Apogee Subsea
– Hardware Manual
APOGEESUBSEAHM.1.1
2. Performance specification
2.1. Inertial measurement unit
As an IMU is the main component of an inertial navigation system, the Apogee IMU has been carefully
designed to take full advantage and performance of MEMS technology.
2.1.1. Accelerometers
The Apogee 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
Scale factor stability (ppm)
< 300
< 300
1 year composite stability
Non-Linearity (ppm of FS)
< 200
< 100
Residual over temperature range
One year bias stability (m
g)
< 1
< 2
Total composite bias
Velocity Random Walk (µ
g/√hz)
< 15
< 85
Allan variance – @ 25°C
In run bias instability (µ
g)
< 2
< 15
Allan variance – @ 25°C
Vibration Rectification Error (µ
g/g²)
< 800
< 125
20 Hz – 2 kHz
Bandwidth (Hz)
> 200
> 200
Attenuation of 3 dB
Orthogonality (°)
< 0.02
< 0.02
Over temperature range
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.
G3
Remarks
Full scale (°/s)
± 200
Scale factor stability (ppm)
< 300
1 year composite stability
Non-Linearity (ppm of FS)
< 100
Residual over temperature range
One year bias stability (°/hr)
50
Total composite bias
In run bias instability (°/hr)
< 0.08
Allan variance – @ 25°C
Angular Random Walk (°/√hr)
< 0.012
Allan variance – @ 25°C
Bandwidth (Hz)
> 100
Attenuation of 3 dB
Orthogonality (°)
< 0.02
Over temperature range
7/34
