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

For higher demand applications, two DPS systems can be configured, combined with MGC/MRU sensors, to achieve:

Complete redundancy: seamless switching between primary and backup systems.

GNSS direction finding: using two antennas to determine the bow direction of the ship as a supplement or backup to MGC.

Anti spoofing detection: By comparing GNSS position/heading with INS calculations, detect and alert potential signal spoofing.

Compatible with existing sensors

The DPS i series can be paired with dedicated MGC or MRU, or can utilize compatible sensors already on board to protect existing investments.

Remote Service and Diagnosis

The DPS i series is ready for K-IMS remote services. Through K-IMS, experts from Kongsberg can remotely access the system for:

Status monitoring: Real time monitoring of system health status.

Fault diagnosis: Quickly analyze the cause of the problem, and many situations that previously required engineers to board the ship can now be solved remotely.

Software update: Safely push firmware upgrades.

This greatly shortens the troubleshooting time and improves the operational efficiency of the vessel.

Technical Specifications

performance parameters

Parameter numerical conditions

Non differential positioning accuracy 1.3 m 95% CEP standard mode

High precision mode<10 cm 95% CEP dependent subscription service

DGNS positioning accuracy<1 m 95% CEP enabled differential correction

SBAS positioning accuracy<1 m 95% CEP enabled SBAS

Speed accuracy<0.01 m/s 95% CEP-

The roll/pitch accuracy can be found in the separate manual of MGC/MRU-

Update rate 1-20/200 Hz position/attitude

Delay<1 ms-

Note: All accuracy indicators are based on actual measurements in the North Sea and may vary in different sea areas.

interface

Type and quantity description

Serial port 8 isolated, 6 configurable RS-232/422

IMU interface 1 RS-422

Ethernet/LAN 4-

USB 3 is used for maintenance and upgrades

data format

NMEA 0183 v3.0：ABBDP、ARABB、DPGG、DTM、GBS、GGA、GLL、GNS、GRS、GSA、GST、GSV、RMC、VDW、VER、VTG、ZDA

RTCM input: v2.2, 2.3, 3.0, 3.1; Seastar XP/XP2/G2/G2+； CMR

Input correction

DGNS correction

RTK correction

Compass input (NMEA HDT/HRC/THS, Robertson LR22 BCD)

Display Control (DDC)

Supported inertial sensors

MGC R3, MGC R2

MRU 5+

Power and Environment

Component power supply operating temperature

DPS i2 processing unit 100-240V AC see detailed specifications

HMI display unit - see detailed specifications

GNSS antenna powered by processing unit -40 ° C to+70 ° C

Humidity: Maximum 95% without condensation

Vibration: Complies with IEC 60945

Electromagnetic compatibility: Compliant with EMCD, IEC 60945

Safety: Compliant with LVD, IEC 61010-1

Product standard: Complies with IMO resolutions and UKOQA certification

Weight and Dimensions

Component weight and size

DPS i2 processing unit --

HMI Unit --

GNSS antenna --

Note: For detailed mechanical dimensions, please refer to the official installation manual.

Application scenarios

Dynamic Positioning (DP) Ship

For DP-1/2/3 class vessels, DPS i2 can serve as the core position reference system. Its high-precision positioning capability without calibration services enables ships to maintain DP capability even in operations far from the coast. Dual system configuration can meet redundancy requirements.

Survey and measurement vessel

Marine geophysical surveys and hydrological measurement tasks that require high-precision positioning can benefit from DPS i2's low latency, high update rate position output, and precise lever arm compensation.

Platform supply and construction vessel

When working near offshore facilities, signal obstruction is severe. The INS filling capability of DPS i2 ensures uninterrupted positioning and improves job safety.

National Defense and Security

The anti-interference and anti deception characteristics make it suitable for military ships and law enforcement vessels in sensitive waters.

Summary of Core Advantages

GNSS+INS deep fusion: Overcoming the limitations of a single sensor, providing continuous, stable, and high integrity positioning.

High precision without calibration service: reduces operating costs, especially suitable for offshore operations.

Enhanced RAIM integrity: INS assistance makes fault detection more sensitive, ensuring DP safety.

Scalable architecture: from single system to multi system redundancy, GNSS direction finding, anti spoofing, adapting to different needs.

Intuitive HMI: Designed in collaboration with DP operators to enhance situational awareness and decision-making efficiency.

Remote Service Ready: K-IMS supports remote diagnostics and upgrades, reducing downtime.

Multi purpose MGC: The integrated high-precision gyro compass can simultaneously serve other onboard systems.