Autonomous Mobile Robots

The Right Automation Choice for your Business?

New to autonomous mobile robots or AMRs? This guide explains what mobile robots are, how they work, and the different benefits these solutions can offer forward-thinking businesses. Jump right in then, and if you have any questions just get in touch

What are autonomous mobile robots (AMRs)?

Autonomous mobile robots (AMRs) are robotic vehicles that operate without the need for human control or intervention. Not to be confused with automated guided vehicles (AGVs), AMRs typically move dynamically around any obstacles they encounter. They are usually also smaller than AGVs.

The advantages of autonomous mobile robots are numerous. AMRs are a highly efficient transportation solution. And they do what they are programmed to do each and every time. With their relatively small vehicle footprints and dynamic movement, they are well suited to space-limited environments such as high-tech manufacturing plants and e-commerce fulfilment centers.

Note: AMRs are sometimes referred to as automated mobile robots, autonomously guided robots or simply mobile robots.

What is the difference between an AMR and an AGV?

The U.S. safety standard for industrial mobile robots, ANSI/RIA R15.08-1-2020 (R15.08) defines the difference between AGVs and AMRs as “how they traverse the specified operating environment”.

According to the standard, an AGV moves through an environment by following predefined guide paths — either virtual or physical — and using collision avoidance (stopping and waiting in case of a blockage). By contrast, the standard defines AMRs as being able to “traverse the specified operating environment by detecting obstacles using sensors, and adjusting paths by computing an obstacle-free path through free space, rather than using a pre-defined path.” In other words, by using obstacle avoidance.

While many in the industry use this definition, others define AMRs as being those mobile robots that use natural navigation to move around (which is largely what makes obstacle avoidance possible).

“The global autonomous mobile robot market was valued at USD 1.9 billion in 2019 and is expected to grow at a compound annual growth rate (CAGR)of 19.6% from 2020 to 2027.” Grand View Research

How do autonomous mobile robots work?

Autonomous mobile robots travel along a pre-determined route or path through a facility, stopping to perform pre-programmed actions. If we take the definition of AMRs mentioned above, whereby vehicles move dynamically around obstacles, then the path followed is a virtual one. This path is programmed in the robot’s navigation software.

An AMR’s position and subsequent movement are calculated and controlled using a combination of software and sensors (such as LiDAR-based laser scanners).

Advanced AMRs can also work as part of a larger connected fleet. Fleet management software such as ANT server is used to schedule jobs, distribute these between robots, and control traffic (for example at intersections).

How do AMRs navigate?

In the vast majority of cases, the autonomous mobile robot navigation technology used by these machines is natural navigation. This is sometimes called free navigation.

The use of natural navigation allows AMRs to avoid obstacles by creating dynamic alternative routes without the robot losing positioning accuracy or becoming lost. Avoiding obstacles is virtually impossible with physical line following technologies, such as those that follow magnetic tape, tags or QR codes.

Types of natural navigation

There are two main types of natural navigation used by mobile robots today:

Scan matching (sometimes called SLAM navigation)
Feature matching (used by ANT natural feature navigation)

With scan matching technology, measurements from the vehicle’s laser scanners are compared (matched) to the cells of a grid-based reference map of the environment. These cells can be compared to pixels in a digital image.

With ANT feature matching technology, measurements from the vehicle’s laser scanners are compared to permanent map references (features) such as walls and pillars. Should part of a site not have enough distinctive features, reflective stickers can also be added to provide additional references.

If the reference map used by scan matching navigation can be compared to a digital image made up of pixels, the reference map of a feature matching vehicle is similar to a line drawing.

scan vs feature matching

Are autonomous mobile robots safe?

Yes. With their controlled movements, consistent speed and certified safety systems, automated vehicles such as AMRs, automated forklifts and automated guided vehicles are a safe, highly reliable solution. Unlike humans, robots do not get tired and are therefore not prone to fatigue-induced errors.

