Dead Reckoning is the process of calculating the current position of an object based on estimates. Despite its origins in seafaring, it can have a significant impact on road transport. In a world dominated by GNSS technologies, understanding the implications of Dead Reckoning in road transport is essential to guarantee safe and efficient navigation.

But what is Dead Reckoning? Dead Reckoning is a navigation method that estimates the position of a vehicle based on its previously known location, considering the direction, speed, and elapsed time. Even though it was traditionally associated with sea and air transport, its principles can be applied to road transport (where conditions can drastically change).

Dead Reckoning: Basic principles

In order to apply Dead Reckoning to road transport, some key elements need to be understood:

1. Initial Position: All calculations are based on a known position that can be determined using a map or GNSS device.
2. Course: Refers to the direction the vehicle is heading towards, measured in degrees from north.
3. Speed: How quickly the vehicle is moving, usually expressed in kilometers per hour (km/h) or miles per hour (mph).
4. Time: The duration of the journey, which can be measured using a watch or chronometer.

The basic formula for calculating the new position is:

New position=Previous position+(Speed×Time)

Integrating Dead Reckoning in GNSS

Combining Dead Reckoning and GNSS offers a robust approach to road transport. Although  GNSS systems are very precise, their accuracy can be compromised in certain situations. It is in those scenarios where Dead Reckoning can prove useful.

How does the integration work?

Additional sensors (such as gyroscopes and accelerometers) are necessary when integrating Dead Reckoning and GNSS. They allow the system to calculate the vehicle’s position even when the GNSS signal is lost. These sensors provide data on the vehicle’s course and speed, which makes it possible to estimate its position in real time.

1. Motion sensors: Accelerometers measure the vehicle’s acceleration and deceleration, whereas gyroscopes identify changes in course. This data is then combined with GNSS information to provide a precise location.
2. Data fusion: Using advanced algorithms, systems can fuse GNSS and Dead Reckoning data. As a result, the system can use Dead Reckoning data to fill in any gaps when the GNSS signal is not available.
3. Correction of errors: When the GNSS signal is restored, the system can correct any error registered whilst Dead Reckoning was being used, thus ensuring navigation is as accurate as possible.

Source: Why You Need Dead Reckoning: Top Applications for INS – pointonenav.com

Advantages of a combined use

Using Dead Reckoning and GNSS together offers clear advantages:

1. Greater precision: Combining GNSS and Dead Reckoning increases precision when determining a location, especially in difficult scenarios.
2. Resilience: In situations where the GNSS signal is unstable, Dead Reckoning ensures the vehicle can keep operating using relevant information.
3. Efficiency: Being able to calculate the position in real time allows drivers and navigation systems to optimize routes and reduce travel time.

Safety: In critical situations, like emergencies or unexpected diversions, using  Dead Reckoning can be vital to ensure drivers and passengers are safe.

Dead Reckoning applications in road transport

Even though GPS has made road transport much easier, Dead Reckoning is still a valuable technique in certain scenarios:

1. Adverse conditions: In places with bad GPS signal, like rural or mountainous areas, Dead Reckoning allows drivers to stay on track.
2. Route planning: During route planning, drivers can use Dead Reckoning to estimate their arrival based on traffic and other factors, adjusting their itinerary if necessary.
3. Navigation inside tunnels: When entering a tunnel where the GPS signal is lost, drivers can use Dead Reckoning to guess their position.
4. Emergency situations: If navigation devices fail, Dead Reckoning can help drivers find their way back.

Challenges and future of Dead Reckoning

Despite its many advantages, there are also some challenges associated with Dead Reckoning.

In the future, artificial intelligence and machine learning are expected to improve the fusion between GNSS and Dead Reckoning data, making navigation more precise and efficient. In addition, the development of new sensors and technologies will ease integration and give drivers and navigation systems more effective tools against any challenges that may come up.

Conclusions on Dead Reckoning

Dead Reckoning is a crucial navigation technique that supplements and improves the efficiency of positioning systems. Its seamless integration in land navigation enables drivers and vehicles to stay on course (even under adverse conditions).

Teldat is continuously working on product evolution in order to use the latest available technologies and support the latest developments. In this spirit, Teldat is trying to incorporate Dead Reckoning technology and combine it with GNSS on its on-board devices.