IMU Processing Unit
EKF/UKF Inertial Navigation Processor
The IMU processing unit is a 1-kilogram embedded processor that calculates continuous pose and velocity by executing Extended or Unscented Kalman Filters to fuse gyroscope and accelerometer data. Consuming 5 watts of power and operating at 100 to 400 hertz, the system incorporates aiding inputs from star trackers, LIDAR, and beacons. In the unshielded lunar radiation environment, the unit relies on radiation-hardened NOR flash memory and a radiation-tolerant FPGA accelerator for matrix arithmetic, supporting an operational lifetime of 100 years and a mean time between failures of 500,000 hours.
Embedded processor running Extended/Unscented Kalman Filter fusing gyro + accel into pose/velocity estimate with aiding from star tracker, LIDAR, and beacon.
Purpose
Embedded processor running Extended/Unscented Kalman Filter fusing gyro + accel into pose/velocity estimate with aiding from star tracker, LIDAR, and beacon.
Context
Child of L2-NAV-IMU within the Lunar Ark system
Principles
- ▸EKF/UKF state vector: pose, velocity, biases, scale factors
- ▸Aiding from L3-NAV-REF-STAR, L3-NAV-LOC-RANGE
- ▸Per-sample integration at 100-400 Hz
- ▸Rad-tolerant FPGA accelerator for matrix math
- ▸Diagnostic outputs for sensor health
Typical implementations
- ▸NASA cFS inertial navigation app
- ▸ESA inertial nav heritage
- ▸Apollo Lunar Module guidance computer (heritage concept)
Lunar considerations
- ▸Long-mission filter tuning evolves with operational data
- ▸Authenticated firmware updates over DTN
- ▸Rad-hard host platform
Specifications
Functional
| primary function | Embedded processor running Extended/Unscented Kalman Filter fusing gyro + accel into pose/velocity estimate with aiding from star tracker, LIDAR, and beacon. |
| update rate hz | 100 |
Physical
| mass kg | 1 |
| materials | Code on rad-hard NOR flash + FPGA accelerator |
| vacuum compatibility | True |
Operational
| power consumption w | 5 |
| thermal range c | -40, 70 |
| lifetime years | 100 |
| mtbf hours | 500000 |
Interfaces
Provides
- Inertial pose/velocity to SLAM fusion
- Pose/velocity to all consumers
Requires
- Sensor triads
- Star tracker aid
Cite this entry
Lunar Ark Codex. "IMU Processing Unit" (L3-NAV-IMU-PROC). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-NAV-IMU-PROC
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.