How Drone GPS Navigation Works?

Estimated reading time: 15 minutes

You may have come across GPS in your phone or car when finding your way in unfamiliar areas. And you have an idea of how useful it can be in knowing where you are geographically and how you can get to your destination.

Drones also have this GPS navigation system, and it does more than help the drone get to its destination.

GPS drones have a GPS receiver that communicates with at least four satellites. This communication is through radio signals that travel at the speed of light. This system helps estimate the drone’s location within meters or even centimeters of its actual location. Once the drone positions itself on the global map, it becomes easier and safer to fly.

Please keep reading to find out more about GPS navigation and how it expands drones’ application.

What Are GPS Drones?

GPS drones are drones fitted with GPS (Global Positioning/Navigation System) technology. Several drones now have a GPS that allows them to navigate quickly, especially in areas where flying in the line of sight isn’t possible.

But before we discuss how GPS helps drones, let’s first discuss how GPS works and other areas where it’s applicable.

How Does the GPS Navigation System Work?

This navigation system uses at least four satellites to determine the location of an object. The GPS receiver within the drone communicates with the satellites orbiting the earth through radio signals.

Most GPS systems place the location within a few meters of the object, but some can place it within a few centimeters from the object.

The US Military invented the GPS in 1973 to make targeting nuclear missiles from a sub-marine easier.

GPS – Triangulation or Trilateration:

Triangulation uses angles to determine an unknown distance. And even though most people associate GPS with triangulation, GPS satellites don’t measure angles. 

On the contrary, the global navigation system measures distances and time to determine an object’s location. And this process is known as Trilateration.

Trilateration utilizes four satellites to give an accurate location. 

The first satellite places the receiver in a sphere. 

The second satellite creates a second sphere that intersects with the one from the first signal. 

The third satellite selects two of the most accurate points within the circle formed by the first two satellites. 

The fourth satellite just gives a more precise position.

The communication between the GPS receiver and the satellites involves calculating distances and the registering of time. 

Even though the signals travel at the speed of time, the earth’s atmosphere affects the signals. So, the receiver not only receives the signals it also corrects any errors to enhance accuracy.

What is the Role of GPS In Drone Technology?

GPS was only reserved for the Military, but they later rolled it out to civilians since they figured it would be useful. At first, civilians only had access to a weaker GPS signal (Selective Ability adjustment), but that changed in 2000.

When GPS became more accurate, it started being utilized in several sectors, including autonomous cars and drones. 

The most crucial benefit of GPS is navigation. And below are some roles it plays in drones.

• Autonomous flying – Autonomous drones allow you to set a pre-determined flight path that the drone will follow. You can do this by establishing waypoints (more on this later) to guide the drone as it accomplishes tasks like filming, photography, or any other task you’ve programmed them to do.

• Return-to-home – Most high-end drones come with a Return-to-home feature. This feature allows the drone to return to the station it flew from due to low batteries, poor connection, or when you initiate it by pressing the Home button.

• Position hold – GPS also helps drones hover at a specific point. Some drones can do this by using sensors, mostly when indoors, but you need a more robust system, such as the GPS, to hold a position outdoors.

Below are some areas GPS drones have become quite useful;

• Surveying – Drones provide a more comfortable and faster way to collect points useful in calculating distances, volume calculations, and generating 3D models.

• Inspection – Drones are also useful for inspecting and monitoring construction sites, pipelines, plantations, and observing wildlife.

• Photography and filming – You may not need a GPS drone for some photography tasks. Still, they are better since they can automatically return home, and they’ll hover over your point of interest better than those with sensors.

Are Drone GPS Accurate?

GPS drones are common in aerial mapping/photography and surveying. The acquisition of data includes an autonomous drone designed to fly along a pre-determined flight path. 

The drone usually has a camera that takes several photographs, which are then mosaicked/stitched together to form an image. Several factors can influence the accuracy of these drones. These include;

• Atmospheric conditions – clouds, the sun’s position, wind, etc.
• Ground Sampling Distance (GSD).
• Flying altitude
• The camera settings
• Degree of overlap
• GPS signal strength.

GSD is one of the most important factors influencing the accuracy of drone images. And it refers to the distance between the centers of pixels on the image as measured on the ground. GSD is also expressed in centimeters per pixel.

The larger the GSD, the lower the accuracy and resolution. GSD is also influenced by the drone’s altitude, and the camera’s sensor, and focal length.

The accuracy you need is determined by the project you’re undertaking. In drone mapping, there are two types of accuracy;

• Relative (local) accuracy – This is the degree to which a point on the image is accurate relating (to) other points on the image. If the distance from one point to another is 1 meter in the image, it should be the same on the ground.