“If a job is repetitive and boring, human workers tend to make a mistake, whereas robots can do these things the same way time after time.” Frank Hearl
Chief of Staff, The National Institute for Occupational Safety and Health (NIOSH)

Brief well to minimize risk

When it comes to mobile robot safety, perhaps the time of highest risk is during a system’s initial installation — when its routes and actions are being tested, and when human team members are getting used to having these solutions on-site. The key to minimizing this risk is to fully brief staff so that everyone is aware of what the robots will do, how they will work, and how to interact with them. Such training can also improve staff acceptance of these technologies (as can personalizing robots with names or faces).

How are AMRs powered?

Mobile robots are almost always battery powered. Most are designed to dock and recharge at automatic charging stations. Since they do not need to be manually plugged in, they therefore suit 24/7 operation.

Do AMRs suit low-emission environments?

BlueBotics mini ABB

Some do, yes. For organizations that require their robots to run in environments like laboratories and clean rooms, there are several solutions available today that feature very low levels of particle emission. The BlueBotics mini™ is just one example.

What types of software are required to run autonomous mobile robots?

The operation of AMRs is based on two main types of software:

Configuration software
This is typically used by a robot’s integrator (e.g., its manufacturer or a third-party integrator) when installing these solutions on-site. This software is used to calibrate the vehicle before it starts working, to map the site, and to program the robot’s routes and actions. An example of such software is ANT lab by BlueBotics, which is used to program ANT driven vehicles.
Mission & fleet management software
By contrast, mission and fleet management software is configured again by an integrator, but then used on a day-to-day basis by a robot’s end operator to manage, call and schedule AMR missions. This type of software, such as ANT server, can often interface via API with equipment (such as elevators and automatic doors) and a site’s existing WMS/MES/ERP software.

Types of automated mobile robots

Since AMRs are defined as systems that navigate dynamically around obstacles, they are usually smaller than automated guided vehicles. They suit the tightest of environments, such as fully automated distribution centers. By contrast, AGVs, with their more predictable ‘stop and wait’ approach to obstacles, suit heavier production and intralogistics applications.

“Industrial robots typically have been used for tasks considered undesirable for human workers – what RIA Vice President Bob Doyle described as 'the three Ds: dull, dirty and dangerous jobs'.” Safety & Health Magazine

The following types of autonomous mobile robots are most common:

Underride robots (automated guided carts or AGCs)
Unit load carrier robots
Forked AMRs
Cleaning robots
Picking robots
Sorting robots

Let’s explore each of these types of AMR in more detail:

Underride robots

Also called: automated guided carts or AGCs

Underride AMRs are one of the most common types of mobile robot, used to transport racks, trolleys and similar payloads. They connect to these, for example, by using pins or fully integrated lifting modules.

Unit load carrier robots

AMRs like the BlueBotics mini™ lite are perfectly suited to the transportation of small and medium weight payloads, such as boxes and trays. A range of top modules, including lifts and conveyors make these AMRs endlessly flexible. Robot arm options and a myriad of custom modules are also available.

Forked robots

Although less common, forked mobile robots do exist. These are usually the smallest form of automated lift truck: the pallet truck AMR. Automated guided forklifts (or AGFs) are heavier vehicles and are classed as a type of AGV.

Cleaning robots

Autonomous cleaning robots such as the Cleanfix RA660 Navi use obstacle avoidance just like any other AMR. However, rather than following pre-programmed routes to transport materials or goods around a facility, cleaning robots are programmed to cover a defined surface area such as a shop floor or the corridors of a mall.

Picking robots

Used to reduce fulfilment times in distribution centers, picking robots can be goods-to-person AMRs, used to bring bins of products to human order pickers, or to retrieve orders from human pickers based in the aisles themselves. Picking robots typically feature a set-height platform onto which different containers can be connected or placed. Note: many picking robots navigate by following QR or other codes/tags on the floor, not natural navigation.

Sorting robots

Sorting robots are used to sort products into pre-programmed batches, for example to transport these to an outbound/shipping zone or deposit goods into the correct bin within a fulfilment center. Similar to picking robots, sorting robots feature a range of tray, box and rack type payloads and connection mechanisms. Note: many picking robots navigate by following QR or other codes/tags on the floor, not natural navigation.

