Ekinox Subsea
– Hardware Manual
EKINOXSUBSEAHM.1.4
2. Performance specification
2.1. Inertial measurement unit
As an IMU is the main component of an inertial navigation system, the Ekinox IMU has been carefully
designed to take full advantage and performance of MEMS technology.
2.1.1. Accelerometers
The Ekinox IMU embeds a set of 3 MEMS capacitive accelerometers. Coupled with advanced filtering
techniques and sculling integrals, these accelerometers will provide consistent performance, even in
vibrating environment.
A1
A3
Remarks
Full scale (
g)
2
10
One year bias stability (µ
g)
300
1500
In run bias instability (µ
g)
10
40
Allan variance – @ 25°C
Velocity Random Walk (µ
g/√hz)
18
100
Allan variance – @ 25°C
Gain (ppm)
300
300
Linearity (% of FS)
0.05
0.05
Noise (µ
g)
90
450
Over 1 to 25 Hz band
Bandwidth (Hz)
100
100
Attenuation < 3 dB
Resolution (m
g)
0.1
0.6
Sampling rate (kHz)
5
5
Orthogonality (°)
0.03
0.03
2.1.2. Gyroscopes
The set of 3 high end tactical grade MEMS gyroscopes is sampled at 1 000 KHz. An efficient FIR filter and
coning integrals computations ensures best performance in vibrating environments.
G4
Remarks
Full scale (°/s)
400
Specified performance, saturates at 450°/
s
One year bias stability (°/hr)
< 300
Total composite bias
In run bias instability (°/hr)
< 3
Allan variance – @ 25°C
Angular Random Walk (°/hr/√hz)
< 30
Allan variance – @ 25°C
Gain (ppm)
300
Linearity (% of FS)
0.05
Noise (°/s)
0.3
Over 1 to 25 Hz band
Bandwidth (Hz)
100
Attenuation < 3 dB
Resolution (°/s)
0.03125
Sampling rate (kHz)
1
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