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  • This episode of Real Engineering is brought to you by Brilliant, a problem solving website

  • that teaches you to think like an engineer.

  • In the past few years there has been a lot of buzz around the possibility of drone delivery

  • services.

  • Most think companies like Amazon will be the first to deploy them in their distribution

  • centres, but few realize the technology is already in use for a far greater purpose in

  • the developing world.

  • More than two billion people across the world lack access to essential medical products,

  • like blood and vaccines, due to poor quality or even non-existent infrastructure.

  • Last month I visited Rwanda with Sam from Wendover Production and Joseph from Real Life

  • Lore.

  • We were all struck by how modern and clean Kigali, the nation's capital, was but just

  • a short drive outside the city the quality of roads deteriorated quickly.

  • The country has been working hard to improve their transportation links over the past 2

  • decades, but of the 14,000 kms of roads in Rwanda, only 2,600 kilometres are paved.

  • The rest consist of uneven dirt roads that become incredibly difficult, if not impossible

  • to navigate during the countries raining season.

  • [1]

  • We got a taste of this while on Safari when our 4x4 got stuck in the mud, forcing us to

  • get out and push, keep in mind we were looking for lions on this trip.

  • Medical supplies, by nature, need to be on hand quickly.

  • If a mother is bleeding out during childbirth, she cannot afford to wait 3 hours for blood

  • to arrive.

  • Leaving people living in remote rural villages in danger.

  • Zipline, the real reason we visited Rwanda, is working to solve this problem with their

  • fleet of autonomous drones.

  • Each capable of carrying 1.6 kilograms of medical supplies, about the weight of a three

  • 500 millilitre blood bags.

  • These amazing little drones have a TONNE of geeky engineering design that was influenced

  • by Zipline's design philosophies.

  • Several unique factors influenced their designs.

  • The first is the speed the plane needs to get into the air.

  • The moment an order comes in, the clock has started and Zipline aims to have the drone

  • in the air in as short a time as possible.

  • This is, after all, an emergency and seconds count.

  • Currently they are averaging just 5 minutes from order to launch.

  • That's the time it takes for an order to arrive in their on-site pharmacy to launch.

  • Getting a plane into the air that quickly is pretty astounding, some would struggle

  • just to get a drone out of its case and flying in that time, and Zipline have come up with

  • some amazing solutions to reduce those seconds.

  • Just like a DJI Drone, Zipline's plane needs a GPS connection in order to fly as they are

  • not piloted, they are autonomous.

  • If you have ever flown a drone you know it can sometimes take a little while for the

  • drone to boot up and make a connection with a GPS satellite.

  • So, to remove that delay, Zipline moved the GPS circuitry from the plane to the battery.

  • This means it's always on and always connected.

  • This innovation alone removed on average 10-15 minutes off the launch time.

  • The battery is one of 4 pieces of the plane that need to be assembled prior to flight.

  • First the order is placed inside the drop hatch of the fuselage, which is then placed

  • on the launcher, the wings are then attached followed by the battery.

  • This modular design makes the plane much easier to handle, allowing staff to easily lift it

  • into place.

  • More importantly, it separates components so if there is a problem found with the wings

  • during the pre-flight check, they are simply swapped out without having to start the entire

  • assembly process over again.

  • Pre-flight checks are often a lengthy process and Zipline have come up with some cool solutions

  • to hasten this step too.

  • Checking the flight surfaces is done with a mobile app that connects to the launcher

  • system.

  • The launch technicians simply point the phones camera at QR codes on each control surface,

  • sending a message to the plane to actuate the control surface.

  • The phone then utilizes a computer vision algorithm to make a pass or fail judgement

  • for each control surface.

  • Once the plane is ready and assembled on the launcher, the next time saving measure kicks

  • into gear.

  • Rather than telling you how this works, I'm just going to show you.

  • -Cut to launch footage.-

  • We spent 2 days at Zipline and this never got old.

  • The rail uses a pulley and an electric motor to quickly and safely get the drone up to

  • speed.

  • Accelerating the plane to its 100 kilometre per hour cruising speed in just 0.3 seconds.

  • It launches the same way every time and reliably clears the obstacles in front of it.

  • Take-off and landing are the most difficult stages of a flight.

  • To avoid having to land at the destination the plane simply drops the supplies in a insulated

  • cardboard box with a simply parachute, which can be thrown away.

  • Meaning the clinics need no infrastructure to sign up as a client of the distribution

  • centre.

  • When the plane does eventually need to land, the procedure to allow it to land with no

  • pilot is even more incredible.

  • Once again, I think it's easier to just show you how it works.

  • Cut to footage - It may be difficult to keep track of everything

  • that happened there, so here is that again in slow motion.

  • There is a small hook at the end of the tail boom, which will grab a wire strung between

  • two actuated arms on either side of the capture system.

  • It's hard to see it in real time, but in slo-motion to can clearly see that the arms

  • actually raise up at the last moment to catch the hook.

  • The plane is communicating its location in 3D space with the radio receivers next to

  • the platform, allowing the wire to stay out of the way until the last moment.

  • Minimising any risk of collision with the wire.

  • The capture system misses about 10% of the time, but the plane is programmed to immediately

  • detect a miss and throttle up it's engines to gain altitude and make another pass.

  • An older design of this system, had a retractable tail hook that caught an actuated wire closer

  • to the ground, which then slowed the plane down enough for it to landed softly on an

  • inflatable pad.

  • This system was fraught with design issues.

  • When it rained the inflatable would pool with water, which was no problem for the water

  • proof plane, but forced the staff to crawl through it and lift a relatively heavy plane.

