The first ever public drone parcel delivery service in Singapore will begin later this year. BILL READ FRAeS reports on how the new service will operate and its significance.

During the 2018 Singapore Air Show in February, Airbus invited the media to witness the first demonstration of a new parcel-delivery drone service which will begin trial commercial operations later this year. First started in 2016, the new project is the creation of four partners: Airbus - which built the drone, the National University of Singapore (NUS) - where the drone is being tested, the Singapore postal service, Singapore Post - which is the local logistics partner for the trial and the Civil Aviation Authority of Singapore (CAAS) - which is looking at the safety and operation aspects of the service with a view to its wider adoption. The project also has the support of the Singapore government.

Skyways drone

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The Skyways drone is fitted with eight rotors to maximise safety.

The drone being used for the project is the battery-powered Airbus Skyways octo-copter designed to carry parcels inside its chassis. The rotors are fitted to eight arms which extend on all sides of the drone. The drone has no horizontal rotors but flies in a similar way to a helicopter tilting on its axis to move in different directions.

The drones will be powered by rechargeable batteries which will carry enough charge to enable it to return to the service station after each delivery. The range of the drone will depend on the endurance of its batteries. “For the NUS trials, the maximum range between stations is about 1km,” explains Leo Jeoh, Head of Design at Airbus Helicopters Southeast Asia, who is leading the Airbus Skyways project. “However, the system is designed to move distances of up to 3.5km on one leg - thus making a total ‘there and back’ range of 7km. We are still working on developing the battery technology. The lifecycle of a battery is influenced by the amount of charge it uses up in one go. We currently have sufficient battery charge to make multiple journeys but what we plan to do in this first phase is to do one delivery and then go back to the maintenance station and replace the batteries. In the long term, we are considering using an autonomous system which will either recharge the batteries without removing them or install fresh batteries. However, to begin with, it is more practical to have them manually replaced by maintenance operators.”

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The drone can carry a package in a medium-sized Singapore Post delivery box.

The maximum payload that the Skyways drone is designed for is 4kg, measuring 300x330x110mm which is equivalent to a mid-size delivery box used by Singapore Post. It will fly at a cruise speed of 10m/s, although it will have a ‘dash speed’ which will enable it to fly faster if circumstances require. It will also be able to operate in wind speeds of 10kt gusting to 15kt.”

The drones can either be flown manually or autonomously. “When we demonstrated the system at the air show in February, we flew the drone using a remote pilot” says Jeoh. “However, we eventually plan to use an autonomous autopilot system which will use our precision landing system. It’s a redundant autopilot system which can tap into a precision landing system produced by Airbus Defense and Space called DeckFinder. DeckFinder has been developed to allow UAS to land independent from GPS inputs and will enable the drone to land more precisely at a designated landing point. However we won’t start to use this until we are sure that it is fully robust and safe before we subject it to the general public.” 

Parcel stations

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The Skyways system is designed with maximum safety in mind with drones landing on top of the parcel tower, well away from people on the ground.

Six Skyways drones will be used for the pilot project which is based at the campus of the National University of Singapore (NUS). The project has required a significant investment (no figures have been released as to the actual cost) into both the drone design and systems and the ground infrastructure needed to operate it. The ground investment has included the construction of three parcel stations towers at different location around the NUS campus. One of these also includes an adjacent maintenance facility where drones are stored, recharged and serviced.

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Once the drone has landed it is pushed into position over the hatchway by two sets of horizontal sliders.

Each parcel station has a flat roof landing pad on which the drone can land. On the side of the base of the tower are 24 lockers into which packages are posted and delivered. When a package is ready to be delivered, a drone flies to a parcel station and lands on the roof. Two sets of horizontal sliders then push the drone into position above a sliding hatchway. “The sliders have two purposes,” explains Jeoh. “Because the drones are part of a system, we have to consider the overall reliability of the ground equipment. The centreing system is there to ensure that the drone is in the correct position for the safe loading and unloading of the parcel. The second purpose is to keep the drone locked to the landing pad until loading or unloading has been completed and it is ready to fly off.”

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An automated robotic arm inside the parcel station transfers the packages to and from the drone.

