Lidar technology enables the precise distance measurement behind numerous modern innovations. This article provides a detailed understanding of Lidar (Light Detection And Ranging), its history and components, and its distinction from RADAR and like technologies. It also explores applications in areas such as surveying, mapping, autonomous navigation, and augmented reality, as well as provides insights into its role in reliable robotics, drones, and smartphones.
What is Lidar Technology
Lidar (Light Detection And Ranging) refers to a process that uses the reflection of a light beam to determine the sensor’s distance from a given object. Millions of distance points are measured and compiled by the Lidar device, piecing together a visual 3D model of the sensor’s surroundings.
The applications of Lidar devices span across numerous industries, increasing the efficiency of gathering data on elevations, land topography, distance, velocity, and mapping, navigating and data gathering processes. From enabling autonomous navigation And since Lidar effectively functions as its own light source, to the system serving as its own
How Do Lidar Sensors Work
Components of a Lidar Device
A Lidar device has 3 essential parts: a laser; a scanner; and a receiver.
The first step to determine proximity via Lidar is to probe the environment for sending out intermittent pulses of light. The source of this light comes from the laser, which emits rapid, high frequency light beams to scan its surroundings.
Each beam contains thousands of pulses, with each pulse bouncing off various objects and returning with more data points. Upon the beam’s return, a receiving sensor collects information on its flight time – from laser, to object, and back to sensor – and transfers that metric to the detector for further analysis.
By comparing each beam’s time of flight against the known value of the speed of light, the Lidar system calculates a relative distance for the object hit by the beam. The rate at which this information transfer happens is mere milliseconds. Enormous amounts of data points are processed simultaneously and continuously throughout the entire duration of Lidar functioning.
Each data point is plotted across a 3 dimensional plane, gathering together in point clouds that precisely represent the environment of the device in real-time. This enables the system to account for dynamic elements with unpredictable behavior, with split-second reaction times to unexpected situations.
Two Types of Lidar
In addition to measuring airpoints intervals of space, Lidar technology is also used to monitor and calculate underwater lengths. The addition of this new capability in the late 1990s split the Lidar category into two:
- Topographic Lidar refers to distance mapping that takes place on land via nearly-infrared laser,
- Bathymetric Lidar refers to distance mapping that takes place under shallow water by using a green laser beam.
Green lasers can work through water (unlike red) because different light colors have distinct properties. Based on its frequency and wavelength, each color is assigned to a specific region on the electromagnetic spectrum – red belongs to the red region, blue to blue, and so on.
The light used for Bathymetric Lidar is in the green spectral region, simply meaning that its color is green. Since water absorbs less green light than other colors, a green laser beam can reach further and deeper distances in water before dissipating.
In addition to better range, green light also experiences less scatter when faced with floating particles, reducing miscalculations related to sediment and vegetation interference. Moreover, the color’s high visibility benefits calibration time and scan resolution, solidifying green as an effective process for mapping coastlines and seafloors up to 40 meters (130ft) deep.
A Brief History of Lidar
Though the term came to modern popularity along with the rise of today’s self-driving vehicles, the process of Lidar has been around for decades. Soon after inventing the laser in 1960, the team of researchers at the Hughes Aircraft Company introduced Lidar in 1962. Their original intent was to use the technology in tracking satellites.
Prior to its invention, Lidar was preceded by a number of technologies which similarly aimed to detect and measure long-range targets. Most notably this included RADAR, which gauged distances via reflection of radio frequency waves, and even earlier predecessor SONAR, which accomplished a similar task by using sound waves.
Lidar saw its first applications in meteorology, prior to “official” invention, with meteorologists using early light-pulse concepts to study atmospheric particles and pollution. After formal introduction, researchers in the 1970s realized the benefit of precise laser measurements in celestial examination, using them to create topographical maps of the moon, Mars, and Mercury.
A wide advancement for the applications of Lidar technology happened alongside the public introduction of the GPS (global positioning system) in the 1990s. While Lidar scanning had been helpful in generating topographical models for decades prior, there had been no way to definitively mark the location of those scans.
What Other Applications Are There for Lidar?
LiDAR, once synonymous with autonomous vehicles and driverless technology, has found many other applications that are revolutionizing various sectors. Its accurate distance measurement and 3D imaging capabilities have proven transformative in a multitude of fields.
In recent years, LiDAR technology has also made its way into our pockets via smartphones. Its integration into mobile devices has enhanced the user experience, particularly in the realm of augmented reality (AR). For instance, LiDAR scanners in phones improve the accuracy of AR applications by capturing precise depth information, providing a more immersive and realistic AR experience.
LiDAR in smartphones also creates possibilities in indoor navigation. With accurate mapping capabilities, it can serve as a guide to users within complex buildings like airports and malls. Also, in photography, LiDAR contributes to improved focus and depth perception, elevating mobile photography to new heights.
As we move forward, these varied applications of LiDAR are set to increase, shaping our world in ways that were once unimaginable.
Lidar vs Radar: The Key Differences
The goal behind both Lidar and RADAR (Radio Detection and Ranging) technologies is similar: to detect and measure long-range objects. However, each of the processes focuses on a different source of energy to calculate this measurement.
Where Lidar focuses on measuring waves of light signals, RADAR focuses on measuring waves of radio signals.
Originating before Lidar, the process behind RADAR remained consistent and even inspired was a point of inspiration for its successor: in RADAR, radio waves are emitted in pulses at a target object. When the signal echoes back from the target to its origin, the signal strength is measured and a corresponding calculation is recorded for the distance in-between.
