10 min read
We’re talking more LiDAR today – but with a twist… We are including radar, ultrasonic and camera technologies to the mix!
Modern remote sensing was born with the invention of the camera more than 150 years ago. The term “remote sensing” was first used during the 1950s by Naval Research in the USA to describe the art and science of identifying, detecting, and measuring an object without actually making any physical contact with the object.
LiDAR versus. alternate technologies
The growth of unmanned ground vehicles (UGVs), unmanned aerial vehicle (UAVs), industrial and Internet of Things (IoT) solutions can be considered to be the driving force behind the adoption of several types of sensors. Radars, cameras and ultrasonic sensors have been in the industry for a long time... and now Light Detection and Ranging (LiDAR) technology has joined the list and is actively being used in all sorts of devices and technologies today!
What makes LiDAR so significant?
One big plus when it comes to LiDAR is that it uses light. LiDAR solutions emit light pulses which are safe for the human eye and can achieve accurate and precise results during the day or at night. Unlike some other remote sensing technologies, LiDARs can function well without the loss of performance even through conditions such as:
LiDARs work on the Time of Flight (ToF) principle – light pulses are emitted from the LiDAR. The distance is then measured by timing exactly how long it takes for that pulse of light to travel to a surface and back again to the sensor.
But what makes LiDAR different from alternate technologies in the market?
Radar, ultrasonic, camera or LiDAR
The ultimate sensor battle starts with explaining what these technologies are and how they work. In a nutshell:
- Radar: stands for Radio Detection and Ranging and measures the range, angle or velocity of an object by using radio or microwaves at various distances.
- Ultrasonic: this remote sensing technology determines distance by using sound waves at a higher frequency beyond the range of human hearing.
- Cameras: use object algorithms to detect what is visible to the camera in its field of view
- LiDAR: is a type of remote sensing technology that measures distance by using pulsed light waves.
Working principles of radar, ultrasonic, LiDAR and cameras
It all comes down to radio waves when we’re talking radar! A radar system can be ground mounted or fitted onto aeroplanes or ships. All radars are made up a basic set of four components:
- Radar: A detection system that uses radio waves to determine distance, angle and velocity of an object.
- Transmitter: Used to emit the radio waves.
- Antenna: The object which is used to receive radio waves.
- Receiver: Accepts signals from the antenna and increases its amplitude.
Powerful radio waves are broadcast by the transmitter, these waves hit objects in the radar wave path and then reflect back to the radar system. The receiver “listens” to the reflected waves, by studying the reflected signals – it can determine the position of objects.
Distance is determined by the time taken for the emitted pulse to return to the antenna after it has been reflected off the surface of the target.
Just like with a bat - the distance of an object is determined by the use of ultrasonic sound waves. Ultrasonic sensors use a transducer (a device that converts energy from one form to another) which acts as a medium to send and receive the echo signal. Distance is determined by measuring time lapses between the sending and receiving of the ultrasonic pulse.
Ultrasonic sensors are made up of two parts:
- Transmitter: Emits the sound waves.
- Receiver: Receives the sound wave/s after it has reflected off the target.
To calculate the distance between the sensor and the object, this equation is used:
Where the speed of sound in air is approximately 341m/s.
Cameras use light waves instead of radio or sound waves - cameras use visual data from the optical sensor behind the lens together with its software to further analyse this visual data. Thanks to Al and machine-learning algorithms - cameras can provide accurate images analysis and object detection. However, as passive sensors, cameras are always dependent on a good light source.
LiDAR sensors work almost on the same principle as radar systems however with one big difference - instead of radio waves, it uses light waves. LiDARs emit light in the form of pulses, the pulse is then reflected from the ground or object it hits and bounces back to the LiDAR sensor.
Here is a summary of how LiDAR works:
- The sensor emits invisible light pulses to objects in its direct path.. These pulses bounce off the objects and return to the LiDAR optical sensor.
- The time taken for each pulse to return can be used to calculate the distance it travelled.
- The LiDAR system times how long it takes for each pulse to return, using this information it can determine the distance between the object and the sensor with great accuracy.
Did you know - Radio and light waves have the same speed of light. So, which one updates data faster? Both LiDAR and RADAR systems have the same speed making it a win win for both.
