ADIS16480 AD [Analog Devices], ADIS16480 Datasheet - Page 29

• Manufacturer Part Number: ADIS16480
• Description: Ten Degrees of Freedom Inertial Sensor
• Manufacturer: AD [Analog Devices]

Data Sheet
DECLINATION
The DECLN_ANGL register provides a user-programmable
input that can shift the reference frame from magnetic north
to geodetic north (or any arbitrary azimuth heading).
Table 93. DECLN_ANGL (Page 3, Base Address = 0x54)
Bits
[15:0]
ADAPTIVE OPERATION
The EKF_CNFG register, in Table 94, offers a number of control
bits for customizing EKF operation.
Table 94. EKF_CNFG (Page 3, Base Address = 0x50)
Bits
[15:13]
12
[11:10]
9
8
[7:5]
4
3
2
1
0
Adaptive EKF Enable Bit
EKF_CNFG[8] (see Table 94) provides an on/off control bit
for the adaptive part of the EKF function. The adaptive part
of the EKF computes the measurement covariance terms (R),
which enables real-time adjustments for vibration and magnetic
field disturbances. See Table 80 through Table 83 for read access
to the measurement covariance terms.
Automatic EKF Divergence Reset Control Bit
The EKF algorithm monitors the normalized innovation
squared parameter to detect divergence. The normalized
innovation is the innovation (predicted measurements minus
actual measurements) divided by the statistically computed
expected error, which is based on the error covariance and the
measurement covariance. With a moderate level of divergence,
the divergence indicator bit (SYS_E_FLAG[13] (see Table 59) is
set to a high state. At higher levels of divergence, EKF_CNFG[12]
(see Table 94) provides an on/off control bit for automatically
resetting the Kalman filter, to help speed recovery from
divergence.
Description (Default = 0x0000)
Declination angle, twos complement
Scale factor = π/2
Description (Default = 0x0200)
Not used
Automatic reset recovery from divergence
1 = enable, 0 = disable
Not used
Fade enable
1 = enable, 0 = disable
Adaptive EKF enable
1 = enable, 0 = disable
Not used
Orientation format control
1 = rotation matrix, 0 = quaternion and Euler
Body frame enable
1 = enable, 0 = disable
Not for external use, always set to 0
Magnetometer disable
1 = enable, 0 = disable
Gravity removal (from accelerometers)
1 = enable, 0 = disable
15
radians/LSB
Rev. 0 | Page 29 of 40
Gyroscope Fade Control Bit
EKF_CNFG[9] (see Table 94) provides an on/off control bit for
the gyroscope fade function, which is an internal adjustment
of the gyroscope’s process covariance terms. This reduces the
impact of gyroscope scale errors during transient events, where
the gyroscope rates are quickly changing. The fade function
effectively reduces the weighting of the gyroscope measure-
ments, with respect to the accelerometers and magnetometers,
during these transient events. The adjustment terminates when
the rates return to zero.
Body Frame Enable Bit
EKF_CNFG[3] (see Table 94) provides an on/off control bit for
the body frame enable function. The reference transformation
matrix establishes the difference between the local navigation
frame and the body frame. Set EKF_CNFG[3] = 1 (DIN =
0x8003, DIN = 0xD110) to establish the body frame as the
reference frame.
Orientation Format Control Bit
EKF_CNFG[4] (see Table 94) provides a selection bit for angle
data format. Set EKF_CNFG[4] = 1 (DIN = 0x8003, DIN =
0xD010) to use the rotation matrix format.
Magnetometer Disable Control Bit
EKF_CNFG[1] (see Table 94) provides an on/off control bit
for the magnetometer disable function, which disables the
magnetometer influence over angle calculations in the EKF.
Gravity Removal Control Bit
EKF_CNFG[0] (see Table 94) provides an on/off control bit
for the gravity removal function, which removes the gravity
component from the accelerometer outputs.
Linear Acceleration/Magnetic Disturbance Detection
The
and magnetometers and compares their values against those of
the corresponding reference vectors. If the difference exceeds
the percentage programmed in the disturbance thresholds, the
algorithm automatically ignores the affected sensor group for
the duration of the external disturbance.
Table 95. ACC_DISTB_THR (Page 3, Base Address = 0x56)
Bits
[15:8]
[7:0]
Table 96. MAG_DISTB_THR (Page 3, Base Address = 0x58)
Bits
[15:8]
[7:0]
ADIS16480
Description (Default = 0x0020)
Not used
Threshold, binary, scale factor = 0.39%/LSB (50%/128)
Description (Default = 0x0030)
Not used
Threshold, binary, scale factor = 0.39%/LSB (50%/128)
checks the magnitudes of the accelerometers
ADIS16480