Advantages of autonomous mobile robots

When it comes to automating a site’s mobile processes, the advantages that autonomous mobile robots offer are numerous. These ‘always on’ robotic helpers do exactly as they are programmed —they don’t require breaks, vacations, or even to work in the light, and they feature built-in safety systems.

Specific AMR benefits include:

Flexibility

Most AMRs use natural navigation to get around, making these systems inherently flexible.

They are quick to install.
Their routes and actions can be modified easily.
They do not require major infrastructure changes prior to operation (such as laying lines on the floor or installing permanent reflective targets on the walls).
Natural navigation is also fleet-ready, allowing mobile robots — such as those driven by ANT — to be connected in a scalable fleet.

Cost optimization

Deploying AMRs is an obvious way in which businesses such as fulfilment centers and manufacturing plants can minimize their human staffing costs.

Mobile robots can run virtually 24/7 (only stopping to charge their batteries), without the additional overheads humans create.
Depending on their usage, AMRs also offer additional cost-related benefits such as: minimal wear and tear on components; likely zero damage to materials/infrastructure (unlike human-operated machines), consistent costs over time etc.

Efficiency

Autonomous mobile robots offer a real efficiency boost by minimizing how much human workers need to move around, for example to pick orders or to transport parts to an assembly line.

An AMR’s movements are programmable and repeatable.
Robots do not need to sleep (or take vacations), only stopping to recharge their batteries.
AMRs, therefore, suit organizations aiming for 24/7 operation.

Quick to install & modify

Since autonomous mobile robots are usually based on natural navigation technology, they are quick to install (no major infrastructure changes required) and their routes and actions can be easily modified.

This is a clear benefit over more traditional types of automated guided vehicles, which might get around by following physical lines on the floor or by firing lasers at reflective targets (laser triangulation) to calculate their position.

Easy to scale up/down

Commissioning (installing) AMRs that run on natural navigation technology is relatively straightforward.

Adding additional robots as requirements or operations expand is simple.
Robots can also be removed from a connected fleet if operational requirements drop, due for instance to seasonal demand. This is especially true if operating robots via a monthly ‘Robots as a Service’ (RaaS) subscription.

Disadvantages of autonomous mobile robots

Despite the many potential benefits of deploying AMRs, there are some potential limitations in certain settings. It is therefore worth being aware of these in advance.

Smaller payloads

Since autonomous mobile robots – by definition – must be able to navigate dynamically around obstacles in their path, they tend to be smaller than AGVs. It follows then that AMRs cannot transport as heavy payloads as AGVs.

In one sense this is a positive, as the idea of having a huge AMR pulling carts full of heavy goods or machinery, moving wherever it wants, is enough to worry most site managers and their employees (that’s why most AGV makers employ ‘stop and wait’ path following, rather than obstacle avoidance, as their navigation mode of choice).

Consider the likely size and weight of your vehicle’s payloads when researching your vehicle choices.

Obstacle avoidance does not always make sense

Does obstacle avoidance always mean greater efficiency? It might seem counterintuitive, but in truth the dynamic obstacle avoidance used by AMRs is not always the most effective approach.

For some types of applications, moving around obstacles makes perfect sense, such as with a scrubbing robot that needs to clean a commercial center with high foot traffic. But for other situations, a vehicle that stops and waits while well-trained staff move a blockage might achieve its tasks more quickly overall.

The best approach for your specific operation depends on various factors, such as your site’s complexity — which impacts the availability of alternative routes and aisle widths, for example — and the number of other robots that might be moving around doing the same.

AMRs have very specific site requirements

Autonomous mobile robots require specific on-site conditions to work effectively.

If AMRs use natural navigation to get around, lighting conditions will not be a factor. However, flooring might be. Most mobile robots do not deal well with uneven floors, slopes, and wet, slippery surfaces.

Therefore, make sure you understand a mobile robot’s environmental preferences before you move forwards with any investment.

6 things to consider when choosing an autonomous mobile robot

You have done your initial research. You have learned the basic of autonomous mobile robots and how they work. And you have analyzed the processes and workflows you would like to automate. Now, how do you move prudently from this stage to shortlisting possible solutions?

