How INS/IMU + GNSS Keeps Railway and Vehicle-Mounted LiDAR Mapping Accurate

In railway surveying or vehicle-mounted LiDAR projects, vehicles move fast through complex environments—tunnels, bridges, forests, or urban areas. GNSS signals can easily weaken or drop out, causing positioning errors, misaligned LiDAR point clouds, and inaccurate track data.

This is where INS (Inertial Navigation System) with IMU (Inertial Measurement Unit) comes in. The IMU is like a high-speed “gyroscope + accelerometer,” measuring motion hundreds of times per second. Even when GNSS signals fail, it continues estimating position and orientation, keeping your trajectory smooth and accurate.

How GNSS + IMU Works

• GNSS: Provides absolute position with centimeter-level accuracy but can be blocked.
• IMU: Tracks every turn and shake at high speed. During signal loss, it predicts movement based on physics.
• Fusion (e.g., Kalman filtering): GNSS corrects long-term drift, IMU fills short-term gaps.

The result: a continuous, reliable trajectory for LiDAR mapping—even through tunnels or GNSS-challenged areas.

Real-World Railway Applications

High-Speed Track Inspection:

• Vehicles run 80–120 km/h scanning rails, catenary wires, and infrastructure.
• INS/IMU + GNSS outputs position, velocity, and attitude at 200+ Hz.
• LiDAR points align perfectly, with sub-meter or millimeter-level accuracy in tunnels.

Metro / Tram Tunnel Modeling:

• Zero GNSS signals inside tunnels.
• Start with GNSS + IMU outside, then IMU continues inside.
• Complete 3D models of tracks, walls, and cables with 5–10 cm accuracy.

Freight Line Patrol & Intrusion Detection:

• Dense vegetation blocks GNSS.
• IMU smooths trajectory despite vehicle sway, removing motion blur in LiDAR.
• Enables reliable detection of obstacles and slope risks.

Why a High-Quality INS Matters

• Bridging Capability: Handles long GNSS outages stably.
• High-Frequency Output: Perfect for LiDAR synchronization.
• Easy Integration: Standard interfaces for LiDAR and survey platforms.
• Rail-Grade Reliability: Resistant to vibration, temperature changes, and long-term use.

Bottom line: Unstable positioning = wasted LiDAR data. A reliable INS/IMU + GNSS setup keeps your surveys precise, efficient, and tunnel-proof.

If you’re working on high-speed track surveys, metro tunnels, or line patrols, contact us with your project details (tunnel lengths, speed, budget), and we’ll recommend the best INS solution for your needs.