Strapdown inertial navigation systems (INS) are self-contained navigation solutions. They estimate position, velocity, and attitude without external references. These sensors directly measure angular rates and linear accelerations in the vehicle’s body frame. Strapdown systems integrate data using onboard algorithms. They rely on inertial measurement units (IMUs), typically made of gyroscopes and accelerometers. The gyroscopes measure angular velocity. The accelerometers measure specific forces. Together, they allow precise motion tracking in three dimensions.
Sensor data are transformed from the body frame to the navigation frame. This transformation uses real-time attitude computation. The strapdown system applies numerical integration techniques. It computes attitude using direction cosine matrices or quaternions. The system derives position and velocity by double integrating acceleration data.
Strapdown inertial systems and aiding sensors
Strapdown systems often integrate aiding sensors to correct these errors. They are resistant to shock and vibration. Their reduced size and weight make them ideal for compact platforms. These include drones, missiles, underwater vehicles, and mobile robots.
Sensor quality plays a critical role in the accuracy of a strapdown INS. Tactical-grade or navigation-grade IMUs offer lower bias and noise levels, which significantly reduce drift during long missions. Even so, all strapdown systems eventually accumulate errors over time. These errors result from sensor bias, scale factor variations, and integration drift.
To correct these errors, strapdown systems are often integrated with aiding sensors. These include GNSS receivers, magnetometers, and barometers. A Kalman filter typically fuses data from multiple sources. This allows the system to maintain long-term accuracy while still offering high update rates.
High-performance digital signal processors handle the required computations. These processors run real-time filtering and coordinate transformations. Advanced strapdown systems include temperature calibration and self-diagnostics. These features improve robustness and reliability.
Strapdown inertial navigation systems offer high bandwidth and low latency. Their fast response time is critical for control systems. They support autonomous navigation, guidance, and stabilization functions.
In modern applications, strapdown INS technology enables precise navigation in GPS-denied environments. It plays a key role in defense, aerospace, marine, and industrial sectors. Its continued development improves autonomy, performance, and reliability in demanding missions.