Transitioning from Conventional AGVs to More Autonomous Alternatives

Through increased levels of automation, not only can the expense of having human operatives conduct laborious tasks be avoided, but numerous other benefits may also be derived - with facilities able to run round the clock, the elimination of costly errors, and greater safety being among them. Furthermore, staff can be upskilled. The mundane aspects of their work can be offloaded onto robots so that they can focus on more important matters where their experience will be better utilised. 

Automatic guided vehicles (AGVs) have now become an integral part of ongoing automation efforts around the world. First emerging more than two decades ago, they are now found in many modern factory and warehousing sites - helping to support the delivery and logistical activities that must be carried out on a daily basis. As the size of the financial investment involved has decreased, the number of units being used has steadily risen. According to a recent report by analyst firm Statista, there should be 270,000 of them in operation by 2025.

Though the popularity of AGVs is definitely growing, it must be acknowledged that these units still have limitations associated with them. Firstly, pre-programmed software defines their operation. That is fine when everything is going as expected, but that will not always be the case. If some sort of issue occurs, they will have no capacity to respond to it.

An AGV will traverse along a predetermined path, not straying from this. Consequently, if something gets in their way, then all it can do is stop - causing frustrating production hold-ups. As they are often quite bulky and heavy, it will often be necessary for them to be kept totally separated from areas where there are people present, so as to prevent potential life-threatening accidents from taking place. This unfortunately restricts their usefulness, particularly in variable-mix variable-lot manufacturing, where production workers need to be continuously provided with different component parts for manual assembly. In such scenarios, adaptability will be a much sought-after attribute.

It should also be mentioned that AGV charging is somewhat problematic. It will normally require a human operative to plug the unit into a dedicated charge point at the end of its shift, so the battery may be recharged. This, once again, leads to the human intervention being required. In addition, it means that each AGV will have a fairly substantial amount of downtime - which could, as a result, curb the productivity of the site where these units are being employed in.

Progression within the automation domain has meant that a new breed of moving robots has begun to be seen, with the prospect of conventional AGVs now being superseded by smarter autonomous mobile robots (AMRs). In simple terms, AMRs have a degree of intelligence - something that is just not found in AGVs. By using data acquired from the numerous different sensors and imaging devices that they feature, these units are able to gain a far better understanding of their surrounding environment. This allows them to adjust to changing situations accordingly.

Though AMR adoption is still at an early stage, there are clear indicators that this technology will become highly prevalent in the years ahead. At the start of the decade, the global AMR market generated a modest annual revenue of $2 billion, but by the end of the decade, it is predicted to be worth far more than that - reaching an annual revenue figure of 12.4 billion. In recent times, several high-profile online retailers have made major investments in AMR technology, implementing mass deployments at their replenishment centres. As well as being of interest in manufacturing and warehousing contexts, there are also likely to be potential openings for AMRs to be used for undertaking delivery services, as well as in smart farming and healthcare, in the near future. 

Unlike AGVs, AMRs are not confined to set paths. By applying their sophisticated navigation algorithms to acquired sensor data, they can calculate the optimal route for completing the work they are responsible for. When they arrive at each of the destinations along their route, they can use their integrated imaging hardware to scan the QR code and thereby find out what items need to be taken there - for replenishing a manufacturing cell, or for shipping out of the warehouse. The AMR can then, using the mapping data that it has access to, determine the location that it needs to go to in order to carry out its newly assigned task. Once this has been accomplished, it will go to the next point on its route and start the subsequent task that it has been given.

AMRs are much better suited to cell production arrangements, being able to use their intelligence to have better control of their movements and have awareness of their surrounding environment. Though AGVs might represent a safety hazard, AMRs are much better at coping with the presence of human operatives. They have the necessary perception to alter their route if it is determined that someone is standing in their way.

On top of all this, in direct contrast to AGVs, AMRs offer the potential for recharging to be done without any staff needing to be involved. By having designated areas where wireless charging can be conducted, AMRs can simply go to the nearest of these areas while not in use and benefit from shorter ‘opportunity charging’ top-ups. This means that they can maintain close to 24/7 operation, only charging when there is a suitable period to do so, and then quickly making themselves available again as soon as their services are required.    

As well as their imaging capabilities, AMRs need to have inertial measurement functionality, so as to facilitate accurate orientation, positioning and navigation. This will mean that GPS data does not have to be relied upon in places where signal reception is going to be difficult. [JP1] Inertial sensors can save time and calculation capacity from imaging and optical sensor processing, by supporting them with dynamic orientation data. Knowing in which direction a camera or lidar is looking at makes navigation, mapping and sensing your surroundings significantly more effective. Precise smooth and fast localization/navigation is typically also benefitting greatly from continuous inertial data and related sensor fusion. It is therefore essential that accelerometers, gyroscopes, and inclinometers are incorporated into AMR system designs. To ensure cost-effectiveness and compactness, MEMS-based devices will usually be specified.

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Figure 2: Murata’s MEMS evaluation units

To support engineering teams with their AMR/AGV development work, Murata offers MEMS evaluation units. Through these, a better understanding of the functional capabilities of its MEMS-based gyroscopes, inclinometers, and multi-axisand accelerometers can be gained. The MEMS sensor device being examined is connected to the evaluation board with a chip carrier PCB or by using an external interface board. An array of different board options, featuring numerous sensor combinations, are available. The sensor’s output data is then displayed on a Java-based graphical user interface (GUI). All of the data acquired is timestamped for later analysis.

Defining a more automated tomorrow

In conclusion, with the ability to rapidly react to situational changes, AMRs support moreflexible operations. They deliver heightened efficiency and do not pose a threat to people’s safety. This is especially important in higher-mix manufacturing set-ups or other places where a versatile approach and closer human interaction will be mandated. That said, there will still be circumstances where AGV use will be applicable, mainly in places that have fully automated low-mix production flows and the transporting of large volumes of materials/components is called for.

By having a source for all the appropriate sensing, battery, power/charging, and wireless connectivity technologies, OEMs will be able to create AMR/AGV units that demonstrate full effectiveness in executing their allotted tasks. Murata is able to provide the constituent components needed in both these cases and is continuing to make further technological innovations here.  

Murata

 [JP1] GPS is basically never available in indoor environments.­