Automated Guided Vehicle Systems: Your Essential Guide to Successful AGV Solutions
Mobile robotics, particularly Automated Guided Vehicle (AGV) systems, are now essential for material transport within companies. Used widely in production and logistics, AGVs automate the transport of goods and serve as assembly platforms, facilitating a seamless and transparent material flow. They are pivotal in advancing Industry 4.0.
Discover key insights about AGV solutions, explore their varied applications, and understand the cost factors involved, all right here.
Definition: What are automated guided vehicles (AGVs)?
Automated guided vehicle systems are used in various application areas, such as pallet transport or order picking. The term AGV is often used to describe an Automated Guided Vehicle (AGV). However, it’s important to differentiate between the AGV system, as part of the overall system, and the AGV itself.
An AGV system consists of individual transport vehicles, a control system, a communication system (WLAN infrastructure), navigation facilities, as well as stationary and peripheral elements.
What are Automated Guided Vehicles (AGVs)?
Automated Guided Vehicles (AGVs) are automatically controlled, contactless industrial trucks used within the European Economic Area and subject to the Machinery Directive. AGVs are equipped with their own drive systems and are primarily utilized for material transport. They manage tasks such as pulling or carrying goods—ranging from pallets and containers to carts—between storage locations and workstations in a warehouse. The fleet manager strategically assigns tasks and routes, always opting for the shortest paths for efficiency.
AGVs come equipped with either active or passive load handling equipment (LHE). Active LHEs, such as roller conveyors, belt conveyors, or telescopic forks, have their own drive systems and can independently handle loads. In contrast, passive LHEs lack a drive system; they move goods using guide slopes or pins and place them on flat, unguided surfaces like platforms.
The choice of AGV type depends on several factors, including the material flow, layout, space conditions, speed of the trucks, their loading cycles, and maximum load capacity. This selection process is critical to optimizing and automating operations effectively.
Thanks to the superstructure including lateral guide rails, the mobile robot has a passive load handling device, which enables it to pick up small load carriers (Image: © SAFELOG).
History of Automated Guided Vehicle Systems
Over sixty years ago, Barrett Vehicle Systems in the U.S. pioneered the first AGV. By 1963, German companies adopted AGVs for intralogistics, utilizing colored floor markings and optical sensors to direct the vehicles along predetermined routes and stops.
Advancements in electrical engineering during the 1970s and 1980s brought significant enhancements to AGVs. They were equipped with onboard computers, and active inductive guidance, which involves following a wire that emits a magnetic field from alternating current, became the standard navigation method.
Since the 1990s, breakthroughs in sensor technology and laser localization have revolutionized the AGV industry. Modern AGVs are powered by greater computing capabilities and employ SLAM navigation (Simultaneous Localization and Mapping), opening up unprecedented possibilities for manufacturers.
Role of Automated Guided Vehicle Systems in Industry 4.0
As the demands of Industry 4.0 grow, companies increasingly rely on Automated Guided Vehicle Systems (AGVs) to enhance their operational efficiencies. AGVs not only save time but, when implemented effectively, also prove to be more cost-effective than traditional automation technologies for material flows.
Both large corporations and small to medium-sized enterprises are turning to AGVs to scale their intralogistics operations. Particularly in response to the rise of one-off production batches and the e-commerce boom, AGVs offer a robust solution for the internal transport of goods. These robotic systems are capable of operating 24/7, ensuring continuous high throughput and making them integral to the functionality of Smart Factories.
How Automated Guided Vehicle Systems work
Control
The control system functions as the brain of an Automated Guided Vehicle (AGV) system, comprising both hardware and software components. Central to this system is a computer program capable of running on multiple systems. It serves as the hub where all pertinent information converges and where all critical decisions are made.
Intelligent algorithms manage all control tasks within AGV systems, efficiently directing any number of vehicles—up to hundreds—safely from start to finish with the transported goods.
The control system’s hardware configuration can range from a single computer to elaborate multi-server systems depending on its integration with the user’s infrastructure. More complex setups might include multiple visualization and operation clients and support various RAID levels for data protection and performance.
However, a centralized control system also has its drawbacks. It’s less flexible and not particularly resilient against disruptions. Furthermore, control systems come with a hefty price tag, representing a significant investment on top of the cost of the AGV system itself, which may include multiple AGVs.
