KONGSBERG DPS i2 Inertial Navigation System: A New Benchmark for GNSS and INS Fusion Positioning

KONGSBERG DPS i2 Inertial Navigation System: A New Benchmark for GNSS and INS Fusion Positioning

Product positioning and design philosophy

DPS i2 is the basic model in the DPS i series, fully utilizing GPS and GLONASS dual constellation data, and integrating with Kongsberg's MGC ™ Deep integration of motion gyro compass. Its design goal directly targets the core requirements of DP applications: to maintain excellent positioning performance and integrity without relying on external differential services.

The design philosophy of the i-series is "Sensors teaming up". GNSS and inertial navigation systems (INS) have a natural complementarity - GNSS provides long-term stable absolute position, but is susceptible to interference in dynamic environments; INS provides short-term high-precision relative displacement and attitude, but errors accumulate over time. By deeply integrating the two, one can overcome their respective limitations and achieve the effect of "1+1>2".

Core technical principles

Multi constellation GNSS reception

DPS i2 has a built-in multi frequency and multi constellation receiver, supporting:

GPS（L1/L2）

GLONASS（L1/L2）

SBAS (WAAS/EGNOS, etc.)

Dual frequency reception achieves self calibration of ionospheric delay, improving positioning accuracy and anti-interference capability. Compared to single frequency receivers, the advantage is particularly evident in equatorial regions or peak solar activity periods.

MGC ™ Integration of motion gyro compass

MGC ™ Not only is it a high-precision gyro compass (providing true north pointing), but it also outputs complete attitude information - roll, pitch, heading, and angular velocity and acceleration in three axes. By integrating MGC ™ As an inertial measurement unit (IMU) integrated with DPS i2, the system obtained:

Continuous position and velocity output: During brief interruptions in GNSS signals (such as under bridges or near platforms), INS continues to provide high update rate position estimation.

Stable attitude positioning: Combined with lever arm compensation, accurately calculate the position of any point on the ship.

High quality heading data: MGC ™ The WheelMark certified compass can simultaneously serve other onboard equipment such as navigation radar and autopilot.

Deep coupled fusion algorithm

DPS i2 adopts a Tightly Coupled or Deeply Coupled architecture, where the raw pseudorange and carrier phase observations of GNSS receivers are fused with INS acceleration and angular velocity data at the Kalman filter level. This design brings the following advantages:

Fast Recapture: When GNSS is interrupted and restored, INS provides initial position estimation, enabling positioning to be restored in seconds.

Enhanced integrity: INS assisted RAIM (Receiver Autonomous Integrity Monitoring) can more sensitively detect and troubleshoot faulty satellites.

Robust performance design

High precision positioning without calibration services

The outstanding feature of DPS i2 is that it can achieve positioning accuracy better than 1.3 meters (95% CEP) without any differential correction service. When enabling high-precision mode (such as utilizing the precise posture of MGC), it can even reach the level of 10 centimeters. This is particularly valuable for deep-sea operations that are far from the coast and cannot receive SBAS or beacon signals.

Anti occlusion and anti-interference

By filling the GNSS signal gap with INS, DPS i2 can still maintain continuous positioning under the following harsh conditions:

Signal obstruction: such as ships approaching drilling platforms, navigating in canyons or ports.

Ionospheric scintillation: common in equatorial regions, causing rapid changes in signal amplitude and phase.

Radio frequency interference: unintentional or intentional interference.

RAIM integrity enhancement

Traditional RAIM relies solely on the geometric distribution of GNSS satellites for fault detection. DPS i2 introduces INS data into the RAIM algorithm, significantly improving the sensitivity of detecting small and slowly changing faults, ensuring highly reliable position data output to the DP system.

Active Decision Support and Human Computer Interface

The human-machine interface (HMI) of the DPS i series was developed in close collaboration with experienced DP operators, aiming to enable operators to quickly and effectively evaluate positioning quality.

Intuitive graphical display: Clearly display key information such as satellite tracking status, calibration source, positioning mode, protection level, etc.

Quality indicator: Use colors and symbols to visually reflect the confidence level of the current positioning, assisting operators in making decisions.

Data replay: Automatically record data and support replay function for post analysis and troubleshooting.

Scalable system architecture

The flexible design of the DPS i series enables it to adapt to various needs from workboats to high-end DP-3 vessels.

Single system configuration

Combining a single DPS i2 with one MGC can provide high integrity position, velocity, and attitude outputs, meeting most DP-1/2 applications.

Dual system redundancy and GNSS direction finding