As you browse your vehicle options, there are several key questions to keep in mind before investing in a mobile robot:

1. How is the robot installed and its operations modified?

Will commissioning a particular mobile robot take hours, days, or weeks? Who will carry out this work? And how might it disrupt your normal operations?

The main thing that determines installation times is the navigation technology used by the robot. Since most AMRs use natural navigation, such as ANT, they are quick and cost-efficient to install with only minimal infrastructure changes required (just adding a few reflective stickers if natural features are lacking).

Outside of initial commissioning, also think further ahead, into the future. Since modern sites regularly evolve, there is a good chance you will want to change the missions your robots perform at some point. Who will handle this reconfiguration work and how?

Will these hours be included in your regular maintenance plan, or will they require an additional paid project by your integrator that you need to budget in? It helps to be clear on such points in advance, to avoid unplanned expenses.

2. How easily can you build out a full AMR fleet?

As your operation evolves and your AMRs start to pay their way, you might want to grow your fleet of robots. Ask how new robots can be added to the existing fleet – is this straightforward or complicated and time-consuming? How is traffic handled, for example at intersections – do you need to program behaviors or is it automatic (and how well does it work)? How are jobs allocated to different robots?

Last but not least, does an AMR’s fleet management system lock your business into only that brand of vehicle? Or can it be used to manage different brands of mobile robots and even AGVs (as is the case with ANT)?

Multi-brand capabilities will vastly expand your fleet-building options while mitigating the risk of being reliant on a single vehicle supplier.

3. How does the robot’s safety system work?

If your autonomous mobile robots will operate around human staff, you want to be sure they do not represent a safety risk. So, learn how their safety systems work.

AMRs running on natural navigation typically have LiDAR-based safety laser scanners installed. These detect any objects that enter a robot’s ‘safety field’ (a pre-defined area around the vehicle) and then either take an alternative route or slow to a stop. What height are these sensors? Are they at both the front and back of the robot? What are the optimal safety field settings for your site?

Do the robots you are considering comply with domestic and international safety regulations such as EN 1525 (“Safety of Industrial Trucks, Driverless Trucks and Their Systems) and ANSI 56.5:2012 (“Safety Standard for Driverless, Automatic Guided Industrial Vehicles and Automated Functions of Manned Industrial Vehicles”)?

You need to know all this information, not only as part of your due diligence but in order to train other staff about how the robots work before they are deployed.

4. What kind of maintenance and support plans are offered?

Autonomous mobile robots driven by natural navigation offer reliable, repeatable accuracy. But only if they are maintained correctly. Make sure a solid hardware maintenance plan is available before you buy.

Carefully check what this maintenance plan includes, as maintenance of your robot hardware is only one piece of the puzzle. You should also ask about making modifications to your AMR’s software project. If you want to alter a robot’s routes and actions, will your AMR integrator handle that? And will this reconfiguration be included in your plan?

Expect to pay approximately 10% of a robot’s sticker price, per year, for maintenance.

5. How many systems are in commercial operation?

If you are planning to invest thousands, or even hundreds of thousands, of dollars in an AMR solution, you want to be sure the system you are purchasing is proven in the real world. In other words, are hundreds of organizations already using this AMR, or will you be one of the first to install it?

Be sure to dig into these numbers with the supplier. And, if possible, try to speak with existing customers in a non-competing industry to hear about their experiences first-hand. There are AMR suppliers on the market with a reputation for performing stunning on-site demos, but which, after the sale, struggle to get commercial operations performing correctly. Avoid becoming one of these cautionary tales.

6. Ensure your processes are automation-ready

A human-based manual process cannot always be automated simply ‘as is’. There is often some adaptation required. Therefore, it is important to analyze, simplify and standardize your mobile transportation processes before slotting AMRs into place.

Bear in mind, mobile robots can only do as they are programmed. They cannot yet improvise on the fly like human operators can (except for avoiding obstacles). By standardizing jobs in advance, you won’t be asking them to.

Put autonomous mobile robots to work

When chosen carefully and installed correctly, AMRs represent a dynamic and efficient way of moving goods and materials around a site. As more companies look to improve their resilience in the face of today’s global challenges, mobile robots could be the difference between remaining competitive and falling behind. The time to begin analyzing your autonomous options is now.