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| first:adis16448_imu_frc [10 Dec 2018 22:20] – Clarified a few sentences and rearranged details. Juan Chong | first:adis16448_imu_frc [12 Dec 2018 17:29] – [Getting Started] Kristen Chong |
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| ===== Getting Started ===== | ===== Getting Started ===== |
| The ADIS16448 IMU Board is designed to plug directly into the MXP port on the RoboRIO. Due to the size of typical FRC robots, AHRS calculations that rely on the magnetometer may be adversely affected by motors and metal objects close to the sensor. The IMU board has two mounting holes which should be used to secure it to the RoboRIO with #4-40 screws. | {{ :first:adis16448_rotation_figure.jpg?nolink&400|}}The [[adi>ADIS16448]] IMU Board is designed to plug directly into the MXP port on the RoboRIO. Due to the size of typical FRC robots, AHRS calculations that rely on the magnetometer may be adversely affected by motors and metal objects close to the sensor. The IMU board has two mounting holes which should be used to secure it to the RoboRIO with #4-40 screws. The figure to the right illustrates the X, Y, and Z axis relative to the device package. Note that the IMU is installed on the board //upside down// compared to the image shown here. |
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| ===== A Note on Offset Calibration ===== | ===== A Note on Offset Calibration ===== |
| To help the robot minimize start-up drift and improve overall sensor performance, an offset calibration function has been built into the IMU driver. This function captures several seconds worth of data and calculates an average offset which is then applied to the sensor outputs. By default, calibration is automatically started once the RoboRIO begins executing user code and usually takes about 10 seconds to complete. If your IMU board has a "Ready?" LED indicator, it will illuminate once calibration is complete. | To help the robot minimize start-up drift and improve overall sensor performance, an offset calibration function has been built into the IMU driver. This function captures several seconds worth of data and calculates an average offset which is then applied to the sensor outputs. By default, calibration is automatically started once the RoboRIO begins executing user code and usually takes about 10 seconds to complete. If your IMU board has a "Ready?" LED indicator, it will illuminate once calibration is complete. |
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| <note important>The gyros used in the ADIS16448 measure //angular rate//, not //angle!// Any movement during the offset calibration routine **will** introduce some error into **every** sensor measurement! Over time, this error, will appear as "drift" in your angle measurement. **It is VERY important that the robot remains completely stationary during this calibration period!**</note> | <note important>The gyros used in the [[adi>ADIS16448]] measure //angular rate//, not //angle!// Any movement during the offset calibration routine **will** introduce some error into **every** sensor measurement! Over time, this error, will appear as "drift" in your angle measurement. **It is VERY important that the robot remains completely stationary during this calibration period!**</note> |
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| <note tip>Offset calibration should be performed as soon as the robot is powered on to prevent the routine from interfering with any autonomous code execution. If your gyro angle readings are drifting drastically, clicking "Restart Robot Code" in the driver station will force the RoboRIO to re-execute the offset calibration routine. This should fix any drift issues caused by a bad offset measurement.</note> | <note tip>Offset calibration should be performed as soon as the robot is powered on to prevent the routine from interfering with any autonomous code execution. If your gyro angle readings are drifting drastically, clicking **Restart Robot Code** in the driver station will force the RoboRIO to re-execute the offset calibration routine. This should fix any drift issues caused by a bad offset measurement.</note> |
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| ===== Using the ADIS16448 IMU on Your Robot ===== | ===== Using the ADIS16448 IMU on Your Robot ===== |
