When we were building the hardware architecture of the new warehouse in Andover, we realised we had developed a world first in radio design.
The new warehouse solution designed for our next generation of CFCs has thrown up lots of interesting technical challenges along the way. One of the first was how to communicate with over 10,000 robots concurrently.
More specifically, how do we get timely information on the locations of thousands of robots so we can efficiently control them? The answer lies in our unending striving for new and novel solutions to technical challenges.
Here is the story of how we taught robots to talk over 4G – and created a number of world firsts in the process.
We started this project by studying the properties of Wi-Fi. The standard Wi-Fi network uses a distributed coordination function which is not a deterministic means of guaranteeing latency. The analogy often used is polite conversation at a dinner party: it is easy to have one single conversation at a table of two, much harder once you get to 12. Now imagine a state banquet; not everyone will have a chance to share their important information. There is provision in the standard for a point coordination function but nothing available on the open market supported this feature.
There is also the issue of scale, as most Wi-Fi access points (APs) can support a maximum of somewhere between 64 and 256 concurrent clients. Consider that we need to communicate with swarms of thousands of robots, talking to each ten times a second and with guaranteed latency. We needed to understand what this meant for the network design as well as how to accommodate it in an already busy spectrum plan.
Through our experience of existing systems, we knew we should enable a maximum of around 80 clients per AP and reduce the cell size to a very small area. This is similar to the approaches taken in high density deployments such as sports stadiums and auditoriums. However, unlike in those areas, the clients would be constantly moving and using the Wi-Fi network as their primary activity, rather than watching the sports game or concert. There is relatively little headroom above the bots, providing a further driver for many small cells.
Roaming would be required between the Wi-Fi APs – this is notoriously unpredictable. The best results we see in the real world are around 300ms, which would impact the command and control of traffic.
Another aspect to consider is that this approach would require complex planning and installation work for each warehouse, which would be expensive and difficult to maintain.
Ultimately, we found that Wi-Fi’s non deterministic performance would hinder our ability to develop an efficient real time control algorithm for the bots. Resolving this problem was therefore critical to the success of the overall project.
We had a few ideas for solutions, but wanted to get a fresh perspective on the problem. Cambridge Consultants with their world class RF (radio frequency) and DSP (digital signal processing) skills were the obvious choice.
They also have the know-how and complete range of equipment onsite to manufacture small batches of the final product; in fact we learned a great deal from them about electronics manufacturing.
The partnership has proven to be very successful because we produced a fully featured prototype within two years (it usually takes three to five). In addition (and maybe quite surprisingly to some), the initial system architecture we defined at the very start of the project remains unchanged.
The system we came up with takes advantage of modern wireless communication principles but has secret ingredients that tailors it to our environment. For example, it works in license-free spectrum so we can deploy it at a moment’s notice.
In fact, it’s the first deployment anywhere in the world to use the unlicensed 4G spectrum for warehouse automation. By making the system private, we were able to improve the performance and simplify overall complexity by minimising handshake and eliminating roaming aspects. The system guarantees a connection ten times a second to each of the 1,000 client hosts per base station – all working within a 150-metre radius.
Like all extremely low-latency, real-time systems, we also needed to include features to provide redundancy. The devices have physical attributes such as dual network and power links and also logical tools to enable failover to hot standby units; this has enabled us to upgrade the base station firmware without impacting its operation. These tools also enable us to automatically recover from network and power outages, which has been invaluable during site commissioning tests.
Through this project, we’ve also bought Precision Time Protocol into the business; one benefit is that it enables very tightly synchronised log capture across multiple machines, which was beneficial during the development of the system.
Building and deploying this system from the drawing board in only three years was impressive in anyone’s book but we haven’t finished yet. By designing this system ourselves, we’re free to alter and add features as we see fit. Soon we’ll be analysing how alternate MAC layers could help improve warehouse efficiency and designing a custom roaming algorithm optimized for our specific application.
This is only one of several wireless projects that are defining new applications for wireless technology – with OSP, we need to expand our capabilities in the RF domain. We’re recruiting!
Right now we’re looking for two team leads: one for traditional Wi-Fi, RFID and Two Way Radio systems and another person to oversee our Internet of Things applications team, which includes this technology. In addition, we’re hiring two wireless engineers for testing and product development.
Because there are many alternative applications for our scalable solution – factories, construction sites, airfields etc – our next task is to create a demonstration system to show off the technology to interested businesses.
Strategically, there are a number of areas we can improve to make the system work even harder, for example: miniaturisation, increased processing power, and beyond. It’s not in our nature to just say job done and stop innovating, and I’m excited to see where we can take the system next.
