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WPCS 2.1.7
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Unmanned Aerial Vehicles (UAVs) and Altitude

Why is altitude important for UAVs?

Altitude is the height of an object or point in relation to sea level or ground level”.

Many factors impact on accurate altitude measurement, and sensors vary in their performance in different environments and across applications – which is why it’s often necessary to augment drones’ onboard altitude measurement. 

LightWare’s microLiDARs are exceptional because of their efficiency in addressing altitude issues.

Altitude measurement applications:

Navigation altitude
LiDAR sensors can be used as altimeters on multi-copter drones. These measure the exact height above ground level or activate alarms when the ground gets too close.
Obstacle detection
 LiDAR sensors for collision avoidance allow  UAVs or drones to fly at low altitudes, detect obstacles and determine the safest route. The result? Fewer collisions. 
Mapping
UAVs equipped with LiDAR sensors are ideal for mapping areas at a height above ground. They can be used with a camera for photogrammetry applications.

Did you know?

There are two different types of altitude: Above Ground Level (AGL) and Above Sea Level (ASL).

AGL is especially important for aircraft, particularly when flying at low altitude. Unlike ASL, it varies according to terrain.

 

Altitude can be measured with: 

  • LiDAR: 

Drones fitted with LiDAR sensors are able measure the exact height above ground level by calculating the time taken for emitted laser pulses to travel from the LiDAR sensor to the ground and back. This makes for high accuracy, and is ideal for measuring low- and mid-level altitude.

 

  • Ultrasonics: 

These sensors generate sound waves and measuring the time it takes for the wave to reflect from the earth, just like a bat. 

 

  • Barometric:

 Altitude can be determined by comparing the atmospheric pressure at the current height with the pressure at sea level: the higher the altitude, the lower the pressure. Measurements may be affected by weather conditions’ impact on atmospheric pressure.

 

  • Radar: 

Radio waves are emitted from the radar, and the height and distance are measured according to the time it takes for these waves to hit the surface of the object and return to the radar.

 

  • GPS: 

GPS sensors establish altitude by triangulating satellite signals. Drawbacks include a lack of accuracy; an inability to operate indoors, underground or in areas affected by high electro-magnetic interference, such as near cell phone towers. They are, furthermore, influenced by weather systems.

 

How does microLiDAR measure up?

microLiDAR is commonly regarded as one of the most accurate and precise tools for measuring AGL. 

 

microLiDARs generate their own light source and can therefore operate in zero light environments. Their size and weight contribute to accuracy, unlike heavier sensors which may impact flying time and aerodynamics. What’s more, they are easily integrated into autopilot systems, making for plug and play operability.

 

Because they measure at the speed of light and can process data at up to 30kHZ, microLIDARs can facilitate autonomous decision-making in real time. 

 

Most compelling is their unique ability to measure first and last return signals, so that drones can determine the varying heights of different features in a landscape and therefore determine absolute altitude above ground by measuring through trees and not just above treetops.

This makes microLiDAR an obvious choice for delivery drones, especially for last mile distribution; for creating access to medical supplies and delivering equipment in hard to reach areas; and for first responders who need to be able to navigate indoors or underground and identify threats and locate survivors with great accuracy.

 

Click here to learn how LightWare’s microLiDARs can help bring vision to your drone.

More LiDAR Basics

IoT
IoT
The Internet of Things (IoT) refers to a seemingly futuristic system of interrelated, Internet-connected machines and objects that are able to both collect and transfer data and make decisions. This data is transferred over a wireless network, without human intervention via sensors, and other embedded technologies.