Everything You Need to Know About Alternative Navigation

When it comes to precise navigation it’s hard to beat a system that combines inertial navigation system (INS) and global navigation satellite system (GNSS) capabilities. That’s why combined INS-GNSS technologies pioneered by Honeywell in the 1990s are used by commercial and military operators the world over.

In a traditional INS-GNSS configuration, the GNSS signals are used to correct errors that cause inertial systems to “drift” over time. But what happens when the INS is disabled or GNSS signals aren’t available?

We recently talked to Mohan Jacob, Honeywell Offering Manager, Alternative Navigation, to find out.  

What is “alternative navigation?”

Alternative navigation enables aircraft, autonomous drones and ground vehicles to navigate when the traditional navigation systems (INS or GNSS) are degraded or unavailable. The term “alternative navigation” describes alternate means of navigating using systems or sensors made up of cameras, LiDAR, radar, radios and star trackers to aid traditional navigation systems.

Advancements in sensor technologies and the emergence of machine learning (ML), artificial intelligence (AI) and the internet of things (IoT) make it possible to reduce dependence on GNSS and INS.

Alternative Navigation is a subset of Alternative Positioning, Navigation & Timing (APNT) initiatives driven by FAA and other government agencies.

Why is alternative navigation important?

These technologies can fill the void left when GNSS signals are jammed, blocked or simply unavailable. Disruptions to GNSS signals are becoming more common, especially in military applications, which can cause enormous operational and flight safety problems.

How does it work?

Alternative navigation augments or aids the vehicle’s INS navigation system. It uses sensors such as cameras, LiDAR, radar, radios and star trackers to determine position and velocity of the vehicle and uses this information to correct the drift errors of the INS, which is essentially the same role GNSS plays when it is available. Alternative navigation can be used when GNSS is degraded or not available and the vehicle needs an alternate method of determining its position.

Broadly all of these solutions consist of a sensor (electro-optical/infra-red camera, radar or star tracker) connected to a processing module that calculates the platform’s position, velocity or both. The processing module is connected to an INS.

What are the strengths and weaknesses of each alternative navigation method?

There is no “silver bullet” that can replace GPS completely. Each alternative navigation technology has its own attributes, as shown in the accompanying chart. It all depends on the customer’s mission profile. Customers can select one or more of the technologies. 

What is Honeywell’s involvement in alternative navigation?

Honeywell is a leader with decades of experience developing and manufacturing INS products for commercial and military aircraft. With advancements in sensor technologies and the emergence of ML, AI and IoT, we have established ourselves as a technology leader in alternative navigation.

Our first Resilient Navigation System is deployed with several customers in India, Israel, the U.S. and Turkey. It has been in operation for more than a year in Israel. This is a hardware solution with embedded software algorithms developed over the last several decades by Honeywell.

The Resilient Navigation System uses a doppler radar and is available now for Group 2 and Group 3 unmanned aerial system (UAS) platforms. Honeywell also offers a vision navigation system using an infrared camera for operations both day and night, and we are developing other offerings for large UAS platforms, surface vehicles and military aircraft.

What’s next for Honeywell?

Our current focus is on UAS platforms and military aircraft, because of their particular need for precise navigation in a GNSS-denied environment. We expect commercial aircraft will require alternative navigation technology in the future. Within the next 10 years alternative navigation will become as common as INS or GNSS.