One of the most critical parts of telemetry data considered by drone pilots is altitude. It should be monitored to ensure that you are complying with regulations to play an essential role in data collection activities. If you flow around a skyscraper, you may want to control its height.
Apart from that, have you ever stopped to think about the accuracy of an altitude sensor for drones? Does it provide the proper accuracy for a few feet for which you would give it a wide allowance? How does this tool work?
Significance of Altitude Sensors for Drones: –
A drone’s altitude reading isn’t the only piece of telemetry data we look for every moment. Basically, it’s about knowing some of the most essential flight parameters in most situations. If you fly in an urban area, you need to set your minimum altitude-level above the MOCA (Minimum Obstacle Clearance Altitude) to bypass skyscrapers.
Keeping a trail of height statistics is also best for legal compliance. In areas of controlled airspace, drone flights are generally limited to altitudes below 400 feet AGL. This ensures that your drone does not interfere with manned-aircraft operations.
High levels of elevation accuracy are crucial in remote sensing applications such as aerial mapping or precision agriculture. However, spatial measurements made by remote sensing are always related to the drone’s position – a parameter that is related to its flight altitude. Not paying attention to a drone’s height accuracy is a sure way to end up with incorrect measurements if you’re mapping an entire field or measuring the height of a building.
The accuracy of various drone altimeters: –
One aspect that intricate this subject is the various mechanisms used by drone altimeters to work. In some situations, drones can have more than one system for measuring altitude that can switch between them under certain circumstances.
Quite a number of drones have sensors facing downward that use this medium. It is also known as VPS (Vision Positioning System). These sensors depend on the flight duration principles to determine the altitude of a drone.
Its altitude-based sensor is very much a proper provider when you use it within the acceptable range, and the drone is not floating over a reflective surface like water. It has been set up into the drones, which will shift out of VPS when they reach a particular altitude threshold, nearly around 20 to 30 feet.
The superiority of this VPS altitude is always measured in reciprocal to the ground or in AGL units. In case you require to count the height of a structure, then utilizing the VPS can be a simple way to get correct readings. So, you do not have to reset the altitude of the drone to get the precise-readings of VPS as its accuracy is somewhat consistent for your floating for long periods without landing.
Barometry is the prevalent altitude-measuring mechanism in drones. It counts altitude as a function of air pressure. The reading of air pressure steadily decreases as the drone gains altitude. A barometer has no rate of effectiveness in terms of altitude though it can measure the altitude of the highest levels that a drone can attain.
Both relative and absolute altitudes can be counted with this device. Which shows that it can register the height in MSL and AGL units simultaneously. Based on the application, either or both of these readings can be essential.
Much like any other instrument, the barometer of a drone should be calibrated periodically. This must be done above sea level, where air pressure theoretically remains around 14.7 psi or 101.325 millibars. The information collected in the calibration can be used by the drone to determine the absolute altitude value.
A drone’s onboard GPS receiver can determine a drone’s location using triangulated data from several GPS satellites. It’s usually employed to determine the horizontal position of a drone. GPS data plays an immense category in drone applications that entails spatial information like mapping and 3D modeling.
Its triangulation is also used to regulate the flight altitude of a drone. Though it is considered to be less accurate and prone to drift than barometry. Both barometry and GPS altitudes are recorded by many drones. Mapping software platforms are usually partial to barometry-based altitude data, its testament shows how unreliable GPS altitude readings are contemplated to be.
The GPS positional data’s righteousness can differ based on GPS signal strength. This relies on the GPS network constellation and can be affected by interference, whether it’s from other sources of electromagnetic signals or any large nearby structures that can block GPS signals. GPS altitude readings have been reported to drift by up to 50 feet within five minutes of drone flight.
So, by looking at this automation used to measure the height, we also understand that each one has its limitations. Noting these limitations is a legend to understanding what we can and cannot do with our drones.
Methods to improve altitude accuracy: –
You would hardly require to worry about altitude inaccuracies in case you’re just flying a drone for fun or to take pictures. The altitude reading of a drone relay drifts enough to be considered severe or dangerous.
If accurate altitude readings are required extra protocols that should be done, like
- Periodic IMU calibration.
- Establishing GCPs.
- Using a ground station.
The Bottom Line: –
So, altitude sensors are one of the essential equipment of drones that can be managed more efficiently with UgCs enterprise. They are reliable – however, not totally exact. Many factors can influence the accuracy of a drone’s height measurement, some of which are not easy to control.
The good news is that drones’ altitude readings usually fall within an acceptable range of values. As long as you calibrate the IMU with reasonable frequency, your drone’s altitude readings will be within 10 feet of the actual values.
The map application is an exception to this level of tolerance. Although centimeter-level positional accuracy can be achieved with some established data correction protocols.