What is an Automated Guided Vehicle (AGV)?

An Automated Guided Vehicle (AGV) system, also referred to as autonomous guided vehicles, self-guided vehicles or mobile robots, are material handling systems that transport goods or materials within a controlled environment without the need for a human operator or driver. They are often employed in manufacturing facilities, warehouses, or distribution centers. This article delves into different types of AGVs, how they work, and their benefits and drawbacks.  

Use Cases for AGVs

Automated guided vehicle systems are used for tasks that would typically be handled by forklifts, conveyor systems or manual carts; moving large volumes of material from A to B. The big advantage over these traditional material handling systems is that they can operate automatically, and without human resources manning the vehicle.  

AGVs can be used in a variety of settings, as long as the environment can be controlled. Let’s look at how AGVs are deployed below:

1. Transportation of Raw Materials

AGVs are often used in the movement of raw materials such as metal, chemicals, plastic or paper within industrial settings. Replacing conveyors, they can facilitate the seamless transfer of these materials from receiving docks to storage areas or directly to production lines. This capability ensures a consistent and reliable supply of raw materials to production areas, eliminating delays and enhancing efficiency.

2. Work-in-Process (WIP) Applications

In manufacturing environments, AGVs are used in the movement of partially completed goods through different stages of production. They transport materials or components from storage to production lines or between workstations, optimizing the flow of goods through the manufacturing process. This continuous movement is vital for maintaining a smooth and uninterrupted production process, thereby increasing productivity and reducing the likelihood of production stoppages.

3. Handling Finished Goods

Upon completion of the manufacturing process, AGVs are used to transport finished goods from the production line to storage or shipping areas. This automated handling minimizes the risk of damage to finished products and ensures timely delivery to storage or shipping docks, preparing them for distribution.

4. Inbound and Outbound Handling

AGVs are in some cases used to manage warehouse operations, including the replenishment of stock and picking processes. They can transport goods from receiving areas to storage locations or from long-term storage to forward picking areas, taking the function as an automated storage and retrieval system (AS/RS). Although conveyors are more common, AGVs can be integrated with AutoStore (see below) to transport fulfilled orders to packaging and shipping areas. Conveyors are less flexible once installed, hence some warehouse operators will choose mobile robots such as AGVs.

This video shows an integration of the AutoStore System and AGVs by Safelog at Sport Okay, an e-commerce company specialized in Alpine clothing and sports equipment and located in Innsbruck, Austria (empowered by Hörmann Intralogistics).

5. Automated Storage and Retrieval: Collaborative Mobile Robots in Picking

In addition to traditional AGVs, collaborative mobile robots (a subset of AGVs) can be used in warehouses to assist in picking operations. These robots work alongside human workers, guiding them through picking tasks and transporting picked orders to packaging and shipping areas. The downside to this, is that AGVs require more space than other automated systems for picking, and the fact that they rely on dust-sensitive sensors for operating properly. Overall reliability for picking operations therefore tends to be lower than other systems as they require strictly controlled surroundings and operate in an environment highly exposed to dust, (the warehouse floor).

Different types of Automated Guided Vehicles (AGVs)  

There are various types of Automated Guided Vehicles (AGVs) available, each designed to suit specific material handling needs and environments. We have listed the most common types below.

Automated Guided Carts (AGCs)

Guided carts or AGCs are the simplest form of AGVs that typically follow predefined paths or magnetic tracks. They are often used for transporting smaller loads or items within a facility, such as components or parts on assembly lines, or for carrying tools, waste, and equipment. Other use cases include:

• Sorting and storage applications
• Cross-docking operations
• Automated hospital cart transporters for meals, linens, waste, and supplies

Forklift AGVs

Forklift AGVs are designed to mimic the functionalities of conventional forklift trucks, but without the need for a human operator. They have forks to lift and place loads at various heights. Forklift AGVs are widely used in warehouses and manufacturing facilities for tasks such as stacking pallets, retrieving items from racks, and loading/unloading trucks.

Some forklift AGV use cases include:

• Warehouse operations for stacking and retrieving goods
• Production environments for supplying raw materials to production lines
• Distribution centers for loading and unloading goods

Unit Load AGVs

These AGVs are designed to transport individual unit loads, such as pallets, containers, or racks. They often have platforms or forks to support and move the loads. Unit load AGVs are commonly used in warehousing, distribution centers, and manufacturing facilities for tasks like pallet movement, loading/unloading, and storage.

