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Lidar principle of operation
LiDAR is an acronym for Light Detection and Ranging - light and distance detection. In LiDAR, laser light is sent from a source (transmitter) and reflected from objects on stage. Reflected light is detected by the receiver of the system, and flyover time (TOF) is used to plot a map of distances to objects in the scene.
LiDAR is an optical technology often cited as a key method for determining distance for autonomous vehicles in mid-2022. Many manufacturers are working on low-cost compact LiDAR systems. Almost all manufacturers involved in autonomous driving in 2022 consider LiDAR a key technology, and some LiDAR systems are already available for advanced driver assistance systems (ADAS).
The basic concept of lidar was proposed by E. H. Singh (Edward Hutchinson Synge) in 1930, who proposed using powerful floodlights to study the atmosphere. Since then, lidar has been widely used for atmospheric and meteorology research.
Lidar is a method of determining range (variable distance) by targeting an object or surface with a laser and measuring the time at which reflected light returns to the receiver. It can also be used to create digital three-dimensional images of regions on the surface of the Earth and the ocean floor in the tidal and coastal zones by varying the wavelength of light. It has ground, onboard and mobile performances.
The LiDAR system can use a scanning mirror, multiple laser beams, or other means to "scan" an object's space. Due to its ability to provide accurate distance measurement, LiDAR can be used for many different tasks.
In remote sensing, LiDAR systems are used to measure the scattering, absorption or re-emission of particles or molecules in the atmosphere. For these purposes, specific laser wavelength requirements may be imposed on systems. It is possible to measure the concentration of certain molecular particles in the atmosphere, for example methane and aerosol load. Raindrops in the atmosphere can be measured to estimate the distance to the storm and the rate of rainfall.
Other LiDAR systems provide profiles of 3D surfaces in object space. In these systems, sounding laser beams are not bound to specific spectral characteristics. Instead, the wavelength of the laser beams may be selected to provide eye safety or avoid atmospheric spectral features. The probe beam collides with a "hard target" and is reflected back into the LiDAR receiver.
LiDAR can also be used to determine target speed. This can be done either by the Doppler method or by measuring the distance to the target in quick succession. For example, atmospheric wind speed and vehicle speed can be measured by the LiDAR system.
In addition, LiDAR systems can be used to create a three-dimensional model of a dynamic scene, for example, one that an autonomous car may encounter. This can be done in a variety of ways, usually using a scanning method.
Lidar arrangement
According to the PPC PHOTONICS[1], several versions of 3D lidar are presented on the Russian market in 2022, including:
- Mechanical with a horizontal viewing angle of 360 degrees;
- Solid with a horizontal viewing angle of up to 120 degrees.
Mechanical Lidars
Photo source: npk-photonica.ru
Surface radiation lasers with a vertical resonator (VCSEL) are used as a laser emitter, the number of which directly affects the quality of the formed cloud of points. The photodetector is typically manufactured on the basis of silicon photomultipliers (SiPM).
Photo source: npk-photonica.ru
At the initial stage, the light from the laser enters the lens, then the diffraction optical element and then reaches the objects surrounding the lidar. At the next stage, the reflected light enters the lens of the photodetector, passes through the optical filter and is fixed with a photosensitive matrix.
Photo Source: npk-photonica.ru
The sensor electronic component base is mounted on a rotating mechanical platform, which allows collecting information about the surrounding space with a horizontal viewing angle of 360 ° and high accuracy.
Another embodiment of a mechanical 3D lidar is the use of a resonant mirror that acts as a rotating element between the emitter and the receiver.
Photo Source: npk-photonica.ru
Solid-state lidars
One feature of such products is the ability to set the desired viewing angle by moving MEMS mirrors. In addition to this, the small weight and size of solid-state lidars is another undeniable advantage when used as a payload on unmanned aerial vehicles (UAVs).
Photo Source: npk-photonica.ru
The solid-state lidar includes a signal processing module, a laser module, MEMS mirrors and lenses. The photodetector device can be an avalanche photodiode, silicon photomultipliers and a VSCEL signal source at a wavelength of 905 nm.
Signal processing
- The laser generates an optical signal, which, reflected from surrounding objects, enters the sensitive area of the receiver.
- The optical signal is converted to digital using an ADC converter.
- Due to the computing power of the AI, FPGA or other circuits, the digital signal is transmitted to the display in real time or stored on the drive for subsequent processing.
Photo Source: npk-photonica.ru
Lidar application
Lidars in Meteorology
The applications of LiDAR are deep and diverse. In atmospheric sciences, LiDAR is used to detect many types of atmospheric components. It has been used to characterize aerosols in the atmosphere, investigate winds in the upper atmosphere, profile clouds, collect weather data, and many other applications. LiDAR data supports activities such as flood and storm surge modeling, hydrodynamic modeling, shoreline mapping, emergency response, hydrographic studies, and coastal vulnerability analysis.
Lidars in cars
One application for LiDAR is situational awareness for destinations such as autonomous navigation. The situational awareness system for any moving vehicle should be aware of both stationary and moving objects around it. For example, radar is already used to detect aircraft. LiDAR has proved to be very useful for land-based vehicles, as it can determine the distance to objects and very accurately determines the direction.