• Absolute accuracy – This is the accuracy of a point on an aerial map in relation to a global coordinate system. It will have the same coordinates (latitudes, longitudes, and elevation) as the point on the grid.

Images taken with a drone often achieve relative accuracy, and you can use them to calculate distances between two points.

However, it’s challenging to achieve a high degree of absolute accuracy with a drone unless you create GCP (Ground Control Points) on the ground. 

These are points with known longitudes, latitudes, and elevation. And they help photogrammetry software to calculate the longitudes and latitudes for the other points.

You need a high-quality RTK (Real-Time Kinematic) or PPK (Post-processed Kinematic) to set up the GCPs. And since they are expensive, only high-level survey and mapping projects may afford such equipment.

What Are the Issues And Challenges Faced While Using GPS?

Even though GPS drones provide a cheaper way of collecting data remotely, they have their fair share of challenges. Below are some of them.

Type of drone:

You can use three types of drones for mapping – multi-rotor, single rotor, and fixed-wing drones. Multi-rotor and single rotor drones are often easier to fly, but they don’t last long due to limited battery life.

Fixed-wind drones can fly for hours and may be the best when you have to map vast areas. But getting them to take off can be quite challenging. They are also not easy to land.

Wind:

Some drones can’t withstand strong gusts of wind. So, it would be best if you looked for a drone that’s strong enough. And in some cases, you’ll have to pause the mapping session until the weather is more favorable.

Weak GPS Signal:

As mentioned earlier, the Drone’s GPS receiver needs to connect to at least four satellites. 

This is not always the case due to atmospheric conditions, magnetic field interference, or malfunctions in the drones. 

Some drones can’t fly when there’s a poor connection, and those that manage to fly the data may have lots of errors.

Expensive System:

To collect geotagged images, you’ll either need an RTK system or a PPK system. Either of these systems cost thousands of dollars. Sometimes they’re even pricier than the drone itself.

Safety:

Since the FAA eased the regulations on drones, more and more people now own drones. Retailers and delivery companies like Amazon Prime Air, Walmart, and Wing are also using drones to deliver packages to customers.

So in the following years, there will be high traffic of drones in the air, leading to accidents. What’s worse is that some drones have flown too close to airplanes, which could be dangerous since they can cause the plane to crash.

GPS drones also pose a privacy invasion risk since they can spy on people’s homes with the cameras and reveal their location.

How Do You Calibrate a GPS Drone?

You may not have realized this, but you have to calibrate your drone to make it fly better. Some drones have the instructions in the manual or even on the apps, but many people don’t utilize this feature.

Calibration ensures it doesn’t drift, doesn’t drop in altitude often, hovers correctly, and maintains a straight flight path when you need it to. If the drone crashes or gets a firmware update, you have to calibrate it. Below is a simple step-by-step process for all GPS drones.

• Switch on your controller.
• Switch on the drone and place it on a flat surface.
• Arm the drone by pulling the left stick down, pull it up, and then down again.
• Pull the right stick down towards the right side and hold for a few seconds.

And that’s it. Your drone is calibrated. You can fix this using the Trim function in some drones, but the steps I just gave are an excellent alternative if it doesn’t work.

Here is an excellent video-

How Far Can a GPS Drone Fly?

Due to the limited battery power, even the high-end commercial DJI drones can only fly for a maximum of 30 minutes and fly as far as 10 miles at a speed of 50 miles per hour.

However, there are custom-built drones that have been built to fly further and for longer.

For instance, airstier, a German company, built yeair! In 2015. Yeair is a fuel-powered drone that uses engines instead of batteries. 

It can fly up to 100 km/h, travel 34 miles, and last at least 60 minutes in flight. This drone can also carry 5 kg of weight, making it suitable for filming, surveying, or any other tasks that require heavy equipment on board a UAV.

It navigates through GPS, but it still has a Wi-Fi connection that’s useful for up to 100 meters. To make it easier to control, the manufacturer also fitted it with an electric-powered alternate. 

Since the combustion power is more reliable than battery power, this drone can withstand even strong winds.

In 2017 two drones broke the World record by traveling 100 kilometers and spending 175 minutes in flight. One was the FOXTECH GAIA 160 Hybrid and the Bumblebee Hybrid.

Here’s an awesome video of how the manufacturers overcame the various limitations in building these drones.

Can Drone Fly Without GPS?

Yes, some flight modes don’t require GPS. But it will be more challenging to control the drone, and it will need lots of practice. 