Towing AGVs (Tuggers)

Towing AGVs, or tuggers, are used to pull or tow carts, trailers, or other wheeled devices autonomously, almost like a train. They are equipped with a hitch or coupling mechanism to connect and transport loads. Tow AGVs are often used in applications where multiple smaller loads need to be moved simultaneously, such as delivering materials to production lines.

Heavy Burden Carriers

For the heaviest industrial applications, heavy burden carriers are AGVs equipped to handle:

• Large assembly components
• Heavy casting and coil
• Plate transport in industries such as steel manufacturing and heavy machinery assembly

Some models feature self-loading capabilities and advanced steering options (standard, pivot, or omni-directional) to navigate through tight spaces and complex industrial environments.

Hybrid AGVs

Hybrid AGVs combine AGV technology with manual operation. They can operate autonomously, following pre-programmed paths, but can also be manually operated by a human operator when required. Hybrid AGVs are useful in scenarios where flexibility and adaptability are important, allowing for both automated and manual material handling operations.

Other mobile robots: Autonomous Mobile Robots (AMRs)

Autonomous mobile robots (AMRs) are, like AGVs, categorized as mobile robots and can often appear quite similar to AGVs at first glance. They do however differ in how they operate.

AMRs more advanced than AGVs in that they are equipped with sensors and cameras that allow them to understand and interact with their surroundings in real-time. They don't rely on predefined paths. Instead, they navigate by creating maps of their environment and making dynamic decisions about the best route to their destination, similar to how a smart car might navigate using GPS. This means AMRs can avoid obstacles, reroute themselves as needed, and adapt to changes in their working environment.

How AGVs Work

AGVs are designed to follow pre-defined paths or guidance systems within a facility. These paths can be determined by physical means such as magnetic tape, wires, or optical lines, or through more sophisticated methods like laser navigation using pre-installed reflectors.

1. Navigation and Guidance

AGVs navigate through environments using various guidance technologies, including:

• Magnetic Tape or Wire: AGVs follow a path defined by magnetic tape or a wire embedded in the floor. The vehicle detects the magnetic field or electrical signal to follow the predetermined route.
• Laser Navigation: AGVs equipped with laser navigation use reflectors placed around the facility. The AGV emits laser beams that bounce off these reflectors, and the vehicle calculates its position based on the time it takes for the light to return.
• Optical Navigation: This method involves AGVs following visual markers or lines painted on the floor.
• Inertial Navigation: AGVs use gyroscopes and accelerometers to track their movement from a known position, allowing them to navigate based on calculated changes in position over time.
• GPS Navigation: In outdoor applications, AGVs can use GPS for navigation, although this is less common in indoor settings due to limited satellite signal reception.

2. Obstacle Detection and Safety

AGVs are equipped with sensors and safety mechanisms to detect obstacles and ensure safe operation. Common safety features include:

• Lidar and Ultrasonic Sensors: These sensors detect obstacles in the AGV's path and can trigger the vehicle to slow down or stop to avoid collisions.
• Bumpers: Physical bumpers may trigger an emergency stop if the AGV comes into contact with an object or person.
• Emergency Stop Buttons: Manual stop buttons allow humans to immediately stop the AGV if necessary.

3. Communication and Control

AGVs are part of a larger automated system and communicate with a central control system to receive instructions and coordinate with other vehicles and systems. Communication can occur via:

• Wi-Fi: AGVs connect to a central control system through wireless networks to receive routing information and task assignments.
• RFID Tags: Radio-frequency identification tags embedded in the floor can provide location data to AGVs and trigger specific actions when detected.

4. Power and Propulsion

AGVs are typically battery-powered, with electric motors providing the propulsion. Battery management is crucial, and systems are in place for charging, either through manual battery swaps, automatic charging stations, or inductive charging paths.

Advantages and disadvantages of AGVs

Automated Guided Vehicles (AGVs) offer a compelling blend of advantages for various industries, particularly those involved in manufacturing, warehousing, and distribution. However, like any technology, they come with their own set of challenges. Here’s a look at the benefits and potential downsides of implementing AGVs in operations.

