- By John Hamlin
- December 14, 2020
AGV guidance and navigation systems are an intricate part of automation and have come a long way since their inception.
Automation can improve machine performance, raise quality and quantity while reducing costs and errors in manufacturing. Production and efficiency are improved by introducing computer-driven mechanisms. AGV guidance and navigation systems are an intricate part of automation and have come a long way since their inception.
What is an AGV?
Automated guidance vehicles are actually mobile robots that are electrically powered and run on their own. They are guided by a computerized system that determines their movement with software applications. AGVs are powered by a battery or electric motor that enables the complete operation of warehouse loading, manufacturing, and other operations.
AGV guidance or navigation system
Every industry has its own requirements and uses for AGV and it is therefore important to consider the navigation or guidance system needed before AGV is implemented in your warehouse. The requirement dictates the functions and routes the AGV. There are a wide variety of navigation systems that are used to guide these robots.
The navigation system will be determined by the path and is classified in:
A fixed path
The way an AGV calculates its current position ( It has to know where it is and where to go) is classified as:
Absolute: Vehicle knows it position at all times for example laser systems
Relative: The vehicle does not always know its location, a calculation from the previous position determines its position for example odometric systems.
Each type of system has its own benefits in the right area or environment. Let’s have a closer look at the main guidance system used in AGVs.
This is a fixed relative system where the AGV is fitted with a magnetic reader in the front that detects magnetic field fluctuation. Tape embedded on the ground creates a magnetic field to guide the path. The magnetic reader, wheel turning, scanners are all connected to a control unit that guides the vehicle into performing complex maneuvers.
RFID cards are used in conjunction with the magnetic strip and are read at the same time. This enables the vehicle to:
Changes of trajectory
Take different paths, make stops
This system is a fixed relative system that is an optical vision-based. Through the use of cameras and sensors, the AGV acquires information about its environment and makes decisions.
There are various types of optical systems, such as:
QR code recognition: Codes and reference points are arranged on the ground in advance with great precision. The AGV recognizes them and knows where it is and how far to move and the right detection or path to get to the next reference.
Ground guidance: The AGVs path is painted on the ground in a contrasting color to the ground. It is similar to the magnetic strip scenario.
3D cameras: This system provides the AGV with images of its surrounding environment in real-time. It adds values like distance intensity and confidence thresholds, allowing detection of landmarks and recognizing obstacles and relating it to a pre-loaded map.
Most of these systems combine odometric or inertial systems with optical information. This allows them to measure the displacement of the vehicle to maintain navigation when a reference point cannot be found.
- Laser systems: These systems operate freely and are absolute. AGVs with laser navigation are also called Laser Guided Vehicles (LGVs). These vehicles are fitted with a device that emits thousands of light beams per second. These light beams bounce off reflectors (catadioptrics) that are captured by a receiver. The system calculates the time that the beam takes to go and come in order to navigate distance. By being able to detect up to 3 reflectors the vehicle can calculate its position in a triangle and then compare it to a map stored in its memory. This is a very accurate and reliable system that lends to great flexibility and when changes are made to the management software, it does not affect the production environment. This allows the AGV to follow multiple paths.
- Slam system: This is a free and absolute system and the name is derived from the acronym “Simultaneous Localization And Mapping.” This navigation technique is quite natural as it allows the AGV to build a map of the environment and navigate through at the same time. This system can also use a laser to detect the environment but with SLAM it is not necessary to install reflectors. The navigation system has a preloaded map with a series of reference points. The secret is that SLAM uses complex algorithms.
Did you enjoy this great article?
Check out our free e-newsletters to read more great articles..Subscribe