Navigation
AGVs typically follow predetermined paths within warehouse aisles, marked by either magnetic tracks or wires.
Wire technology controls Automated Guided Vehicles (AGVs) through an electromagnetic field generated by a metal wire embedded in the floor. This older method is now rarely used due to its high installation costs and the inflexibility of the fixed wires, which cannot be easily moved or reconfigured. In contrast, magnetic tracks offer significantly more flexibility. These tracks can be easily relocated within the warehouse, adapting quickly to changes in layout or operational needs, making them a preferred choice in modern AGV systems.
Additionally, AGVs can utilize advanced navigation technologies such as cameras, lasers, or radio waves to align and orient themselves. In laser guidance, the AGV follows a virtual track stored in the system’s internal environment map. Orientation is achieved using reflectors evenly distributed across the floor. The AGV navigates by emitting a laser beam towards these reflectors and determining its position from the reflected signals, a method known for its precision and reliability.
In environments with fixed features such as columns or machine cells, navigation can also be based on the contours of these structural features.
If AGVs are equipped with a camera, they navigate by following a pre-stored map of the warehouse. The camera helps the AGV determine its exact position by comparing its current location against the map.
There are two primary methods for environmental detection utilized in AGV systems: SLAM (Simultaneous Localization and Mapping) and LiDAR (Light Detection and Ranging). SLAM can be conducted visually using cameras or with lasers. In visual SLAM, cameras record the warehouse environment to aid navigation. The laser variant uses a light laser to detect and categorize objects, providing detailed three-dimensional information about their surfaces and properties, which helps create a virtual representation of the environment. These sensors are notable for their high data density and ability to rapidly capture coordinates.
Laser SLAM calculates changes in position and distance by comparing clusters of data points collected at different times, which helps in precisely positioning the AGV. This method is highly accurate, minimizes cumulative errors, and ensures effective navigation.
For outdoor navigation, GPS is commonly used. Although it relies on satellites, GPS offers the least accuracy compared to SLAM and LiDAR technologies used for indoor navigation.
Magnetic track localization is particularly easy to integrate (Image: © SAFELOG).
AGVs without control stands
Due to the disadvantages associated with costly control stands, AGVs with decentralized control systems are becoming increasingly popular. These systems enhance both flexibility and reliability.
Decentralized control is implemented through intelligent multi-agent systems. In these systems, all vehicles and peripheral devices capable of interaction serve as agents. These agents continuously communicate, sharing their respective positions, speeds, and information about any disturbances along their routes. They also dynamically redistribute tasks among individual swarm members, enhancing the system’s responsiveness and efficiency.
Decentralized systems offer several advantages, including higher reliability. If one component fails, the overall system remains intact, demonstrating the robustness of decentralized systems compared to centralized ones. Additionally, these systems are scalable and flexible; new AGVs can be integrated without significant changes to the existing control infrastructure, leading to lower acquisition and operational costs.
Where are AGVs used?
Mobile robots are versatile tools suitable for businesses of all sizes, from small firms to large corporations.
Common applications:
- Supplying production lines in manufacturing settings.
- Transporting goods, components, and pallets between departments and production stations.
- Handling cart-box transport and towing operations.
- Supporting commissioning and sorting tasks based on the Goods-to-Person principle.
- Serving as assembly platforms.
While AGV systems are a staple in the automotive and manufacturing sectors, and intralogistics, their efficiency in automated transport tasks has led to increased adoption in other areas as well, including hospitals and paint shops.
The transportation of pallets is a common application for the use of mobile robots (Image: © SAFELOG).
Examples: What types of AGV systems are there?
Depending on the requirements, there are different types of AGV systems.
Subvehicles
These AGVs are built with a low profile, allowing them to drive directly under pallets, shelves, or elevated containers. Equipped with lifting devices, these subvehicles can raise their loads off the ground for transport. Typically, they handle general cargo and smaller loads up to 500 kg.
Thanks to their flat design, subvehicles are ideal for transporting racks, as they can drive directly underneath them and lift them out (Image: © SAFELOG).
Universal vehicles
These AGVs are highly flexible and can be customized with various attachments. They feature mechanical and electrical connections for mounting structures like superstructures, conveyor belts, roller conveyors, or racks. Additionally, these universal vehicles can also function as subvehicles, enhancing their versatility in different operational settings.
