, the last Inertial Sensor block executed might be the only block that is active.

Specify the sample time in seconds to determine how often the block reads values from the sensor. When you specify this parameter as -1, Simulink® determines the best sample time for the block based on the block context within the model.

Select Outputs

Select the Euler angles (deg) parameter to enable Yaw, Pitch, and Roll ports. For more information, see Yaw, Pitch, and Roll.

Select the Quaternion parameter to enable Quat port. For more information on the Quat port, see Quat.

Data Types: double

Select the Angular rate (deg/s) parameter to enable Ang rate port. For more information on the Ang rate port, see Ang rate.

Select the Acceleration (m/s^2) parameter to enable Accel port. For more information on the Accel port, see Accel.

Select the Calibration Status parameter to enable Status port. For more information on the Status port, see Status.

Additional Options

Specify if the yaw mode has to be reset by external signal or not.

  • No reset – The block does not reset the inertial sensor reading and outputs the total angle of rotation.

    For example, at T = 1 in the table the inertial sensor rotates 20 degrees in a counterclockwise direction,so, the output is 20.

    Between T = 1 and T = 2, the inertial sensor rotates 10 degrees in a counterclockwise direction. Therefore, the yaw rotation is 30 at T = 2 (20 from T = 1 and 10 from T = 2).

    In this reset mode, the output at any time instant is a cumulative sum of the previous yaw rotation and the current yaw rotation.

  • Reset by external signal – The inertial sensor reading is reset to 0 based on the input value to Rst port. When you send a value other than 0 to the block input, the inertial sensor reading is reset to 0. For each sample period, the block outputs the inertial sensor reading since the last reset.

    Reset mode

Dependencies

To enable this parameter select Euler Angles parameter.

Specify the yaw angle limit for the inertial sensor.

Set the parameter to one of these values:

0 to 360 -- The yaw angle rolls over to 0 after reaching 360 degrees.

-180 to 180 -- The yaw angle rolls over to -180 degrees after reaching 180 degrees.

No wrap around-- The yaw angle can go over 360 degrees.

Dependencies

To enable this parameter select the Euler Angles parameter.

Extended Capabilities

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

Version History

Introduced in R2021a

See Also