Delivering blood and other essential medical products in remote areas can be quite challenging—meaning patients often don’t get the supplies they so desperately need fast enough, if at all. Drivers must deal with rough terrain and gaps in infrastructure, just a few of the issues that can cost precious time.
In Rwanda, for example, it often takes hours for hospitals to pick up blood at a regional center, hours many patients don’t have. That changed for the western part of the country in 2016, when the Government of Rwanda contracted Zipline International, headquartered in San Francisco, to launch the world’s first national drone delivery operation. Zipline established one distribution center with 15 Unmanned Aircraft Systems (UAS) to deliver blood, plasma and platelets to 21 hospitals, and plans to open a second distribution center later this year to cover the eastern side of the country.
The Zipline drones (Zips) can deliver blood directly to remote clinics in approximately 30 minutes or less, flying over washed out roads and unpassable mountains. So far, Zips have transported more than 15,000 units of blood and about a third of those missions have been emergency deliveries where someone’s life was on the line.
When developing a solution for such a critical mission, the team at Zipline knew not just any UAS would do, said Bryan Wade, Zipline’s electrical engineer who leads the development of the aircraft.
“We’re flying in places with low infrastructure so we needed a robust system that could operate in rural settings as well as around buildings and different sources of interference,” Wade said. “It had to be able to operate in the real world, not just under ideal conditions. We knew it would be flying in some of the hottest and coldest places in the world.”
To ensure the Zips could achieve centimetre-level positioning accuracy—which is key when delivering packages at the clinics and when returning to the Zipline Distribution Center—the team opted to go with NovAtel’s OEM719 multi-frequency GNSS receiver with Real-Time Kinematic (RTK) positioning. They knew from their testing that NovAtel offered the best GNSS receivers on the market, so Zipline incorporated the OEM719 into all of the Zips as well as the ground infrastructure at the distribution center.
How the Zips use the OEM719
Zips must achieve centimetre-level accuracy when dropping off packages at the clinics, Wade said. The drones never actually land at a site, but must be able to place the package, which makes its way to the ground via parachute, in a small designated area that’s about the size of two parking spaces. Hospital staff know exactly where to find the package, so they can pick it up and deliver it to the doctor and patient who need it as soon as possible. There really is no room, or time, for error.
No special infrastructure is required for the receivers, Wade said, so there’s no need to install anything at the hospital sites. The RTK and dual-frequency the receiver offers provides the accuracy and speed the Zips need to do their job.
How does the OEM719 help with speed? Typically, it takes time for receivers to lock onto the satellites with centimetre-level accuracy when a UAS is turned on, Wade said. NovAtel’s dual-frequency RTK speeds up this process. When the Zipline team receives a text from a clinic indicating they need blood right away, they can turn on and launch the vehicle within seconds.
“Ultimately, it comes down to getting our product to the customer reliably and quickly. Everything boils down to that,” Wade said. “How fast can we turn on the Zips, have them ready to launch, reliably make it to the customer site, hit that target and then make it home safely. It all comes down to delivering the product safely and efficiently. Being able to quickly turn on the vehicle and then have it ready to launch in seconds is critical for us.”
At the Distribution Center
High-level positioning accuracy is also required to recover the Zips when they return to the distribution center after a delivery, Wade said. An actively controlled line snags the UAS out of the air, latching on to the small tail hook at the back of the drone. The fixed tail hook is only about a centimetre long, making this no easy task. The recovery system has to wait to snap up and catch the UAS as it’s flying by, at the exact right moment in time.
“As the plane is approaching, it is transmitting the position it obtained from the receiver to the ground,” Wade said. “This tells the ground system precisely where the plane is 10 times per second, allowing the system to track the airplane and snag it by the tail hook. This is largely to avoid the wear and tear that happens when you land an airplane by traditional means on the ground.”
The team also has found a few surprising uses for the precise positioning the OEM719 receivers offer, Wade said. The receivers can detect if a vehicle is oriented correctly or if it’s on the right launcher, for example, helping to reduce human error.
“We never thought of using GPS while the vehicle was on the ground, but it turned out to be beneficial,” Wade said. “We can report their position within a few centimetres and make sure the Zip is on the correct launcher and is oriented in the right position. That’s really been helpful.”
NovAtel was on Zipline’s radar from the very beginning, Wade said. The team knew about NovAtel’s strong reputation and that they had developed many proven GPS and GNSS products over the years. They were confident NovAtel could provide the technology they needed to make the Zips successful.
Zipline was able to achieve the centimetre-level accuracy through NovAtel’s RTK system, without ever having to be on the ground at the customer sites. The fast dual-frequency solution was also attractive, making the OEM719 a no-brainer investment for the team.
“NovAtel had a solution for us we could validate rapidly and it worked,” Wade said. “They also offered the full set of technology we needed. They were willing to work with us to find the optimum solution to meet our needs as we scale up.”
Zipline has plans to grow in Rwanda and all over the world, including the United States. With this in mind, Zipline introduced an even more robust Zip in April.
The fixed-wing drone now features a redesigned logistics system that improves launch, autonomous flight and landing capabilities. This reduces the time it takes to get a Zip in the air once an order is received from 10 minutes to one minute which increases the number of flights it can make from 50 to 500 and expanded the radius of each distribution center to serve populations of up to 10 million people.
“Billions of people on Earth lack access to critical medicine,” Zipline CEO Keller Rinaudo said, according to a press release about the updated Zips. “In East Africa, Zipline’s drones bring people the medicine they need, when they need it in a way that reduces waste, cost and inventory while increasing access and saving lives. We’ve been hard at work to improve our technology and are ready to help save lives in America and around the world.”
Precise positioning is critical to this expansion and the work Zipline already does in Rwanda, making it possible to deliver medical supplies to those who might not have access to them otherwise.