ASTROC developed a multi-sensor fusion system that combines LiDAR, optical cameras, IMU, and barometric data to create real-time 3D terrain models. This enables safe autonomous drone operations in hilly and mountainous terrain where standard altitude hold systems are insufficient.
Operating drones in hilly terrain poses unique challenges: rapid altitude variations, GPS multipath errors from canyon walls, and obstacle collision risks. Standard barometric altitude hold can't react fast enough to terrain undulations, and GPS altitude is notoriously inaccurate in such environments.
The ASTROC Sensor Fusion module uses an Extended Kalman Filter (EKF) to fuse data from multiple sensors in real-time. A downward-facing LiDAR provides precise ground distance, while optical flow cameras estimate lateral drift. The IMU provides high-rate attitude data, and the barometer gives medium-term altitude stability.
The fused output feeds directly into the flight controller's terrain following mode, enabling the drone to autonomously maintain a constant Above Ground Level (AGL) altitude even over rapidly changing terrain.
The system has been validated in field trials across the Western Ghats and Araku Valley. Terrain following accuracy of ±1.5m AGL was achieved at flight speeds up to 8 m/s, enabling safe survey and mapping operations previously impossible with standard drones.