Automated guided vehicle systems must be precisely controlled and coordinated. Learn everything about AGVs and their advantages!
Definition of automated guided vehicle systems: They consist of different components, which must be coordinated and controlled precisely. VDI Guideline 2510 defines and classified AGVs according to their design.
The design of automated guided transport systems
The components of an AGV:
- Automated guided vehicles defined in accordance with industrial trucks
- A master control
- Means for locating and detecting position and state of transport vehicles
- Means for data transmission to and from vehicles in the AGV
- Infrastructure and peripheral facilities such as charging stations etc.
Why automated transport systems are important in logistics
More than 50 years ago, the first automated guided vehicle systems were developed and used in the USA. These systems are now an integral part of modern logistics. Automated guided vehicle systems are used to autonomously transport and handle various goods and materials by means of active and passive load handling devices. The AGVs are floor-mounted and can be used inside buildings as well as outside and in external warehouses. Thanks to the continuous optimization of the systems, the vehicles and the technology used, more and more companies can exploit the advantages of these transport systems and benefit from their flexible and efficient use in their own intralogistics.
Possible applications of AGVs: speed, safety and handling of heavy loads
Automated guided vehicle systems are used globally and in diverse applications. They can be used both in work areas frequented by people and in fully automated work areas. They are designed extremely flexible. Thus, the AGVs can be easily adapted to the respective tasks. In small warehouses, for example, there are vehicles in use that can transport only a few kilograms of goods, while large systems can carry loads of up to 50 tons. However, automated guided vehicles differ not only in terms of their maximum load, but also in terms of their speed. However, this also depends on many external factors. While vehicles in work environments frequented by people are often not allowed to exceed a speed of one meter per second, higher speeds can also be achieved in fully automated environments. Limiting factors are above all the braking distances and the load changes caused by the transported goods. This means that automated guided vehicle systems offer a high degree of flexibility.
Different types of automated guided vehicle systems
Automated guided vehicle systems are referred to and defined as industrial trucks. This definition is important because of accident prevention regulations. The design of these vehicles is defined as follows:
- They run on wheels in a corridor and are freely steerable.
- They are designed for transporting, pushing or pulling loads.
- They are used on a company’s premises.
This definition is extended by industrial trucks with lifting devices, which are now used in most warehouses. These transport systems are also characterized by the fact that they are suitable for lifting, stacking and "storing loads on shelves” and that they can pick up and set down loads automatically.
How autonomous transport systems are driven
Industrial trucks have been in use for many years. There are various types which could be equipped with various drive technologies. Meanwhile, modern systems, which do not require direct human interaction, generally use electric drives, as these transport systems can also be used in moderately ventilated warehouses. The definition of automated guided vehicle systems basically starts with that of industrial trucks, but complement their performance with their autonomous interactions with goods. Automated guided vehicle systems are therefore a further development of industrial trucks with modern means and technical extensions.
Examples of automated guided vehicle systems: Amazon and Kiva-Systems
A very good example of automated systems in the intralogistics sector is Amazon, the world's largest mail order company. In 2015, the company invested $ 775 million in Kiva-Systems, which at that time already was an advanced manufacturer of storage robots. Currently, the entire company has been taken over by Amazon and is working specifically on AGV solutions for Amazon. According to Amazon, the company wants to use AGVs to improve the effectiveness of its employees by a factor of four. This can already be observed in practice. The orange Kiva robots are already in use in many Amazon warehouses. These robots collect both the goods and the assigned packaging from the respective warehouses and deliver them autonomously to the responsible employee, who packs the goods and prepares them for dispatch. However, these systems only work because goods receipt, picking, packaging and goods dispatch work according to strictly defined criteria and all goods and materials are captured both locally and by the software used. On fixed routes and using intelligent navigation systems, automated guided vehicle systems can handle these tasks without any problems. Since Amazon uses dynamic warehousing, i.e. the individual materials and goods are not stored at pre-defined locations, the software for the automated guided vehicle systems must be closely connected to the company's merchandise management system. The Kiva-Systems industrial truck automatically searches for the stored goods and takes them to the next available warehouse employee. Thus, Amazon is able to avoid long transport routes and waiting times intelligently. Amazon can not only maintain the number of employees and their workload on a constant level, but also to effectively handle the ever-increasing volume of goods while ensuring reliable and sustainable logistics. Since the AGV operates autonomously and can also be easily expanded, the systems that have already been tried and tested can easily be used in new warehouses and for warehouse expansions.
This example shows the automated transport robots from Kiva-Systems in action and can follow their work and loading capacity in detail. You can see degree of automation used by the robots and how smoothly the interaction between AGVs and human employees works.
Advantages of automated guided vehicle systems
AGVs are available in many different versions. However, automated guided vehicle systems have a whole series of advantages that clearly set them apart from the alternatives and significantly expand their range of applications. By automating workflows, companies profit for many advantages. On the one hand, the human factor is deducted from many areas of work, which not only significantly reduces the error rate, but also increases productivity. An AGV does not need a break, is not bound to fixed working hours and can therefore be used permanently and around the clock. Thus, a continuous supply with the required goods can be guaranteed at any time. In the areas of logistics and production, the use of AGVs can realize enormous increases in productivity, while personnel costs in these areas are significantly reduced.
