Data Sheet

BNO055

Data sheet

Page 23

BST-BNO055-DS000-14 | Revision 1.4 | June 2016 Bosch Sensortec

to third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.

Note: Specifications within this document are subject to change without notice.

3.3.3.1 IMU (Inertial Measurement Unit)

In the IMU mode the relative orientation of the BNO055 in space is calculated from the

accelerometer and gyroscope data. The calculation is fast (i.e. high output data rate).

3.3.3.2 COMPASS

The COMPASS mode is intended to measure the magnetic earth field and calculate the

geographic direction.

The earth magnetic field is a vector with the horizontal components x,y and the vertical z

component. It depends on the position on the globe and natural iron occurrence. For heading

calculation (direction of compass pointer) only the horizontal components x and y are used.

Therefore the vector components of the earth magnetic field must be transformed in the

horizontal plane, which requires the knowledge of the direction of the gravity vector. To

summarize, the heading can only be calculated when considering gravity and magnetic field

at the same time.

However, the measurement accuracy depends on the stability of the surrounding magnetic

field. Furthermore, since the earth magnetic field is usually much smaller than the magnetic

fields that occur around and inside electronic devices, the compass mode requires calibration

(see chapter 3.10)

3.3.3.3 M4G (Magnet for Gyroscope)

The M4G mode is similar to the IMU mode, but instead of using the gyroscope signal to

detect rotation, the changing orientation of the magnetometer in the magnetic field is used.

Since the magnetometer has much lower power consumption than the gyroscope, this mode

is less power consuming in comparison to the IMU mode. There are no drift effects in this

mode which are inherent to the gyroscope.

However, as for compass mode, the measurement accuracy depends on the stability of the

surrounding magnetic field.

For this mode no magnetometer calibration is required and also not available.

3.3.3.4 NDOF_FMC_OFF

This fusion mode is same as NDOF mode, but with the Fast Magnetometer Calibration

turned ‘OFF’.

3.3.3.5 NDOF

This is a fusion mode with 9 degrees of freedom where the fused absolute orientation data is

calculated from accelerometer, gyroscope and the magnetometer. The advantages of

combining all three sensors are a fast calculation, resulting in high output data rate, and high

robustness from magnetic field distortions. In this mode the Fast Magnetometer calibration is

turned ON and thereby resulting in quick calibration of the magnetometer and higher output

data accuracy. The current consumption is slightly higher in comparison to the

NDOF_FMC_OFF fusion mode.