AGV Solutions

AGVs are a flexible warehouse automation solution

Automated guided vehicles – sometimes called self-guided or autonomous guided vehicles – are driverless machines that handle repetitive tasks traditionally managed by forklifts, conveyors, or carts. These computer-controlled vehicles follow a predetermined path of sensors, magnetic tape, or other navigation aids.

Computer control means these machines can perform repetitive tasks more accurately than human workers, without distraction or fatigue. Their compact size and flexible programming make it easy to slot them into whatever application is needed at the moment and move them if needs change.

AGVs are far more adaptable than other types of warehouse automation. They need less infrastructure than an automated storage and retrieval system (ASRS) and can be easily modified to take on new tasks. They can be used throughout your facility or stay localized to one area, and can work with other software-based systems or with human workers.

Applications for AGVs

Self-guided vehicles are commonly used to move large quantities of material around a warehouse or manufacturing facility. Here are some typical applications:

Keeping production lines stocked

An AGV can keep production lines running smoothly by making sure each workstation always has the materials it needs. When stocks are running low, the vehicle can fetch more while the line continues to move. Production never needs to stop while someone runs to the warehouse for more raw material.

Moving work in process

As products are finished at one workstation, an automated vehicle can move them along to the next. The right AGV maximizes production line efficiency by eliminating the downtime of moving products by cart or forklift. It also makes the best use of space by reducing the need for bulky conveyor systems.

Warehouse replenishment

There is no reason to waste the abilities of a human worker on simple, repetitive work like moving product from receiving into storage and from long-term storage to forward picking locations. An automated vehicle is ideal for monotonous tasks like these.

Losses due to damage are reduced as the vehicle is programmed to handle every load with the care it requires. Its high-tech guidance ensures product is placed in the right location every time.

Warehouse picking

Some smart vehicles, like collaborative mobile robots, make picking faster and more efficient. They can guide warehouse associates right to the product they need and transport picked orders directly to packaging and shipping stations.

With the help of automation, warehouses can pick and ship more orders in less time. Improved order accuracy means fewer losses from wrong-order returns.

Benefits and challenges of AGV automation systems

Like any tool, automated guided vehicles come with pros and cons.

Benefits

All warehouse automation systems come with similar advantages – improvements to safety, accuracy, and productivity; loss reduction; and scalability.

Improved safety

Machines don’t get tired or distracted. They handle the last load of the day with the same level of care as the first. As human workers grow tired, safety protocols may be missed and those that are followed can become sloppy.

Most vehicles also include built-in safety features reducing the frequency and severity of accidents resulting in injury.

Improved accuracy

Human judgment can result in human errors like stocking inventory in the bay next to where it’s supposed to go or picking a product with a SKU ending in 67 instead of 61. An automated system doesn’t make those mistakes.

Improved efficiency

Automating repetitive tasks frees up human workers for more complex tasks. Introducing an automated system to a process like order picking reduces downtime and allows workers to use their time more productively.

Reduced losses

Warehouse automation systems reduce losses due to handling damage. The machine’s sensors tell it when a load is off balance or unsafe to pick up. Its programming guides it in how gently to put down a load. Together, this results in fewer broken products.

Scalability

Automated systems make scaling an operation easier and more affordable. Improved efficiency means you can handle more orders while delaying hiring more people. The ability of AGVs to fit into any part of your facility means you can dial their use up or down in different areas as you scale.

Challenges

Implementing AGVs is not without its challenges. It’s important before you begin that you understand what’s required to successfully use these machines.

Reconfigured plant layouts

Some legacy plant layouts aren’t conducive to using automated vehicles. Designing a logical path for the machine to travel might require moving workstations or existing heavy equipment. Workflows might have to be reconfigured to move product efficiently.

Navigation confusion

AGV sensors scan their environment and compare it to their preprogrammed map to navigate around obstructions.

Sometimes these sensors might misread the environment. For example, the vehicle might interpret a storage rack up on legs as a passage rather than a wall and try to pass through it. To avoid accidents, you have to understand how the vehicle sees its environment. You may have to make adjustments like wrapping the space between rack legs so the vehicle doesn’t make a mistake.

Movement limitations

Your vehicle’s top speed, turn radius, and directions of movement are determined by the manufacturer. If you need a vehicle capable of moving in reverse, for example, make sure the model you choose has a backup feature. Features like rear-facing sensors and zero-turn radius do not come standard and may drive up the cost of your desired model.

Hit-and-run collisions

Built-in safety features should stop most vehicles from plowing through a collision. However, the machine’s objective is to complete its course. If it hits an obstruction – whether that obstruction is a misplaced pallet, a moving forklift, or a person – the machine will stop, look for an alternate route, and continue. It’s not making a conscious decision to “flee the scene,” it’s just trying to do its job.

This means it’s not a good idea for forklifts and AGVs to share pathways, or for the AGV lane to overlap lanes where other equipment is moving quickly.

True cost of ownership

Compared to a full-time employee or an ASRS, the upfront cost of an AGV is a bargain. But it’s important before investing in your fleet that you think through the full cost of ownership, including changes to plant layout, software licenses, and the additional power draw.

The facilities best suited to AGVs have a steady year-round workflow. The daily pace is also consistent, so the vehicle remains constantly busy throughout the day. If your business is heavily seasonal or the machines are likely to sit idle for long periods of time, these vehicles will probably not be the best investment for you.

The AGV implementation process

AGVs are a flexible and cost-effective way to automate warehouse processes. But your savings can disappear if you don’t take care to implement them carefully in the locations that make the most sense.