Lifting AGVs
These AGVs are equipped with load handling equipment (LHE) like belt and chain conveyors, roller conveyors, or belt conveyors, ideal for handling mesh boxes, small load carriers, or pallets. They are capable of transporting weights up to 1,000 kg. For effective height compensation, transfer stations should either maintain a standard height or incorporate a lifting device for height adjustments.
Assembly line AGVs
Employed in both manual and automated assembly processes, these AGVs are designed to transport heavy goods, handling weights up to 5,000 kg. They are particularly prevalent in the automotive industry, primarily functioning as towing vehicles for moving cars.
Automated Guided Forklift (AGFs)
Automated Guided Forklift (AGFs) replace traditional forklifts. They transport palletized loads along predefined aisle routes. Loads weighing up to several thousand kilograms are transported and vertically sorted into shelves using AGFs.
Tugger AGVs
Also known as Tuggers, these AGVs are designed to transport heavy loads across long distances within a warehouse. They are especially effective for moving large items from one location to another.
Advantages of Mobile Robot Systems
AGV systems significantly enhance flexibility and scalability within intralogistics processes, offering several notable benefits:
- Automation of Transportation Tasks: AGVs handle repetitive transport duties, freeing employees to focus on value-added activities.
- Addressing Labor Shortages: These systems help fill gaps caused by a shortage of skilled workers.
- Continuous Operation: AGVs are highly available and capable of operating 24/7.
- Optimization of Material Flow: They improve the efficiency and transparency of internal material handling.
- Adaptability to Demand: AGVs can flexibly manage peak orders and market fluctuations.
- Just-in-Time Delivery: These systems facilitate precise timing in logistic operations.
- Space Efficiency: AGVs require less space than traditional conveyor belt systems.
- Increased Process Security: Automated, standardized tasks reduce transportation errors, damage, and accidents.
- Reduced Error Rates: There is a lower likelihood of mistakes in picking and transporting goods.
Disadvantages of Automated Guided Vehicle systems
For small and medium-sized enterprises (SMEs), leveraging automated guided vehicle systems productively and economically has posed several challenges:
- High Costs: Most AGVs are custom-built for specific projects, making them expensive.
- Complex Control Systems: Control via a centralized control center is not only complex but also costly.
- System Dependence: If one robot fails, it can halt the entire fleet until the issue is resolved.
- Ongoing Operational Costs: Control centers require continuous maintenance and upkeep.
- Additional Staffing Needs: This typically necessitates hiring more IT personnel or securing a support contract with the manufacturer.
However, these disadvantages can be mitigated by using agent-based and decentralized control systems, which streamline operations and reduce dependency on centralized control.
Costs of AGV systems
Before investing in a mobile robot system, companies need to conduct a detailed cost-benefit analysis to ensure the investment is economically justified. This involves defining the required features and specific use cases upfront.
AGV systems are best suited for operations with a continuous, uniform material flow. When comparing AGVs to conveyor technology and manual transport, the following key performance indicators should be considered:
- Number of daily working hours
- Workplace or operating conditions
- Type and weight of goods (transport parameters)
- Transport distance
- Number of transports per hour
- Task description
- Specific requirements
- Number of AGVs needed to ensure material flow during peak periods
A thorough assessment of these factors is essential to determine the cost-effectiveness of deploying AGV systems.
Additionally:
Mobile robot systems, while effective, are generally expensive to acquire and maintain. Many AGV manufacturers recommend a centralized control center to operate the system, which further increases costs.
A University of Hanover survey among European manufacturers revealed that the invoiced system prices per vehicle vary widely, ranging from €15,000 to €300,000, with about 60% of these falling between €60,000 and €150,000.
In response to high costs, companies like SAFELOG are moving towards mass production of transport robots, significantly reducing acquisition costs while maintaining quality.
SAFELOG’s AGVs feature agent-based control, which allows for cost-effective operation without the need for an expensive control center. This makes them especially suitable for small to medium-sized enterprises.
SAFELOG AGVs utilize the IntelliAgent software, enabling device communication via WLAN and allowing different AGV models to be combined flexibly in a tailored hardware and software solution. An app provides real-time system overviews and displays operational statuses. Additionally, these mobile robots easily integrate into existing production and logistics frameworks, with connectivity through external interfaces like VDA 5050 available if required.
SAFELOG’s approach offers a cost-effective alternative for companies looking to automate their intralogistics without the hefty price tag of traditional control center-driven systems.