UAV LiDAR & Autonomous Vehicle LiDAR Technology: LiDAR Sensors

LiDAR Sensors for UAVs, Drones and Autonomous Vehicles

What is LiDAR and how does it work?

Lidar, or LiDAR (a portmanteau of light and radar, also interpreted as an acronym for “Light Detection And Ranging”), is a distance-measuring and imaging technology that uses pulses of light in the form of a laser beam from the ultraviolet, visible and infrared portions of the electromagnetic spectrum.

These pulses of light are reflected, typically via backscattering, by the object under measurement. The LiDAR sensor measures the time taken for the pulse reflection to return and can thus calculate the distance from the object.

LiDAR sensors are often mounted to UAVs and other unmanned vehicles for mapping and surveying applications. Unmanned LiDAR systems offer significant time and cost savings over traditional manned mapping and surveying methods.

Methods of LiDAR Detection

There are two general methods of detection – incoherent or direct energy detection, which is used for amplitude measurements, and coherent detection, for phase-sensitive measurements. LiDAR can be used to scan a wide variety of materials and the wavelength of the emitted laser is varied to suit the target.

How LiDAR is used by airborne unmanned vehicles and drones

When combined with a GPS receiver, inertial measurement unit and onboard computer, a LiDAR sensor can be installed on a drone or UAV and used to scan a large area, with tens of thousands of points per second being measured.

The reflection time interval data is post-processed, converted to distance and correlated with data from the GPS receiver and IMU, which provide highly accurate information on the unmanned aircraft’s position and attitude respectively. The resulting 3D point cloud can be used to build up a detailed image of the surveyed area and provide vital insights to decision-makers.

UAV LiDAR Survey and Mapping Applications

LiDAR technology has many applications and is especially ideal when high-accuracy measurements are required, or when the area under survey or inspection is dangerous or physically difficult to reach. Drone LiDAR mapping provides many additional benefits, including reduced mission time and manpower requirements, and the ability to obtain quicker results by gathering all required data in a single pass.

Modern LiDAR scanners are capable of achieving a wide field of view (FOV) and offer 360 degree visibility and very high data rates. LiDAR mapping has been used in surveying, cartography, agriculture, forestry, meteorology, mining, environmental management, inspection of utility lines and transport networks, and many other fields.

LiDAR for obstacle detection and collision avoidance

In addition to mapping, UAVs and other unmanned systems may also utilise LiDAR for obstacle detection and collision avoidance, and for safe automatic landing. LiDAR is one of the leading technologies currently being utilised in the development of autonomous driving vehicles and self-driving cars.

UAV LiDAR Sensors: Frequently Asked Questions

LiDAR is a distance-measuring and imaging technology that uses pulses of light from a laser beam utilising the ultraviolet, visible or infrared portions of the electromagnetic spectrum.

Pulses of light from an ultraviolet, visible or infrared laser beam are reflected, typically via backscattering, by an object under measurement. The LiDAR sensor measures the time taken between emission of the pulse and the detection of the pulse reflection, and can thus calculate the distance from the object.

The term LiDAR originated as a portmanteau of light and radar. It has also come to be interpreted as an acronym for “Light Detection And Ranging” or “Laser Imaging, Detection And Ranging”, following the reasoning that radar was originally an acronym for “Radio Detection And Ranging”.

LiDAR mapping and surveying is used to gather accurate, precise data on both manmade and natural environments. Applications include cartography, agriculture, forestry, meteorology, mining, environmental management, inspection of utility lines and transport networks, and many other fields.

LiDAR is also used in UAVs and other unmanned systems for obstacle detection, collision avoidance and safe automatic landing. It is currently one of the leading technologies being utilised in the development of autonomous driving vehicles and self-driving cars.

LiDAR mapping uses measurements of reflected laser pulses to produce highly accurate maps and elevation models of terrain and buildings. LiDAR mapping payloads may be fitted to UAVs, USVs and ground robots.

LiDAR using green wavelength lasers provides maximum penetration of water – many other wavelengths will be rapidly absorbed within a few centimetres of water depth. Bathymetric LiDAR sensors can be used to measure river beds, the seafloor and other underwater features.

Doppler LiDAR uses the frequency shift of moving objects (caused by the Doppler effect) to directly measure velocity. The reflected backscatter signal is recorded and mixed with a reference laser beam of known frequency. The frequency shift of the mixed signal is used to calculate the velocity.

Due to the relatively short wavelengths, LiDAR pulses are unable to penetrate through most thicknesses of cloud cover.

An airborne LiDAR system consists of one or more LiDAR sensors mounted on a fixed-wing or rotary manned or unmanned aircraft.

LiDAR surveys are carried out with manned or unmanned aircraft and gather data that can be used to create digital terrain or elevation models. Depths of water features can also be measured.

The accuracy of LiDAR mapping depends on the equipment used, the distance to the target, post-processing of the data and many other factors. It is possible to achieve sub-centimetre accuracy.

Both LiDAR and radar make measurements using reflected pulses. LiDAR uses laser signals, whereas radar uses radio waves.