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Review of Jungheinrich PowerCube and Comparison with AutoStore

At Logimat 2022 in Stuttgart, Jungheinrich officially launched its goods-to-person picking system PowerCube, making Jungheinrich – an established brand name for warehouse trucks – the newest member of the ever-growing group of goods-to-person (GtP) picking solution providers. The market launch raised the attention of all competitors, not least because at first sight the system looks like, and is probably best described as, an upside-down AutoStore. While at AutoStore, bots are roaming on top of the storage cube, lifting up the bins needed at the work stations, Jungheinrich have their bots (called shuttles) roam in a dedicated transportation level below the storage cube. Bins needed for picking or decanting are pulled out of the stack of totes from below. And this is the most visible difference between the two systems. There are several other differences between the two systems (see the Comparison Table), some of which are likely to disappear over time, but this one won’t. 

You might wonder why anyone would do this. Why would you build a cube storage system with bots roaming below the cube? What are the advantages? Probably AutoStore, Ocado, Attabotics – they certainly have their reasons to let bots roam on top of the grid. I was wondering about this, too, so I reached out to Jungheinrich and asked for an interview. I was lucky enough to receive a positive response. So, I had about an hour to talk to Jungheinrich’s PowerCube expert and to ask him everything I was curious about. Some of the impressions of my conversation I am summarizing in this text and in the accompanying comparison table. 

Moreover, the fact that AutoStore just announced their 1.000th system is a good reason to compare Jungheinrich PowerCube – the most recent market entrant – with AutoStore, the incumbent and pioneer of cube storage systems.

Systemic Differences Between PowerCube and AutoStore

As pointed out above, the most visible difference between PowerCube and AutoStore is the level the bots are roaming on, and accordingly the direction of access to the bins. This difference is not only the most visible, but it comes with some important implications. 

AutoStore bots place storage bins directly on the floor; the grid is needed for the bots to move around, but it does not hold any weight from the bins. This makes the grid comparatively simple and cheap and allows for a high degree of standardization. Also, it makes the system very sensitive to irregularities on the surface of the floor: a stack of bins standing on a little bump on the floor slab would inevitably become lopsided, endangering process safety. Hence, the booming sales of AutoStore storage systems is feeding countless companies who are in the business of grinding floor slabs. 

Jungheinrich bots (“shuttles” in Jungheinrich terminology) store bins in a rack which accordingly holds the entire load. This requires a more sturdy (and probably more expensive, but that’s my speculation) rack than the lightweight aluminium frames AutoStore use. But it does make the system less dependent on floor slab quality, facilitating deployment in brownfields. 

By lifting bins from the top of the cube, AutoStore bots in the best case need to lift one or only a few bins per retrieval movement. The natural ABC sortation of bins in a multi-deep storage cube makes it more likely that the total amount of weight moved per retrieval movement is minimized.

Retrieving bins from the bottom of a stack comes for free, more or less, for Jungheinrich’s shuttles. PowerCube, too, creates a natural ABC sortation in the cube, and retrieval movements work in the direction of gravity. Storage, however, requires the lifting of several hundred kg (maximum 750 kg) for every single storage movement as the stack of storage bins needs to be lifted up. And while double-deep bin transportation is doable, it is not going to happen that two bins be stored in one movement: since transportation to and from picking as per today is limited to single-deep transportation, every single bin storage movement will require lifting of an entire stack of bins. From an energy conservation standpoint, this does not seem appealing. In my conversation with Jungheinrich, it was argued that all things taken into consideration, the difference in energy consumption between Jungheinrich’s shuttles and AutoStores bots should be tiny, but I guess I could not quite follow the argument. 

Another difference relates to the shape of the storage cube. Since in AutoStore systems, bots roam on top of the grid, the top obviously needs to be level. In PowerCube, this is not the case. The fact that shuttles roam below the storage cube allows a flexible upper height of the system that can make better use of the building height in case the roof is uneven. I am not sure how often this is a relevant feature, however, and I am even more uncertain about the complexity (and thus pain, cost…) induced in the software if you really want to have bin stacks of different height in the same system. Especially with high loads per bin, which is one of the sales propositions of PowerCube, this benefit is unlikely to come into play since total weight per bin stack will be capped by the weight constraint of 750 kg (see below), necessitating lower bin stacks.

Bins: Capacity and Flexibility

One of the selling points of PowerCube is its capacity of 50 kg net load per bin. Net load of AutoStore storage bins is limited to 30 kg. On top of allowing higher load per bin, PowerCube allows much higher stacks of bin: up to 31 bins / 12 m – almost twice as high as AutoStore’s maximum system height of 6.3 m. If you want to make use of the full system height, load per bin needs to be reduced, however: the maximum weight per bin stack is 750 kg. And in practice, building systems of 12 m height will face a very different challenge – see section “Fire Protection, Insurance, and Approval”.