Adam Green, Principal Wireless Engineer
Adam Green November 24th, 2016
Posted In: Blog
Today Ocado is revealing more details about the 4G-based wireless protocol used to control the robots powering its new warehouses. These highly-automated warehouses will be offered as part of a managed service called the Ocado Smart Platform which enables international partners to build scalable, sustainable and profitable online retail businesses.
The protocol marks the first deployment anywhere in the world to use the unlicensed 4G spectrum for warehouse automation and guarantees a connection ten times per second to each of the 1,000+ robots roaming around the warehouse – all working within a 150 meter radius.
While building a robot can be a relatively straightforward task, creating a swarm of thousands of robots and making sure you can communicate with every single in a tenth of a second is a whole different ball game. We have worked closely with Cambridge Consultants to develop an innovative system that takes advantage of modern wireless communications principles but has secret ingredients that tailor it to our specific environment. Since the protocol works in the license-free spectrum, we can also deploy it at a moment’s notice in any location around the world. – Adam Green, wireless team leader at Ocado
Moreover, the wireless protocol can be repurposed for other IoT applications that mandate reduced communications delay between many devices: vehicle-to-vehicle connectivity for smart cars, air traffic control systems or large scale industrial systems.
For more details, please visit this blog article.
Established in 2000, Ocado is a UK-based company admitted to trading on the London Stock Exchange (OCDO), and is the world’s largest dedicated online grocery retailer, operating its own grocery and general merchandise retail businesses under the Ocado.com and other specialist shop banners. For more information about the Ocado Group, visit www.ocadogroup.com
About Ocado Technology
Ocado Technology is a division of Ocado developing world-class systems and solutions in the areas of robotics and automation, artificial intelligence, big data, cloud, IoT, and more. The fusion between the Ocado retail and Ocado Technology divisions creates a virtuous circle of innovation that leads to disruptive thinking. For more information about Ocado Technology, visit www.ocadotechnology.com
Alex Voica November 24th, 2016
Posted In: Press releases
One of the areas where IoT is set to make a huge impact is the online grocery retail sector. This comes at a time when more consumers are starting to understand the benefits of shopping online.
For example, Ocado has an active customer base that counts over 500,000 users; in addition, we’ve noticed that customers tend to stay loyal to Ocado over time thanks to a combination of great customer service and an easy-to-use shopping platform.
However, we believe there are several areas where IoT is helping us improve efficiency, reduce waste, and enhance the shopping experience for our customers. The two examples mentioned below illustrate some of the projects we’re actively working on and the initial results we’ve achieved thanks to the amazing team of engineers working at Ocado Technology.
The Ocado Smart Platform (OSP) represents the most important breakthrough in online grocery retail. One of the many innovations implemented by the OSP is the use of robots for collecting customers’ groceries; you can find a diagram of how that works below:
To make such a complex system of software and hardware function correctly, we needed a new kind of communications protocol to enable thousands of robots to rapidly communicate over a wireless network. We’ve therefore partnered with Cambridge Consultants to build a wireless system like no other.
This new network is based on the same underlying technology that connects your 4G mobile phone to the internet but operates in a different spectrum that allows thousands of machines to talk to each other at the same time. Each robot integrates a radio chip that connects to a base station capable of handling over 1,000 requests at a time. A typical grocery warehouse can thus use up to 20 base stations to create a small army of connected robots on a mission to ensure that your delivery gets picked in a record time of less than five minutes.
Moreover, since this system uses an unlicensed part of the radio spectrum, it could potentially be deployed for many other IoT applications that require low latency communications between thousands of devices. In addition, it can be deployed quickly too, as there’s no need to submit any form of paperwork related to standards compliance.
We employ a large fleet of vans to deliver orders from Customer Fulfilment Centres (CFCs) to Ocado customers who purchase their groceries online. In order to manage this fleet efficiently, we equipped our delivery vans with a range of IoT sensors logging valuable information such as the vehicle’s location, wheel speed, engine revs, braking, fuel consumption, and cornering speed.
The vans then stream back this data in real time and also in greater granularity when they return to their CFCs. Ocado engineers then feed the data into our routing systems so the routes we drive tomorrow will hopefully be even better than the ones we drove today. We can also direct vans to park at the best possible location for a given time of day and take into account factors such as the current day of the week or school holidays.
At a time when inner city pollution is a growing health concern, reducing fuel consumption is not only a wise business decision but also an easy way to cut back on our carbon footprint. Furthermore, having a fleet of connected vehicles that is constantly exploring every corner of the UK enables us to gather lots of useful mapping information, including potential traffic jams and road closures.
This information could then be shared with other connected cars and help drivers manage their journeys more effectively. An example of such an initiative is the recent partnership between Mobileye, GM, Volkswagen and Nissan to create a set of crowdsourced maps that acts as the digital infrastructure for the self-driving cars of the future.
Alex Voica, Technology Communications Manager
Alex Voica September 22nd, 2016
Posted In: Blog