1. Magnetic nail navigation
This navigation method still uses magnetic navigation sensors to detect the magnetic signal of the magnetic nails to find the path of travel. It only changes the continuous induction of the magnetic stripes when using magnetic stripe navigation to intermittent induction. Therefore, the distance between the magnetic nails cannot be too large, and the AGV between the two magnetic nails is in a distance measurement state, in which an encoder is required to measure the distance traveled. Secondly, the control module used for magnetic nail navigation is the same as the magnetic stripe navigation control module.
2. Magnetic stripe navigation
Magnetic stripe navigation is considered a very mature technology, which mainly obtains the position deviation of the vehicle relative to the target tracking path by measuring the magnetic field signal on the path, thereby achieving vehicle control and navigation. Magnetic strip navigation has high measurement accuracy and good repeatability. Magnetic navigation is not easily affected by changes in light, etc. During operation, the magnetic sensing system has high reliability and robustness. Once the magnetic strip is laid, the maintenance cost is very low, the service life is long, and it is easy to add or change paths.
Advantages of magnetic strip navigation: simple on-site construction. Low cost, mature and reliable technology. No interference with sound and light. Obvious operation of AGV lines. The second change of the route is easy, the cost of change is low, and the change cycle is short. Low technical requirements for construction personnel
Disadvantages of magnetic strip navigation: magnetic strips are easily damaged; Due to the laying of magnetic strips on the ground, the overall aesthetics have decreased. The magnetic strip cannot be continuous, as AGV turns and rolls over the magnetic strip, some of the magnetic strips will be cut off and not laid. Magnetic strips can attract metallic substances, leading to AGV equipment malfunctions, and so on. Other sensors are required to achieve the function of locating the site.
3. Laser navigation
Laser navigation is the installation of a laser reflector around the AGV's driving path. The AGV emits a laser beam while collecting the laser beam reflected by the reflector to determine its current position and direction, and achieves AGV navigation through continuous triangular geometric operations.
Advantages of laser navigation technology: AGV positioning accuracy. The ground does not require other positioning facilities, and the driving path can be flexible and adaptable to various on-site environments. It is currently an advanced navigation method preferred by many AGV manufacturers both domestically and internationally.
Disadvantages of laser navigation technology: high cost and relatively strict environmental requirements (external light, ground requirements, visibility requirements, etc.). The price of laser navigation equipment is high. Laser navigation equipment is suitable for unobstructed environments. The cost of reflective panels is high.
At present, laser navigation technology has become the mainstream solution for domestic and foreign AGV manufacturers. Due to factors such as high positioning accuracy, flexible route changes, and mature navigation technology, laser navigation has become popular.
4. Electromagnetic navigation
Electromagnetic navigation is one of the more traditional navigation methods, which is still adopted. It buries metal wires on the driving path of AGV and loads guidance frequency on the metal wires. By identifying the guidance frequency, the navigation function of AGV is achieved. This navigation technology is similar to magnetic stripe navigation. Due to its shortcomings such as insufficient aesthetics and difficulty in changing paths, this technical solution has gradually been abandoned by AGV manufacturers. However, specific site conditions are also suitable for this navigation technology, depending on the working environment requirements of AGV. For example, in high temperature environments, strict requirements for line straightness are required.
5. QR code guidance
The QR code guidance method is to lay QR codes discretely, and obtain real-time coordinates by scanning and analyzing the QR codes through AGV on-board cameras. The QR code guidance method is also the most common AGV guidance method on the market, and the composite navigation form of QR code guidance and inertial navigation is also widely used. Amazon's KIVA robot achieves autonomous movement through this navigation method. This method is relatively flexible and convenient for laying and changing paths. The disadvantage is that the QR code is prone to wear and requires regular maintenance.
Applicable scenario: warehouses with good environment
6. SLAM laser navigation (natural navigation)
SLAM laser navigation is a natural navigation method that does not require the use of reflective plates. It no longer requires auxiliary navigation signs (QR codes, reflective plates, etc.), but instead uses the natural environment in the work scene, such as columns and walls in the warehouse, as positioning reference objects to achieve positioning navigation. Compared to traditional laser navigation, its advantage is lower manufacturing costs. According to the editor's understanding, there are also manufacturers (such as SICK) that have developed laser sensors suitable for AGV outdoor operations.