Probing beams can be guided at precise angles and quickly scanned to create a point cloud for the 3D model. The ability to scan quickly is key to this application, since the situation around the car is very dynamic.
Lidars in Geography
Lidar systems are a way to remotely determine changes on the surface of the Earth and on it. Beams of light are emitted by a laser, which is reflected from objects in a geographical area. The return rate of the light beam is used to calculate the distance between the laser scanner and the ground.
Laser range data is combined with location and orientation data provided by integrated GPS systems and inertial measuring devices, scanning angles and calibration data. The result is a three-dimensional set of geographic coordinates (latitude, longitude, and height) known as a point cloud.
A laser, special GPS receiver and scanner are the main components of LiDAR devices, which are often mounted on an aircraft or helicopter for use in a large area. Lidar can also be collected using ground-based lidar systems.
The LiDAR system sends a pulse of light to the surface of the Earth, and the inverse pulses transmit information about the location of the object and the distance from the LiDAR system. Depending on the order in which these pulses are returned, different return pulses may transmit geographic location information.
Lidar data is classified by the order in which light is reflected back into the system. The first return is measured as the highest point of the landscape. It can be a hilltop, mountain, building or forest canopy. The latter return is recorded as the lowest point of the landscape and is known as "bare land."
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Street and building layouts are easily identifiable. The height of the buildings is shown by the color scale. The tallest buildings are painted red and the lowest elevations, such as street level, are painted blue. Lidars can also be used in fighting forest fires and assessing their consequences.
Agriculture
Agricultural robots are used for a wide variety of purposes, ranging from seed and fertilizer dispersal, detection techniques, and to monitor crops to control weeds.
Lidar can help determine where to apply expensive fertilizers. It can create a topographic map of fields and show slopes and solar lighting of farmland. Lidar-derived topographic data with agricultural yield results from previous years can be used to divide land into zones of high, medium or low yield. To understand where to use fertilizers, to maximize the harvest.
Lidar is used to monitor insects in the field. The use of lidar makes it possible to detect the movement and behavior of individual flying insects with identification up to gender and species. In 2017 patent , an application for this technology was published in,, and USA. To Europe China
Another application is mapping crops in orchards and vineyards to detect foliage growth and the need for pruning or other care, to detect changes in fruit yields, or to count plants.
Lidar is useful in situations where GPS use is not possible, such as in walnut and orchards, where foliage blocks satellite signals for precise farm equipment or a driverless tractor. Lidar sensors can detect the edges of rows, so agricultural equipment can continue to move until the GPS signal is restored.
Weed control requires the identification of plant species. This can be done with 3D lidar and machine learning. Lidar creates plant contours as a "point cloud" with range and reflectance values. This data is converted and characteristics are extracted from it. If the type is known, the characteristics are added as new data. The view is labeled and its characteristics are initially stored as an example to identify the species in the real environment. This method is effective because it uses low-resolution lidar and supervised learning. It includes an easy-to-calculate set of functions with general statistical characteristics that are independent of enterprise size.
Lidars in archaeology
Lidar has many uses in archaeology, including planning field campaigns, mapping objects under a forest canopy, and surveying wide continuous objects indistinguishable from the ground. Lidar can create high-resolution datasets quickly and cheaply. Lidar products can be easily integrated into a geographic information system (GIS) for analysis and interpretation.
Lidar can also assist in the creation of high-resolution digital relief models (DCMs) of archaeological sites that can reveal microtopography hidden by vegetation. The intensity of the returned lidar signal can be used to detect features hidden under flat plant surfaces, such as fields, especially when mapping using the infrared spectrum. The presence of these features affects plant growth and therefore the amount of infrared light reflected. For example, at Fort Bosejour - Fort Cumberland National Historic Site, Canada, Lidar discovered archaeological sites associated with the siege of the fort in 1755. Features that could not be distinguished on the ground or in aerial photography were identified by superimposing hues of hills on a DTM created with artificial lighting at various angles.
In 2012, lidar was used to search for the legendary city of La Ciudad Blanca or "Monkey God City" in the La Mosquitia area of the Honduran jungle. During the seven-day mapping period, evidence of artificial structures was found. In June 2013, the re-opening of Mahendraparvata City was announced. In southern New England, lidar was used to identify stone walls, building foundations, abandoned roads, and other landscape features hidden from aerial photography due to the forest's dense canopy.
In 2012, lidar showed that the Purepecha Angamuco settlement in Michoacán, Mexico, had about as many buildings as in 20th century Manhattan.
Lidars in Space
By 2022, lidar is increasingly being used to determine the range and calculate the relative velocity of an orbital element in approach operations and keep spacecraft in place. Lidar was also used for atmospheric research from space. Short pulses of laser radiation emitted by the spacecraft can be reflected from the smallest particles in the atmosphere and returned back to the telescope combined with the spacecraft laser. By accurately calculating the lidar "echo" and measuring the amount of laser light received by the telescope, scientists can pinpoint the location, distribution and nature of the particles. The result was a tool to study atmospheric components, from cloud droplets to industrial pollutants that are difficult to detect by other means.
