Satellite Launcher Navigation with One Versus Three IMUs: Sensor Positioning and Data Fusion Model Analysis

Area of Science:

• Aerospace Engineering
• Navigation Systems

Background:

• Single Inertial Measurement Units (IMUs) limit integration possibilities.
• Higher quality single IMUs are often preferred over multiple lower-quality IMUs.

Purpose of the Study:

• To evaluate the performance of using three IMUs versus a single higher-quality IMU for satellite launcher navigation.
• To compare different sensor fusion strategies for multi-IMU configurations.

Main Methods:

• Tested IMU placement: collocated versus distributed along the launcher.
• Evaluated three fusion methods: single INS, stacked filter, and stacked filter with geometrical constraints.
• Navigation solutions were aided by a three-axis attitude reference sensor and tested with/without GPS.

Main Results:

• Distributed IMUs did not improve navigation performance over collocated IMUs.
• Fusing multiple IMUs into a single Inertial Navigation System (INS) yielded results comparable to a single IMU.
• Fusing multiple INSs significantly reduced estimation errors, with further improvements from geometrical constraints.

Conclusions:

• IMU distribution along a satellite launcher does not enhance navigation performance.
• Multi-INS fusion, particularly with geometrical constraints, offers superior performance over single INS or fused IMU approaches.
• Relative velocity and position constraints should be used cautiously during extended GPS outages to prevent filter divergence.