Before committing to a vehicle model, assess the workflows in your facility. Determine where automation could be the most useful, and choose your equipment accordingly.

How to implement an AGV warehouse system

1. Once you know where and how you want to use automated vehicles, set up the pickup (Point A) and dropoff (Point B) locations. Consider the following questions:

• • - How often will the machine make this trip?
  • - What kinds of loads will it carry?
  • - What are the loading requirements?
  • - How much material will be in a typical load?
  • - What is the largest load we might expect?
  • - What is the most efficient route from Point A to Point B?
  • - What is the most efficient alternate route?
  • - What special considerations (lifts, ramps, gates, etc.) might the machine encounter?

2. Assess your IT infrastructure. An AGV isn’t a plug-and-play piece of equipment. Before you begin, consider any systems the vehicle’s programming will need to integrate with, such as a warehouse management system. Review your building’s electrical capacity to ensure charging stations can be fully powered. Assess your wireless network to be certain the vehicle won’t hit any dead spots on its travels.

3. Set up the machine’s routes. It’s advisable to have a primary route and an alternate route in case the primary route is temporarily unavailable. The route infrastructure depends on the type of vehicle you choose. Common navigation mechanisms include

• • - Magnetic guide tape
  • - Buried wires
  • - Laser targets
  • - Gyroscopic navigation
  • - Vision guidance sensors
  • - Geoguidance
  • - LiDAR

4. Install and test the vehicle interface. This includes software, I/O boxes, and PLC controllers.

5. Once everything is installed and tested, train employees in how to work with the AGV. Those workers who will be directly involved with the machines should learn how to charge them, how to engage with them, basic maintenance, and troubleshooting. Those workers who will not work directly with the machines but will work on the floor alongside them should be trained in how the machines operate. The machines will execute their programming and may not be able to tell if a human is blocking their path. Everyone must be trained in how to work with these automated systems safely.

Choosing the right AGV

Once you’ve decided to implement an AGV warehouse system, you still have to decide which vehicle is right for you. There are a variety of sizes and features available to accommodate the most common uses. Before choosing a model, consider what you need it to do.

Choose the right type

Just like passenger vehicles, automated guided vehicles come in a variety of models, and the best one depends on your use case. You wouldn’t buy a sports car to travel with a large family. Likewise, a wholesale distributor moving heavy pallets shouldn’t buy a compact AGV.

Most AGV models fall into one of four categories: compact, standard, custom, and hybrid.

Compact

These are the smallest and most basic automated guided vehicles. They might be just a little bigger than the robot vacuum you have at home. Like your robot vacuum, they may navigate using sensors and AI, or they may simply follow a magnetized path.

The most common type of compact vehicle parks itself beneath a rack then uses hydraulics to lift the entire rack. They’re a good choice for facilities moving small, containerized loads.

Standard

Standard-size AGVs are typically equipped to work as forklifts, towing vehicles, or unit load handlers. They’re about the size of a narrow-aisle forklift, and designed for moving product in bulk.

Fork vehicles are essentially a driverless forklift and perform the same tasks a manned forklift would handle. Towing or tugger vehicles pull carts behind them like a train. Unit load handlers carry individual loads such as a single pallet, object, or tote.

Custom

If you’re working with products with an unusual shape or odd size that can’t be managed by traditional material handling equipment, you can have a standard AGV customized to meet your needs.

Heavy-burden carriers are a common type of custom vehicle. They’re typically used in heavy assembly; some even have the ability to load themselves.

Hybrid

A hybrid AGV has the best of both worlds. Like all automated vehicles, it uses guidance systems to follow a programmed routine. However, it also has manual controls. When needed, a human operator can take over. Whatever path you take for the bulk of your fleet, you may want to consider including one or two hybrid models for the flexibility they offer.

Choose the right traffic control measures

Traffic control is critical for avoiding collisions. Remember, the machine doesn’t have the human ability to see oncoming traffic and judge when it’s safe to proceed. When selecting vehicles for your facility, you will have the option of choosing a vehicle with zone control or collision avoidance.

Zone control keeps AGVs from crashing into one another. A signal is sent from a wireless transmitter and picked up by a sensor on the vehicle. The transmitter may be stationary, or each vehicle might be equipped with its own.

If there are no other AGVs in the area, the transmitter will send an “all-clear” signal telling the vehicle it’s safe to proceed. Once that vehicle enters the area, the transmitter sends other vehicles a “do not enter” signal that tells them to stop and wait.

Collision avoidance systems are similar to sonar. They send out a sonic or infrared signal and wait to see if it bounces back, indicating an obstruction. Most vehicles are also equipped with bumper sensors, which work to avoid – or at least minimize – a collision when they sense physical contact.

If you plan to have multiple AGVs navigating the same area, your best bet is to equip them with both zone control and collision avoidance sensors. This helps them to avoid collisions with each other and other obstructions in their environment, and provides a fail-safe if their primary traffic control system goes down.

Choose the right steering mechanism

Automated vehicles steer using steered wheel control, differential speed control, or a combination of the two.

Steered wheel control is the smoother and more precise of the two options. It works much like the steering system in your car, and in a hybrid vehicle it can be controlled by an operator. It’s the best choice for towing applications because the sharp turns of differential speed control can cause trailers to jackknife.

Differential speed control is more like the steering system of a remote-control car. It uses two drive wheels, which each turn at a different speed to allow the vehicle to turn. It is the simpler of the two options and the best for tight spaces.

In a combination model, the vehicle has two drive motors on diagonal corners and swiveling casters on the other two corners. It can be steered with a wheel or in differential mode in any direction.