AGV and AMR: What's the difference?

The SYNAOS Intralogistics Management Platform holistically manages and optimizes intralogistics. Here, fleets of self-propelled transport units are increasingly being controlled. A typical fleet includes AGVs and AMRs — but what is actually the difference between these two types of vehicles?

In logistics centers and production halls, there are always lots of pallets, crates, mesh boxes, racks and numerous other things to transport. Forklifts with people driving, for example, do this job. In addition, there is an increasing number of driverless transport systems (AGVs) with vehicles that move goods autonomously from A to B.

These driverless transport vehicles (AGVs) include Automated Guided Vehicles (AGVs) and Autonomous Mobile Robots (AMRs). Although both perform the same tasks, the abbreviations should not be used synonymously — both vehicle types differ and have specific characteristics.

The A in AGV stands for Automated, while the A in AMR for Autonomous stands — a small difference with great significance. As the name suggests, AMRs act autonomously and avoid obstacles that suddenly block their path, for example. AGVs, on the other hand, travel on fixed routes and can only perform predefined tasks by automatically following instructions. In contrast, AMRs make their own decisions when a situation requires it.

FOLLOW THE MAGNETIC STRIP!

The first driverless vehicles found their way back in the 1960s with photoelectric control, i.e. via a colored strip on the ground, which they stubbornly followed. Today, AGVs are also controlled inductively or magnetically, for example via magnetic strips laid in the hall floor. The setup is inexpensive and fairly simple, and the process has also been tried and tested for many years. However, subsequent changes to the routes require a certain amount of effort, as the magnetic strips have to be relocated, which limits the flexibility of driving courses. Repairing guidelines also requires more effort.

Software controls AGVs so that they move material through halls without accidents. Sensors serve as “eyes and ears” for them. In addition, vehicles need physical control elements on the routes to guide them — such as the mentioned magnetic strips or individual magnets and transponders for grid navigation. Laser navigation and guidance through virtual guidelines require reflector marks as reference points in the area. These are attached to walls or pillars, for example, and reflect the incoming laser light back to the sensor. By triangulation, the vehicle can determine its current position.

BE CAREFUL, OBSTACLE!

AGVs are pre-programmed and always take fixed routes. They recognize obstacles with lidar sensors: If they detect a worker who is suddenly in the way of the vehicle, it stops and waits until the path is clear again. Because AGVs only travel on specified routes, they cannot simply drive around the obstacle. If a pallet falls onto the track, the vehicle brakes and waits until an employee removes the obstacle. Only then does the journey continue.

Such disruptions not only extend transport times, but can also have far-reaching effects on production: If, for example, an urgently needed component does not arrive on the production line in time, there is a risk of an expensive production stop. The SYNAOS Intralogistics Management Platform helps to react quickly to unforeseeable events: As soon as a route is blocked, the software finds another path and diverts AGVs in good time.

FREE NAVIGATION FOR AMRS

AMRs are considered a technical development of AGVs. They virtually mark the next stage of evolution within driverless transport vehicles. The mobile robots work with their own algorithms to find the right path. They do not require any conductive magnetic tracks in the ground, fixed reflectors or stationary transponders. Instead, AMRs rely on their own sensors, computer vision, and software. As a result, their routes are more dynamic and flexible than those of AGVs.

Because of their capabilities, AMRs' responsibilities are more diverse. They are particularly suitable for dynamic environments in department stores or factories. The vehicles are able to make independent decisions and select the best solution for the current situation from a variety of possible solutions. AMRs — just like AGVs — receive their orders from a control system or a fleet manager.

With machine learning, AMRs are getting better at completing their jobs quickly. They get to know their surroundings and can reach almost every corner in a factory or warehouse. They act more efficiently and more accurately than AGVs, and they are also more flexible when problems arise or unexpected situations arise. However, the vehicle computers must be powerful because they must process a large amount of data in real time, which their sensors provide them with.

When a person or an object blocks their path, AMRs react more dynamically than AGVs by stopping as well, but then driving around the obstacle and looking for a new path. The quick Re-routing saves time and reduces process disruptions. There is no need for human intervention.

IT DEPENDS ON THE SOFTWARE

The degree of autonomy may vary. It is also dependent on the built-in camera and sensor technology and their ability to recognize spatial conditions. Of course, it also depends on the quality of the software and algorithms: After all, you have difficult tasks to solve, over and over again.

A digital indoor map of the environment stored in the vehicle makes it easier to navigate the operating environment. The AMR can also create such a map completely by taking orientation trips. This form of localization and mapping is known as SLAM (Simultaneous Localization and Mapping). The SLAM algorithms also process deviations in the real world and compare them with the stored map information and adjust it. So when a new shelf is set up in a warehouse, the AMR includes it in its card.

SUMMARIZED AGAIN

In general, AMRs should be regarded as an evolution of AGVs. Because the vehicles have greater autonomy, they can be used more flexibly. Some manufacturers see SLAM navigation as a unique selling point of AMRs. In practice, however, not every vehicle can be clearly classified in one of the two categories — the offer is too fragmented for that. Here and there, the abbreviation AGV has also established itself as a general generic term, which also includes AMRs or LGVs (Laser Guided Vehicles).

However, one thing is certain, whether AGV or AMR and all forms in between: The choice of the right higher-level control and optimization software is decisive for success! Die SYNAOS Intralogistics Management Platform With its hardware-independent design using DNA, is predestined for this complex task. The operating system monitors, controls and optimizes everything in intralogistics — AGVs, AMRs, forklifts and order pickers. The algorithms distribute pending orders holistically across all vehicles so that they can process the entire pool much more efficiently. SYNAOS makes the difference.

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