Pros and Cons
Each technology has different advantages and drawbacks. These are summarised in the tables below.
Comparison table of radar vs. LiDAR
|Use||Measures the distance & velocity of an object||Measures distance, depth & height of objects|
|Range||Long operating distance||Long operating distances: excellent at detecting small objects due to short wavelengths|
|Environment / Weather conditions||Suitable to operate in more varied & sensitive environments, i.e., heavy clouds and fog||Effective in all weather conditions - especially at night|
|Safety||Safe to use||Emits eye-safe laser waves making it safe to use|
|Beam||Has a wide beam spread||Small beam spread|
|Cost||Cheap||More expensive than the other remote sensing technologies|
|Accuracy||Under ideal conditions - radar is accurate however it cannot identify or distinguish multiple targets||High accuracy - LiDAR can collect data accurately & precisely and can be used during the day or night. LiDAR data can create 3D images|
|Other||Does not require a medium since it uses electromagnetic waves||LiDARs can survey & obtain large amounts of data in a short period of time. Being able to determine objects & their distance is a strong reason for using LiDAR. It's also important to remember - LiDAR detects objects & not images so your privacy is protected|
Comparison table of ultrasonic vs. LiDAR
|Use||Measures distance using ultrasonic waves||Measures distance, depth & height of objects|
|Range||Limitations when it comes to detecting range||Long operating distances: excellent at detecting small objects due to short wavelengths|
|Environment / Weather conditions||Can be used in dark environments||Effective in all weather conditions - especially at night|
|Safety||Safe to use - however ultrasound more than 120 decibels may result in hearing damage||Emits eye-safe laser waves making it safe to use|
|Beam||Wide beam spread||Small beam spread|
|Cost||Low-cost option||More expensive than the other remote sensing technologies|
|Accuracy||High accuracy||High accuracy - LiDAR can collect data accurately & precisely and can be used during the day or night. LiDAR data can create 3D images|
|Other||Not affected by colour or transparency of objects||LiDARs can survey & obtain large amounts of data in a short period of time. Being able to determine objects & their distance is a strong reason for using LiDAR. It's also important to remember - LiDAR detects objects & not images so your privacy is protected|
Comparison table of cameras vs. LiDAR
|Use||Creates images of objects||Measures distance, depth & height of objects|
|Range||Cameras are more reliable as visioning system however they lack the range detecting feature||Long operating distances: excellent at detecting small objects due to short wavelengths|
|Environment / Weather conditions||Works well in all weather conditions, however severe weather conditions such as snow and wind can limit functionality of the sensor. Cameras do require a good light source to function||Effective in all weather conditions - especially at night|
|Safety||Safe to use||Emits eye-safe laser waves making it safe to use|
Small beam spread
|Small beam spread|
|Cost||Expensive technology||More expensive than the other remote sensing technologies|
|Accuracy||Cameras cannot be used on its own - the imaging feature is a big plus however it needs to be combined with other sensing technologies to make it more effective||High accuracy - LiDAR can collect data accurately & precisely and can be used during the day or night. LiDAR data can create 3D images|
|Other||Cameras have excellent visual recognition which helps identify objects and it can also read, i.e., road signs||LiDARs can survey & obtain large amounts of data in a short period of time. Being able to determine objects & their distance is a strong reason for using LiDAR. It's also important to remember - LiDAR detects objects & not images so your privacy is protected|
Which remote sensing technology should you use?
The big question is which remote technology is the best?
The application or specific use-case should dictate your choice in remote sensing technology. Some of the latest research is aimed at combining the inputs from multiple sensor data in what is known as “sensor fusion technology”.
Although there is no single technology that can meet every market’s needs. LightWare offers unique advantages which tilts the balance in favour of LiDAR-based solutions.
Let LightWare help find a LiDAR solution for you!
Finding the right LiDAR solution can be a bit of a puzzling task. Questions such as “can any LiDAR be used for every application?” “How will LiDAR integrate with my onboard systems” and many more… This is where LightWare comes in. We have a team of dedicated engineers who can help you with product queries or when you need support. We love to solve complex problems!
We offer customised microLiDAR solutions to meet your technical challenges. Our sensors will always outperform our stated specifications. Our devices are distributed globally, cementing our reputation as a global LiDAR technology leader in the autonomous navigation and collision-avoidance application space.