ANKA is the drone we developed for the “METU VTOL 2024” competition. This blog introduces our UAV.

Design

The aluminum parts designed in SOLIDWORKS and used for motor mounting were analyzed in ANSYS by calculating the magnitude and direction of the applied loads. The analysis results confirmed that these parts meet all requirements.

We determined the wing airfoil for the VTOL based on mission requirements using XFLR5. Using this profile, we created the wing design in SOLIDWORKS. We then calculated the dynamic loads that would affect the wing and performed modal analysis using ANSYS.

We decided to 3D print the connection parts for the VTOL. These parts were designed in SOLIDWORKS and analyzed for structural durability using ANSYS, confirming they met all requirements.

Motor Configuration in Design

The VTOL design incorporates five engines: four for vertical lift during takeoff and landing, and one for horizontal thrust during forward flight. During cruising, the four lift engines are deactivated, and the aircraft maintains stable flight using only the single cruise engine.

Tests have demonstrated that each motor generates up to 5.4 kg of thrust in drone mode. We selected 16-inch diameter propellers to maximize thrust efficiency. For optimal VTOL balance, we mounted the motors on carbon fiber tubes attached to the wings. To prevent propeller collisions between the front engine and drone motors, we positioned the motors on the upper part of the frame. Based on previous designs and engineering standards, we set the frame size to 950 mm.

Structural Characteristics and Capabilities

Based on volume calculations that considered the size, weight, and placement of electronic components, we determined the appropriate fuselage dimensions. We carefully positioned the avionics equipment to achieve the optimal center of gravity for the VTOL. The fuselage design prioritizes ease of assembly while maintaining functionality. Using a one-piece production method enhances vertical mode stability by minimizing vibration, bending, and oscillation—advantages that would not be possible with a multi-part assembly.

Electronics

The RFD900+ module on the ground station communicates with its counterpart on the aircraft using the 900 MHz frequency, establishing the primary data link between the ground station and aircraft. Additionally, serial communication between the Pixhawk Cube Orange and the ground station's RFD900+ module enables complete control and data transfer to the airborne system.

The Radiolink R12DS communicates using the S-BUS protocol, allowing the flight control system to receive commands quickly and reliably. Operating at 2.4 GHz, the receiver maintains a seamless connection with the controller during flight, enhancing safety through dependable control signals.

Software

Image Processing

Performance tests have shown that the Pyzbar module delivers enhanced speed and stability. We optimized our code to match the hardware specifications of our companion computer (Orin). The QR code detection system—a critical component of the task—now processes data with high accuracy. These optimizations ensure reliable and efficient performance within our hardware environment.

In our study, we first uploaded the dataset to the Colab platform. We trained a deep neural network model to learn visual features from this dataset, enabling it to recognize and classify objects in the data. We then integrated this trained model with the YOLOv8 algorithm for object detection and classification. This approach combined deep neural networks' feature learning capabilities with YOLOv8's efficient detection framework, resulting in an effective system that balanced accuracy with computational efficiency.

Graphical User Interface

We are developing a web-based Ground Station Interface to better meet mission-specific needs compared to existing open-source solutions. This custom interface allows our operating team to incorporate mission-tailored features while ensuring seamless UAV integration. Being web-based, it can be accessed from any internet-connected device, facilitating remote collaboration. We chose the Bento design system to create an at-a-glance dashboard that enhances operational efficiency during missions.

Mission Mechanism

For Missions of the 2024 METU VTOL Competition, teams were required to design a system capable of carrying and storing a 4 kg payload. We designed a box with internal dimensions of 164 × 84 mm and a depth of 87 mm to accommodate the specified load dimensions. Through structural analysis, we determined that a 3 mm wall thickness would provide adequate strength. The box features four connection points at the bottom that align with the chassis and can be secured with screws before mission start. Due to the lower section's complex geometry and our desire for a single-piece construction, we opted to 3D print the entire mechanism. Mounting the mechanism on the vehicle's upper side not only maintains the vehicle's rigidity during flight but also helps preserve its structural integrity.

The mission mechanism uses two fixed parts to support the payload, preventing direct load transfer to the servo motor. When activated, the servo moves a pipe that carries the payload, causing the holding component to release and deploy the payload. The mechanism's flush design with the body minimizes aerodynamic drag.

Aircraft Specifications

• Length : 1383,8 mm
• Width : 2337,2 mm
• Height : 614,40 mm
• Weight : 7,8 kg
• Payload : 4 kg
• Horizontal Propeller Size : 16 in x 6 in
• Vertical Propeller Size : 16 in x 6 in