Advantages of AGVs

1. ‍Reduced Labor Costs: AGVs can significantly lower the costs associated with manual labor by taking over repetitive and routine tasks. The initial investment in AGVs may be substantial, but over time, the reduction in expenses related to salaries, benefits, and potential human resource issues can lead to considerable savings.
2. ‍Increased Safety: Equipped with advanced sensors and safety features, AGVs reduce the risk of workplace accidents. They can operate in environments that may be hazardous or challenging for human workers, such as extreme temperatures or areas with hazardous materials.
3. ‍Increased Accuracy and Productivity: AGVs reduce the likelihood of errors associated with human fatigue or oversight. Their ability to operate continuously, without breaks or shifts, means they can significantly enhance productivity, ensuring a steady flow of operations round-the-clock.

Disadvantages of AGVs

1. ‍Not Suitable for Non-repetitive Tasks: AGVs excel in controlled environments where tasks are consistent and repetitive. In operations where tasks vary widely or require human judgment, AGVs may not be as effective, limiting their applicability to certain types of work.
2. ‍Decreased Flexibility of Operations: The reliance on pre-set paths and tasks can make AGVs less adaptable to sudden changes in operational requirements. While human workers can quickly shift roles or tasks, AGVs may require reprogramming or system adjustments to adapt to new demands, potentially reducing operational agility.
3. ‍Reliance on dust sensitive sensors: AGVs rely on sensors, cameras, and other navigation technologies to move and perform tasks within their operating environments. Dust and particulate matter can interfere with these systems, potentially leading to operational inefficiencies and downtime. For instance, dust accumulation on sensors may reduce their accuracy or block their function entirely, requiring regular cleaning and maintenance to ensure optimal performance.
4. ‍Increased space requirements for warehousing: In comparison to other automated storage and retrieval (AS/RS) solutions like cube storage systems, AGVs require wider aisles to accommodate their movement and operational clearance. This increased footprint must be considered in the total cost of operation and can impact the overall warehouse design and efficiency. When compared with other automated technologies like conveyors however, AGVs are far more flexible and space-efficient.

Alternatives to AGVs

AGVs have revolutionized manual operations in warehouses and manufacturing environments, enhancing efficiency and reducing the need for manual labor. However, they might not be the perfect fit for every business scenario. Warehouse automation technology has developed significantly over the last decade, making room for more efficient automated storage and retrieval systems. Below are some examples that tend to have higher reliability, space optimization and long-term ROI:

Conveyor Systems vs. AGVs

The main difference between AGVs and conveyor systems are their fundamental design: conveyors are stationary systems that require a fixed path for operation, whereas AGVs are mobile, allowing them to navigate freely across a facility. This distinction brings us to a crucial consideration—the impact on facility space utilization. Conveyor systems, by their very nature, demand a significant amount of dedicated space within a facility to be set up and operational. This requirement can pose challenges for operations with limited space or those that need to maintain flexibility in their layout design.

In contrast, AGVs offer a more flexible solution that requires less dedicated infrastructure, making them a viable option for facilities with space constraints or those prioritizing adaptability in their operations. However, the choice between adopting a conveyor system or deploying a fleet of AGVs isn't solely a matter of space. It also hinges on the specific demands of your operation. For instance, environments with a continuous or near-continuous flow of goods might find conveyor systems more beneficial due to their ability to handle high volumes of materials efficiently and reliably.

Automated Storage and Retrieval (AS/RS) vs. AGVs

Automated Storage and Retrieval Systems (AS/RS), such as cube storage solutions, offer a comprehensive alternative to AGVs by providing both transportation and storage capabilities. Both AGVs and AS/RS can deliver goods-to-person for order fulfillment and replenishment, eliminating the need to walk, but AS/RS systems also take care of the storage aspect.

However, AGVs require accessible aisles and often more spread-out storage configurations to navigate through the warehouse, which can lead to a higher use of warehouse space. A significant advantage of cube storage AS/RS is its ultra-dense storage capacity, which can free up to 400% of the space occupied by traditional shelving required for AGVs.

Furthermore, cube storage systems within the AS/RS framework can serve other roles within an operation, including providing buffer storage between different stages of the workflow, staging orders for shipping, and integrating seamlessly into a G2P strategy. This versatility allows operations to address a wider range of logistical challenges beyond mere material transport—challenges such as inventory management, order fulfillment efficiency, and space optimization.