But AGVs offer even more advantages that make them superior to many other autonomous transport systems.
- Automated guided vehicle systems can be easily integrated into existing warehouse structures and therefore require less integration effort.
- Automated guided vehicle systems can be used to transport a wide variety of goods with different weights and specifications. For instance, different vehicles can be used in the AGV system to transport goods within a closed system.
- Changes to the warehouse layout, to the warehouse structure and to the goods structure can be made and optimized during operation.
- Furthermore, automated guided vehicle systems can easily be adapted to fluctuating performance requirements, allowing focal points to be defined and processed at any time via a control system. Since the system operates autonomously, order peaks can be identified early on and prioritized accordingly.
Disadvantages of automated guided vehicle systems
Unless a malfunction occurs, the goods are transported automatically. If the AGV encounters obstacles or is damaged, manual intervention is required. Modern systems cannot automatically respond to malfunctions. If, contrary to expectations, the vehicle is standing in front of an empty shelf space, it waits for replenishment before continuing the order to transport the components from the warehouse to the assembly line. Scientists at the Institute for Integrated Production Hannover (IPH) are developing an expert system for the automatic reaction to operational disturbances in the research project "AGV Expert".
Technology and navigation - AGV systems in logistics
If automated guided vehicles are to be used in logistics and warehousing, it is above all their technical design that determines the outcome. Above all, the navigation and spatial orientation of the vehicles and the clear marking of the storage areas or the allocation of the goods to specific storage areas are of decisive importance. To ensure effective operation, AGV systems can be spatially located by different methods. However, these systems often differ hugely from each other in terms of both efficiency and investment costs.
Magnetic or inductive guiding rails in the floor
The simplest and most cost-effective method are probably guiding rails in the floor of the warehouse. These rails can be designed both optically and inductively or magnetically and serve as the AGV’s boundary of the travel paths. However, these systems have a significant disadvantage. Although the integration is inexpensive and simple, these solutions can only be maintained with greater effort. Changes to the warehouse and to the routes can therefore only be implemented with difficulty.
Transponders and magnets for grid navigation
In grid navigation, transponders and magnets embedded in the ground are used to generate optical grids that enable the industrial truck to orient itself. This system is often a little more expensive than the just the guiding rails, but maintenance and changes to the routes can be carried out much easier. The expansion can be carried out quickly by changing the grids or adding further transponders.
AGV systems with laser navigation
The most modern, but also the most expensive form of navigation uses lasers. In this case, the automated guided vehicle is equipped with a modern laser scanner, which allows simple and above all extremely precise navigation on all routes. To this end, the system uses stationary reference points. Additional reference points allow the routes to be extended and changed very easily. Industrial trucks equipped with such a navigation unit can also be used in new and existing warehouse elements without any problems. However, the expenses for both the investment and the maintenance of the system are very high. That is way such systems are only used in large warehouses and by correspondingly large companies.
Navigation of automated guided vehicle systems via GPS
If AGV systems are used in open-air storage areas, navigation can also be carried out using the GPS system. This system works by means of radio direction finding, but its basic values are only accurate down to +/- 10 meters. Only with the Differential Global Positioning System (dGPS) can the accuracy be noticeably increased. If a dGPS with phase evaluation is used, the accuracy can be increased by a factor of approximately 100. This allows AGVs to be controlled in outdoor areas using GPS. In such cases, the AGVs can be used autonomously and flexibly.
This video shows the sensory abilities of AGV systems and the extent to which logistics can benefit from this new form of autonomous work equipment. Thanks to ever better technical innovations, this market will expand noticeably in the next few years and its possibilities will increase by leaps and bounds.
AGV systems are also used for a wide range of picking tasks
For a long time, AGV systems were mainly used in large-scale logistics, where they were tested several times. Meanwhile, there is a whole series of companies in the wholesale and retail sector that also use automated guided vehicle systems in order picking, i.e. in a traditionally extremely personnel-intensive sector.
In such cases, the demands placed on the industrial truck and the AGV increase considerably. There, different goods from different storage locations have to be picked individually and then transferred to dispatch. Analyses have shown that in most companies the route to the shelf can account for up to 50 percent of an employee's working time. The use of automated guided vehicle systems can significantly reduce the time required for order picking. This has positive consequences throughout. On the one hand, this measure can increase productivity by up to 10 percent. Thus, the investment costs for AGV systems can usually be amortized without any problems. In addition, the employees are also relieved of physical strain, as the lifting and carrying effort of the individual employee is significantly reduced. This reduces strain on the back and joints, which is reflected in the company's health statistics.
Industry 4.0 - The future of automated guided vehicle systems
Thanks to the simple scalability of the individual systems and the various system components, AGV systems can be used in a wide range of applications and offer a a high degree of comfort and control. It offers a significantly higher degree of compared to traditional logistics methods. If the basic tasks of goods recording and storage-relevant inventory are carried out thoroughly and effectively, the systems can autonomously and easily facilitate and noticeably accelerate a wide variety of logistics tasks. Accordingly, in the future the systems will not only be used in large companies, but also increasingly in the retail trade where it will change the logistics industry perceptibly. As a first step towards industry 4.0, automated guided vehicle systems are contributing a large part of the increase in productivity through their numerous automatisms and consistent work performance.
This article was first published by MM Logistik.