AGVs (Automated Guided Vehicles) not only improve overall production efficiency and logistics management, but also automate, intelligentize, and flexibly manage the entire production logistics process, increasing safety. AGVs, consisting of small vehicles, play a crucial role in automated production, ensuring the accuracy and timeliness of material transport and effectively preventing and eliminating product and transportation damage caused by human error.
The mainstream navigation methods for intelligent handling robots are as follows:
Magnetic strip navigation
Magnetic strip navigation is considered a very mature navigation technology. Magnetic strips are laid along the running path of an intelligent handling robot. The intelligent handling robot obtains the positional deviation between the vehicle and the target tracking path by measuring the magnetic field signals on the path, thereby realizing vehicle control and navigation.
The advantages of magnetic strip navigation are low cost, mature and reliable technology, good positioning stability, and ease of use.
The disadvantages of magnetic strip navigation are that it requires a construction site, the construction workload is large, the surface card is easy to lose, the magnetic strip needs to be re-laid when the route changes, it has poor flexibility, high maintenance costs, and can only travel along the magnetic strip. It can avoid obstacles or change the task in real time through the control system.
Magnetic nail navigation
The magnetic nail navigation mode finds its path by detecting the magnetic signals of the magnetic nails using a magnetic navigation sensor. However, since magnetic tape navigation relies on intermittent sensing, the distance between the magnetic nails cannot be too large. The intelligent transport robot between two magnetic nails is in a distance measurement state, requiring an encoder to measure the travel distance. Furthermore, the control module used in magnetic nail navigation is the same as that used in magnetic tape navigation.
The advantages of magnetic nail navigation are low cost, mature and reliable technology, good concealment due to the magnetic nails being buried underground, and aesthetic appeal. Magnetic nails also have strong anti-interference properties, high wear resistance, and are resistant to acids, alkalis, oil stains, and other contaminants, making them suitable for both outdoor and indoor use.
The disadvantage of magnetic nail navigation is that other magnetic materials cannot be present in the navigation path of the intelligent handling robot. Once the magnetic nail navigation path is laid, any subsequent modifications require a second operation. The construction of magnetic nail navigation for intelligent handling robots will cause some damage to the ground, namely, drilling holes and then backfilling, requiring strict construction techniques to restore the original aesthetic appearance of the ground.
Slam laser navigation
SLAM laser navigation, also known as natural navigation, is currently the most advanced navigation technology for intelligent handling robots that uses a two-dimensional laser scanner to measure the on-site environment. By learning and mapping the navigation environment, the intelligent handling robot can locate itself and incrementally build a map of the surrounding environment based on its own sensors and perception of the surrounding environment, even without information about the surrounding environment.
The advantages of SLAM laser navigation include its ability to locate objects such as walls in the work environment without requiring road construction or reflectors. SLAM eliminates the need for pre-laid tracks, facilitating upgrades and route changes to factory production lines. Furthermore, SLAM laser navigation offers real-time obstacle avoidance and strong environmental adaptability.
Compared with traditional laser navigation, natural navigation is simpler to implement and has a shorter construction period.
The disadvantages of SLAM laser navigation are poor positioning stability, easy loss of positioning in some complex factory environments, and high susceptibility to environmental influences. Laser-guided intelligent handling robots are also more expensive.
Laser navigation (with reflector installed)
The intelligent transport robot is equipped with precise reflectors along its travel path, and a laser scanner is mounted on the roof of the intelligent transport robot. The intelligent transport robot emits a laser beam, and the laser scanner moves along with the intelligent transport robot. The laser beam is directly reflected by multiple sets of reflectors laid out along the intelligent transport robot's travel path, while the reflected laser beam is collected. Through continuous triangular geometric operations, the intelligent transport robot is guided to determine its current position and orientation.
The advantages of laser navigation are that intelligent handling robots can be accurately positioned, there are no other positioning facilities on the ground, and the driving path can be flexibly changed.
The disadvantages of laser navigation are its complex control and high investment cost. Furthermore, laser sensors used in reflectors and intelligent handling robots cannot be directly in contact with obstacles, nor are they suitable for handling airborne material flows.
Visual navigation (QR code)
A vision camera is installed on the chassis of the intelligent handling robot, and QR codes are laid along its operating path. During operation, the intelligent handling robot obtains its current location information by analyzing the QR code information. QR code navigation is usually combined with inertial navigation to achieve accurate positioning.
QR code navigation has advantages such as good positioning stability, mature technology, high navigation flexibility, less environmental interference, and low cost.
The disadvantages of QR code navigation are that it requires laying a large number of QR codes along the operating route of the intelligent handling robot, resulting in a large amount of construction work. Additionally, the QR codes need regular maintenance and replacement, leading to significant maintenance workload. Furthermore, the navigation range of QR codes is limited, and it is generally used in unmanned environments such as warehouses.
Fusion Navigation
1. When encountering complex terrain (such as corridors, roads with glass on both sides, or factories with highly variable environments), traditional laser navigation systems (such as those with glass on both sides of the road or those with highly variable environments) are prone to losing their positioning.
2. In some cases (where high docking accuracy is required), the positioning accuracy cannot meet the accuracy requirements of automatic loading and unloading.
To address the aforementioned issues, navigation can combine two or more navigation methods. This is called integrated navigation. Currently, the commonly used integrated navigation methods include the following.
1. Combination of laser navigation and magnetic stripe navigation
2. Combination of laser navigation and QR code navigation
3. Combination of QR code navigation and inertial navigation
4. Combination of laser navigation and 3D visual navigation
Magnetic strips and QR codes need to be laid on the ground, which are prone to wear and tear over time. They also need to be re-laid when the production line is changed, resulting in high maintenance costs.
Intelligent material handling robots, as important tools for automated transportation and handling, are technologically mature and widely used in smart factories. They can accurately and efficiently transport materials to their target locations. However, when choosing a navigation method, companies must select one that suits their specific needs to achieve satisfactory results.