Another notable difference when it comes to storage bins is flexibility of use. AutoStore have been rather restrictive with the use of storage bins. While technically they are conveyable outside the storage cube, they are not of great use. Storage bins are to be used as storage bins inside the cube and nothing else. Manual handling is not foreseen. This is understandable considering the importance flawless storage bins have for the functioning of the system. A bulged bin, for instance, becomes unusable in the cube, and not detecting deformation of the bin would threaten process safety. Accordingly, bins are best left in the cube. This is different for Jungheinrich’s PowerCube: bins can be used outside the storage cube and can even leave the warehouse. Whether this additional flexibility can be considered a benefit depends on the specific use case and process setup. It certainly allows more flexibility in the replenishment process. Decanting, for instance, can take place in the goods-in section of the warehouse or in an overstock area, and full bins can be conveyed to the storage cube, reducing the transportation efforts inside the warehouse.

Currently, Jungheinrich offer one type of storage bin for PowerCube while AutoStore offer bins in three different heights and ESD versions of their bins. 

Comparison of Robots

Transportation Batches

Because Jungheinrich offer a system that can be built about twice as high as AutoStore with up to twice as many bins stacked, it is important to note that all robots can store and retrieve two bins at once. This is quite important since sensitivity towards the slope of the Pareto distribution of orderlines in the system would otherwise become too high. 

The fact that PowerCube shuttles can store and retrieve two bins at once does not necessarily imply that retrieving a particular bin from the grid will be quicker:

  • First of all, double-deep transportation happens only inside the grid. As per today, bots do not transport more than one bin to or from a workstation at once. And even if they did collect two bins before approaching a workstation, this would not make retrieval and transportation time shorter.
  • Secondly, with a steep ABC distribution and a higher probability that target bins are stored at the highest (AutoStore) or lowest (PowerCube) storage level, double-deep retrieval would not make a difference.
  • Thirdly, even when the target bin is stored on the second level, a PowerCube shuttle would have to store away the first bin before being able to fetch the target bin. Here, double-deep retrieval is of no benefit. 

Accordingly, double-deep storage and retrieval will provide a benefit only where lots of digging is required. For bin stacks of comparable height, PowerCube is likely to have an advantage over AutoStore for flat ABC distributions.

Power Management

There are differences in power management, too. While AutoStore’s R5 bots need a break for recharging in dedicated charging stations and thus are unavailable for a certain period of time, Jungheinrich have implemented opportunity charging (or “in-process charging”) for their PowerCube shuttles. Every time a shuttle visits a pick station, it will be charged, rendering charging breaks unnecessary. 

For their B1 bots (“Blackline”), AutoStore have implemented a battery swap system instead. Bots can independently swap their batteries as needed, reducing down time for charging. So, while B1 bots are more expensive than R5 bots, you will need fewer of them.

Use in Different Temperature Regimes

PowerCube can operate in ambient temperature; it is not fit for chilled or deep-freeze environments. With AutoStore, the situation has been the same until very recently. Only in 2022, AutoStore released versions of its storage system that are approved for use in chilled and deep-freeze temperatures. This is one more example of a difference that may be leveled over time. Economically, it is certainly a good decision by Jungheinrich to first focus on one temperature regime with the broadest use case rather than spread their resources thin on technology development for niche applications.

Fire Protection, Insurance, and Approval

The fires in Ocado’s warehouses in Andover (2019) and Erith (2021) did not make getting approval and fire insurance for cube storage warehouses easier. In spite of certification by major fire insurance companies, some AutoStore projects have met resistance by local authorities, and reportedly some projects were even cancelled for that very reason. I would assume that building a cube storage system twice as high doesn’t make getting approval by local fire safety authorities, or getting insurance coverage, any easier. This suspicion was confirmed by Jungheinrich: apparently, this has been a show stopper for some projects that were underway. Certification with fire insurance companies is ongoing, as I learnt in my interview; a bunch of systems are currently being studied as they burn in the lab, so there is hope insurance will be less of an issue soon. Jungheinrich offer an oxygen-reducton variant of PowerCube out of the box. With energy prices reaching painful levels, building oxygen-reduction systems is not an option for most use cases, however, so sprinkling solutions are what is needed to reach acceptable operating cost. 

