MEMS IMU Integration — US Drone Fleet

Client Challenge

A leading US-based commercial drone delivery operator was scaling its autonomous fleet from pilot testing to full urban operations across multiple metropolitan areas. Their existing flight control system relied primarily on GPS/GNSS for positioning, which presented critical challenges in dense urban environments:

• GPS signal degradation — Urban canyons, tunnels, and under-bridge flight paths caused frequent GNSS dropouts lasting 10–30+ seconds
• Multi-path interference — Signal reflections from tall buildings introduced positioning errors exceeding 5 meters
• Safety-critical positioning — FAA-type certification required sub-meter accuracy during all phases of autonomous flight, including GPS-denied segments
• SWaP constraints — The sensor package had to weigh under 50 grams and fit within a 40 × 40 × 25 mm envelope to maintain the drone's payload capacity

Our Solution

GyroNavi provided a compact 6-DOF MEMS inertial measurement solution combining the GN3-IMU1-20 IMU module with our GN3-MEMS-G-50 tactical-grade MEMS gyroscope elements, coupled with custom sensor fusion firmware:

• GN3-IMU1-20 — Compact 6-DOF MEMS IMU measuring 38 × 38 × 22 mm, weighing 45 g, with tri-axial MEMS gyroscope (≤0.5°/√h ARW) and tri-axial MEMS accelerometer
• GN3-MEMS-G-50 — Tactical-grade single-axis MEMS gyroscope with ≤2°/h bias stability and ≤0.03°/√h ARW, integrated as the primary heading reference
• Sensor fusion engine — Extended Kalman Filter (EKF) with tightly-coupled INS/GNSS integration, barometric altimeter aiding, and magnetic declination compensation
• GPS outage bridging — Pure inertial dead-reckoning mode activated automatically upon GNSS signal loss or quality degradation below threshold
• Factory calibration — Each unit calibrated across -20°C to +60°C with rate table and thermal chamber, with calibration coefficients stored onboard

Results

The integrated solution was validated across 2,000+ flight hours in urban environments including downtown San Francisco, Chicago, and Miami:

Metric	GPS-Only	With GyroNavi IMU
Position Error (GPS available)	1.2 m CEP	0.4 m CEP (tightly coupled)
Position Error (10-second GPS outage)	8+ m drift	0.8 m CEP
Position Error (30-second GPS outage)	20+ m drift (unsafe)	1.8 m CEP
Heading Accuracy	±3° (magnetic)	±0.5° (gyrocompass)
Operational Temperature Range	0°C to +40°C	-20°C to +60°C

The client has deployed 500+ units across their operational fleet and reported sub-meter positioning accuracy throughout 30-second GPS outages, meeting FAA certification requirements for beyond visual line of sight (BVLOS) operations.