However, cube storage AS/RS requires inventory to be placed in Bins or totes that are stacked in a very tight Grid. Robots navigate at the top and sort, optimize, and retrieve inventory bins and deliver them to workstations for picking or replenishment by humans. This means that products must fit in the Bins in order to be automated with cube storage technology. AGVs can be a highly suitable option for integrating with cube storage and automating the material handling of larger items that are not suitable for storing within the Grid configuration.

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Autonomous Mobile Robots (AMRs) vs AGVs

As mentioned earlier, AMRs are quite similar to AGVs, but differ in their navigation methods. Whereas AGVs require pre-determined paths to operate autonomously, AMRs navigate using onboard sensors and maps, allowing them to maneuver around obstacles and choose different paths to a destination, similar to a robot vacuum cleaner. This flexibility makes AMRs more suitable for dynamic environments where the layout changes or where they need to interact with humans and other equipment. They can be particularly useful in facilities that require a high degree of adaptability or in spaces where installing physical guides for AGVs is impractical.

In choosing between the two, it boils down to the predictability of the operational environment for AGVs, versus the need for flexibility and the ability to adapt to changes for AMRs.

Overhead Trolleys vs AGVs

• Overhead trolley conveyor systems present an intriguing option for warehouse and distribution center operations, standing out as a distinct alternative to both traditional conveyor belts and Automated Guided Vehicles (AGVs). These systems, which can be powered or non-powered, offer a unique method of transporting products and materials by utilizing a chain that moves within an enclosed track in a closed-loop configuration. From this chain, various fixtures—such as hangers, trolleys, or wire baskets—are suspended to carry the specific materials being transported.

Compared to AGVs, overhead trolley conveyors offer a few advantages:

• Space Efficiency: By utilizing overhead space, these conveyors free up floor space for other operations, something particularly beneficial in crowded or limited-space environments.
• Specialized Handling: They provide solutions for specific handling requirements that AGVs might not be able to accommodate as efficiently, such as the transport of GOH or items requiring hanging or specific orientations during transit.
• Continuous Operation: Overhead trolley systems can offer a continuous flow of materials, which is especially useful in production line applications where steady material delivery is critical.

Integration of AGVs to AutoStore and other systems

If you are considering AGVs, integration with existing warehouse systems is a crucial step. AGVs can be integrated with various warehouse management systems (WMS) types or enterprise resource planning (ERP).

Integrating AGVs into the AutoStore cube storage AS/RS, warehouses can extend the efficiency beyond the Grid. Although conveyor technology is the typical choice, AGVs can be used to transport packed orders from the AutoStore workstation to other parts of the warehouse, or directly to shipping areas. This reduces manual handling and speeds up the process of getting products from storage to their next destination. In cases where warehouses require more flexibility compared to conveyor technology, AGVs can be an excellent choice.

Summary

To summarize, AGVs are self-operated vehicles designed to transport goods within controlled environments such as warehouses, often taking over tasks typically done by forklifts or conveyor systems. The adoption of AGVs enhance material handling with automation, boosting safety and productivity compared to manual operations. Although AGVs are suitable for many material handling tasks in the warehouse, options such as cube storage AS/RS require significantly less space and are more suitable for high-throughput operations of smaller to medium sized items. Integrating AGVs with cube storage AS/RS can be a compelling solution. Learn more about SportOkay where they installed both AutoStore cube storage AS/RS and AGV technology.

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FAQ

What is an AMR vs AGV?

An AMR (Autonomous Mobile Robot) is a broader category that includes AGVs, with AMRs being more flexible and capable of navigating in dynamic environments, while AGVs typically follow predetermined paths.

What are the types of automated guided vehicles?

There are several types of AGVs, including unit load AGVs for transporting pallets or containers, tow AGVs for pulling carts or trailers, forklift AGVs for lifting and placing loads, guided carts for smaller loads or assembly line tasks, AGVs with custom attachments for specialized tasks, and hybrid AGVs that combine automated and manual operation.

What are the challenges associated with implementing AGVs in a warehouse or factory setting?

Challenges associated with implementing AGVs in a warehouse or factory setting include the need for infrastructure modifications, ensuring compatibility with existing systems, addressing safety concerns and regulations, conducting thorough training for employees, and optimizing AGV workflows for seamless integration into existing operations.