Project Planning and Execution

Due to the fact that AutoStore have been around for more than 25 years, their storage system has been established in a large number of different countries around the world. Jungheinrich are wise enough to not spread their resources too thin by trying to match this immediately. For the time being, the system is available in the German-speaking countries of Europe (“DACH” region). This makes sense. When your automation experts are based in Germany, you don’t want your first systems to be deployed in Australia or North America. Other companies in the warehouse automation space have made this mistake before, and it has not helped their bottom line. Moreover, Jungheinrich decided to tackle sales and execution of their system themselves while AutoStore rely on 22 licensed distributors around the globe to sell and build AutoStore systems. But again, it took AutoStore 25 years to get there, and getting the first distributor on board certainly was more difficult than getting the 22nd

Due to the very recent market entrance, Jungheinrich currently do not have the same kind of sophisticated planning tools available for PowerCube as AutoStore. While it takes AutoStore sales engineers 15 minutes to sketch a fairly precise 3D layout and to get an estimate about the number of bots needed, the planning process currently takes considerably longer at Jungheinrich. Four weeks for a budget offer for a PowerCube compete with one day at AutoStore. Clearly, this is one of the areas where over time Jungheinrich will be able to catch up. Here, they have to. 

Target System Size and Setups

When a decision has to be made for one out of many possible automated storage and retrieval systems, you would look at the ratio of static capacity requirements (= bin locations needed) to dynamic capacity requirements (= number of storage and retrieval movements per time unit) in order to select the right system. Systems with large storage requirements and comparatively low throughput used to be the domain of traditional miniload stacker cranes; systems with focus on dynamics have been the hometurf of shuttle systems. The domain of AutoStore is overlapping with the domain of miniload stacker cranes. With the release of the Router software and the B1 robot line, economic application has been widened to systems with higher throughput. With the release of Pio, which can be thought of as a kind of economy line, AutoStore target the opposite end of the spectrum: smaller systems with even lower throughput. AutoStore’s attempts to broaden the use case are clearly visible. The largest AutoStore system at the time of this writing has 1.200.000 bin locations with maximum throughput of almost 10.000 bins per hour. The most dynamic AutoStore system (which is a different site) currently does up to 16.000 bins per hour. Whether these systems make sense or different AS/RS technology would have been a better fit is beyond my judgment since I have no details about them. It is obvious, however, that AutoStore have come a long way in terms of system size and dynamics. In November 2022, AutoStore celebrate their 1.000th project.

Jungheinrich currently aren’t there, and they do not want to be there just yet. System boundaries for current PowerCube projects are at about 15.000 storage bins and up to 300 bins per hour throughput. Compared to AutoStore, this does not sound impressive, but again: there are about 25 years of difference in development time between the two systems. The first AutoStore reference (Elotec, Norway) had less than 6.000 bin locations. I applaud Jungheinrich for being wise enough to start small. Of course, these boundaries will shift as feedback and experience from first customer projects become available and technological development of PowerCube progresses. The first projects are just underway.

Conclusion

While Jungheinrich’s PowerCube for obvious reasons makes the impression of a me-too solution, it does come with some interesting features which AutoStore systems do not have. PowerCube expands weight limits per bin and flexibility of the shape of the storage cube with the possibility to stack bins not only higher, but to have stacks of different heights simultaneously in the same system. 

Because PowerCube is a much younger system, it does, of course, lack the maturity the AutoStore system has reached, and it certainly will have to prove itself on the market. The patience AutoStore have had with its system, improving it over the course of a quarter of a century, has been impressive, especially since they only got real traction on the market after about 20 years and were pretty much irrelevant before that. While AutoStore as a company have existed since 1996, its first commercial reference is from 2005. I am convinced this patience is the much more difficult aspect to copy than any of the technological features AutoStore systems possess. In the warehouse automation industry, companies frequently develop new systems (or variants of new systems), try them out on the market and scrap them again if sales success does not come immediately – instead of addressing the reasons why success does not happen and improving the products. There is reason to assume that with their public listing at the Oslo Stock Exchange, AutoStore cannot afford this kind of patience in the future. Jungheinrich, too, are publicly listed, though majority ownership and control still lie with the founding families. It remains to be seen if the popularity of cube storage systems, which I am inclined to believe is solely and entirely owed to AutoStore’s market success in the past five to eight years, will propagate to competing suppliers like Jungheinrich (or Attabotics or Blue Robot Company or Intellistore). 

While Jungheinrich with PowerCube do offer some advantages over AutoStore, it is not evident that a “better” system will enable market success. Instead, as I describe in my recent article “On the Power of Good Enough”, a solution that is “good enough” but proven will often remain dominant. In that sense, AutoStore systems fall into the same category as a Volkswagen Golf. The system is certainly not “perfect”, but it reliably and predictably does what it is supposed to do. Its users do not expect the highest picking rates or the highest flexibility. They expect an improvement over what they have today, typically a manual system, and they expect it to work hassle-free. Which is exactly what AutoStore will do for them. So, in spite of the seemingly ever-expanding cake that is the warehouse automation market, it is tough competition Jungheinrich have chosen for their new GtP system. 

Bonus: This table attempts to summarize the main differences between Jungheinrich PowerCube and AutoStore.