Light Detection and Ranging (LiDAR) measures distances. It uses light in the form of a pulsed laser to remotely generate measurement. In short it produces beams of laser light and measures how long it takes to return to the sensor in order to measure the distance. This measurement when combined with other data, we can generate precise, three-dimensional visual about the object. LiDAR sensors are paving the path to several future developments. So, in order to keep up with this fast-advancing development we must understand what it is and what it is capable of doing.
What exactly is LiDAR?
Similar to Radar and Sonar, which use radio and sound waves respectively – LiDAR is a remote sensing system which uses laser beams to accurately map out its surrounding. Emitted laser beams carry information about the distance and optical characteristics of the object. The time it takes to reflect off of the object and return to the sensor is the deciding factor used for analysis.
Radar, which has found great application in air traffic control does not have the same precision as LiDAR. Radar can only detect location of a vehicle from miles away as a featureless point. On the contrary LiDAR can map an environment as densely populated points that signify even the features of the objects.
What does a LiDAR instrument consist of?
LIDAR instruments mainly consist of a laser(transmitter), sensor(detector), and a GPS receiver. The exponential sizing down of electronics coupled with development of deep learning over the past years has solidified the many applications that LiDAR can aid. From topographic analysis and hazard assessment to automated driving, the possibilities are limitless.
- A laser device sends out pulses and records the time delay between a light pulse transmission and reception.
- Sensor and Inertial measurement unit (IMU) detects when light pulse returns and measures linear and angular motion.
- GPS (global positioning system), detects the geographical location of the LIDAR sensor.
The LiDAR sensors used today have 360-degree vision and can map accurate depth information. The sensor continually fires millions of beams of light per second. These measurements from this sensor can produce a 3D map of any object around you
Applications of LiDAR Technology Today
LiDAR can be seen in a plethora of applications across various industries. But lets first discuss one such application that pledges to change the world – Self driving cars.
Vehicle Automation
LIDAR can ‘visualise’ the road and map the objects in real time. This data analysis then makes well- informed driving decisions. For example, it can detect the lanes marked by lines on the road and learn to stay in them (already seems smarter than most drivers!) in addition to learning to use indicators and read road signs. Some commercial vehicles already have Adaptive Cruise Control (ACC) which uses this technology. It prompts the vehicle to slow down when there is a vehicle in the front and speed up when there is no traffic.
Automation in vehicles has seen more advancement due to LiDAR, as compared to any other industry. Sensing obstacles and other vehicles to avoid accidents on the road is an important application. This technology can moreover detect the speed and direction in which other vehicles are moving using continuous detection of distance from the object. The only foreseeable replacement or addition to improve self-driving cars are cameras. Integrating actual vision into a car is a hot topic nowadays and may soon sweep the market off its feet.
Until then, LiDAR shows all the signs of market domination in automated vehicles and even robots. Other useful applications of LiDAR include,
Oil and Gas Exploration
Due to the short wavelength of LiDAR beams, it detects various molecules in the air. This information about their relative size and density is then analysed to understand the content in the atmosphere. Differential Absorption LIDAR known as DIAL can find Oil and Gas deposits. This is done by tracing amount of gases above the hydrocarbon region.
Archaeology
Since LIDAR can detect micro topography it has become popular amongst archaeologists in order to map geographical surfaces. Elevation of surfaces creates digital elevation models (DEMs). This information can help find quarry and mineral sites which are crucial to finding out about human civilization in that area.
Astronomy
This can be chalked back to 1976 when it was used create a topographic map of Mars on NASA’s Mars Global Surveyor.
NASA’s Phoenix Lander, in 2008 also used LIDAR technology to the detect snow falling in the Mars atmosphere.
Atmospheric Physics
LiDAR sensors measure concentration of gases like oxygen, nitrogen, potassium, sodium and others. This is mapped and analysed to track changes in the atmosphere and even pollution levels. The analysis results in density maps of the middle and upper atmosphere.
The Future of LIDAR
LiDAR has two main challenges: cost decrease and resolution & range increase. Finding a solution to these problems will increase the market usage of this technology and open up new applications that are restricted by these challenges now.
Cost:
The two types of LiDAR sensors: fixed and surround view. The fixed sensors are made to be embedded into the application. Both contain lasers, GPS, lens and detectors. Surround view sensors reuses the lens, lasers and detectors across the field of view. This is both the most economical and reduces the error associated with merging points in real-time. However the average cost of fixed sensors, which are smaller and thus can be used in many more systems needs also to be reduced in order to expand into various other industries as well.
Resolution and Range:
The expansion in applications of LIDAR demands higher resolution and range (200m in some cases) in order to provide better object recognition. This makes a huge difference in the market especially as some sensors have a much higher range than others. The discrepancy in both price and range is currently a trade-off that needs to be improved.
Several startups have started investing time and money in quality LiDAR sensors. There are many available sensors, amongst which LiDAR is one. Reading more about these sensors and how they continue to evolve may inspire you to come up with application ideas of your own.
