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BYU UAV Team

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BYU UAV Team Technical Design Paper for AUVSI Student UAS

Competition 2017

Brigham Young University

Abstract The BYU UAV Team has designed and built a complete UAS specifically engineered to complete all mission tasks in the 2017 AUVSI Student UAS Competition. The team consists of volunteer students from the departments of Mechanical, Electrical, and Computer Engineering. This technical design paper describes the overall design process and the final design solutions reached by the development team. The ROSplane autopilot, developed by the BYU MAGICC Lab and enhanced by the BYU UAV Team, is one of many innovative systems resulting from this process. The team conducted extensive testing throughout development to ensure all design decisions yielded a safe system capable of fulfilling mission requirements. Descriptions of past and ongoing tests are highlighted in this paper including individual component tests and full mission trials. Safety procedures and risk mitigation methods are also detailed.

BYU UAV Team

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Table of Contents

ABSTRACT ...................................................................................................................................... - 1 -

1. SYSTEMS ENGINEERING ................................................................................................... - 3 - 1.1 MISSION REQUIREMENT ANALYSIS .............................................................................................. - 3 - 1.2 DESIGN RATIONALE ..................................................................................................................... - 3 - 1.3 PROGRAMMATIC RISKS & MITIGATIONS ..................................................................................... - 4 -

2. SYSTEM DESIGN ................................................................................................................. - 5 - 2.1 AIRCRAFT ..................................................................................................................................... - 5 - 2.2 AUTOPILOT ................................................................................................................................... - 6 - 2.3 OBSTACLE AVOIDANCE ................................................................................................................ - 9 - 2.4 IMAGING SYSTEM ....................................................................................................................... - 10 - 2.5 TARGET DETECTION, CLASSIFICATION, LOCALIZATION ............................................................ - 11 - 2.6 COMMUNICATIONS .................................................................................................................... - 14 - 2.7 AIR DELIVERY ............................................................................................................................ - 14 - 2.8 CYBER SECURITY ....................................................................................................................... - 14 -

3. TEST & EVALUATION PLAN ........................................................................................... - 15 - 3.1 DEVELOPMENTAL TESTING ........................................................................................................ - 15 - 3.2 INDIVIDUAL COMPONENT TESTING ............................................................................................ - 15 - 3.3 MISSION TESTING PLAN ............................................................................................................. - 17 -

4. SAFETY, RISKS, & MITIGATIONS .................................................................................. - 18 - 4.1 DEVELOPMENTAL RISKS & MITIGATIONS.................................................................................. - 19 - 4.2 MISSION RISKS & MITIGATIONS ................................................................................................ - 19 - 4.3 OPERATIONAL RISKS & MITIGATIONS ....................................................................................... - 20 -

5. CONCLUSION ................................................................................................................... - 20 -

REFERENCES ................................................................................................................................ - 20 -

BYU UAV Team

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1. Systems Engineering 1.1 Mission Requirement Analysis After not competing in the AUVSI SUAS competition for 10 years, the 2017 BYU UAV Team was tasked with creating a new platform from the ground up. To complete the competition tasks, sub-teams were formed corresponding to the four main systems that needed to be developed: Airframe, Autopilot, Imaging, and Interoperability. With limited development time as the biggest obstacle, the members of each sub-team defined critical and secondary tasks related to their system. Throughout development, special emphasis was placed on these critical tasks in order to maximize scoring potential during the Mission Demonstration. The tasks and their corresponding level of priority, derived from this analysis, were as follows:

Critical Tasks: Autonomous Flight, Stationary Obstacle Avoidance, Manual Target Detection, Classification, and Localization, and Air Delivery Secondary Tasks: Moving Obstacle Avoidance, Autonomous Target Detection, Classification and Localization

1.2 Design Rationale

Table 1 Rationale system for hardware selection System Options Considered Product Chosen / Rationale Imaging Sony EV7500

Hitatchi DI-SC 120R Sony EV7500

- Small, light-weight - Fast shutter to minimize motion blur - 30x adjustable zoom

On Board Computer

Brix i5 Odroid xu4 Raspberry Pi 2 B

Brix i5 - Operates well with Ubuntu 16.04, the OS on which

ROSplane and peripheral applications are built - i5 processor allows both flight estimation and image

processing to happen onboard - Possesses all necessary USB and Ethernet ports

Data Link Ubiquiti PicoStation 3DR Radio

Ubiquiti PicoStation - Long-range communication capabilities at a high

bandwidth - No need to actively point antenna to maintain

connection with the UAS during flight Autopilot ROSplane/ROSflight

Pixhawk APM Pixhawk PX4

ROSplane/ROSflight - Familiarity with autopilot architecture - High fidelity simulations with Gazebo - Easily modified and manipulated

Airframe MyTwinDream Anaconda Custom Airframe

MyTwinDream - Belly-landing capability - Large cargo volume and weight - Long, efficient flight

BYU UAV Team

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1.2.1 Airframe The first major design decision for the airframe team was whether to use a fixed-wing or multi-rotor aircraft. While multi-rotor aircraft provide a significant advantage in many competition tasks including autonomous landing, waypoint capture, air delivery and geolocation, previous experience with fixed-wing aircraft and research into other systems led to the decision to develop a fixed-wing UAS. A battery-powered aircraft was selected due to its reliability and ease of use. Noting that airframe design only minimally factored into the competition points, purchasing an airframe allowed more time for the active development of other systems. Modifications were made to the purchased airframe, as discussed in Section 2.1. 1.2.2 Autopilot After evaluation of various autopilots, a standard, out-of-the-box autopilot was not found with sufficient functionality to fulfill the design requirements of the UAS. Instead of trying to dig into the undocumented, poorly structured, and unnecessarily complex software implemented on many of these autopilots, ROSplane, an autopilot created by students at BYU, was implemented and improved to fulfill the design requirements. The open-source nature of ROSplane, along with its corresponding firmware, ROSflight, provides an accessible platform for development of new algorithms and addition of functionality to complete competition tasks (Jackson, Ellingson, & McLain, 2016, June). Structured around the Robot Operating System (ROS), ROSplane provides the architecture for easy communication with and straight-forward troubleshooting of the autopilot system. A Gigabyte Brix serves as the onboard computer due to its light weight and large processing power. This processor was found to have sufficient power to run ROSplane and to process images onboard. 1.2.3 Imaging The payload capacity of the airframe limited suitable camera choices. As a result, the search was limited to cameras with adequate resolution and image quality that were within the allocated weight budget for the camera. In addition, the chosen cameras needed to provide clear images from an altitude of at least 100 feet while moving. The cameras chosen are described in Section 2.4. The UAS carries two cameras, each providing different functionalities. The front-facing camera has a wide field of view for locating targets on the first pass through the search area. The second camera helps facilitate image classification with its high resolution and optical zoom. 1.2.4 Interoperability Since TCP throughput scales over time in relation to reliability, an interoperability system that maintains a single connection with the judges server was designed. This was necessary because of the frequency and size requirements of data to be submitted. To send data on a single connection, all valuable intranet data is read by a unique ROS node and transmitted via http. 1.3 Programmatic Risks & Mitigations There are many inherent

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