Innovative Fusion Strategy for MEMS Redundant-IMU Exploiting Custom 3D Components

Area of Science:

• Sensor Fusion and Signal Processing
• Micro-Electro Mechanical Systems (MEMS)
• Additive Manufacturing

Background:

• Micro-Electro Mechanical Systems (MEMS) inertial sensors show improved performance, approaching tactical-grade levels.
• High cost of tactical-grade sensors necessitates performance enhancement of affordable consumer-grade MEMS.
• Redundancy is a viable strategy for improving the performance of low-cost inertial sensors.

Purpose of the Study:

• To develop and evaluate a strategy for fusing raw measurements from multiple MEMS inertial sensors.
• To assess the impact of a 3D-printed reinforced ONYX structure on sensor performance.
• To achieve cost-effective inertial sensing solutions for applications like small unmanned aerial vehicles (UAVs).

Main Methods:

• Raw acceleration and angular rate data from multiple MEMS sensors were fused.
• Sensor measurements were averaged using weights derived from Allan variance analysis, prioritizing lower noise figures.
• A 3D-printed structure made of reinforced ONYX was utilized, and its mechanical and environmental effects were evaluated.

Main Results:

• The prototype system demonstrated performance comparable to a tactical-grade inertial measurement unit, with heading measurement differences as low as 0.3 degrees in stationary conditions.
• The reinforced ONYX 3D structure provided superior mechanical characteristics (250 MPa tensile strength) without significantly impacting thermal or magnetic field measurements.
• Real-world UAV testing showed root-mean-square error in heading measurements as low as 0.3 degrees over 140-second intervals.

Conclusions:

• The proposed sensor fusion strategy effectively enhances the performance of low-cost MEMS inertial sensors.
• Reinforced ONYX 3D printing is suitable for creating robust sensor structures for avionic applications.
• This approach offers a cost-effective alternative to tactical-grade inertial measurement units for UAVs and similar applications.