The differences of the two processes are best contrasted when side-by-side:
Lidar
- Components: the laser, the scanner, and the detector.
- Quality: Higher resolution of detected objects, due to the light’s shorter wavelength.
- Accuracy: Highly precise distance calculations, within a few inches
- Range: Lower range, up to several miles in perfect visibility conditions and less in bad weather.
- Interference: Highly affected by weather conditions and hazy environments with reduced visibility
- Cost: Higher up-front cost. Higher maintenance cost to process large amounts of high-quality data.
Radar
- Components: the transmitter, the antenna, and the receiver
- Quality: Lower resolution of detected objects, Objects are deteProduces a slightly lower resolution due to the long length of radio waves.
- Accuracy: Accurate distance calculations for larger objects, but may be disrupted by noise pollution or miss smaller objects.
- Range: High range spanning up to hundreds of miles
- Interference: Much less affected by environmental conditions and are more reliable in severe weather
- Cost: Lower up-front cost. Lower maintenance cost for smaller resolution data.
For processes requiring incredibly precise calculation, such as those in the fields of robotics, surveying, and mapping, Lidar may be the best option. But for tasks involving detection of larger items, especially in environments prone to inclement weather, RADAR may win out.
As with most options, making a choice between the two technologies will be solely dependent on the individual’s use-case scenario.
Lidar Drones: Next Chapter for surveying
At the end of the 20th century, cross-industry applications of Lidar technology increased dramatically thanks to the novel accessibility of the Global Positioning System. GPS allowed each point in a Lidar model to be aligned with a precise geographic coordinate in the real world.
The combination of GPS and Lidar was transformative, particularly for the industries of surveying and mapping. Geospheric data provided by GPS allowed Lidar scanners to be mounted to aircraft for unprecedented levels of large-scale, high-resolution land surveying. Similar breakthroughs were seen across Forestry, Archaeology and Urban Planning industries.
Over the past few years, technological trends have created a new opportunity for evolution. Enter, Lidar drones.
How Drones Incorporate LiDAR
Light, agile, cost-effective – the popularity of Unmanned Aerial Vehicles (UAVs), or drones, has surged over the last decade, with some drones now offering the ability to leverage onboard Lidar systems for more flexible data gathering.
While GPS certainly enhanced the range of Lidar applications, deployment methods of the technology remained fairly limited, with choices between:
- Hand-Held Lidar Scanners: less expensive, but time-consuming, and with limited range and accessibility in rough terrains)
- Manned aircraft with Lidar attachments (very expensive, with lower resolution and flexibility),
LiDAR drones bridge this gap effectively. They offer a middle ground by providing high-resolution data gathering at a fraction of the cost of manned aircraft. Moreover, the flexibility of drones allows them to be used in various terrains, making them a disruptive force in industries like surveying and mapping.
When equipped with LiDAR, a drone becomes a highly efficient surveying solution. It can quickly scan large areas and generate detailed 3D maps. This advancement is expected to revolutionize several industries. From infrastructure management to forestry, archaeology, and urban planning, the applications of LiDAR drones are vast and varied.
As the accessibility of drone ownership continues to increase, so does the potential for further integration of LiDAR technology. This trend is set to continue, opening up new possibilities for data gathering and analysis across different sectors.
The integration of LiDAR technology and versatility of drones marks a significant step forward in surveying and related industries. As we continue to innovate and explore new applications for this combination, it’s clear that LiDAR drones will play an increasingly important role in shaping the future of these fields.
LiDAR Safety at Quasi Robotics
When creating a robot to operate around dynamic objects and unpredictable humans, safety is the top concern. Throughout our design process for Models R2 and Model C2, the Quasi team wanted the safety of our users and their facility to be at the forefront of each feature choice.
This meant expecting the unexpected from humans, their workplaces, and their other objects. In a busy environment like a research lab or clinical trial, operations shift constantly and structure in real-time would be unreliable at best. So, it would become our robots’ job to be reliable on its behalf.
How can we account for a distracted person stepping into the direct path of a busy Model R2? How do we know that an accidentally placed box or obstacle won’t cause C2 to miscalculate its turn? And most importantly: How do we protect the human and ensure safe completion of the robot’s task, when situations like these do arise?
For this, we incorporated Lidar as one of our standard pieces of distance technology across all models.
In order to accurately “see” surrounding objects, each Quasi autonomous solution comes equipped with a Lidar scanning system. This system enables continuous 360 degree rotational scans of the robot’s environment, with each rotation gathering 20,000 various object distances.
Continual scans throughout operation allow hundreds of thousands of data points to be compiled in real-time. These points come together to form a map of the facility. The reliability of Lidar ensures that this map is updated and that the system can detect any changes. even in low or varying light conditions.
Accurate sensing of elements in the environment is central for dependable autonomy. As each rotational scan displays an update to the elements’ distances, the robot is able to identify movement via moving points. In this way, it understands the difference between static and dynamic objects in its path and can react accordingly.
In the event of unexpected motion, like our distracted colleague, that information is interpreted and relayed to various motion-related processes. Collision avoidance procedure initiates at the precision of milliseconds, and the robot will halt to make way while it begins to recalculate a better route to its destination.
Conclusion
LiDAR technology has become an important tool in many fields, including mapping, surveying, self-driving cars, environmental monitoring, and archaeology. This technology allows us to create detailed 3D models of objects and landscapes, which has brought big changes to many industries.
These changes include better decision-making, more efficiency, and improved safety. As LiDAR technology keeps getting better and easier to use, we expect it to be used more widely and bring even more changes to how we understand and interact with the world.