Introduction to Inertial Technology

(3) System Composition of an Inertial Navigation System

The Inertial Navigation System (INS) is a fully autonomous navigation solution widely used in aerospace, UAVs, marine vessels, robotics, and high-end industrial applications. Unlike satellite-based systems, an INS does not rely on external signals. Instead, it computes position, velocity, and attitude purely through internal sensors and algorithms.

This article explains the complete system composition of an INS and how its subsystems work together to deliver precise and reliable navigation.

1. Inertial Navigation System Overview

An INS determines the motion of a platform by continuously measuring acceleration and angular rate. These measurements are processed through navigation algorithms to compute:

• Position

• Velocity

• Attitude (Roll, Pitch, Yaw)

To achieve this, an INS integrates a combination of precision hardware, mechanical structures, electronics, and calibration methods.

2. System Composition

The core components of an Inertial Navigation System include:

(1) Inertial Measurement Unit (IMU)

The IMU is the sensing core of the INS. It integrates:

• Gyroscope
  Measures angular rate of rotation around three axes.

• Accelerometer
  Measures linear acceleration along three axes.

Together, these six degrees of freedom provide the raw motion data required for navigation calculations.

(2) Navigation Computer

The navigation computer is responsible for converting the IMU’s raw signals into usable navigation information.

It performs:

• Data Acquisition & Processing
  Filtering, sampling, and converting sensor outputs.

• Navigation Solution
  Implements algorithms such as strapdown calculation, attitude integration, velocity update, and position computation.

• Error Compensation
  Applies calibration data, bias removal, scale factor correction, and temperature compensation.

(3) Damping System

To ensure consistent accuracy, the damping system stabilizes platform motion and reduces the influence of vibrations, shock, and mechanical disturbances.

Its functions include:

• Minimizing sensor noise caused by vibration

• Providing damping for mechanical oscillations

• Assisting precision alignment

The damping design is especially critical in airborne and mobile applications.

(4) Electronic System

The electronic system provides power management, signal conditioning, and communication interfaces.

Key elements:

• Power regulation & distribution

• Digital signal processing circuits

• Communication protocols (CAN, RS422, Ethernet, etc.)

• System monitoring and protection

(5) Mechanical Structure

Mechanical structure provides the physical foundation of the INS.
A well-designed mechanical structure improves:

• Vibration resistance

• Thermal stability

• Long-term structural integrity

• Environmental ruggedness

This part ensures the system performs consistently under demanding conditions.

3. Parameter Initialization & Calibration Mechanisms

To achieve optimal accuracy, an INS requires multiple layers of calibration and initialization.

(1) Initial Parameters

These include sensor biases, installation angles, scale factors, and environmental coefficients.

(2) Initial Position

The system needs an accurate starting coordinate to begin navigation calculations.

(3) Temperature Calibration

IMU sensors are highly temperature-sensitive.
Temperature calibration compensates for:

• Bias drift

• Scale factor changes

• Non-linear temperature effects

This is essential for high-precision performance.

(4) Initial Alignment & Calibration

Initial alignment establishes the attitude reference (Roll / Pitch / Heading).
Two common alignment types:

• Static alignment – performed when the system is stationary

• Dynamic alignment – performed while moving, assisted by algorithms

Proper alignment ensures accurate heading and attitude output throughout operation.

4. Output of the INS

After processing all sensor data and applying corrections, the INS outputs:

• Attitude (Roll, Pitch, Yaw)

• Velocity (north/east/down or XYZ)

• Position (GPS coordinates or local coordinate system)

• Error Parameters (diagnostics, status, quality indicators)

The accuracy of these outputs depends on sensor quality, calibration completeness, and algorithm performance.

5. Conclusion

The Inertial Navigation System is a complex yet powerful technology built on precise sensors, sophisticated algorithms, and advanced calibration processes. Its ability to provide uninterrupted navigation in GNSS-denied environments makes it irreplaceable in modern aerospace, defense, robotics, and industrial applications.

Understanding the complete INS system composition—IMU, navigation computer, damping, electronic subsystem, mechanical structure, and calibration workflow—helps users appreciate its depth and technical importance.