Once the drone is in position, the hatchway opens up beneath it and a panel opens in the base of the drone. Inside the tower, an automatic robotic arm collects the parcel from its box and lifts it up through the hatchway. The sorting arm would work on a first-in, first out service, giving priority to the first packages to be delivered. The parcel is then lifted up inside the drone in which it is fully contained. The panel in the tower then closes and the drone lifts off and flies to another tower where the process is repeated in reverse. Once a parcel has been delivered, the recipient receives a message on their mobile phone saying that he or she has a parcel ready for collection.

Aerial corridors

Infographic showing existing aerial corridors over the NUS campus plus plans for future drone operations to ships moored next to the island. (Airbus)

Because the drones will be operating over public area, the Skyways team is taking safety very seriously which is why the only take-off and landing sites are on top of the parcel stations, well away from the public. The drones will also fly along pre-determined ‘aerial corridors’ between parcel stations which pose the least risk to people on the ground below - including flying over covered walkways. “The design of the UAS has to account for three levels of risk mitigation,” explains Jeoh. “The first level is what is called strategic separation provision or strategic flight management. The aerial corridors are designed in such a way that we know what is there and the height is such that we have adequate separation from known obstacles. The only hazards we might encounter are things that come into this air corridor temporarily, such as birds or flying debris such as plastic bags. Then we have the second layer of separation provision which ensures that drones are well separated from each other including any ‘non-collaborative (non Skyways) traffic’. Finally, the third level is the collision-avoidance set-up where the drone would be able to sense something close or getting closer and be able to take a sidestep action or stop to mitigate the risk of a collision.

Even if a collision occurs, the drone is designed to keep flying. “With regard to robustness, we’ve already done structural proof load testing pertaining to scernarios such as bird strike or overstresses have been analysed to not cause a loss of control,” says Jeoh. “This is also part of standard certification of aircraft. We have subjected the rotors to plastic bags in our rotors testbed to see what happens and the good news is that it’s not so catastrophic as we think. It’s not going to shatter a propeller in flight.”

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Skyways drone in flight.

Jeoh explains more about the Skyways design. “It’s important to distinguish the Skyways unmanned systems drone from consumer electronic drones,” he says. “Drones carrying parcels in cities operate in environments where the public may be subjected to aviation risk. Skyways is thus designed more like an aircraft or a helicopter with the same principles of aviation safety. For example, there are eight rotors for multiple redundancy to ensure safety in the event of a rotor failure. The blades are not shrouded but neither are those on a helicopter, as they do not get that close to the public to pose a risk. These rotors and motors are commercial off-the-shelf parts and it is part of our tests to ensure that they are suitable for certification. So far we have found that the control characteristics of a multi-copter are standard with a pitch attitude that is relatively benign. For example, we haven’t seen any issues with the drones remaining stable in a high wind when manoeuvring for take-off or landing.

As for safety, we work out a minimum probability of failure that can be accepted for aircraft certification. From a thrust perspective we only need four rotors working to be able to continue to fly. From a control perspective, we could sustain up to three rotor failures and still be able to fly. The remaining rotors are able to compensate with differential thrusting. So, if one rotor goes, then you reduce the thrust in the opposite rotor - this is standard logic in multi-copters.”

Weather conditions

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Skyways control tower and service centre.

The project team is also conducting tests for different scenarios in which the drones might have to operate, one of which is different weather conditions. “We’ve still got more tests to do but we’ve already started testing in some basic environments,” says Jeoh. “From a design perspective, we’re using the same principles as designing an aircraft which includes flying in rain or windy conditions. We haven’t looked at icy conditions yet but these could be validated as the project moves ahead. We are not expecting weather to be a problem for the pilot project, as the test drones are flying a maximum distance of 1km and will not be spending that long in the air. We should have sufficient advance notice of any change in the weather and can stop flight operations if conditions become hazardous. However, when drones begin to fly over longer distances, this is something that we need to look into, including provision for additional emergency landing areas along the aerial corridors. Like all roads you sometimes need little cul-de-sacs to be able to pull over.”

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Service personnel will replace the batteries after each drone flight.

Testing is also being conducted on the ground systems. “As with aircraft flight certification we now need to do compliance verification where we verify that the system’s design and implementation meets the airworthiness standards of the civil aviation authority,” explains Jeoh. “After that we will need to operate the system across the campus before we open the service, we need to calibrate the operational procedures to make sure that everything is smooth in terms of delivery, in terms of the notification of customers - all these processes need to be tried and tested before we can release this service.”

