Application of gyroscopic inertial navigation in global navigation satellite systems

Application of gyroscopic inertial navigation in global navigation satellite systems

A gyroscope-based inertial navigation system is an autonomous navigation system that does not rely on external information or radiate energy to the outside world. It mainly consists of gyroscopes and accelerometers.

Advanced inertial Navigation Systems supplier-Hitech Sensors Tech Co., Ltd

A. What is Gyroscope-based Inertial Navigation?

A gyroscope-based inertial navigation system is an autonomous navigation system that does not rely on external information or radiate energy to the outside world, but the term itself is unrelated to GNSS (Global Navigation Satellite System) navigation.

1. Gyroscope-based inertial navigation has the characteristic of stably pointing in one direction, independent of external motion. When this device is installed on an object that rotates, it can measure the object's rotation angle.

2. Accelerometers can measure the acceleration value of an object's motion, and the distance can be calculated as S = (1/2)a * t^2. The acceleration value is constantly changing.

A three-axis gyroscope points to the x, y, and z axis of a coordinate system, and accelerometers are added to these three axes to form an inertial navigation device. By changing the angles of the three axes and accumulating the distances along the three axes, the three-dimensional positional movement of the object in three-dimensional space can be measured, i.e., three-dimensional displacement. However, you will find that such a device can only measure relative displacement, that is, the displacement between two points in time.

B. Gyroscope Inertial Navigation and Global Navigation Satellite Systems

GNSS navigation is a system that guides users based on location information provided by GPS/BD and a pre-planned route.

We know that GPS/BD calculates its position by receiving signals from satellites. When satellite signals are obstructed, the positioning device cannot determine its location. Obstruction can occur in various situations, such as passing under overpasses or through tunnels. In this case, the car icon in the navigation system may not move until the vehicle reaches an open area, at which point the position will jump to the correct location.

Furthermore, based on the relationship between speed, time, and distance, the speed calculated from a single satellite signal can be used to infer a possible position, thus continuing navigation. However, if the vehicle's acceleration and deceleration change significantly, the estimated position will deviate considerably from the actual current position, which will inevitably lead to a poor user experience.

The application of gyroscope inertial navigation combined with GNSS not only solves the problem of GNSS devices losing navigation position when satellite signals are lost, but also addresses the problem of relative displacement that exists with gyroscope inertial navigation alone. When the positioning accuracy of the GNSS device decreases, inertial navigation equipment is used to compensate for and calculate the navigation position; when the accuracy of the gyroscope inertial navigation decreases, the GNSS device is used for position compensation and calculation.

In the field of navigation, the combination of GNSS and inertial navigation can effectively solve positioning and driving problems in environments with obstructions such as tunnels, tall buildings, bridges, or forests. However, due to the inherent technical shortcomings of gyroscope inertial navigation (time and temperature are the main factors affecting the error of inertial navigation systems, and accumulated errors tend to increase), long-term navigation remains very difficult. Today, global navigation satellite systems have become the positioning technology for many application areas, and the technological advancements in the geospatial industry over the past 30 years have been impressive.