Magnetometer Calibration Tool; Yaw Drift - Kauai Labs navX-MXP User Manual

Robotics navigation sensor

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Table Of Contents

Table of Contents

Guidance

Gyro/Accelerometer Calibration

This On-the-fly Gyro Calibration can help deal with cases where the sensor was moving during

Startup Calibration, but note that the yaw is not zeroed at the completion of On-the-fly

Calibration. So once again, it's important to keep the sensor still during Startup Calibration.

Runtime Yaw Zeroing

Your robot software can optionally provide the robot operator a way to reset the yaw angle to

Zero at any time. Please see the documentation for the

The importance of stillness

This is the most important takeaway from this discussion: It is very important that navX-MXP be

held still during the above Initial Gyro and Initial Yaw Offset calibration periods. In support of

this, navX-MXP indicates when it is calibrating; we recommend you incorporate this information

into your software. Please see the discussion of the navXUI, and the

more details on this indication.

Please visit navX-Sensor Support for

A gyroscope measures the amount of angular rotation about a single axis. Since the gyroscope

measures changes in angular rotation, rather than an absolute angle, calculation of the actual

current angle of that axis is estimated via

measurement.

Any Inertial Measurement Unit (IMU), including navX-MXP, that integrates a signal from a

gyroscope will also accumulate error over time. Accumulated error is due to several factors,

including:

Quantization noise

continuous analog value to a discrete integral value)

Scale factor error (which occurs due to manufacturing errors causing a specified scale

factor [e.g., 256 bits per unit G] to be incorrect)

Temperature instability (which occurs when a sensor is more or less sensitive to an input

as temperature changes)

Bias error (which occurs because the value the sensor reports at 'zero' is not known

well enough to 'subtract' that value out during signal processing)