Traffic management

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NUS tower network. (Airbus)

As for regular drone operations, the project is going to begin small and then build up. “In our initial tests, we’ve going to treat the highways in the sky as one-way roads,” Joeh says. “Our initial routes will be hub and spoke in which the drone goes out from a hub and then comes back which would mean backtracking along the same corridor. In this first phase we will use the drones to do one delivery, after which they will go back and replace the batteries. To start with we will only fly during the day but, if demand is sufficient, flying at night is something we could also consider. It’s technically viable but would need public acceptance. As we get more confident in our navigation system, we can then determine what would be the lane width and whether we could have two-way roads which could also be vertically stacked. As we expand, then this could develop into point-to-point and the drone being able to fly onwards between different stations.

The way the drones will operate is that they will only take-off when their route is clear. “We are looking at this as part of our traffic management study and flight capacity optimisation and do not currently envisage a situation where there is a queue of drones waiting to collect or deliver parcels,” Jeoh remarks. “Where possible we would only launch a drone where there is no such congestion foreseen. Thus, as each drone leaves, you could have the next drone coming in. However, this still needs to be calibrated and tested to see how we can optimise that. If there is congestion at the station we will have to think of ways to manage it accordingly. However, there’s plenty of battery endurance, so having to hover while waiting to get clearance to land really isn’t going to be an issue. Once we get the traffic management sorted, waiting shouldn’t happen.”

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Parcel delivery box from Skyways promotional video. (Airbus)

Using an initial fleet of six drones, the maximum capacity of the system will only be limited by locker capacity “Currently, there are three parcel stations each with 24 lockers, so the maximum capacity of packages in the system would be 72 parcels,” continues Jeoh. “We could potentially speed things up by having the drone bring one parcel to the parcel station and then bring back another parcel. In the initial trials we will include a system which allows the drones to take back parcels which aren’t collected after a certain number of days.”

Economics, safety and public opinion

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The Skyways team with representatives from Airbus, Civil Aviation Authority of Singapore, National University of Singapore and Singapore Post.

Once the provisional trails have been completed, the aim is to begin operating commercial services in the first half of this year. “To begin with, we will just use the system for deliveries to the university,” observes Jeoh. “These will be handled by Singapore Post to deliver anything that’s available on-line. Singapore Post will be taking parcels to a delivery centre from where the parcels will be delivered out to the various parcel stations across the university campus. After this, the next stage of evolution could include university personnel being able to use it to send parcels to destinations outside the campus. However, this might involve some security aspects which would need to be addressed, particularly as the parcels are going to be carried in a flying vehicle. At present there are no general restrictions, to the type of payload, provided that is within the weight and volume limits. The only exception are strongly magnetic items which may affect the operation of the drone."

The operational aspects of the service are being handled by Singapore Post and not all the details have yet been finalised. It is not known yet what the price to users will be for carrying parcels by UAV and whether this will cost more than regular postal services. “At the moment our focus is on testing new technology regarding regulation and requirements that we’ve worked with CAAS to develop,” Jeoh explains. “Once we’ve done this, then such questions as delivery costs can become clearer. We intend to use the technology to provide the logistics in a way that simplifies Singapore Post’s deliveries.”

In addition to testing the technical and safety aspects of the system, another important factor of the initial trials is to gauge public opinion. In the build-up to making the system live, the staff and students at NUS are well aware of the urban delivery project and the project partners will be listening carefully to their opinions once the drones start buzzing over their heads. “The plan is to test the initial version of system for a couple of months,” says Joeh. “If the trials are successful, the partners in the Skyways project will then continue the service for longer. Then by the end of this year we can draw up conclusions about the commercial viability of the tests with regard to urban UAV deliveries. How the service evolves after that will be determined by the specific interests of the users.”

To Singapore and ships

CAAS says that, if the trials are successful and prove that the drones can operate safely and are accepted by the general public, then the drone delivery service may be extended across the rest of Singapore. However, such a move would obviously involve some large scale investment into new infrastructure and operational systems and no hint has been made of the likely timescale. “I am not at liberty to say the level of investment needed into infrastructure to extend the service to cover deliveries across the island,” admits Jeoh. “However, the CAAS and the Singapore government are willing to allow us to expand the service into further areas.”