Laser altimetry is used to create digital planet altitude maps, including mapping Mars using the Martian Orbital Laser Altimeter (MOLA), Lunar Orbital Laser Altimeter (LOLA), and Lunar Altimeter (LALT) to map the Moon, and mapping Mercury using the Mercury Laser Altimeter (MLA). It is also used to assist the Ingenuity helicopter in its flights over Mars territory.
Russian market
2022: Russian scientists from MTUSI and IOF RAS tested mobile lidar
On March 14, 2022 Moscow Technical University of Communications and Informatics (MTUSI) , it announced the completion at its quantum center of the first stage of testing a mobile lidar developed by scientists. Institute of General Physics named after A.M. Prokhorov of the Russian Academy of Sciences (IOF RAS) The study was carried out at the scientific MTUSI "Hardware and software complex for assessing the main technical characteristics of wireless underwater equipment," laser communications created by specialists. higher education institution More. here
2021
Market Leaders Overview
According to a study by the Photonik NPK, the main segments of lidar use in Russia in 2021 are - Autopilot transport, UAV, Production automation and security.
Throughout 2021, there is a decrease in the share of autopilot vehicles, which is caused by the useful life of lidars over 1 year. At the same time, the "Payload for UAV" sector grew from 51% to 77%.
The leading companies in 2021 were:
- American company Velodyne, headquartered in San Jose, California. The products of this manufacturer have found wide use in the automotive industry and are actively used to create autopilot vehicles. Velodyne lidars are also used as a payload for unmanned aerial platforms, with which information can be obtained about the objects under study at a distance of up to 200 meters in a short time.
- The American company Ouster, whose head office is located in San Francisco. The advantages of Ouster products include a high degree of protection, small size and light weight of the case. Lidars of this manufacturer are also successfully used in autopilot cargo vehicles and as a payload for UAVs. The capabilities of Ouster lidars allow you to build digital relief models, as well as inspect buildings and structures at a distance of up to 120 meters.
- The Chinese company Robosense, whose head office is located in Shenzhen. Robosense specializes in the manufacture of mechanical and solid-state lidars for autopilot vehicles. The organization has experience in building end-to-end solutions using NVidia AI modules and in-house software to identify various obstacles in its path.
- Chinese manufacturer Hesai Technology specializes in creating high-precision solid-state and mechanical lidars. The company was founded in 2014 and has extensive experience in creating optical sensors for robotic platforms, autopilot vehicles and UAV payloads when solving the problems of creating digital terrain models at a distance of up to 300 meters.
- German solid-state lidar developer Blickfeld. The company was founded in 2017 in Munich. The advantages of Blickfeld lidars include small weight and size and software-controlled technical characteristics.
- Canadian manufacturer of lidar modules and solid-state lidar LeddarTech with its head office in Quebec. Lidar modules of this developer are widely used in collision prevention systems on quarry equipment, and solid-state lidars are widely used in traffic control systems and in perimeter security systems.
- Solid-state lidar manufacturer for drones DJI China from Livox. The manufacturer's products are used to create collision prevention systems and as part of solutions for autopilot mobile platforms.
Yandex launched the production of lidars for unmanned vehicles
On November 23, 2021, it became known about the production by Yandex of its own lidars intended for unmanned vehicles. The company has equipped all its fourth-generation self-driving vehicles based on Hyundai Sonata with such sensors, and in the future it is planned to use only these solutions instead of third-party ones. Read more here.
2020
2019: Yandex began using lidars and cameras of its own production in unmanned cars
In mid-December 2019, it became known that Yandex"" began to be used in unmanned cars lidars vehicles and cameras of its own production. The company claims that its solutions are half cheaper than foreign counterparts. More. here
Global market
2021: Market growth of lidar for cars by 28% to $560 million
According to a 2021 study from Precedence Research[2], the growth of the global automotive market LiDAR is increasing with a CAGR of 28.5%. According to the company, the market volume in 2021 amounted to $560 million.
According to Allied Market Research, the main problem on the path of introducing lidars in 2021 was their cost. So, according to the researchers, the total cost of lidar, including the sensors themselves, the hardware for processing, and the necessary software, can range from $20 thousand to $75 thousand.
2019
Intel entered the lidar market
December 11, 2019 Intel presented the first in its assortment. lidar Such a high-resolution mini-camera turned out to be the smallest in the industry, the company said. More. here
Google began selling lidars of its self-driving cars
On March 6, 2019, Google announced the start of sales of lidars, which the company uses in its self-driving cars. The sensor developed by Waymo's automotive division is called Honeycomb and is used to determine distances, classify objects and recognize people, as well as create three-dimensional maps of the area. Read more here.
2018: Tests of virtual wall with lidars at U.S.-Mexico border
In September 2018, California-based Quanergy finished testing its lidar border protection system, which it conducted with the permission of the Val Verde County Sheriff's Office at one of the local ranches near the Mexico border. The company contracted with US Customs and built a virtual wall on the border with Mexico that would deter illegal immigrants. Read more here.
Notes
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