156B 2018 Spring Team03

Project Laputa - A Flying Basestation in Disaster Recovery Scenarios

Raymond Silver, Chengta (Dale) Lei, Charles Knight, Brynn Hall

Sponsored By: Professor Xinyu Zhang, UCSD Electrical and Computer Engineering

Project Overview

Often times in disaster scenarios, city infrastructure is destroyed and with it cellular and internet service. One potential solution to this problem is to use a drone as a temporary flying cellular basestation to provide wireless service to citizens and disaster relief teams. The sustainability of such systems has proven to be a great challenge; existing multi-rotor systems last a maximum of 30 minutes in the air before needing to come down to recharge. The goal of this project is to design a drone that can fly for hours for effective emergency response. The basic idea is to use solar batteries or other assistive facilities to significantly extend the drone’s operational cycle. The specific objectives include:

1. Prototype the drone, based on existing open-source hardware/software.

2. Design the mechanical structures to mount the assistive facilities on the drone

3. Design and implement the control mechanisms to maintain stability

4. Design the firmware and software to control the drone remotely

5. Testing the drone’s sustainability (first in indoor environment, and later in authorized outdoor sites)

Final Design Solution

The final design solution is a single rotor duct drone made out of carbon fiber that is capable of maneuvering using a thrust vectoring system to redirect airflow, allowing the system to pitch, yaw, and roll. A CAD model of the design can be seen above. The main components of the design consist of the carbon fiber frame, the counter-rotating propeller system, and the thrust vectoring control system. The carbon fiber duct lip with a uniquely calibrated curvature on the top allows for additional lift to be generated by the Coanda Effect. The Coanda Effect describes the effect in which high-velocity air moves over the top of the duct creating a low-pressure area, which is met by high pressure underneath the lip. This high-pressure zone generates additional lift for the system. Additionally, the duct diameter is made to be a tight fit around the propellers to minimize efficiency loss through wingtip vortices. The counter-rotating propeller system is what allows the drone to generate approximately 10kg of thrust while restricting unwanted yawing motion. Having two propellers rotating in opposite directions creates equal momentum in opposites direction, thus preventing the duct from rotating about its center axis. Finally, the thrust vectoring system allows the drone to be maneuverable by redirecting airflow, allowing for control of the pitch, yaw, and roll of the drone. The thrust vectoring system is made up of a combination of 4 rudders, each independently controlled by a servo motor. These servos receive input from the microcontroller to stabilize the system and react to inputs from the pilot.

Project Laputa - A Flying Basestation in Disaster Recovery Scenarios

High-Density Foam Prep and Tooling

Carbon Fiber Layup

Final Solution