Stanford undergraduates learn to make delivery drones

Flying from the other side of Lake Lagunita at Stanford University, a quadcopter approaches a group of students, lands on the ground, deposits a box and zips away. Inside the box is a cupcake.

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This was just one in a series of drone deliveries across the dry lake bed that day with payloads that included a dry erase marker, emergency supplies, a key and a burst of confetti – all projects from students in the engineering course Aerial Robot Design last quarter. In the past, this class, led by David Lentink, assistant professor of mechanical engineering, has had students come up with concepts for delivery drones. For the first time, this year’s class went on to build and test actual quadcopters outfitted with custom delivery mechanisms.

“Most of our students have never designed anything that has to take to the air and fly at all,” said Eric Chang, a graduate student in the Lentink lab who is a teaching assistant for this course. “This is their first step into considering the factors that go into designing an aerial robot.”

Students in this class worked in mixed teams of undergraduate and graduate students. They produced designs for two types of drones – rotor-based and winged – and, through collaboration with the d.school, they applied design thinking to make their delivery projects reliable, realistic and consumer-friendly. Along with offering hands-on experience with drone technologies, Lentink and the teaching assistants hope their course fosters skills in robotics, aerodynamics, user-centered design, and systems engineering that their students can apply to careers beyond drone design.

Drones in the real world

Whether they are bringing you lunch or transporting important papers on deadline, delivery drones would probably need to travel a good distance in order to be of much use. For that reason, it is unlikely that delivery drones will resemble quadcopters.

“One of the first things we learned in this course is you really can’t get much range at all with quadcopters,” said Luke Asperger, a graduate student in mechanical engineering who was part of the cupcake delivery team. “Whereas, if you got that wing, you’ve got a lot of lift. And the actual cruising part of the flight doesn’t take much power, so you can go pretty far.”

For the theoretical part of the class, the students had to design a drone that could take off vertically, like a quadcopter, transition to winged flight and land vertically to perform its delivery. Working with computer simulations, students optimized aspects of their drone, such as wing shape and rotor size, and graduate students created a further aerodynamically optimized wing with airfoil design techniques.

The lab portion of the course focused on testing the delivery mechanism but also required the students to learn how to build, program and fly quadcopter drones. Each team needed one pilot, who was trained with help from the student club, Stanford Unmanned Aerial Vehicle Enthusiasts, Engineers, Entrepreneurs (SUAVE) and all of the students were versed in drone safety. By the end of the course, the teams all had drones that, once in the air, flew autonomously between set GPS waypoints outside.

In the test run, each team mimicked a sample mission. The cupcake team, for example, devised a flight path from a real bakery to campus and programmed those parameters into their code to assure their drone could travel that distance while still delivering their fresh-baked cargo quickly. The lockout prevention team imagined a system where customers would have copies of their keys in a remote repository and request them as needed. They had to maximize their drone’s hover time at the delivery point where the key was lowered by winch to the client, used and returned to the drone.

Iterate and improvise

The unique missions and mechanisms that the students developed in this course meant that failure and redesign were expected and embraced.

For example, the cupcake team thought through designs that involved a trapdoor mechanism, a parachute and a spring-loaded box, which popped open upon landing. They eventually opted for a claw mechanism that released a standard box once the drone landed. When their first claw turned out to be excessively shaky during the test flights, they redesigned and rebuilt it. It was finally working well – until they returned from Thanksgiving break to find a major part of it had mysteriously broken.

“We had to do a lot of improvising,” Asperger said. “We added a lot more glue and tape than we would’ve wanted to. We got it to work and that’s what you saw flying today.”

To help participants surmount these inevitable hurdles, the course includes design thinking sessions, where the students learn how to facilitate rapid ideation. Their design thinking lessons also helped them account for market and consumer needs, which they would have to consider if their drone delivery concepts were implemented outside the classroom.

“We learned a lot about ideation and design thinking in general – coming up with a mission, empathizing with the users, trying to figure out what the real problem is and how to best solve it for the extreme users,” said Alexander Massialas, BS ’17, who was a member of the key delivery team.

From start to finish, the students took part in lessons and experiences that touched on various disciplines, including computer science, business, product design, communication and several kinds of engineering.

“We think of this class as a think tank for coming up with novel delivery ideas, where drones can really take part in improving the delivery experience,” Chang said. “But we teach quite a wide range of skills in this class, so even if our students don’t end up designing drones as a career, they can still apply a lot of these techniques in other fields.”