In part 1 of our brief overview of outdoor environment detection processes, we discussed time-of-flight as well as radar technology. In part 2, we presented ultrasound and mono/stereo video processes. In this third and last part of our article series, we want to take a closer look at laser technology.
Environment Detection with Laser/LIDAR
When discussing the sensing technology LIDAR (light detecting and ranging), we are talking about a visual measuring process. The distance to existing objects is here measured by the time it takes for a laser beam to go from a sensor to an object and back. This is done through laser pulses, not a continuous laser beam. Fundamentally, the process is very similar to time-of-flight measurements by PMD sensors that are used in TOF cameras. However, in contrast to the TOF camera, LIDAR technology does not detect the complete scene in one instant, but scans the environment in a series of points. In most cases, a rotating mirror is also used. The laser beam is thereby deflected, describing a circular plane. The sensors, which are equipped with movable components for this purpose, are commonly referred to as laser scanners.
The leading manufacturers of LIDAR technology, as well as several ambitious start-ups, are now working on a new generation of LIDAR sensors. These do not require movable components and create the image of the environment, for example, by means of laser arrays arranged in a grid pattern. These types of sensors are generally called solid state LIDAR sensors. Laser scanners or solid state LIDAR sensors thus create a point cloud that consists of many individual scanning points and thereby represents solid objects. In this way, this measuring technology creates a virtual image of the real world in real time.
LIDAR processes in a wide range of applications
LIDAR technology is extensively used for distance measuring on construction sites. In the meantime, cost-effective equipment that allows highly accurate and fast distance measurement is now available in almost every do-it-yourself-store. Even the recognition of clouds, dust, and gases can be achieved in most cases. Additional applications for LIDAR systems include mobile speed control, measuring systems such as wind measurement, leak testing in natural gas systems, and many other areas. Furthermore, LIDAR sensors are used in the field of indoor navigation of automated guided vehicle systems (AGVS) and are also frequently used in unmanned outdoor vehicles.
Simulation of environment detection using a 2D laser scanner in the cultivation of a row crop
Bottom line
Fundamentally, every form of environment detection has its pros and cons. Which tools should be selected for the detection of the direct surroundings should be decided dependent on each specific application. There is no blanket solution for all applications. Due to differing physical processes and other characteristics, each system has its own limitations and possibilities – these should be analyzed prior to purchasing. In many cases, combining several different sensor systems may be necessary in order to get the required information about the direct environment. As an expert in mobile automation, Robot Makers GmbH is at your service in selecting the right process for environment detection and options for sensory data fusion. Please feel free to contact us.
Please also read the other articles of article series concering environment detection:
Part 1
Part 2