  • It was neither comfortable or ergonomic.

  • The retractable tail boom needed a motor to control the retraction, which could fail and

  • added weight compared to the simple metal hook attached to the carbon fibre tail boom

  • of the current generation plane.

  • Factoring safety into an autonomous drone network is another unique factor that has

  • shaped Zipline's designs.

  • Zipline works on a philosophy of redundancy of parts in order to ensure safety.

  • It has two of everything.

  • Two motors, when it only uses one during flight.

  • Two of every actuator, and if somehow two of something breaks the plane will automatically

  • deploy a parachute.

  • Allowing it to softly touch back down to earth.

  • This procedure can also be initiated by the control tower if a command from the air space

  • authorities is received.

  • As a result of this focus on safety Zipline has had zero accidents causing injury since

  • they started service in October 2016.

  • The next design factor, which will be common to any aeronautical design.

  • Is the weight of the aircraft and in turn it's range.

  • Zipline uses planes because quadcopters use far more energy to fly, and just can't get

  • the range necessary from batteries and are relatively slow.

  • Map Animation: These planes cruise at 100 km/h with a range

  • of 160 kms, allowing the drone to serve an 80 km zone around this location.

  • The inner skeleton consists nearly entirely of a light weight carbon fibre composites,

  • which is then covered in a light weight foam shell which is easy and cheap to replace if

  • it gets damaged.

  • As a result, the entire fuselage weighs just 6.4 kilograms.

  • The wings weigh 2 kilograms with wing span of 3 metres.

  • The structurally integral wing spar, that is the beam that runs along the length of

  • a wing, is also made from a high strength carbon fibre composite.

  • With the aerodynamic surfaces being formed with high density polystyrene, and 3D printed

  • plastics.

  • The batteries are by far the heaviest part of the vehicle, making up half of the total

  • weight of the aircraft at 10 kilograms.

  • Zipline employed lithium ions batteries with a total capacity of 1.25 kwhs.

  • For comparison, a Nissan Leaf has 24 kWhs and your average Tesla has about 120.

  • As mentioned before, these removable sections aren't just batteries.

  • They contain the GPS circuitry, but also include the data storage that hold the flight data

  • from all the sensors on board.

  • The moment the battery is hooked up to charge at this charging station, the data begins

  • to poor into Zipline's server.

  • For every hour of flight these drones generate 1 gigabyte of data.

  • This for me, is Zipline's greatest asset.

  • These drones don't just face engineering challenges, but regulatory challenges too.

  • Fitting a large autonomous network of drones into the already busy and highly regulated

  • American airspace would be incredibly difficult.

  • Rwanda serves as not just a worthy cause, but a valuable test bed for integrating a

  • network of autonomous drones into a countries air traffic control.

  • Zipline communicates directly with Rwanda's central air traffic control in the Kigali

  • Airport, in the nation's capital.

  • Having this test bed, in my mind, is more valuable than any hardware technology Zipline

  • has developed.

  • Ryan Oksenhorn, one of Ziplines founders, gave us a guided tour when we arrived.

  • He's Zipline's head of software and has worked tirelessly to make Zipline's autonomous

  • drone control system the best in existence.

  • A quick look through patents attributed to Ryan will uncover a slew of designs related

  • to automated drone management systems, like Patent 9997080 “Decentralized air traffic

  • management system for unmanned aerial vehicles”, which describes software solutions to allow

  • multiple UAVs, which have no way of detecting other UAVs in their airspace, to avoid collisions.

  • This testbed and data is going to allow Zipline to continue to churn out designs and concepts

  • to optimize the control of the drone delivery network, and ultimately allow them to expand

  • into new territories with busier airspaces.

  • This month they are expanding within Rwanda opening a second location to serve the east

  • of Rwanda.

  • This could eventually grow into a supply chain, allowing drones to hop between bases, get

  • their battery swapped out in a couple of minutes, and be on their way once again.

  • This technology is useful outside of just developing countries.

  • It could be used in disaster relief scenarios when roads become impassable due to flooding.

  • It also allows supplies to be centralized.

  • Hospitals often have to carry more medical supplies than they need.

  • Keeping stocks of medical supplies with short shelf lives inevitably leads to waste.

  • Incredibly expensive waste that costs the taxpayer money.

  • This is a problem Zipline could potentially reduce by allowing centralization of an emergency

  • supplies that can quickly be dispatched when needed.

  • When quarantines are an issue, these drones could minimize human exposure to contagious

  • diseases, and so help stop the spread of disease.

  • These are both scenarios that Wendover Productions and Real Life Lore explore in their videos

  • released today.

  • We could not have made this trip without the help of Brilliant, so if you would like to

  • see more videos like this please check them out.

  • If you have an interest in this kind of design, I would highly recommend you take this course

  • on classical mechanics, which will form the bedrock of understanding for you to start

  • applying physics, like figuring how much batteries to include for a drone design.

  • This is just one of many courses on Brilliant, with more courses due to released soon on

  • things like automotive engineering and Python Coding.

  • If I have inspired you and you want to educate yourself, then go to brilliant.org/RealEngineering

  • and sign up for free.And the first 73 people that go to that link will get 20% off the

  • annual Premium subscription.

  • As always thanks for watching and thank you to all my Patreon supporters.

  • If you would like to see more from me the links to my instagram, twitter, subreddit

  • and discord server are below.

This episode of Real Engineering is brought to you by Brilliant, a problem solving website

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How Rwanda Built A Drone Delivery Service

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    joey joey に公開 2021 年 04 月 19 日
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