Nowadays, almost every drone has GPS. And for flight modes like position-hold, return-to-home, and autonomous flight, you can’t do them without GPS.

To fly a drone without GPS, look for areas with no obstacles. The drone will often drift since it has no idea where it, and you have to control it actively.

Since GPS limits the drone’s altitude to 400 ft, you can fly it without GPS to go higher.

You can also hold the altitude/hover using sensors when the GPS is off. But make sure you switch on the GPS once you’re done practicing.

Flying without GPS is also applicable when indoors. If you accidentally press return to home when indoors, the drone will move to a higher altitude crashing into the ceiling. 

So, it would help if you switched GPS off when indoors or when flying at low altitudes in areas with several obstacles.

Drones don’t need GPS, but it makes it easier to control them and is a safety feature when the drone experiences challenges in flight.

Waypoints: – What they are and what they’re used for?

Generally, waypoints are references to a location in a physical place. In GPS, a waypoint is a pre-determined location where its longitudes, latitudes, and elevation are known.

Drone pilots can use waypoints to create preplanned flights and program the drone to hover or carry out a specific task once they reach each waypoint.

For instance, in surveying, you have to follow a particular flight path to ensure there’s adequate overlap and to ensure you capture the necessary information in each photograph.

Since it’s challenging to control the drone and still take the photographs, you can plan the flight using waypoints and focus on the photography aspect. 

You can also practice drone photography by letting the drone fly on its own, as you learn the best ways to take great photographs.

Waypoints are very useful in construction, film making, real estate, disaster management, and conservation.

Top 5 GPS Drones 2020:

A drone with a sound GPS can be useful in professional and hobbyist activities. And by good, I mean a drone that effectively connects to the satellites to get accurate coordinates. 

Traveling for a long range is a big bonus, especially when you have lots of ground to cover. With that in mind, below are my top picks.

DJI Mavic 2 Pro:

The DJI Mavic 2 Pro pops up in most drone reviews thanks to the high quality 48 MP sensor and 4K video quality. But the reason I include it in this list is the powerful GPS connection that powers the Autonomous flight, ActiveTrack. 

It also uses OcuSync for long-range communication, and it can travel up to 6.2 miles. The powerful battery offers a 30-minute flight time.

DJI Phantom 4:

The Phantom 4 comes with robust GPS navigation with dual Inertia Measurement Units (IMUs) and compass modules. It also has access to both GPS and GLONASS satellites, which are essential in creating accurate waypoints. 

The other features that make it easier to fly include the Auto take-off, Active Tracking, Return-to-home, Hover, and visual tracking.

Altair OUTLAW SE GPS Drone:

This is the first Altair’s drone with an inbuilt GPS, and it matches the functionality of the DJI drones. It gives you an option to switch the GPS mode on or off. When it’s on, the drone hovers and positions itself, making it easier to fly it.

This drone also supports waypoint mapping, Return-to-home, and GPS-enabled stabilization. 

If you find it challenging to control the drone, you can switch to gesture mode, where the drone will hold the altitude, but it will give you more control over its positioning.

DJI Matrice 200 Series:

Now if you have the budget for a drone that can manage a larger payload, the Matrice 200 series of drones are your best bet. 

The DJI Matrice 200 has two mounts, the 210 has three mounts, and the 210 RTK works with an RTK system for accurate data collection.

Besides the RTK, these drones can also achieve a 6K video quality, 38 minutes flight time, and a 50 MPH top speed. 

DJI Matrice can cost up to $10,000 to set up these drones, but their performance makes them worth every penny.

Parrot Anafi Base:

And lastly, we have the Parrot Anafi Base. It’s a reasonably priced drone that comes with GPS-enabled flight modes such as the circle, 360 degrees rotation, and autopilot. It can also follow waypoints. 

The Parrot Anafi is renowned for its 21MP resolution camera and the option to switch between 2K and 4K resolutions. It also takes ten pictures per second, which makes the 25-minutes flight time more fruitful.

Final Thoughts:

GPS navigation is vital in drones. It not only makes it easier to fly, but it has also opened up more areas where drones can now be used.

It’s now commonplace to find drones in construction sites, surveying projects, monitoring, and sectors where spatial data is needed.

But as we’ve established, both GPS drones have their limitations. You shouldn’t use them to replace surveying and other remote data collection equipment. They should only supplement them.

HAPPY FLYING!!

Summary

Article Name

How Drone GPS Navigation Works?

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This article will explain you all about the Drone GPS Navigation system and how it works in detail.

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Nick Cast

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Remoteflyer Private Limited

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