Another interesting development is that there are also plans to use the system for deliveries between Singapore and ships moored in the straits next to the island. There are also a large number of questions as to how this would be carried out, including whether the ships would need any modifications to enable the drones to take-off and land and how the service would be monitored. “This is one of the projects which we have identified but it is too early to say when we might start trials,” comments Jeoh. “Once we have certificated the system, then we can use that technology for ship-to-shore applications. However, it is likely that the service would be used more for shore-to-ship applications, delivering parcels out to ships at anchorages.”

A new mode of urban transportation

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Airbus is also working on the Vahana all-electric self-piloted VTOL platofmr which made its first flight on 31 January. (Airbus)

The final word from Leo Jeoh. “Unlike other companies developing urban delivery systems, which are looking at how to use UAVs based on consumer electronic parts, Airbus is approaching this from a different angle. We are using a top-down approach, using our expertise as a helicopter manufacturer to design a system which will initially be used to carry parcels and then potentially passengers downstream. The lessons learned from Skyways could be used to develop larger aerial platforms which could carry larger payloads. Skyways is part of Airbus’ overall ambitions for urban air mobility. Over the next decade we hope to also have flying taxis in the form of the Vahana long-distance intercity flying taxi platform, or CityAirbus multi-passenger electric VTOL demonstrator.

We hope for a successful future for Skyways. It will definitely give us a good idea of what is needed to have an autonomous system that flies around a city and we hope for positive commercial viability. Skyways is a big step for Airbus towards having an alternative transportation means in a city.”

Dawn of the drone age?

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A screen shot from Amazon’s promotional video for its PrimeAir parcel delivery drone showing it delivering to a doorstep. (Amazon)

The Skyways project is significant in a number of different ways, as it is the first public launch of a commercial urban drone delivery system. It is also of interest, as it the service does not follow quite the same format as we might have been led to expect. Over the past few years, there has been much media hype over the introduction of autonomous parcel-delivering drones in urban areas, particularly in taking over the role of vans in delivering Internet-purchased goods. In much of the futuristic publicity presented by companies such as Amazon, drones are shown delivering parcels straight to the customer’s door. However, the Skyways system is different as it has, quite sensibly, had to take account of air traffic regulations and public safety factors and envisaged a network of fixed dispatch and delivery points to which the customer has to go to send and collect parcels. However, while this system is undoubtably safer, it also has the drawback that it undermines the key advantage of using drones to deliver parcels in urban areas, in that they can fly directly to a location much faster than surface transport when the roads are congested with traffic. To use the Skyways service, customers need to go to and from the parcel stations, which may take a longer overall time than sending or delivering packages through the conventional postal service. There is also the problem that the Skyways drone can only deliver certain sizes, weights and dimensions of parcels. Anything heavier or larger will again have to go by conventional post.

There is also the question of cost. To set up the infrastructure of local parcel stations required to provide a service to the whole of Singapore will be a significant and expensive undertaking. The service will also have to be able to pay its way, which poses the question of how much extra it will cost to send a parcel by UAV and whether customers will be willing to pay it.

There are also a number of other factors to be considered. While the Skyways system is deliberately designed for maximum safety, it would only take one accident in which a falling drone injured or even killed someone on the ground for the whole concept to be compromised. There may also be concerns about the risk of someone hacking into the drone control systems to misdirect them or the security checks needed to ensure that drones were not used to carry illegal or hazardous items.

Another interesting element is the proposal for using the drone service to include delivery to ships moored off the island. A key advantage of a drone is that it can go whether other modes of transport cannot - such as to remote or inaccessible areas - and this would seem to be an ideal example of what a drone can do that other forms of transport cannot.

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Are take-off and landing towers the future of safe autonomous drone operation?

As this article has described, the trial project has wider aims than just testing not only the platform, the infrastructure and the systems needed to operate it which is to win public acceptance. In the end it will be this latter element that will determine the future direction of the urban delivery drone. It will be interesting to see what happens next, particularly in line with Jeoh’s remarks about how the Skyways project is linking in with Airbus’ broader objectives to develop an alternative urban transport mode. If it is successful, many of the aspects of the Skyways project, particularly with regard to safety, could equally well be used for passenger-carrying air taxi drones. Perhaps, rather than just constructing a network of parcel stations across Singapore, the future might see a network of larger dual-purpose towers across the city that could be used by all sizes of autonomous UAVs, including those that carry passengers?





Bill Read
9 March 2018

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