To evaluate an IMU, the system integrator has to pick the solution that best meets the size, weight, and power (SWaP) requirements of the particular application while providing the very best performance possible. Cost usually factors into the equation as well. MEMS technologies offer the lowest SWaP characteristics while optical (FOG and RLG) offer the best performance characteristics. Many characteristics and parameters quantify the performance of accelerometers and gyros, but system integrators are typically most interested in noise and stability. When evaluating IMUs, Greensea measures noise and stability and illustrates the performance of the IMU through a simple free-inertial drift test on both translation and rotation axes.
Below is a SWaP comparison of four typical IMUs.
| IMU | Size (mm) | Volume (mm3) | Weight (kg) | Power |
|
3DM-GX4-25 |
36(l)x24.4(w)x11.1(h) |
9.75e3 |
.017 | 0.55 |
|
Landmark 40 |
50.9(l)x45(w)x30(h) |
6.87e4 |
.103 | 0.45 |
|
NAV440 |
76.02(l)x76.1(w)x76.5(h) |
4.43e5 |
.580 | 4.00 |
|
KVH 1750 |
74.3(h)x89.1(d) |
4.63e5 |
.700 | 5.00 |
The next table shows the Allan variance (AVAR) comparison of four typical IMUs.
| Degree of Freedom | 3DM-GX4-25 | Landmark 40 | NAV440 | KVH 1750 |
| X |
2.3e-3 |
7.4e-4 |
1.4e-3 |
3.2e-4 |
| Y |
2.5e-3 |
6.5e-4 |
1.2e-3 |
2.0e-4 |
| Z |
2.9e-3 |
7.9e-4 |
6.2e-4 |
4.5e-3 |
| Roll |
58.489 |
5.320 |
54.939 |
0.022 |
| Pitch |
58.171 |
4.957 |
68.170 |
0.022 |
| Heading |
20.641 |
6.255 |
60.314 |
0.036 |
